THE EFFECT OF SOIL CONDITIONER-FERTILIZER INTERACTIONS
ON BIOCHEMICAL AND PHYSICAL PROPERTIES OF
SOME OHIO SOILS
DISSERTATION
Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University
by Milton Bennion Jones, B.S.
******
The Ohio State University 1955
Approved by
Department of Agronomy ACKNOWLEDGEMENT
The author wishes to express his sincere apprecia tion to Dr. W. P. Martin, Chairman of the Department of
Soil Science at the University of Minnesota, under whose direction the greater part of this study was completed, to Drs. G. W. Volk, J. L. Mortensen, and other members of the staff of the Agronomy Department of The Ohio
State University, and to Dr. P. F. Pratt, Assistant
Chemist, Citrus Experiment Station, Riverside,
California, for their assistance and encouragement.
The writer is grateful for the financial assistance provided by the Monsanto Chemical Company through a grant-in-aid agreement with the Ohio Agricultural Experi ment Station.
For her helpfulness and encouragement throughout this study, the author is grateful to his wife.
ii TABLE OP CONTENTS Page
Introduction 1
Review of Literature 2
Factors Affecting the Physical Properties of Soils 2
Cropping Systems 2 Addition of Organic Matter 4 Effects of Some Inorganic Substances 9 Synthetic Polyelectrolytes 10
Effects on Soil Physical Properties 10 Effects on Plant Growth 13 Effects on Microorganisms 15 Effects on Inorganic Nutrient Elements 16 Mechanism of Aggregate Stabilization 19
The Effect of Fertilizers on the Effectiveness of HPAN, VAMA and IBMA in Stabilizing Aggregates and Some Methods Used in Evaluating These Effects 21
Method and Materials 21
Soils 21 Conditioners 21 Fertilizer Materials 23 Methods of Testing the Effectiveness of Conditioners 25
Results and Discussion 27
A Study of the Methods Used in the Evaluation of the Effectiveness of Soil Conditioners 27 The Effect of Fertilizers on the Effectiveness of HPAN, VAMA and IBMA in Stabilizing Aggregates 58
The Effect of HPAN and IBMA on the Chemical Solubility and Uptake of Fertilizers Elements by Plants 52
Methods and Materials 52
iii Laboratory Methods 52 Greenhouse Procedures 52 Field Methods 5^
Results and Discussion 55
The Effect of Conditioners on the Chemical Solubility of Nitrogen, Phosphorus and Potassium 55
The Effect of HPAN and IBMA on Availability of Fertilizer to Plants 60
Greenhouse Tests 60 Field Tests 73
The Effect of Conditioners on Crops Under Field Conditions 77
Methods and Materials 77
Depth Treatments 77 Surface Treatments 79
Results and Discussion 80
The Effect of VAMA on Aggregation of Brookston Clay Loam One Year After Treatment 80 The Effect of HPAN and VAMA on Trumbull Silty Clay Loam 82 Surface Applications for Crust Control 86
Summary 89
Literature Cited 93
Appendix 101
Autobiography 107
iv LIST OF TABLES No. Page
1. Certain chemical properties of the soils used in laboratory, greenhouse and field experiments. 22
2. Total nitrogen, and nitrogen driven off from conditioners by alkali distillation. 24
5. Per cent of water stable aggregates when dry sieved Paulding clay aggregates between 5.0 and 2.0 mm were treated by the pouring method. 28
4. Per cent of water stable aggregates when dry sieved Paulding clay aggregates < 2.0 mm were treated by the pouring method. 28
5. The effect of natural and artificially formed aggregates on the aggregate stabilizing power of 0.1 per cent HPAN using the pouring method. 30
6 . The effect of 17-34-17 and 29-21-10 on the aggregate stabilizing power of HPAN using the pouring method. 33 7. The effect of wetting, drying and handling on aggregation at different conditioner rates. 34
8 . The effect of applying soil conditioners at various rates by different methods on soil aggregate stability. 36
9. The effect of ten fertilizer carriers applied at five rates on the aggregate stabilizing power of HPAN applied at 0.1 per cent by the spray method on Paulding clay. 39 10. Effect of one rate of potassium chloride on the aggregate stabilizing power of HPAN applied at different rates to Paulding clay by the spray method. 40
11. The effect of ten fertilizer carriers applied at five rates on the aggregate stabilizing po wer.' of VAMA applied at the rate of 0.1 per cent by the spray method on Paulding clay. 42
v 12. The effect of ten fertilizer carriers applied at five rates on the aggregate stabilizing power of IBMA applied at 0.05 per cent by the spray method on Paulding clay. 44
13. The effect of five fertilizers on the aggre gate stabilizing power of HPAN, VAMA and IBMA on Brookston clay using the spraying method. 46
14. The effect of different carriers, mixed to give three 13-26-13 fertilizers, on the aggregate stabilizing power of conditioners when three variations of the pouring method of application and three conditioners were used. 48
15. The effect of various ions on the aggregate stabilizing power of HPAN and IBMA using Brookston clay and the pouring method of preparation. 50
16. The effect of HPAN and fertilizer on the chemical extraction of ammonium and nitrate nitrogen, phosphorus and exchangeable potassium when these fertilizer elements are added to Paulding clay with and without HPAN. 56
17. The effect of potassium fertilizers and condi tioners on exchangeable potassium of several Ohio soils. 59
18. The effect of HPAN on yields and percentages of potassium, nitrogen and phosphorus in Sudan grass from first crop. 61
19. The effect of conditioner and potassium fertilizer treatments on yield and composi tion of corn grown on Miami silt loam. 69
20. The effect of conditioner and potassium fert ilizer treatments on yield and composition of corn grown on Clermont silt loam. 70
21. The effect of conditioner and potassium fert ilizer treatments on yield and composition of sudan grass grown on Miami silt loam. 71
vi 22. The effect of conditioner and potassium fertilizer treatments on yield and composi tion of sudan grass on Clermont silt loam. 72
25. The effect of certain conditioner and ferti lizer starter solutions on the growth of Rutgers tomatoes. 74
24. The effect of 10-52-17 fertilizer, HPAN and IBMA, used as starter solution, and IBMA mixed .with the soil on tomato yields. 76
25. The effect of VAMA on aggregation of Brook- ston silty clay loam. Horticulture Farm, Ohio State University, 1951 and 1952. 8l
26. The effect of VAMA on yield of lettuce and corn grown one year after treatment, on Brookston silty clay loam. Horticulture Farm, Ohio State University. 85
2 7 . The effect of HPAN and VAMA on aggregation and potato yields on Trumbull silty clay loam. 84.
28. The effect of surface applications of con ditioners on emergence, height of plants, and yield of tomatoes. 87
vii LIST OF FIGURES
No. Page
1. The effect of different methods of applying soil conditioners on aggregate stability. 37
2. Sudan grass grown on Clermont silt loam. 67
3. Corn grown on Miami silt loam. 68
viii INTRODUCTION
With the advent of synthetic polyelectrolytes which have been used as soil conditioners it has been possible to modify soil structure without adding readily-decompos- able organic matter and plant nutrients to the soil. Condi tioner applications to soil enables one to study the rela tionships between fertility, organic matter, and soil structure in greater detail than has been formerly possible.
Synthetic polyelectrolytes have thus become an important research tool to the agronomist.
In order to make the best use of this tool much more information should be obtained regarding the effect of these polyelectrolytes upon the physical and chemical pro perties of soil. This study was part of a broad investiga tion to determine the effect of soil conditioners on the biochemical and physical properties of some Ohio soils.
The objectives of this study were (a) to study methods of evaluating conditioners, (b) to determine the effect of various fertilizers on the aggregate stabilizing power of several soil conditioners, (c) to determine the effect of conditioners on the availability of some fertilizers, and
(d) to observe the effects of conditioner treatments on seedling emergence, crop growth and soil aggregation in the field.
1 REVIEW OP LITERATURE
Factors Affecting the Physical Properties of Soils
Cropping Systems
Many studies have been carried out to determine what factors affect the structure of the soil. The effects of various crops and cropping systems on the physical properties of soils is an important area re ceiving consideration. Moser (56), in studying the effects of various cropping systems on erodibility and some physical properties of soil, found that Bermuda grass increased organic matter and aggregation. Vetch and lespedeza, when used in a rotation, were less effective than Bermuda, but more effective than corn- cotton rotations not including a legume. Woodruff (80) reported that natural aggregates in virgin soils were much more stable than aggregates from cropped plots.
Baver and Farnsworth(5) noted that sugar beet yields on the heavy clay soils of northwest Ohio have been declining gradually even though farmers have been adding commercial fertilizers. These investigators con cluded that the dominate factor in such yield reduction was a deterioration of structure.
Alderfer and Merkle (1) observed that aggregate stab ility was reduced by a rotation of corn, oats, wheat, and clover over a period of 58 years compared to sod land. A vegetable cropping system including no sod crop, but with cover crops, produced poorer structure than the rotation above.
Rynasiewicz (69) reported that soil structure deter iorated when onions and mangels were grown, and that red top was beneficial to.structure. Corn and buckwheat were less destructive to structure than onions.
Olmstead (60 ), working in Kansas, found that all cropping systems which included continuous small grains, continuous row crops, and rotations including fallow, show ed no significant differences in water-stable aggregation.
All plots showed about an 80 per cent loss of their initial aggregation, when compared to present aggregation of virgin buffalo grass pasture. This author reported that aggrega tion was increased from about 11 per cent in the plow layer to 22 per cent, in five years, by seeding buffalo grass.
Page and Willard (6l) reported that continuous corn grown on Paulding clay decreased productivity rapidly; a corn, oat, alfalfa rotation had little effect on soil pro ductivity; and that productivity was increased by a corn, oat, alfalfa, alfalfa rotation. These investigators noted that physically the continuous corn polots were extremely difficult to till. The plots were difficult to plow and remained harsh and cloddy throughout the season, and these plots drained very slowly as compared to other rotations. Addition of Organic Matter
Along with the observations that cropping practices have a profound effect on the physical properties of soil, it has been noted that additions of organic matter also affect soil structure. Woodruff (80) reported that culti vated soils receiving treatments of manure through 50 years, or soils cropped to a rotation including the regular use of green manure, were in a higher state of aggregation than the untreated plots which were cropped continuously. This observation agrees with the findings of Alderfer (2), who observed that farm manure produced physical improvement whenever used. Alderfer (2) and Rynasiewicz (69 ) noted a significant positive correlation between organic matter content of the soil and aggregation.
Martin (45), in studying the effects of various types of organic substances on structure, concluded that the greater the percentage of readily decomposable constituents the organic matter contained, the greater its effect upon soil aggregation. Adding decomposed organic material in fluence aggregation less than adding fresh organic materials, and the time required for maximum aggregation to occur was greater when the decomposed materials were used as compared to the fresh.
Working with a loessial subsoil practically devoid of organic matter, McCalla (4l) found that water intake was very low even when it was covered with straw to protect the surface from the impact of falling water, and that sawdust thoroughly mixed with the soil had little effect on water intake. Suspensions of humus mixed with the soil formed a water stable structure which absorbed a great deal more water when covered with straw than the untreated soil.
Swaby (75 ) also found that humus improved the physical properties of soil.
In another study, McCalla (40) reported that percola tion rate was increased by organic substances, such as starch and sugars as well as sawdust or lignocellulose, if these substances were in a state of decay.
In an experiment to determine the effect of 1, 2, 4,
6 and 8 ton applications of organic matter, using various crop residues and sucrose, Browning and Milan (8 ) observed that there was a significant increase in aggregation for each unit increase in organic matter; that sucrose was much more effective than other organic matter in the forma tion of aggregates, and that larger sized aggregates were formed from sucrose than from other materials. These authors also found that organic materials which decompse rapidly exert their binding effect much more rapidly than do those materials which decompose more slowly.
The work with organic residues has led to much experi mentation with microorganisms and their products. Cooper, et al. (12) reported that the polysaccharide produced by
Azotobacter contains 90 per cent glucose units and about 3-4 per cent uronic acid residue. Myers and McCalla, (57)
observed a highly significant relationship between bacter
ial numbers and aggregation, the increase in aggregation
was slower than the increase in bacteria.
Martin (43, 44, 45, 46, 47) found that the action of
microorganisms resulted in a marked binding and aggregation
of soil particles, particularly when supplied with sugars
or other easily decomposable materials. Martin and
Anderson (50) reported that molds have the power to form
soil aggregates and that the changes in chemical composition
in substrate organic matter during decomposition brings a-
bout a change in kind of mold that developes. Each mold
differs in its power to aggregate soil particles.
Peele and Beale (63) studied microbial activity and
soil aggregation during the decomposition of organic matter.
The greatest microbial activity, as determined by C02 evolu
tion, occurred during the first 6 days of the decomposition
period. The rate of formation of water stable aggregates
was highest during this time.
Studying the nature and relative effectiveness of some
of the soil aggregating agents resulting from microbial
activity, Martin (46) reported that up to 50 per cent of
the aggregate stabilizing effect of the fungus was brought
about by substances produced by cell material, and the re mainder was due to the binding influence of the fungus mycelium. In contrast with this, about 80 per cent of the aggregate stabilizing effect of the soil bacillus was produced by the products of the cells and 20 per cent by the cells themselves. A hemicellulose-like polysaccharide, synthesized by the soil bacillus was found to be primarily responsible for the marked effect in increasing aggregate stability. The aggregating material was attacked by bacteria and its binding effect was thus temporary in nature.
Investigations of natural and synthetic aggregates, and incubation studies in which fresh and decomposed organic materials were incorporated with soil, were made by Kroth and Page (35). All aggregating agents were found to be uniformly distributed throughout the aggregates.
Polar substances resulting from decomposition of fresh or ganic matter were explained as being the most effective in stabilizing aggregates.in cultivated soils. More resistant humus, fats, waxes, and resins were also found to be effect ive in aggregate stabilization.
Comparing the rate of carbon evolution from uronic units of known polyuronides of plant gums and materials, and bacterial gums to that of apparent uronic units of soil,
Puller (19) furnished further evidence by boiling organic matter in HC1 that the carbon dioxide yielding constituents in the soil are uronic in nature and that they are of micro bial origin.
Geoghegan and Brian (23)* in studing the binding effect of bacterial polysaccharides of the levan and dex-
tran types, reported that the nitrogen content of these compounds is not correlated with aggregating effect or mole cular weight of the compounds. Further work by these same authors on aggregation of soil particles by viscous sub stances other than levans (egg albumin, trypsin, pepsin, pancreation) revealed that while some biological products have a moderate aggregating effect, it does not follow that all viscous substances will improve soil structure.
Studying the influence of mold species and organic matter on aggregation on different soils, Gilmour, et al.
(24) found that inoculated soils, to which no organic matter was added, underwent only a slight to moderate degree of aggregation. When straw or alfalfa was added without in oculation there was little aggregating effect. On the other hand, the addition of these substances in presence of molds decreased the quantity of unbound silt and c3ay.
Rennie, et al. (67 ) observed that the polyaccharide content of numerous samples of two soils correlated well with their respective levels of aggregation.
When soils are under prolonged submergence, Allison
(3) reported that the permeability usually decreased until the soil virtually seals. In sterile soils this reduction is only slight and there is no evidence of purely physical breakdown. The reduction appears to be due to sealing entirely by microbial cells. 9
Effects of Some Inorganic Substances on Aggregation
Many studies have been carried out on the effect of various inorganic substances on aggregation. Lutz (39) concluded from a study of the relation of free iron to aggregation that it serves a dual purpose. The iron in solution functions as a flocculating agent and a cement ing agent. Free iron is an important factor influencing the granulation of semi-lateritic and lateritic soils.
Laws and Page (j54) reported a marked increase in the degree of aggregation as a result of applications of sili cate of soda. Van Bavel (76 ) found that the water stabil ity of the soil was increased by exposing it to fumes of a mixture of two methylchlorosilanes.
Hubbell and Stubblefield (31) applied calcium sulfate, calcium nitrate, calcium oxide, calcium carbonate, ammonium sulfate, sulfuric acid, sulfur, and gypsum to the soil, but found no significant effect on the formation of water stable aggregates, regardless of quantity or kind applied.
Dutt, (16, 17) reported that potassium silicate in creased aggregation and yields. He concluded that high stability of aggregates observed on treated plots was a re sult of the presence of silica in a soluble combination which cemented the soil particles together and became ir reversible on dehydration.
The flocculating action of calcium on the soil colloids has made this cation the object of several studies. McCalla (40) studied the effect of lime, ammonium nitrate, magnesium oxide, and sand and concluded that none of these substances tended to improve structure, but rather had the opposite effect. These findings agree with those of Martin
(44), Myers (57)* and Alderfer (1) who concluded that lime has little or no effect upon aggregation. Browning (9) found however, that lime benefited aggregation, but he attributed this to its influence on biotic forces which in turn increased growth. Lime probably has an indirect effect in that crop growth is usually increased which influences the amount of residue and consequently the amount of or ganic matter added.
Synthetic Polyelectrolytes
Effects on Soil Physical Properties
Sherwood and Engibous (64) in briefly summarizing the history of soil conditioner chemicals, reported that sever al hundred chemical compounds were screened in a research development program designed to find effective synthetic soil structure improving chemicals. Prom these tests some compounds were found which stabilized aggregates to a very high degree when mixed with the soil at concentrations from
.01 to 0.1 per cent (dry weight basis). Hedrick and Mowry
(27) have reported the results of this work. Two of the most effective to be found were hydrolyzed polyacrylonitrile
(HPAN) and modified vinyl acetate maleic acid (VAMA). Later, 11 a copolymer of isobutylene and the half ammonium-half amide salt of maleic acid (IBMA) was found to be very effective.
These workers reported further that treatment of soil with these compounds increased infiltration and percolation of water which reduced the amount of run-off. Aeration in the treated soil was improved as a result of an increase in water-stable aggregates. Numerous workers have consis tently observed an increase in water stable aggregates and increased infiltration as a result of conditioner treatment.
(Weeks, et al. (7 8 ), Allison (4), Quastel (6 5 ), Hagin and
Bodman (25)* Mortensen (55)* Chepil (11), Martin, et al.
(51)* Martin and Aldrich (48).)
Another outstanding characteristic of these polyelec trolyte chemicals is their resistance to microbial decompos ition. Hedrick and Mowry (2 7 ) and Engibous (18) reported that treatments remained effective for more than two and a half years. Fuller and Gairaud (21), working with Arizona soils and sand culture, noted that a small portion of VAMA and a very small portion of the HPAN and IBMA were immediate ly available to attack by soil microflora. In a more quantitative study using Carbon-l4 labeled HPAN and VAMA,
Mortensen and Martin (55) reported that 2.74 per cent of added HPAN and 0.20 per cent of VAMA added to the soil was decomposed and released as carbon dioxide in 130 days.
Studies by Hedrick and Mowry (27) showed that the moisture equivalent of treated soil was increased over un- 12
treated soils, and that the wilting point remained un
changed, thus, the treated soils held more water for plant
growth. The Bouyoucos method of determining moisture equiva
lent which Hedrick and Mowry used was of questionable
accuracy. In subsequent work, Peters, et al. (62), observ
ed that additions of as much as 0.2 per cent VAMA and HPAN
to soils, varying in texture from sandy loam to clay, did
not change moisture equivalents or wilting percentages.
Taylor and Baldridge (75) used sodium carboxymethyl cellu
lose and found no change in the moisture equivalent by its
use.
Increased Stability of the aggregates to water slaking
and greater water infiltration, as a result of soil condi
tioner treatment, is reflected in decreased run-off and ero
sion. Weeks and Colter (78) found that HPAN was approxi
mately as effective as straw mulch for minimizing soil
losses and reducing run off. It was concluded from this
study that satisfactory stabilization of the surface could
be obtained by treatment with HPAN, and that it serves as
a temporary method for controlling erosion until vegetation
can become established.
Chepil (11) noted that VAMA was beneficial in produc
ing good soil tilth and reducing water erosion. On the
other hand, these same conditioner increases the erodibil-
ity due to wind. In a previous study (10), it was found
that a soil must contain an appreciable proportion of water
( stable aggregates 0.84 mm or fine water-dispersible particles 0.002 mm in diameter to resist the force of wind. It was concluded by Chepil that VAMA tends to
increase erodibility of soil by wind by . aggregating some
of the fine, wind resistant, water-dispersible particles.
Another use of soil conditioners has been for the
amelioration of crusting. In a field study, carried on by
DeMent et al. (14), only the top half inch of soil direct
ly over the seed was treated. The chemicals reduced
crusting as compared to check plots.
Effects on Plant Growth
The reports on the effect of conditioners on plant
growth have been many and variable. Martin, et al. (51)
worked with several Ohio soils and noted that not all crops
responded to treatment, but that in many instances yields
were appreciably increased. Corn, oats, and carrots were
most responsive to conditioner treatment in these studies.
In subsequent work by Mortensen and Martin (55)# condition
er treatments also increased corn yields. These same work
ers observed that corn plants growing in conditioner treated
plots were greener, more vigorus, larger, exhibited vgry
little wilting during drouth, and matured earlier. It was
suggested that the conditioner treatment increased the
"physiological availability" of water since it was noted
that the root systems of corn and other crops were larger
in the treated plots. In the second year of this study, 14 conditioner treatments has little effect on oat yield.
Wester (79) > working with vegetable crops, reports
that VAMA incorporated at the rate of 0.1 per cent to a depth of six inches, on an originally structurally poor soil, increased the early yield of broccoli, lettuce, and cabbage, and that HPAN as well as VAMA increased tomato yields under these conditions.
Working on the calcareous soils of Arizona, Puller,
et al. (20) observed that yields of corn, lint cotton, grain sorghum, and sudan grass were significantly higher on polyelectrolyte treated soil than on untreated soil.
These same authors also observed that stands were increased by conditioner treatments. Allison (3) also noted an in
crease in stand on treated saline and saline-alkali soils.
DeMent (14) carried out several experiments on emer gence of tomatoes, corn, soybeans, and turnips. When wea
ther and soil conditions were.right for the formation of crusts, increased stands were noted on conditioner treated soils.
Martin and Jones (49) applied VAMA to several Califor nia soils. Treatment of San Joaqin loam, a poorly aggre gated soil, nearly doubled the growth of avocado seedlings but had little effect in Yolo sandy loam, a well aggregated soil.
In general, the above workers reported no conditioner toxieities. Swanson and Jacobson (74) carried out an experiment using soil conditioners in nutrient solutions.
NaPAN, VAMA and .025 molar sodium chloride produced no deliterous effects on c o m seedlings, but sodium acrylate solutions exhibited toxic effects. Haise, Jensen, and
Alessi (29) observed the effect of soil conditioners on soil structure and yield of sugar beets. VAMA and HPAN show ed an apparent improvement in structure, but each addition al increment of conditioner gave a linear and highly signi ficant decrease in yield. Martin, et al. (51) reported no significant difference in sugar beets as a result of conditioner treatments.
Effect on Microorganisms
Engibous (18), Puller and Gairand (21), Mortensen and
Martin (55)# and DeMent (l4) studied the effect of condi tioners on microbiological activity and measured it by collecting the carbon dioxide evolved from incubated soils.
It was generally concluded by these workers that the condi tioners increased microbial activity, however, there was not complete agreement on all points. Fuller and Gairud
(21) reported that VAMA stimulated biological activities while HPAN and IBMA had little effect under the conditions of their experiment. DeMent (l4) noted that IBMA added at the concentration of 0.1 per cent induced greatest in creases in carbon dioxide evolution on the finer textured soils. He also found that addition of 0.1 per cent rates of conditioners increased the rate of ammonification and 16
and nitrification on all soil tested, but that these pro
cesses were more closely correlated to the texture of the
soils used than to the increase in aggregation obtained from
the use of synthetic soil-aggregating chemicals.
Hely, et al. (50) investigated the nodulation and
growth of lucerne seedlings in a loess soil artificially
aggregated to various levels. When plants were grown close
together in the top soil so that the mass was fairly well
occupied with roots, significant increases as a result of
treatment were obtained, both with regard to yield and
number of nodules. In his work on symbiotic fixation,
DeMent (14) found no differences in alfalfa nodulation re
sulting from conditioner treatment on Miami silt loam. In
general, the treatments caused no difference in nodulation
or yield the first crop, but when new plantings were made
on the undisturbed soil, there were significant increases
as a result of conditioner treatments.
Effect of Conditioners on Inorganic Nutrient Elements
Polyelectrolytes are not fertilizers, although HPAN
may contain varying amounts of nitrogen, depending on how
far the hydrolysis has been carried. IBMA is the ammonium
salt of maleic acid copolymer and thus may contain consid
erable nitrogen available to plants; however, these chemi
cals are added to the soil for the purpose of conditioning
the soil, not as a fertilizer. Nevertheless, various workers in the past several years have noted the effects of these conditioners on mineral salt absorption by plants.
Hedrick and Mowry (27) reported that spectroscopic analysis
of kidney beans, wheat, and radish plants, grown in treated
and untreated soils, indicated that nutrients and trace el
ements were not rendered unavailable in any way by these
treatments. Bould and Tolhurst (6) studied the effect of
HPAN and VAMA on nutrient availability and uptake by plants.
Their results indicated that HPAN had no effect on exchange
able potassium or magnesium, nor did it effect the available
potassium as measured by the Neubauer rye seedling method.
This same test showed that soil available phosphorus was in
creased by HPAN treatment. Another conclusion reached by
these investigators was that HPAN had no effect on the avail
ability of potassium and phosphorus fertilizers. They did
find that VAMA had a significant positive effect on the avail
ability of potassium and phosphorus at one rate of applica
tion.
The work of Engibous (l8) on this subject may be sum marized as follows: No change in available phosphorus and
potassium was noted in Paulding clay as a result of condi
tion treatment: VAMA and HPAN supplied enough calcium and
sodium, respectively, to cause a significant increase in
available calcium and sodium, but this increase was not con
sidered to be of practical importance; conditioner applied
at the rate of 0.15 per cent reduced the exchange capacity
of Paulding clay; VAMA treatments increased phosphorus ab- 18 sorption in corn but not in rye grass. HPAN treatment mark edly increased sodium absorption in rye grass but not in corn. Both conditioners increased nitrogen uptake in rye grass but not by corn.
In a complex factorial split plot experiment with nit rogen, phosphorus, and .potassium fertilizers in combination with HPAN and VAMA, Mortensen (54) observed that, on the average of all fertilizer treatments, nitrogen content of leaf tissue samples and grain was reduced by HPAN treatment, but in the presence of nitrogen fertilizer the percentage nitrogen was increased by the HPAN compared to the nitrogen treatments alone. The percentage phosphorus and potassium was not significantly affected by either conditioner. The high levels of available phosphorus and potassium in Hoyt- ville silty clay are cited as possible reasons for lack of significant differences in accumulation of these elements.
Pouwer (64) studied the effect of conditioner on the availability of potassium sulfate on soils of different texture. A swamp soil with an exchangeable potassium con tent of less than 50 parts per million was raised, by fert ilization, to 180 parts per million without conditioner and
500 parts per million with conditioner. Increases in avail able potassium were not so large when coarser textured soils were used. It was concluded that possible action by condi tioner on potassium fixation might be adverse or favorable, according to soil texture. MacIntyre (42) carried out an experiment to ascertain 19 the effect of HPAN on cation uptake by red clover, millet, red clover, and rye grass, grown in that sequence in pots.
Phosphorus and potassium were added at 80 and 50 pounds per acre respectively. Considering the totals of all four crops, the phosphorus, potassium, and sodium uptake was increased, while the calcium and magnesium decreased as measured by the total amounts of these elements utilized by the plant. It should be remembered, as stated pre viously, that yields were not ..increased significantly by
HPAN treatments.
The Mechanism of Aggregate Stabilization
The mechanism by which aggregates are stabilized is not well understood. Quastel (65), in discussing the in fluence of organic matter on aeration and structure, stat ed that hydrogen bonding is considered a major mechanism whereby polysaccharides are bound to soil particles. Hen dricks (28) concluded in his work on this problem that or ganic cations are held, not only by colomb forces between ions, but also by van der Waals attraction of molecules to the surface.
Ruehrwein and Ward (68) studied the mechanism of ag gregation by both polyanions and polycations. They conclud ed that the latter are adsorbed in the interplanar spacings of the expanding lattice of montmorillonite clay, while the former are not. Both types of polyions are effective sta- billzing agents for flocculated clay, but only the poly cations are considered flocculating agents by these workers. The polymer molecules are long enough to bridge the gap between clay particles, and they are capable of strongly adsorbing on the clay to form anchor points for the bridge. The adsorption process is probably one of ion exchange. THE EFFECT OF FERTILIZERS ON THE EFFECTIVENESS OF HPAN, VAMA AND IBMA IN STABILIZING AGGREGATES AND SOME METHODS USED IN EVALUATING THESE EFFECTS
Methods and Materials
Soils
Paulding clay, Miami silt loam, and Brookston silty
clay were the soils used in these laboratory studies.
These soils were chosen because they represent a range of
texture and structural conditions.
Some chemical properties of the soils used in labora
tory, greenhouse, and field work are listed in Table 1.
The Beckman glass electrode was used to determine pH values
exchangeable potassium by extraction with neutral normal
ammonium acetate, and available phosphorus by the Bray-
Kurtz procedure (7). Organic matter was determined by the
Walkley-Black modification of the chromic acid digestion method (77).
The Brookston and Miami soils were taken from the Univ
ersity Agronomy Farm, the Hoytville soil from the Northwest
Ohio Substation near Hoytville, the Paulding clay from the
farm of Mr. Claude Springer in Paulding County, and the
Clermont soil from the farm of Clyde Braden, Brown County,
Ohio. For laboratory and greenhouse work all soils were passed through a 5.00 millimeter screen before treatment.
Conditioners
Three conditioners were used in these studies. The 21 Table 1. Certain chemical properties of the soils used in laboratory, greenhouse and field experiments.
PH Lime Organic Exchangeable Available Soil type value requirement matter Potassium Phosphorus tons/acre % pounds/acre pound/acre
Brookston clay loam(l8 )* 6.9 0.0 2.9 436 1200 Hoytville clay(54)* 6.6 0.0 5.4 468 380
Miami Silt loam 6.3 i.O 1.6 120 36 Paulding clay(18)* 6.4 0.0 3.7 475 142 Clermont Silt loam 4.9 3.5 1.5 159 44
*Value taken from the literature cited except exchangeable potassium.
ro ro 23 sodium salt of hydrolyzed polyacrylonitryle (HPAN) was applied in solution and as a solid. The solid material was provided in the "pure" form but was diluted with clay in some instances. A mixture of CaCOHjg* a co-polymer of vinyl acetate, and the partial methyl ester of maleic acid
VAMA) was supplied only in the solid state, both 100 per cent active and diluted with clay. This polymer was dis solved in water for some of the laboratory experiments.
Iso butyl maleic acid co-polymer (IBMA) was supplied in both solid and liquid form. No diluted solid formulations of this chemical were used.
Fertilizer Materials
The compounds used as fertilizer materials were chosen primarily on their occurance in fertilizers. These compounds are listed in the various tables in the section on results.
It may be noted that some insoluble compounds were used. In such instances a suspension was mixed and used as if it were a solution. This mixture was shaken well each time an aloquit was taken.
The amounts of fertilizer applied in these tests were chosen to give a solution concentration comparable to that recommended for starter solutions. Sayer (70) recommends that 4 pounds of 13-26-13 be added to 50 gallons of water for tomato settings. One-half pint of this solution per tomato plant was used. Table 2. Total nitrogen, and nitrogen driven off from conditioners by- alkali distillation.
Percent Approximate Per cent N Physical active molecular by alkali Conditioner State material* weight* distillation Total
HPAN Solid 10.0 75,000 0.4 2.4
HPAN Liquid 4.9 2.7 10.0
IBMA Solid 100.0 3.7 8.0 IBMA Liquid 11.6 7.4 10.0
VAMA Solid 100.0 200,000 0.0 0.0
♦Monsanto Chemical Company supplied information with regards to amount of active material in the various formulations that they furnished. 25
Methods of Testing the Effectiveness of Conditioners
Fertilizers and conditioners were mixed in 70 milli liters of solution and added to a 200 gram sample of air dry soil, which had previously passed through a 5*0 mm screen. Both conditioners and fertilizers were used at various rates as specified in each experiment.
Spray Method: The conditioner-fertilizer mixture were poured in a paint spray gun, sprayed intermittently onto the soil sample, and mixed with the hand in order to obtain uniformity in wetting. The soil was then placed in glass tumblers, covered, and allowed to stand overnight in order that the soil crumbs might become wetted throughout. The sample was spread out, air dried, and then passed through a 4.7 millimeter screen. These aggregates that would not pass through a 2.0 millimeter screen when gently sifted were retained for aggregate analysis by a modification of
Yoder?s method (83). Each treatment was conducted in duplicate and each duplicate was divided for aggregate analysis, thus all results are for an average of at least four wet sievings.
Pouring Method: In this method JO milliliter of solu tion containing conditioner and fertilizer was poured on
200 grams of air dry soil which was contained in a tumbler.
After the treatments were made, the tumblers were covered and allowed to stand over night so that the mixture would come to equilibrium, after which the soil was spread out to 2 6 to dry, and prepared for aggregate analysis in the same manner as described in the spray method.
Hedrick Method (28): The manner in which the condi tions are added to the soil in this method is similar to that described in the pouring method. Hedrick used pul verized soil; and after equilibrium had been„attained, crumbs were formed by forcing the wet soil through a 4 millimeter sieve with a spatula. The crumbs were dried for two days at 25° C and at a relative humidity of 40 to
50 per cent and then wet sieved.
In the present study Hedrick's method was modified in that the crumbs were air dried at room temperature and humidity. All three methods were all modified in various ways in testing the effects of fertilizers on conditioner effectiveness in stabilizing aggregates. These modifications, including those listed above are: (a) Conditioner and fertilizer mixed together in solution, (b) fertilizer added to the soil as a dry solid, and conditioner added later in solution, (c) conditioner . added dry and the fertilizer added later in solution, (d) the conditioner added in solution, the soil dried, and the fertilizer added in solu tion, and (e) the fertilizer added in solution, the soil dried and the conditioner added in solution.
Other methods used in this work will be mentioned as they occur in the results and discussion. 27
Results and Discussion
A Study of the Methods Used In the Evaluation of the Effectiveness of Soil Conditioners
In order to determine the effect of fertilizer on the effectiveness of conditioner, three methods were used:
The spray, the pouring and the Hedrick methods. The spray method was used for the first series of tests, and later the pouring method was developed. The Hedrick method was used only for comparative purposes.
It has been proposed by Ruehrwien and Ward (68) that conditioners do not aggregate the soil, but stabilize aggre gates already present, or those formed by tillage operations.
To test this idea, and to find a shorter method than the spray technique a pouring method was developed. It was first necessary to establish whether or not pouring a solu tion of conditioner into the soil would stabilize the structure.
In one test of the effectiveness of the pouring method, dry sieved aggregates of Paulding clay between 5.0 and 2.0 millimeters were treated with VAMA and HPAN. The results of this test are shown in Table 5. The 0.1 per cent VAMA treatment stabilized 90.5 per cent of the aggregates at a size greater than 0.25 millimeters. These values for the
0.1 and 0.05 per cent HPAN treatments were 89.2 and 84.0 per cent. The no conditioner treatment gave a value of 35.4 per cent. This experiment indicated that pouring a solution of conditioner over graded aggregates was effective in 28
Table 5. Per cent of water stable aggregates when dry sieved Paulding clay aggregates between 5.0 and 2.0 mm. were treated by the pouring method.
Size of aggregate Treatment > 2 mm 2.0-0.25 mm 5*0.25 mm Per cent aggregation
Water 6.4 29.0 55.4
0.1# VAMA 79.6 10.9 90.5
0.1# HPAN 77.5 11.7 89.2
0.05# HPAN 58.5 25.7 84.0
Table 4. Per cent of water stable aggregates when dry sieved Paulding clay aggregates <"2.0 mm. were treated by the pouring method.
Size of aggregate Treatment > 2 mm 2.0-0.25 mm ,>0.25 mm Per cent aggregation
Water 0.2 14.1 14.5
0.1# VAMA 18.2 26.7 44.9 29
stabilizing a high percentage of them.
In order to find out if any slaking and rebonding of
aggregates occurred when the conditioner solutions were
poured into the soil, dry. sieved aggregate of less than
2.0 millimeters were treated with a solution of VAMA.
Table 4 shows the results of this test. The 0.1 per cent
VAMA treatment stabilized 44.9 per cent of the aggregates
greater than 0.25 millimeters. Some slaking occurred and
particles thus formed were bonded. This is indicated by the
18.2 per cent of the aggregates greater than 2.0 millimeters.
The control had 0.2 per cent aggregates greater than 2.0 millimeters, and 14.3 greater than 0.25 millimeters.
In order to test the stability of the aggregates form
ed under different conditions, soil that passed through the
2.00 millimeter screen from the above experiment was soak
ed with water and put out to dry, thus forming hard clods.
These were broken and forced through a 5.0 millimeter screen.
The artificial dry aggregates larger than 2.00 millimeters
were treated by the pouring method. This treatment was re
peated on the soil passing through the 2.00 millimeter
screen the second time. Table 5 shows the results. The
natural aggregates gave an aggregation value of 89.2 per
cent, while those formed from mud gave values of 83.9 and
73.3 per cent, showing a decrease each time the soil was
slaked and dried. What this test amounted to was a frac
tionation. In each instance of wetting and drying, the 30
Table 5. The effect of natural and artifically formed aggregates* on the aggregate stabilizing power of 0.1 per cent HPAN using the pouring method.
Size of aggregates Type of aggregate > 2.0 mm 2.0-0.25 mm >0.25 mm
Per cent aggregation • 1. Natural aggrega tion > 2.00 mm 77.5 11.7 89.2 2. Artificial clods * 2.00 mm 76.4 7.5 83.9 3. Artificial clods *2.00 mm 67.8 5.5 73.3
♦Particles between 5 .0 and 2.0 mm were treated in each case. 51 most stable air dry aggregates were held on the 2.0 mm screen and stabilized. That portion of the soil passing through the 2.0 mm screen and slaked again would not be expected to form aggregates as stable as those formed the first time, because the most readily bonding fraction has already been taken off.
The next experiment was carried out to see if the effects of fertilizers on conditioners could be detected by the pouring method. Fertilizers were used that increas ed and decreased aggregation with HPAN in a previous study which is reported in Table 13. These fertilizers were applied in solution with the conditioner for one treatment, and before the conditioner was applied in another. The results are given in Table 6 . HPAN with fertilizer number
3 increased aggregation compared to HPAN alone. Aggrega tion was greater where the heaviest application of fertili zer was used. Aggregation was reduced with HPAN and ferti lizer number 5» compared to HPAN alone. The heavier applica tion of the fertilizer reduced aggregate stability more than the lighter fertilizer rate.
When fertilizer number 3 was added to the soil first, and the conditioner later, the heavy fertilizer application increased aggregate stability as compared to the HPAN alone, but the light application had little effect.
The results of this experiment are in agreement with those obtained using the spray method. It was concluded 32 that the effect of fertilizers on conditioner effective ness in stabilizing aggregates could be detected by means of the pouring method.
With the objective of finding out how much rewetting and a small amount of handling the treated soil would re duce the aggregation, a test was established using HPAN,
VAMA, and IBMA at different rates. The results are reportal in Table 7. In every instance the per cent aggregation was increased by the conditioner treatments, and aggregation also increased as the concentration of the conditioners in creased, except where VAMA was increased from 0.05 to 0.1 per cent and the aggregates were not dried and rewet. It is believed that the reason for this was the higher visco sity of the VAMA solution when applied at the 0.1 per cent rate. A sticky slime accumulated on the surface of these treatments indicating that equal distribution of the VAMA throughout the soil mass was not taking place. This theory would account for the higher aggregation at the 0.05 per cent rate than at the 0.1 per cent rate, using the pouring method.
Where low levels of conditioner were used, handling and wetting, drying the soil somewhat reduced aggregation, but when 0.05 and 0.1 per cent IBMA and 0.1 per cent VAMA were applied no reduction occurred due to this extra handling.
It is believed that mechanical breakdown of the crumbs 33
Table 6 . The effect of 17-24-17 and 29-21-10 on the aggregate stabilizing power of HPAN using the pouring method.
Aggregation Treatment Particle-size No. Fertilizer Rate/200 gms. soil .>0.25 mm
0.1$ HPAN
3. 17-34-17 0.4 67.7 0.6 76.0
5 . 29-21-10 0.4 54.1 0.6 45.4 6 . none 61.0
No Conditioner
5 . 29-21-10 0.4 16.6 0.6 17.7 Fertilizer added to the soil in solution. After the soil dried, HPAN was added at the 0 .1$ level.
3. 17-34-17 0.4 71.4 0.6 79.3 6 . none 72.6 34
Table 7. The effect of wetting, drying and handling on aggregation at different conditioner rates.
Conditioner Soil Treatment 1* Soil Treatment 2** Treatment Particle sizes > . 2 5 mm ^.25 mm
0.1 $ HPAN 61.0 58.4 0.05$ HPAN 56.7 53.2 0.25$ HPAN 49.0 37.0 0.01$ HPAN 29.1
0.1$ VAMA 85.3 84.4 0.05$ VAMA 86.1 85.8 0.025$ VAMA 78.9 70.0 0.01$ VAMA 61.9 47.9
0.1$ IBMA 90.9 95.6 0.05$ IBMA 89.1 89.5 0.025$ IBMA 84.1 77.4 0.01$ IBMA 67*9 55.0
Control 17.7
#The soil was treated by the pouring method, dried, and aggregation was determined in the usual way. **The soil was treated by the pouring method, spread out to dry, returned to the tumblers, rewet, and dried. This was done in order to determine the effect of handling and wetting and drying on the aggregate stability... Aggregation was then determined in the manner described. 35 is responsible for the reduction in aggregation. Laws (36) found that grinding aggregates stabilized by VAMA completely destroyed the effects of the conditioner as a stabilizing agent. After dehydration, the conditioner did not rehy drate to stabilize the structure a second time. Hedrick and Mowry (27) made the same observation as Laws, but the former authors found that when sufficient ammonium hy droxide was added to raise the pH to 1 0 . in remoisten ing the pulverized soil, this soil reformed water stable crumbs. A similar reactivation was accomplished by use of sodium hydroxide or by compounds providing phosphate ions.
In order to compare the methods of testing condition ers an experiment was established using three soils and three conditioners applied by pouring, spraying, and Hed rick's methods. Monsanto Chemical Company's HPAN, General
Tire Company's HPAN, and IBMA were applied to Paulding,
Miami, and Brookston soils at different rates. The results of this experiment are summarized in Table 8 . The values gi ven represent the treatment means for all soils and condi tioners. It is apparent from the data that the Hedrick and spray methods give a greater gange in values, than does the pouring method as the conditioner rate varies from the untreated soil to the 0.1 per cent treatments. See Figure
1. However, the error mean square of the former treatment is larger than the latter. Bartlett's test of homogeneity of the error mean squares given in the appendix (Table I) 36
Table 8 . The effect of applying soil conditioners at various rates by different methods on soil aggregate stability.
Amount of Methods Conditioner Pouring Spraying Hedrick's 1°______^...Wa t e r. stable aggregates ( particles ^.25 mm) 0.0 39 21 18
0.01 62 47 38
0.02 75 75 56
0.05 80 88 75 0.1 87 94 84
L.S.D.(0.05) 4.5 8.5 9.7 Figure 1. The effect of different methods of applying of methods different of effect The 1. Figure vn CM Per cent of water stable aggregates O 20 Grams of conditioner added/100 grams of soil of grams added/100 conditioner of Grams olcniinr o grgt stability. onaggregate conditioners soil Spraying Method Spraying L.S.D. (0.05 level) (0.05 L.S.D. Pouring Method Pouring Hedrick Method Hedrick
37 indicates that there is a significant difference between
the error mean squares of the treatments. It is believed
that this lower value of the error means square in the
pouring method is a result of the simplicity of this
method. When either the Hedrick or spray method is used,
aggregate stability is somewhat dependent on the technique
used, since the aggregates are formed by mechanical mix
ing. By contrast in the pouring method, the conditioner
is poured onto the soil and there is no mechanical mixing.
This feature also accounts for the smaller range in aggre
gation with a change in concentration of the conditioner
when the pouring method is used.
The Effect of Fertilizers on the Effectiveness of HPAN, VAMA and IBMA in Stabilizing Aggregates
The spray method was used for the first series of
fertilizer compatability tests, the results of which are
found in Tables 9 through 12. The data in Table 9 shows
the effect of some fertilizers, applied at different rates,
on the aggregate stabilizing power of HPAN.
Potassium chloride and ammonium nitrate consistently
reduced the level of aggregation. Potassium nitrate re duced aggregation to 79 per cent when applied at the heaviest rate, and increased it to 9^ per cent when applied
at the lowest rate. Monopotassium phosphate increased aggre gate stability at every rate. The effects of the other com pounds on HPAN effectiveness used in this test is not clear. Table 9. The effect of ten fertilizer carriers applied at five rates on the aggregate stabilizing power of HPAN applied at 0.1 per cent by the spray method on Paulding clay.
Amount of Fertilizer Treatments Fertilizer KC1 KNOj NH4NO2 NaNO-j Urea KHgPO^ Ca(H2P04 ) (nh4 )2so4 khso4 Na2HP04 gms/200 gms of soil
Per cent Aggregation (Particles *0.25 mm)
.02 65 94 80 95 90 91 89 91 88 84
.08 60 92 76 89 90 9i 87 85 87 -
.14 54 88 75 87 88 95 88 84 85 81
.20 64 87 66 85 - 94 89 87 84 92
.50 58 79 57 81 - 91 85 82 — 90
0.1 per cent HPAN with no fertilizer mixed gave an aggregation value of 86 per cent.
VjO vo 4o
Table 10. The effect of one rate of potassium chloride on HPAN applied at different rates to •Paulding clay by the spray method.
Rate of ______Treatments______Application HPAN HPAN plus Ratio ^______0.2 gm. KCl/200 gms. soil______
Per cent aggregation (particles .>.25 mm.) 0.0 21 21 1.0
0.01 42 56 1.17
0.025 58 51 1.87
0.05 75 47 1.55
0.1 86 64 1.54 An important aspect of this study is the variation of aggregation with different rates of fertilizer application.
It was generally noted that those compounds which reduced aggregation at a low rate of application reduced it more as the rate of fertilization increased. Potassium chlor ide is an exception to this general observation. It should be noted in Table 9 that aggregate stability is not reduced by each additional increment of potassium chloride. The concentration of the conditioner may also be important in this respect. Table 10 shows the effect of a constant rate of potassium chloride to the effective ness of HPAN when the latter is applied at different rates.
When HPAN is applied alone the aggregate stability drops off with each decrease in the amount of conditioner applied, but when potassium chloride was applied with the HPAN, the decrease in aggregation was not continuous.
Table 11 shows the aggregates stabilized by 0.1 per cent VAMA as affected by different fertilizer rates. The fertilizers had less effect on the VAMA than they did on
HPAN under the conditions of this experiment. The lowest aggregation value was produced by the heaviest application of potassium nitrate. Some very high values were given by monopotassium phosphate at all treatment levels, and by ammonium nitrate, where lighter applications were used.
Table 12 shows the per cent of water stable aggrega tes of Paulding when treated with 0.05 per cent IBMA, as Table 11. The effect of ten fertilizer carriers applied at five rates on the aggregate stabilizing power of VAMA applied at the rate of 0.1 per cent by the spray method on Paulding clay.
Amount of Fertilizer Fertilizer Treatments gms/200 gms KC1 KNO-j NH4NO2 NaNO-5 Urea KH2P04 Ca(H2P04 ) (NH4 )S04 KHSO4 Na2P04 of soil
Per cent aggregation (particles>0.25 mm)
.02 94 94 99 92 95 98 96 96 95 96
.08 96 95 99 94 94 99 97 97 95 97
.14 96 91 97 94 94 99 95 97 96 96
.20 95 90 95 95 99 94 95 94 96
.50 95 86 95 94 96 99 96 95 98 97
0.1 per cent VAMA with no fertilizer gave an aggregation value of 94 per cent. affected by various fertilizers. The high level of 98 per cent water stable aggregates was noted when no fertili zer was added. Potassium chloride, potassium nitrate, ammonium nitrate and potassium sulfate reduced aggregation at the high rate of application. These compounds did not have much effect at the lower rates of application. Mono potassium phosphate consistently gave the highest aggrega tion values.
One important point on technique was brought out by these experiments. It may be noted in Figure 1 that there was relatively little change in aggregation where the con centration of conditioners was increased from 0.05 to 0.1 per cent. Using the spray method, the 0.1 per cent con centration stabilized about 9^ per cent of the aggregates.
Conditioner at the 0.05 Per cent concentration stabilized about 88 per cent of the aggregates. It can be seen that a fertilizer which reduced the effectiveness of condition ers as much as 50 per cent, would not produce much change if the conditioner was added at the rate of 0.1 per cent.
This may be a reason that the fertilizer generally has less influence on the VAMA and IBMA than on the HPAN. It would be expected that if all three conditioners were applied at the same rate, the most effective conditioners would be least effected by the fertilizers. This inference is sub stantiated by the data.
The effect of a group of mixed fertilizers (supplied by Table 12. The effect of ten fertilizer carriers applied at five rates on the aggregate stabilizing power of IBMA applied at 0.05 per cent by the spray method on Paulding clay.
Amount of Fertilizer Fertilizer Treatments CQ 0
gms/gOO gms KC1 KNO^ NH4NO2 NaNO-j Urea KH2PO4 Ca(H2PC>4 ) *w Na2HP04
Jr KHSO4 of soil ro Per cent aggregation (particles-^ .25 mm) .02 93 99 96 95 95 99 96 96 96 94
.08 90 97 95 97 95 99 96 94 95 95
.14 89 94 92 96 94 99 93 92 96
.20 88 91 90 95 98 97 95 81 99
.50 79 89 84 91 98 98 93 73
0.05 per cent IBMA with no fertilizer gave an aggregation value of 98 per cent. Monsanto Chemical Company) on conditioner was next deter mined by the spray method. The treatments and results are compiled in Table 13. The fertilizers were all water solu ble and of the type that could easily be used in starter solution mixtures, and each fertilizer was supplied with and without a wetting agent. Fertilizer treatment number five (29-21-10) reduced the effectiveness of HPAN most at both application rates with the heavies application re ducing aggregation most. The other fertilizers were not so definite in their effect. Treatment number three (17-3^-
1 7 ) produced the most consistant increase in aggregation when mixed with HPAN. With VAMA as the conditioner, all of the fertilizer treatments increased aggregation, ex cept treatment number five (29-21-10). The IBMA condi tioner was affected most by fertilizer number five which reduced aggregation. Other fertilizers had little con sistant effect on IBMA under the conditions of this ex periment.
Fertilizer which consistantly reduced aggregate stability was composed of di- and mono-basic ammonium phosphate, urea and potassium nitrate. The fertilizer which consistantly gave highest levels of aggregate stabi lity when mixed with conditioner, was composed of urea, and potassium and sodium phosphate.
The next experiment was established to see if a fertilizer starter solution could be made that would affect the conditioner as one would predict from the results of Table 13. The effect of 5 fertilizer mixtures on the aggregate stabilizing power of HPAN, VAMA and IBMA on Brookston clay using the spraying method.
Conditioner treatments in per cent and amount of fertilizer added in gm./200 gms. HPAN HPAN VAMA VAMA IBMA IBMA 0 .1$ 0 .1$ 0 .1$ 0.05$ 0 .03$ 0 .02$ Treatment Fertilizer 0.6 g. 0.4 g. 0.6 g. 0.4 g. 0.6 g. 0.4 g. Number* Analysis fert. fert. fert. fert. fert. fert.
Per cent aggregation (particles->0.25 mm)
1 . 23-23-23 89 90 99 90 97 77 WA** + 23-23-23 93 88 99 87 87 83
2 . 17-36-18 83 90 98 89 100 77 WA + 17-36-18 90 92 96 91 98 81
3. 17-34-17 91 92 100 93 96 85 WA -fa 17-34-17 91 92 97 92 93 86 4. 26-21-14 85 93 98 91 100 77 WA + 26-21-14 83 86 99 89 97 76
5. 29-21-10 76 80 93 82 93 70 WA + 19-21-10 78 80 95 85 93 72 6 . No fertilizer added 86 86 94 86 98 87
*The carriers used to make up the various fertilizers are as follows: 1. Urea, KH2P04 . 2. Urea, (NH4 )2HP04 , KH§P04. 3. Urea, K4P207 ,Na 2H2P07 . 4. Urea, KNO3 , N a ^ O - ^ , Na2H2P207 . 5 . NH4H2POh, (NH4 )2HP04Urea, , KNO,. ' **WA signifies that fertilizer contained a wetting agent. 47 previous tests.
A water soluble fertilizer with the analysis
15-26-13 has been used as a starter solution in the field
at the rate of 3 pounds per 50 gallons of water, and as
a side dressing at 25 pounds per 50 gallons of water.
Using these rates, three different fertilizers were mixed
equivalent to 13-26-13. On the basis of previous tests
fertilizer carriers were chosen which were known to in
fluence the effectiveness of the conditioners in stabiliz
ing aggregates. . The results are given in Table 14.
Fertilizer A made up of ammonium nitrate, ammonium phosphate and potassium chloride reduced the aggregate
stabilizing power of HPAN when the two were added together,
and also when the fertilizer was added first. Little difference is noted where the conditioner is added first.
The light application of fertilizer B (ammonium sulfate,
ammonium phosphate, and potassium nitrate) reduced aggre gation, but the heavy application had little effect. When
the fertilizer was applied first it affected the condition
er very little.
Fertilizer C (urea, sodium phosphate and potassium phosphate) increased aggregation when mixed with HPAN. The heavy rate increasing it more than the light. When the fertilizer was added to the soil first it also increased aggregation. The fertilizer had little effect when the conditioner was added first. 48
Table 14. The effect of different carriers, mixed to give three 13-26-15 fertilizers, on the aggregate stabilizing power of conditioners using three pouring methods of application and three ■______conditioners.______Rate Applied per Carriers used 200 gms, of Soil Method of treatment* ______( g m . ) ______1 2_____ 5 Per cent aggregation (>0.25 mm) 0.1% HPAN A. NH^NOg, NH^HgPO^ .64 44.... 65 60 3.69 54 62 59
B. (NHhUSO,,; NMpPOi, .55 48 70 56 and KNO^ 4.50 62 74 61
C. Urea, NaHPOh .55 68 85 59 and K2HP04 5.60 76 86 60 Control 61 72.6 58 0.05$ VAMA A. NH4NO-Z, NHhH2P04 .64 85 85 75 and KC1
B. (NHiiJoSOj,, NELHpPCk .55 78 82 76 and KNO-j H H
C. Urea, NaHPOh .55 85 84 87 and K2HPO4 Control 86 84 0.025% IBMA A. NH^NOg, NH4H2P04 .64 68 70 74
B. (NH4)gS04, NH4H2P04 .55 74 72 78
C . Urea, NaHP04 •55 70 67 78 and K2HP04 Control 84 77 *Methods-1. Conditioner and fertilizer were added together in solution. 2. The fertilizer was added to the soil in solution alone. The soil was then dried, and the condi tioner was added in solution by pouring. 5. The conditioner was added first in solution, the soil was dried and the fertilizer was added in solution. 49 VAMA, when mixed with the fertilizer, was affected
very little by A and C, but B reduced aggregation. The oth
er methods of adding the conditioner and fertilizer had
little influence on the conditioner.
All of the fertilizer treatments reduced aggregation when they were added with IBMA, but when fertilizers and
this conditioner were added separately, little effect was
noted. In general the maximum effect of a fertilizer on
the aggregate stabilizing power of a conditioner was
attained when the two were added to the soil in solution
together. Lesser effects, of the fertilizer were noted when
dry fertilizer was added to the soil followed by the addi
tion of the conditioner in solution. No effect of the
fertilizer on the conditioner was observed when the condi
tioner was added to the soil before the fertilizer.
Table 15 gives the per cent water stable aggregates
greater than 0.25 millimeters, using 0.025 per cent HPAN on
Brookston clay, when they were mixed with one millequivalent
of the different compounds listed, per 100 grams of soil.
The aggregate stabilizing power of HPAN was reduced most by magnesium nitrate, magnesium chloride, calcium
nitrate, and calcium chloride, and was increased most by potassium, sodium, and magnesium hydroxide, and potassium phosphate. Considering the anion treatment means, the nitrate and chloride ions reduced aggregate stability most while the hydroxide and phosphate ions increased it most. Table 15. The effect of various ions on the aggregate stabilizing power of HPAN using Brookston clay and the pouring method of preparation.
Cations Anions (l me/100 gms. of soil) _ (1 me/100 gms. soil) Cl~ NO^- H2PO4- S0^~ OH7” Mean of Cation
Per cent aggregation (particles > 0 . 2 5 mm)
0.025^ HPAN
Na+ 64.2 55.2 64.8 66.0 71.5 64.5
K+ 58.5 59.2 71.5 6o.4 75.0 64.9
NH+ 55.6 61.5 55.4 51.0 62.0 57.1
Ca++ 42.5 40.9 54.0* 55.4* 65.1* 51.2
Mg** 40.4 55.2 62 .9* 48.4 69.7 51.5
H+ 57.1 50.6 61.9 57.0 61.8 57.7
Mean of Anions 55.0 50.4 61.7 56.0 67.5 57.7
♦Compounds were insoluble, and were added in suspension. 51 Sulfate was Intermediate in it's effect. Among the cations, calcium and magnesium reduced aggregate stability most, while potassium and sodium increased it. Hydrogen and ammonium were intermediate.
The results of the test are in general agreement with the earlier studies of this section. It may be noted that both the cations and anions followed an order similar to the lyotropic series. The cations such as sodium and potassium which have the largest effective radius affected
HPAN most favorably while the smallest cations like calcium and magnesium reduced aggregation most consistently. It is suggested that the smaller cations reduced the effective charge on the polyanions more than did the larger cations, thus decreasing the attraction of the polymer to the
"positive spots" on the clay. Considering the anion series, the small anions like chloride reduced aggregation and the larger anions increased it. In this instance the small anions reduced the effective charge on the "positive spots" on the clay more than the larger anions, thus decreasing the attraction of the clay to the polymer. EFFECT OF HPAN AND IBMA ON THE CHEMICAL SOLUBILITY AND UPTAKE OF FERTILIZER ELEMENTS BY PLANTS
Materials and Methods
Laboratory Methods
In these studies fertilizers and conditioners were mixed in 30 milliliters of solution and added to a 100 gram sample of soil. The soil was then incubated for four days, dried at 60°C, pulverized and mixed thoroughly to increase uniformity. The soils and conditioners used in these studies were described in the previous section.
Ammonia and nitrate nitrogen were determined on 60 grams of soil by a modification of Olsen’s method (82).
Available phosphorus was determined by the Bray method and exchangeable potassium was extracted with neutral normal ammonium acetate determined by flame photometry.
The rate of fertilization used in all of the labora tory tests are based largely on the recommendations of Sayre
(70 ) and fertilizer companies selling water soluble fertili zers for starter solutions.
Greenhouse Procedures
The initial study consisted of growing sudan grass in one gallon pots containing Clermont silt loam which was pre viously treated with HPAN and different rates of fertilizer.
The soil was treated with 60, 80 and 123 pounds of potassium per acre and zero and 0.1 per cent HPAN, making a total
52 53 of six treatments arranged in a randomized block design with four replicates. Nitrogen and phosphorus were added at constant rates to all pots at 60 and 44 pounds per acre, respectively.
In the second experiment using two crops on two soils, the treatments were 0 , 50, and 100 pounds of potassium per acre and 0.1 per cent I B M , 0.1 per cent HPAN, and no conditioner, making a total of nine treatments. Thirty six hundred grams of soil was placed in each one gallon pot. Corn and sudan grass were grown on Miami and Cler mont silt loams, their chemical characteristics being given in Table 1. All pots were treated with $0 pounds of nitrogen and 80 pounds of phosphorus before the crops were planted, and another 30 pounds of additional nitrogen was added on July 20, 28 and August 1, making the total nitro gen application 150 pounds. The sudan grass was planted
June 25 and harvested August 6 , and the corn was planted
June 29 and harvested August 11.
In both greenhouse experiments, conditioner and potass ium were added to the soil in sufficient amount of solu tion bringing the soil to about field capacity.
In the first experiment, the crop was planted immedi ately after treatment, but in the second test the pots were allowed to stand 24 hours after treatment, removed from the pots and air dried to increase potassium fixation. The soils were then mixed, forced through a 5.0 millimeter. 54 screen, in order to increase uniformity, and returned to the pots.
After crop harvest, all plant materials were dried at
70°C, weighed, and ground in a Wiley mill. Nitrogen was determined by the Kjeldahl method, potassium extracted with neutral normal ammonium acetate and determined with the flame photometer, and phosphorus by a modification of Kit- son and Mellon's method (32).
Field Methods
Two experiments were established in the field using conditioner fertilizer mixtures as starter solutions on tomato transplants, one in 1953 and the other in 1954. In both years Rutgers tomatoes were transplanted into a seed bed prepared by double disking of plowed ground followed by cultimulching to break up large clods. The area had been fertilized with 1000 pounds per acre of 5-10-10, drilled in before disking.
For transplanting in 1953* a small hole was dug with a spade, 1 pint of solution containing fertilizer (3 pounds per 50 gallons of water) and/or conditioner (0.2 and 0.4 per cent solutions) was poured into the hole, the trans plant was set, the soil pushed around the plant, and where appropriate, conditioner solutions were poured on the sur face around the plant. Plants were set out June 16, 1953.
Plant height was measured July 21, ripe tomatoes picked 55
September 11, 21, and October 3. At the last picking all the tomatoes were picked, sorted, counted, and each plant was pulled up and weighed.
The experiment was a randomized block split-plot de sign, with twelve replications. The experimental area con sisted of eight rows 6f tomatoes six feet apart with forty five tomato transplants per row, four feet apart in the row.
In 195^ the entire experimental area was rotary tilled when the IBMA powder treatments were encorporated. This was in addition to the land preparation listed above.
There were eight treatments in a randomized block design with five replications. A tractor cultivator opened a furrow down the row. This was made deeper with a hand trowel as the plants were set. One pint of solution was then poured around the plant roots and more soil was pressed in on top. The plants were set out June 16, 195^# and ripe tomatoes were picked September 10, 22, and October 9.
Results and Discussion
The Effect of Conditioners on the Chemical Solubility of Nitrogen, Phosphorus and Potassium
In the first study, the chemical extraction of nitro gen, phosphorus and potassium was determined in Paulding clay to which fertilizers and HPAN had been added. The results of this study are shown in Table 16.
The HPAN treatments increased the ammonium extracted 56
Table 16. The effect of HPAN and fertilizer on the chemi cal extraction of ammonium and nitrate nitrogen, phosphorus, and exchangeable potassium in Paulding clay.
Treatments Amount of element extracted Lbs ./acre from the soil 1(pp2m) fertilizer * Nitrogen added HPAN NH4 NO^ Sura P K N-P-K
0-0-0 0.0 52 75 107 125 549
460-570-570 0.0 156 286 442 460 568
460-570-570 0.1 272 505 577 456 575
250-450-170 0.0 262 49 511 584 547 250-450-170 0.1 512 95 407 447 602 250-450-170 0.2 580 94 474 587 608
440-580-560 0.0 204 252 456 168 686 440-580-560 0.1 296 265 561 145 748
L.S.D. (0.05) 65 20 45 40 57 except the treatment consisting of 0.1 per cent HPAN and
8-15-6 fertilizer (See appendix, Table II). It is be lieved that these increases are a result of the nitrogen contained in the conditioner since approximately 90 pounds per acre of ammonia nitrogen was added in the 0.1 per cent
HPAN application. Nitrate nitrogen was also increased by the HPAN treatments. These increases may have been brought about by the nitrogen added in the conditioner and also by an increase in rate of nitrification (12).
With one exception, the solubility of phosphorus was not influenced by the conditioner treatments. On the other hand the conditioner treatments increased the potassium extracted in every instance except one. An example of the statistical analysis of the data from this experiment may be seen in the appendix, table II.
A more detailed study of the effects of fertilizers and conditioners on the chemical extraction of potassium from different Ohio soils is presented in Table 17. In every instance the exchangeable potassium was highest when
HPAN or IBMA was added in combination with fertilizer.
Where HPAN was used, all of the increases were highly signi ficant, except the potassium phosphate carrier on Brookston silt loam and potassium sulfate on Miami silt loan. Addi tions of IBMA to Paulding clay resulted in only one increase of available potassium, that increase occurring in the treatment containing potassium chloride. Table 17. The effect of potassium fertilizers and conditioners on the exchangeable potassium of several Ohio soils.
Fertilizer and ______Exchangeable K Conditioner Paulding Miami Brookston Clermont Hoytvi! Treatment clay silt loam silt loam silt loam cla:
HPAN
None 399 466 126 468 HPAN — 392 456 116 461
KC1 490 947 628 412 640 KC1 + HPAN 623 1268 696 454 712
KN03 529 977 619 402 627 KNO^ + HPAN 576 1104 726 453 731
K0HPO4 564 953 625 271 627 K2HP04 + HPAN 594 1089 628 372 646
K0SO4 921 615 358 619 K2SO4 + HPAN - 954 689 422 704
L.S.D. (0.01) 15 83 45 13 .19
vn 00 Table 17. (Continued) The effect of potassium fertilizers and conditioners on the exchangeable potassium of several Ohio soils.
Fertilizer and Exchangeable K (pp2m) Conditioner Paulding Miami Brookston Clermont Hoytvilie Treatment clay silt loam silt loam silt loam Clay
IBMA
None 398 578 412 156 IBMA 380 588 .368 150
KC1 376 691 510 4o6 KC1 + IBMA 482 876 564 424
KNO3 400 693 514 419 KNO3 + IBMA 422 871 617 44o
K0HPO4 415 778 507 379 K2HP04 + IBMA 440 910 522 407
K2SO4 422 695 513 4l6 K2S04 449 812 599 433
L.S.D. (0.01) 41 33 26 12
ui vo 6o
On the other soils IBMA resulted in highly significant increases except in combination with potassium phosphate on Brookston silt loam. A highly significant interaction was obtained between conditioners and fertilizers in this experiment. An example of the statistical analysis of the data from these experiments may be seen in the appendix, Table III.
The manner in which the conditioner decrease potassium fixation is not well understood. The possibility is suggested that the conditioners, which are polyanions, and are probably held by positive charges on the clay edges (68), may blobk the entrance of the potassium into the mineral lattice, or the long chain of the polyelectro lyte may cause stearic hindrance for potassium adsorption.
This would account for the very slight reduction in ex change capacity as a result of conditioner treatment (18).
Effect of HPAN and IBMA on Availability of Fertilizer to Plants
Greenhouse Tests
The results of the preliminary greenhouse study are given in Table 18. Yields were increased by the HPAN treatments in all of the three fertilizer treatments, but only in treatment number two was the increase significant.
Chemical analysis of the plant material showed an in crease in potassium content of the grass with fertilizer number one as a result of conditioner treatment. Nitrogen Table 18. The effect of HPAN on yields and percentages of potassium, nitrogen and phosphorus in Sudan grass from first crop.
Ht. in Dry wts. inches of Treatment Sept. 10 grass/pot % N % P % K
F t 35.1 9.4 1.55 0.19 2.45 Fi + HPAN 31.7 10.4 1.94 0.18 2.68
Fp 34.0 11.7** 1.57 0.2 6 2.28 F2 + HPAN 36.2 16.4 2.04 0.26 2.32
F3 35.8 13.5 1.72 0.22 2.31 F, + HPAN 34.8 14.6 2.10 0.25 2.58 3 L.S.D. (.05) 3.0 0.31 N.S. -.23
Fi is equivalent to 60 lbs. N, 100 lbs. P2O5 , 60 lbs. K.
F2 is equivalent to 6q lbs. N, 115 lbs. P205, 80 lbs. K.
F_ is equivalent to 60 lbs. N, 111 lbs. P205, 123 lbs . K. 3 Date planted, July 30 Dates harvested, Sept. 14, Oct . 24, 1954 Soil used, Clermont silt loam 62
content of all HPAN treated plants was increased signifi
cantly. This is in agreement with the findings of Engi-
bous (l8). Differences in phosphorus uptake were not
significant. No significant differences in yield or
plant composition were noted in the second and third crops.
It was hoped that the fertilizer additions would be at
about the critical level so that slight changes in phos
phorus or potassium availability could be noted in the
plant. A trend was apparent with potassium, and this was
used as a basis for setting up the more detailed study of
this problem.
The yield and chemical composition of the corn and
sudan grass grown in a second experiment are given in
Tables 1 9 , 20, 21, and 22. This experiment was designed
to determine the effect of conditioner on potassium, parti
cularly, but the apparent availability of the nitrogen in
the conditioners made this task more difficult. This nitro
gen difference became apparent as the growth of the plants
progressed. In the corn pots, and particularly on the Cler
mont silt loam, treatments 1, 4 and 7 appears definitely
lighter green and the lower leaves were drying by July 20
in these treatments. The corn in all conditioner treated
pbfos was dark green. By the time the crops were harvested
they had been fertilized with 150 pounds of nitrogen, but
90 pounds of this was added after July 20. On both soils and both crops, the conditioner treated pots were a darker 63 green than in the untreated pots. (See Figure 3)
The plants in the untreated pots wilted less than did those in the treated. The grass and corn grown on the
Clermont silt loam, treated with 0.1 per cent I B M , showed
considerable wilting. This treatment appeared to water proof the Clermont soil and the water holding capacity was greatly diminished. When 1 liter of water was added to the
3.6 Kgms of soil in the pots, the untreated and HPAN treated
soils held all of the water, but excess water came out of
the pots with I B M treated soils.
Yields were significantly influenced by conditioners.
HPAN increased the yield of both crops on both soils, but
I B M , while increasing crop yields on Miami silt loam, re duced them on Clermont silt loam (see Figure 2).
In general, the potassium treatments has little signi ficant effect on yields. Two exceptions to this generality are: (1) The potassium treatments in combination with HPAN reduced sudan grass yields significantly when compared to
HPAN alone on Miami silt loam; and (2) one hundred pounds of potassium with I B M increased corn yields on Miami silt
loam compared to I B M alone.
On the Miami soil the per cent potassium in the plant was increased by the conditioner treatments in combination with potassium fertilizer treatments, compared to the potassium fertilizer treatments alone. Some of these in creases were significant. On the Clermont soil the results 64 were quite variable. The per cent potassium in sudan grass,
treated with HPAN and 50 pounds potassium, was signifi
cantly lower than 50 pounds of potassium alone, and the
IBMA with no fertilizer increased the per cent potassium
in sudan grass.
The total potassium was increased in every instance
on Miami silt loam by the conditioner treatments, and in
the corn these increases were highly significant except for
the HPAN with no fertilizer. There was also a significant
interaction between conditioner and fertilizer treatments
in this instance. In the sudan grass the IBMA treatments
produced a highly significant increase in the total
potassium, but the increases brought about by HPAN treat
ments were not significant.
On the Clermont silt loam the HPAN produced increases
in total potassium compared to fertilizer treatments alone.
The IBMA treatments reduced total potassium on this soil.
The potassium fertilizer treatments increased the per
cent and the total potassium in the plants in every instance,
and most of these increases were significant.
In this experiment the typical data show that as yields
Increased as a result of conditioner treatments, the per
cent potassium in the plants Increased, when compared to
fertilizer treatments with no conditioner. Sometimes this increase was significant. Ordinarily, with an increase in yield, a decrease in per cent of potassium might be expected 65 if the availability of the potassium remains constant.
Since there was no significant decrease in potassium con tent, the interpretation might be that the conditioners had the effect of increasing potassium availability. This is in agreement with the findings of Maclntire (42), who applied 50 pounds of potash to all pots in a greenhouse experiment and observed an increase in potassium uptake by plants in the HPAN treated pots.
The noted increase in potassium uptake may be a re sult of the increase in exchangeable potassium, as reported in Table 17, and/or the improvement of structure and aera
tion as reported by Lawton (57)» Worsham and Sturgis (8l).
Their findings were that organic matter markedly increased available potassium. Perhaps similar mechanisms are in
volved in the increased availability of potassium in soils
to which conditioners and organic matter have been added.
The per cent nitrogen in the plant tissue was increas ed, without exception, throughout the experiment by condi tioner treatments. These increases were highly significant on the Miami silt loam, (see Figure 5) and generally so on the Clermont silt loam. The increase in total nitrogen was highly significant in every conditioner treatment on Miami silt loam, but on the Clermont silt loam only the HPAN treat ments increased nitrogen significantly in the sudan grass pots, and one of the treatments significantly increased the nitrogen percentage in the corn. Increasing the application 66 of potassium usually tended to decrease the per cent and total nitrogen, but in general, these differences due to potassium treatments were not significant.
It is believed that at least three factors contributed to the increase in nitrogen uptake by plants in the condi tioner treated pots: (a) The nitrogen added to the soil in
the conditioner appears to be partly available, (more work should be done on this particular point), (b) DeMent (14) reported increased rates of ammonification and nitrifica
tion as a result of conditioner treatments, (c) since the ammonium ion is fixed in the soil by the same mechanism as potassium (7 2 ), there may be more ammonium ions available
to plants and microorganisms in conditioner treated soil.
Increased nitrogen was observed in plants growing in condi
tioner treated pots, even though 150 pounds of nitrogen
fertilizer was added to all pots. The effect of the nitro gen on the potassium uptake cannot be separated from the
other effects of conditioners in this experiment, but
Lawton and Cook (58) in a review on potassium, point out
that the addition of nitrogen usually reduces potassium absorption by plants.
The conditioner treatments had very little effect upon
the per cent phosphorus in the plant. HPAN and potassium treatments on Clermont silt loam, reduced the percentage of phosphorus in sudan grass. This was the only conditioner 67
Figure 2. Sudan grass grown on Clermont silt loam. Treatments, left to right: Untreated, 0.1 per cent IBMA, and 0.1 per cent HPAN. 68
Figure 3. Corn grown on Miami silt loam. Treatments, left to right: Untreated, 0.1 per cent IB M , and 0.1 per cent HPAN. Table 19. The effect of conditioner and Kifertilizer treatments on yield and composition of corn grown on Miami silt loam.
Yield KN P Treatments Dry Wt./pot Total Total Total Conditioner Potassium in gms. Content uptake Content uptake Content uptake
lbs./acre # mgm/pot ... # mgm/pot # mgm/pot
1. None None 19.8 0.74 147 1.45 287 .255 50.4 VO r 2. 0.1# HPAN None 23.4 0.66 154 1.76 408 • 55.2 3. 0.1# IBMA None 26.6 0.87 234 1.97 555 .223 59.4 4. None 50 21.2 0.82 176 1.52 280 .225 47.9 5. 0.1# HPAN 50 21.8 1.03 225 1.72 574 .223 48.7 6. 0.1# IBMA 50 26.9 1.34 362 1.70 459 .207 55.7 7• None 100 20.7 1.12 232 1.59 292 .184 38.1 8. 0.1# HPAN 100 23.0 1.24 288 1.70 59.1 .207 47.7 9. 0.1# IBMA 100 24.0 1.18 283 1.75 417 .193 46.3 L.S.D. (0.05) 2.4 0.25 23 0.20 48 0.039 6.7 CT\ vo Table 20. The effect of conditioner arid K fertilizer treatments on yield and composition of corn grown on Clermont silt loam. Yield KNP Treatments Dry Wt./pot Total Total Total Conditioner Potassium in gms. Content uptake Content uptake Content uptake lbs./acre # mgm/pot __ #__, mgm/pot # mgm/pot 1. None None 16.2 1.01 164 1.48 238 .238 38.6 2. 0.1# HPAN None 19.5 1.02 200 1.77 342 .255 49.6 . 3.0.1# IBMA None 12.9 1.04 134 2.44 315 .234 30.1 4. None 50 16.7 1.27 211 1.29 216 .223 37.7 5. 0.1# HPAN 50 21.8 1.16 249 1.42 305 .225 48.4 6. 0.1# IBMA 50 15.4 1.40 214 2.24 342 .229 35.1 7. None 100 18.3 1.48 270 1.32 241 .211 38.5 8. 0.1# HPAN 100 21.4 1.55 350 1.70 360 .194 42.5 9. 0.1# IBMA 100 15.8 l.6o 253 2.21 344 .199 30.5 L.S.D. (0.05) 2.8 .18 40 .43 187 .022 0.59 o Table 21. The effect of conditioner and K fertilizer treatments on yield and composition of sudan grass grown on Miami silt loam. Yield K N P Treatments Dry Wt./pot Total Total Total Conditioner Potassium in gms. Content uptake Content uptake Content uptake lbs./acre % mgm/pot $ mgm/pot $ mgm/pot 00 o 1. None None 16.3 • 130 1.29 209 .185 29.8 2. 0.1$ HPAN None 20.9 .84 176 1.64 342 .181 38.1 3. 0.1$ IBMA None 22.9 .91 208 1.90 436 .171 39.2 .. 4. None 50 14.6 * 136 1.44 208 .170 24.7 5. 0.1$ HPAN 50 17.1 1.09 178 1.70 292 .166 28.4 6. 0.1$ IBMA 50 20.0 1.29 253 1.69 340 .165 32.2 7. None 100 15.8 1.27 200 1.39 220 .155 24.3 8. 0.1$ HPAN 100 15.6 1.51 232 1.83 284 .166 25.8 9. 0.1$ IBMA 100 22.3 1.38 309 1.92 44o .146 33.2 L.S.D. (0.05) 3.2 .23 47 .19 61 .021 0.58 M Table 22. The effect of conditioner and K fertilizer treatments on yield and composition of sudan grass grown on Clermont silt loam. Yield K NP Treatments Dry Wt./pot Total Total Total Conditioner Potassium in gms. Content uptake Content uptake Content uptake mgm/pot lbs./acre .. $ mgm/pot * . % . mgm/pot 1. None None 12.8 1.02 130 1.42 182 .219 28.0 2. 0.1$ HPAN None 18.0 0.91 164 1.45 266 .206 37.3 3. 0 U $ IBMA None 10.0 1.20 121 2.38 24l .225 22.8 4. None 50 11.8 1.30 152 1.40 164 .201 23.8 5. 0.1$ HPAN 50 19.2 i.o8 209 1.80 • 347 .174 23.5 6. 0.1$ IBMA 50 8.9 1.43 127 2.30 207 .185 16.3 7. None loo 12.5 1.76 224 1.66 226 .201 27.2 8. 0.1$ HPAN 100 17.6 1.76 279 2.07 356 .194 34.4 9. 0.1$ IBMA 100 8.4 1.82 151 2.72 230 .210 17.5 L.S.D. (0.05) 2.9 .17 46 .43 71 .020 0.71 ro 73 treatment causing a significant difference in phosphorus accumulation. The total phosphorus increased and decreased where yields increased and decreased as a result of condi tioner treatment. With few exceptions the potassium fertili zer treatments reduced both the per cent and total phos phorus of the plant. An example of the analysis of variance of this green house data may be found in the appendix, Table IV. Field Tests Experiments were established in the field to deter mine if soil conditioners applied in liquid form to the root zone of seedling tomatoes during transplanting would improve yield in structurally poor Hoytville silty clay, and whether or not a typical starter solution would be more effective in the presence of absence of soil conditioners. The results from the first of these experiments are found in Table 25. A statistical analysis was run only on the total yield of ripe tomatoes (see the appendix, Table V for the summary table of the statistical analysis). All of the fertilizers alone produced significant Increases in yield and they all prpduced significant increases with 0.2 per cent IBMA, when compared to IBMA alone. Only the 10-52-17 fertilizer significantly increased the yield of tomatoes when mixed with 0.2 per cent HPAN compared to HPAN alone. There was no significant difference between the conditioner treatments, and there was no significant interaction between 74 Table 23. The effect of certain conditioner and fertili zer starter solutions on the growth of Rutgers tomatoes. Tomato Yields/plant______Starter Solution Ht. of Wt. of Total Wt. ______applied Plants Wt. of Green of ripe Fertilizer Conditioner July 21 Plants Tomatoes Tomatoes Water Water 14.1 5.05 6.17 7.06 10-52-17 None 17.1 5.22 5.85 10.31 17-34-17 None 17.3 4.86 5.05 9.63 29-21-10 None 15.9 5.43 5.59 9.41 None 0.2$ IBMA 15.9 5.62 5.99 8.04 None 0.2$ IBMA* 16.4 5.61 6.18 8.15 None 0.4$ I B M 16.1 5.00 4.26 8.80 None 0.4$ I B M * * 15.1 5.92 5.64 8.56 None 0.2$ HPAN 15.6 4.84 4.85 7.91 None 0.2$ HPAN*** 14.6 4.95 4.82 8.12 None 0.4$ HPAN 15.0 4.98 4.88 7.16 None 0.4$ HPAN**** 15.2 5.14 5.10 7.22 10-52-17 0.2$ IBM 15.2 5.28 5.55 8.80 10-52-17 0.4$ I B M 15.8 5.40 5.72 8.17 10-52-17 0.2$ HPAN 17.1 5.82 4.69 10.64 10-52-17 0.4$ HPAN 15.9 4.84 4.$9 8.09 17-34-17 0.2$ I B M 17.1 5.78 5.08 10.28 17-34-17 0.4$ I B M 17.0 5.61 4.92 9.86 17-34-17 0.2$ HPAN 16.2 4.92 5.12 8.59 17-34-17 0.4$ HPAN 16.2 4.22 4.32 8.14 29-21-10 0.2$ I B M 16.3 5.32 5.49 10.24 29-21-10 0.4$ IBM 16.3 5.48 3.89 9.36 29-31-10 0.2$ HPAN 15.8 6.29 6.50 9.31 29-21-10 0.4$ HPAN 15.3 5.49 5.85 8.87 None None* 14.8 5.40 5.89 9.76 10-52-17 None* 15.9 5.22 4.78 10.34 None None*** 14.4 5.02 4.54 8.16 10-52-17 None*** 15.2 4.69 4.65 7.96 *0.2$ I B M on the surface around the plant **0.4$ I B M on the surface around the plant ***0.2$ HPAN on the surface around the plant ****0.4$ HPAN on the surface around the plant 75 conditioners and fertilizers. It is noted that the control treatment of no fertili zer and no conditioner gave the lowest yield. The next low est yields were the 0.4 per cent HPAN treatments. The high est yield was produced by 10-52-17 and 0.2 per cent HPAN. It Is interesting to note that in every case, except IBMA alone, increasing the concentration of conditioner from 0.2 to 0.4 per cent decreased the yield. This may have been due to a water proofing affect as noted in the pot experiment with IBMA on Clermont soil. The results of the second experiment are reported In Table 24. There were no significant differences due to any of the treatments in this experiment. It is suggested that the insignificance of the results may have been caused by the following factors: (a) Only a very small amount of soil was treated as compared to that volume occupied by the roots, (b) the high fertility status of the soil would make it difficult if not impossible to observe small changes In availability of nutrients, (c) the structural condition of the soil did not appear to be limit ing. It was noted in the second year that IBMA incorporated to six inches did not affect crop yields even though aggre gation was increased. The use of conditioners in starter solutions seems to be an impractical approach to structural or fertility problems. 76 Table 24. The effect of 10-52-17 fertilizer, HPAN and I B M , used as starter solutions, and I B M mixed with the soil on tomato yields. Date of Harvest Treatment Sept. 10 Sept. 22 Oct. 9 Total Average weight of tomatoes in lbs/plot 1. Water .18.4 94.6 207.1 320.1 2 . 10-52-17 15.1 86.1 189.5 290.7 5. I B M (Sol) 18.5 101.6 169.2 289.3 4. I B M (Sol) + 10-52-17 21.5 123.4 184.7 329.6 5. HPAN 16.2 85.9 191.7 293.8 6 . HPAN + 10-52-17 19.8 108.0 177.8 305.6 7. I B M (Solid)* 11.3 82.6 207.2 301.1 8 . I B M (Solid)* + 10-52-17 10.9 85.2 178.2 274.6 L.S.D. (0.05) N.S. N.S. N.S. N.S. Average number of tomatoes per plot 1. Water 56 277 643 976 2. 10-52-17 43 237 566 846 3. I B M 58 302 520 880 4. I B M + 10-52-17 66 383 624 973 5. HPAN 51 256 592 899 6. HPAN + 10-52-17 59 323 576 958 7. I B M (Solid)* 32 228 673 933 8. I B M (Solid)* + 10-52-17 31 252 579 862 L.S.D. (0.05) N. S. * I B M was applied at the rate of 0.05 per cent to a depth of six inches. It was incorporated by rototilling. THE EFFECT OF CONDITIONERS ON CROPS UNDER FIELD CONDITIONS Methods and Materials Depth Treatments In order to determine the effect of conditioners on the physical properties of soil in the field and their influence on crop growth on these soils, several experi ments were established. The first of these to be consid ered was established by Martin, et al. (51) and Engibous (18) in 1951. These workers reported that significant increased aggregate stability occurred as a result of conditioner treatments. No significant differences were noted in potato quality or yields, but yields of marketable carrots were significantly increased. The experimental area was on Brookston clay on the University Horticulture farm. The three conditioner treatments, check, 0.1 per cent and 0.2 per cent VAMA were arranged in a randomized block design with eight replications. The area was irrigated as needed and 1000 pounds 5-10-10 fertilizer was broadcast before planting. In April 1952, lettuce plants were set out on these plots. This crop was harvested June 6, after which the area was disked and sweet corn was planted June 14. This crop was picked September 2 and £, 1952. Soil samples were taken in April, June, and September from three locations in plots of two replications at a depth of from 0 to 4 inches. A modification of the Yoder (83) method, using a 77 78 graded sample (2.00 to 4.76 millimeters) was used for aggregate analysis. Another experiment was established on Trumbull silty clay loam near Youngstown, Ohio on the farm of Mr. A. Agnew. There were three conditioner treatments (check, 0.1 per cent HPAN, and 0.1 per cent VAMA) in a randomized block design and ten replications. A very heavy stand of rye and vetch was plowed under as green manure, and 500 pounds of 8-16-16 was broadcast on these plots. The area was irrigated three times during the summer. Conditioners were applied on June 2, 1952, and on June 5» the potatoes were planted. This crop was^ harvested October 25. Soil samples for aggregate analysis were taken July 1 and October 25. The per cent moisture in the surface soil was determined July 1. The samples were taken from three locations from the surface inch of four replications with a small lath, and by placing the sample in a moisture proof bag for transport to the laboratory, weighing, and oven drying at 105°C. Trumbull silty clay loam was chosen for this experiment as it is particularly noted for its structural instability, and for the tillage problems it presents to the farmers of northeast Ohio. In both of the above experiments the polymers were spread on the surface of the soil and incorporated to a depth of 4 to 6 inches by double disking. Surface Treatments An experiment was established in 1954 at the North western Substation to determine the effect of soil condi tioners when applied in liquid form to the soil surface on seedling emergence and stand. The seed bed was prepared by double disking plowed Hoytville silty clay, followed by cultimulching to break up large clods. The seed bed was so cloddy and hard that it was necessary to rake each row by hand before planting. A standard fertilizer application of 1000 pounds of 5-10-10 was drilled in before disking. Early red tomatoes were seeded with a hand seeder on May 20, 1954. The plot size was 80 feet by 6 feet and the total area size was 70 feet by 520 feet. There were 8 treatments and five replications which were placed in a ran domized block design. Details of treatments are given in the results. A 0.2 per cent conditioner solution (calculated on a water basis) was applied to the soil directly over the seed in two ways: (a) A garden sprinkler can was used to treat a band over the seed about 4 inches wide and about one half inch deep. Three gallons of solution were used per 80 feet of row, (b) a tee jet nozzle was used to apply the solution under a pressure of about 15 pounds per square inch. It was turned so as to tre&t a band about one half Inch wide directly over the seed. Under these conditions about 1.5 80 quarts of solution were used per 80 feet of row. Stand counts were taken by counting the number of seedlings per 30 foot of- row in each plot. The tomatoes were blocked and thinned on July 1, to one plant every four feet. The height of the tomato plants was measured on July 10. . Ripe tomatoes were picked September 24, October 9 and 10. At the last picking all of the green tomatoes were picked counted and weighed. Results and Discussion The Effect of VAMA on Aggregation of Brookston Clay Loam One Year after Treatment In 1951 Martin (51) and Engibous (18) established a conditioner experiment on the Ohio State University Horti culture farm on a Brookston silty clay loam soil. The effect of VAMA incorporated at two rates, as reported by these workers is shown in Table 25. There was a signifi cant increase in aggregation as a result of conditioner treatment, and a significant increase in marketable carrots, but no significant differences in yield of potatoes grown on these plots was noted in 1951. This experiment was continued through the growing sea son of 1952. It may be seen from Table 25 that an increase in aggregation carried over into the second year, although the aggregation values were somewhat lower in the treated plots. This may have been a result of mechanical breakdown of the aggregates from freezing, thawing, wetting, drying, 81 Table 25. The effect of VAMA. on aggregation of Brooks ton silty clay loam. Horticulture Farm, Ohio State University, 1951 and 1952. Per cent aggregation (Particles .> 0.25 mm) Treatments* 1951 1952 Date sampled July April June Sept. Check 56 56 55 42 0.1# VAMA 77 50 44 56 0.2# VAMA 84 57 57 57 L.S.D. (0.05) 4 — 15 8 ♦Conditioner treatments were made in May 1951. and tillage practices. Mixing with untreated soil could also be a factor in this reduction. Laws (55) showed that once the bonds holding the aggregates together are broken they do not reform unless treated with hydroxide or phos phate ions (27). It is also noted that the least signifi cant differences are larger the second year than the first. This would be expected, since with time all of the variables mentioned above might enter the picture and the chances of getting representative samples of each treated plot would be less. The yield of lettuce and sweet corn on the Horticulture plots are given in Table 26. There were no significant differences in yield, number of, or size of lettuce heads. Lettuce yields were lower on plots receiving the 0.2 per cent VAMA treatments and the check had the highest yields. The highest corn yields were obtained from the 0.1 per cent VAMA plots, and the lowest from the check plots, but these differences were not significant. Analysis of variance for corn yields are presented in the appendix, Table VI. The Effect of HPAN and VAMA on Trumbull Silty Clay Loam Another experiment where conditioners were incorporated into the soil was established in 1952 on Trumbull silty clay loam using potatoes as an assay crop. The results of this test are reported in Table 27, and an example of the analysis of variance is given in the appendix, Table VII. 83 Table 26. The effect of VAMA on yield of lettuce and sweet corn grown one year after treatment of Brookston silty clay loam. Horticulture Barm, Ohio State University. Marketable Marketable Small Total Treatments Lettuce Corn Ears Corn Pounds per plot Check 74 23.8 5.3 29.1 0.1# VAMA 73 28.9 5.9 34.8 0.2# VAMA 71 28.5 5.1 33.6 L.S.D. (0.05) N.S. N.S. N.S. N.S. Conditioner treatments applied: May 24, 1951 Planted: Letttice: April 1952. Corn: June 14, 1952 Harvested: Lettuce: June 6 , 1952. Corn: Sept. 2, and 5j 1952 Fertilizer: 100 pounds 5-10-10 per acre. Irrigated: As required. Plot size: 25 feet by 12 feet 6 inches. Design: Randomized block with eight replications. Table 27. The effect of HPAN and VAMA on aggregation and potato yields on Trumbull silty clay loam. * July 1* 1952 October 23, 1952 % Aggregation % Aggregation % water particles particles Yield Treatment in soil** ->2.0 mm >0.25 mm .>2.0 mm > 0.25 mm Bu/Acre Untreated 50 23 , 59 50 66 348 0.l£ HPAN 52 50 60 47 77 341 0.156 VAMA 29 66 84 68 89 351 L.S.D. (0.05) N.S. 7 8 N.S. *Near Youngstown, Ohio on the farm of Mr. Agnew. **Soil moisture was studied because of the much dryer appearance of VAMA plots on the morning of July 1, 1952, following a heavy rain the preceeding night. Treated: June 2, 1952. Disked into six inches. Planted: June 3, 1952. Harvested: October 23* 1952 Fertilizer: 500 pounds of 8-16-16 broadcast, and a heavy stand of rye and vetch was plowed under as green manure. Irrigated: Yes. Three times. Plot size: 25 feet by 30 feet. Design: Randomized block with ten replications. co It is seen that an application of 0.1 per cent VAMA increased the water stable aggregates greater than 0.25 millimeters to 84 per cent, while the 0.1 per cent HPAN and control were 60 and 59 per cent, respectively. The fact that HPAN did not significantly increase aggregation was accounted for by the conditions under which the treatment was made. The conditioners were spread in the evening when the relative humidity of the air was very high. The soil was also quite moist at that time. The HPAN took up mois ture rapidly, forming a gelatinous mass in many places before it was disked, even though the time between spread ing and disking was short. These gelatinous masses were evident throughout the summer and a few remained at harvest time. Aggregation increased in all treatments from July 1 to October 23. The greatest increase was in plots treated with HPAN. With time, the gelatinous material was more widely disbursed throughout the soil and thus, was more effective in stabilizing aggregates. The high level of aggregation in the check plots may have been a result of the heavy crop of vetch and rye which was plowed under as a green manure only a few days before the potatoes were planted. This may also account for the increase in the check plots from 59 to 66 per cent during the season. The yield differences were not significant. It was 86 reported by Mr. Agnew, owner of the farm, that some seasons large clods form making potato harvest very difficult. Such was not the case the year of this test. Surface Applications for Crust Control The effect of surface applications of conditioner on soil crusting, in solution and as solids, have been investi gated by DeMent (l4). He observed that where conditions were right for crust formation, that surface applications were effective in preventing slaking, and thus crust forma tion. The applications were made by hand in this work. It would, of course, be impractical to make such applications on a large scale. It was the purpose of this experiment to apply the conditioner in a way that might be used under field condi tions. The equipment and methods used could be readily adapted to regular planting equipment. The results of this test are given in Table 28. At the time the experiment was established, the soil was very dry. One week later on May 27* the area was still dry and no germination was noted. By June 15* it had rained several times and the tomatoes had grown from one to three inches in height. Crusting conditions were not severe un der the conditions of this experiment. A good stand of tomatoes was obtained in the control plots. Nevertheless, the conditioner treatments, using both methods, significantly Table 28. The effect of surface applications of conditioners on emergence, height of plants and yield of tomatoes. No. of Ht./plant Ripe Green Total seedlings inches tomatoes tomatoes tomatoes Treatments 30 ft. of row July lbs/plot lbs/plot lbs/plot Sprinkled Water 128 11.9 150 165 215 0.2$ IBMA 172 12.9 185 150 225 0.2$ HPAN 169 12.4 170 170 340 0.2$ SMA 174 12.1 178 156 224 Jet Water 99 12.8 172 151 324 0.2$ IBMA 154 11.8 166 161 227 0.2$ HPAN 155 12.3 150 175 225 0.2$ SMA 149 12.0 160 167 227 L.S.D. (0.05) 23; 0.8 N.S. N.S. N.S. Treated: May 20, 1954 Planted: May 20, 1954 Variety: Early red Harvested: September 24, October 9 and 20 Fertilizer: 1000 pounds 5-10-10 Plot size: 80 feet by 6 feet Design: Randomized block with five replications and eight treatments. increased the number of emerging plants* The statistical analysis of this data may be seen in the appendix, Table VIII. An orthogonal comparison of this data revealed that the number of plants in the sprinkled plots were significant ly greater than in the jet spray treatments. The latter treatments covered only a band of soil one-half inch wide, while the former covered a band of soil about four inches wide. It is possible that the jet stream was not always directed exactly over the.seed. This difficulty could be reduced by attaching the sprayer directly to the seeder. The height of the tomato plants was measured in July. In the sprinkled plots there were significant increases in plant heights as a result of conditioner treatments. There were also significant differences in plant height in the jet treatments, the largest plants grew in plots which had re ceived the water treatment. There were no significant differences in tomato yield between treatments. This is indicative of the fact that good stands occurred on all plots, and that crusting was not a serious problem the year of this experiment as it is some years. DeMent (14) noted that reductions in yield on tomatoes grown the previous year were correlated with the reduced number of tomato plants in untreated plots. 89 SUMMARY 1. Three methods of evaluating the effectiveness of conditioners were tested. In general, the results indicate that polyelectrolytes are effective in stabilizing aggre gates of the soil when poured on the soil in solution with no mixing. This pouring method did not give as wide a range in aggregation values as concentration of conditioner varied, as did the Hedrick and spray methods where aggre gates were formed by mechanical mixing. However, the latter methods have a larger error mean square, and the results from these methods are thought to be more dependent on technique than is the pouring method. All of the methods were sensi tive to conditioner concentration changes, except in the case of VAMA changing from .05 per cent to 0.1 per cent using the pouring method. It was noted that the surface of soil treated at the 0.1 per cent rate with VAMA solution was covered with a sticky layer even after 24 hours of stand ing in a covered tumbler. The 0.1 per cent VAMA solution is the only conditioner that showed this characteristic. Hand ling and rewetting the treated aggregates decreased aggrega tion, particularly where conditioner treatments wer light. More fertilizer compounds reduced or increased the effectiveness of HPAN than VAMA or IBMA. The aggregate stabilizing power of HPAN was reduced most by magnesium nitrate, magnesium chloride, calcium nitrate and calcium chloride, and was increased most by potassium, sodium, and 90 magnesium hydroxides, and potassium phosphate. Potassium chloride and ammonium nitrate consistantly reduced the level of aggregation produced by HPAN. Water stable aggregates produced by IBMA were reduced most by the calcium salts of chloride, and nitrate and phos phate, and some reduction was noted by treatments of the potassium salts of sulfate, chloride and nitrate. Hydroxides and potassium phosphate increased the aggregate stabilizing power of IBMA. The effectiveness of VAMA was reduced by potassium nitrate and increased by potassium phosphate. 2. The chemical solubility of nitrogen, phosphorus, and potassium fertilizers was studied in a preliminary experiment. The results are summarized as follows: The addition of HPAN to Paulding clay with a complete fertilizer increased the ammonium and nitrate fractions extracted by an acid (pH 1) sodium chloride solution. HPAN had little effect upon phos phorus solubility. HPAN added with the fertilizer increased exchangeable potassium. A detailed study on several Ohio soils showed that HPAN and IBMA increased the exchangeability of potassium fertili zers when they were added as any of four different carriers as measured by extraction with ammonium acetate. 5. A preliminary greenhouse study was established to determine the effect of HPAN on the availability of nitrogen, 91 phosphorus, and potassium fertilizers to plants. It was concluded that: HPAN increased the per cent of nitrogen in sudan grass, phosphorus was not affected by the conditioner treatments, potassium uptake by plants was increased by HPAN treatments, this increase being significant where sixty pounds potassium per acre was the fertilizer treatment. In another pot experiment, HPAN and IBMA were added to two soils with varying amounts of potassium. Sudan grass and corn were the crops used. The results indicate that: The conditioner treated pots had greater yields than those not treated, except where water proofing occurred in Cler mont silt loam treated with IBMA, potassium treatments had no significant effect on yield, nitrogen uptake was increas ed markedly by conditioner treatments and reduced slightly by potassium fertilization, the percentage phosphorus in the plants was not significantly affected by the conditioners, potassium treatments reduced per cent phosphorus in every case and many of these reductions were significant, total phosphorus was reduced by potassium treatments and increased by conditioners, potassium uptake was increased by both conditioner and potassium fertilizer treatments. 4. Two field experiments were established using condi tioners in conjunction with fertilizer starter solutions, in order to determine the effect of conditioners on plant growth. The first year, fertilizers increased yield significantly, but the second year the fertilizer produced no such increase. 92 The conditioner did not change yield significantly either year. There was no conditioner fertilizer interaction. 5. Crop yields and aggregation data are presented from two field experiments where the conditioners were incorpor ated into the soil. The results were as follows: Aggrega tion was increased by applications of HPAN and VAMA. Where HPAN was applied to moist Trumbull silty clay loam clay June 2, aggregation was the same as the control plots on July 1, but by October 2J>, there was a marked increase in the treated plots. VAMA produced higher aggregation than HPAN. In one experiment aggregation was higher in VAMA treated plots more than a year after treatments. Lettuce, sweet corn, and potato yields were not signi ficantly increased by conditioner treatments. It was con cluded that poor structure was not a limiting growth factor in these cases. 6. Prom the experiment established to ascertain the effectiveness of conditioners in controlling crusting it was concluded that: Conditioners in solution applied from the sprinkler or the jet were effective in reducing the soil crust enough to permit more tomatoe seedlings to emerge in condi tioner treated plots than in those treated with water. After the seedling tomatoes had been thinned to proper spacing, under the conditions of this experiment there were no signifi cant differences in yield due to treatments. LITERATURE CITED Alderfer, R. B., and Merkle, P. G., 1941, The measure ment of structural stability and permeability and the influence of soil treatments upon these properties. Soil Sci. 51:201-211. ______1954, Physical condition of the soil effects fertilizer utilization. Better Crops and Plant Food, 58, No. 10, 24, 44-45. Allison, L. E., 1947, Effect of micro-organisms on permeability of soil under prolonged submergence. Soil Sci. 65:459-450. ______, 1952, Effect of synthetic polyelectro lytes on the structure of saline and alkali soils Soil Sci. 75:445-454. Baver and Farnsworth, 1940, Sugar beet yields on the heavy clay soils of Northwest Ohio. Soil Sci. Doc. Amer. Proc. 5:45. Bould, C. and Tolhurst, J., 1952, Soil conditioners: I. The effect of sodium salt of hydrolyzed polyacry- lanitrile (CRD 189) and of CRD 186 on nutrient avail ability and uptake by plants. Long Ashton Res. Sta. Rept. 49:54. Bray, R. H. and Kurtz, L. T., 1945, Determination of total, organic and available forms of phosphorus in soils. Soil Sci., 59:59-45. Browning, G. M. and Milan, F. M., 1944, The rate of application of organic matter in relation to soil aggregation. Soil Sci. Soc. Amer. Proc. 6:96-97. ______, 1944, The effect of different types of Organic matter and lime on soil aggregation. Soil Sci. 57:91-106. Chepil, W. S., 1955, Factors that influence clod structure and erodibility of soil by wind: I Soil texture. 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Engibous, James C., 1952, The effect of synthetic poly electrolytes on some physical and biochemical pro perties of certain Ohio soils and upon yield and composition of plants. Ph. D. Thesis, Ohio State University. 19. Puller, ¥. H., 1946, Evidence of the microbiological origin of uronides in the soil. Soil Sci. Soc. Amer. Proc. 11:280-283. 2 0 . ______, Gomness, N. C., and Sherwood, L. V., The influence of soil aggregate stabilizers, VAMA and HPAN, on stand, composition, and yield of crops on calcareous soils of southern Arizona. Ariz. Expt. Sta. Tech. Bui. 129. 21. ______and Gairand, C., 1954, The influence of soil aggregate stabilizers on the biological activity of soils. Soil Sci. Soc. Amer. Proc. 18:35-40. 22. Geohegan, M. M. and Brian, R. C., 1948, Aggregate form ation in soil. I Influence of some bacterial poly saccharides on the binding of soil particles. Biochem. Jour. 43:5-13. 95 23. Geohagan, M. J. and Brian, R. C., 1948, Aggregate formation in soi. 2. Influence of various carbo hydrates and proteins on aggregation of soil particles. Biochem. Jour. 43:14. 24. Gilmour, C. M., Allen, 0. N. and Truog, E., 1948, Soil aggregation as influenced by the growth of mold species, kind of soil, and organic matter. Soil Sci. Soc. Amer. Proc. 13:292-296. 25. Hagin, J. and. Bodman, G. B., 1954, Influence of the polyelectrolytes-CRD-186 on aggregation and other physical properties of some California and Israeli soils and some clay minerals. Soil Sci. 78:367-578. 26. , 1952, Influence of soil aggregation on plant growth. Soil Sci. 74:471-478. 27. Hedrick, R. M. and Mowry, D. T., 1952, Effect of synthetic polyelectrolytes on aggregation, aeration, and water relationships of soil. Soil Sci. 73:427-441. 28. ______, 1954, Laboratory evaluation of poly electrolytes as soil conditioners. Jour, of Ag. and Pood Chem. 2:182-185. 29. Haise, H. R., Jensen, L. R., Alessi, J., 1955* The effect of synthetic soil conditioners on soil structure and production of sugar beets. Soil Sci. Soc. Amer. Proc. 19:17-19. 30. Hely, P. W., Bonnier, C. and Manil, P., 1954, Investi gations concerning nodulation and growth of lucerne seedlings in a loess soil artificially aggregated to various levels. Plant and Soil 5:121-131. 31. Hubbell, D. S. and Stubblefield, T. M., 1948, The effects of soil amendments on soil aggregates and on soil water movement. Soil Sci. Proc. 13:519-522. 32. Kitson, R. E,, and Mellon, M. G., 1944, Colorimetric determination of phosphorus as molybdivanado phosphoric acid. Ind. Eng. Chem., Anal. Ed. 16:379-583. 33. Kroth, E. M. and Page, J. B., 1947* Aggregation forma tion in soils with special reference to cementing substances. Soil Sci. Soc. Amer. Proc. 11:27-34. 96 24. Laws, W. D. and Page, J. B., 1946, Silicate of soda as a soil aggregating agent. Jour. Amer. Soc. 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B., 1954, Chemical effects of a soil conditioner upon plant composition and uptake. Ag. and Pood Chem. 2:463-468. 43. Martin, J. P. and Waksman, S. A., 1940, Influence of microorganisms on soil aggregation and erosion. Soil Sci. 50:29-47. 44. and , 1941, Influence of microorganisms on soil aggregation and erosion: II Soil Sci. 52:381-394. 45.__ , 1942, The effect of composts and com post_materials upon the aggregation of the silt and clay particles of Collington sandy loam. Soil Sci. Soc. Amer. Proc. 7:218. 97 46. Martin, J. P., 1945# Microorganisms and soil aggre gation; I. Origin and nature of some of the aggre gating substances. Soil Sci. 59:162-174. 47. , 1946, Microorganisms and soil aggre gation: II. Influence of bacterial polysaccharides on soil structure. Soil Sci. 61:157-166. 48. ______and Aldrich, D. G., 1954, Influence of soil exchangeable cation ratios on the aggregating effects of natural and synthetic soil conditioners. Soil Sci, Soc. Amer. Proc. 19:50-54. 49. ______and Jones, W. ¥., 1954, Greenhouse plant response to vinyl acetate maleic acid copolymer in natural soils and in prepared soils containing high percentages of sodium or potassium. Soil Sci. 7 8 :517- 524. 50. Martin, T. L. and Anderson, D. A., 1942, Organic matter decomposition, mold flora, and soil aggregation relationships. Soil Sci. Soc. Amer. Proc. 7*215. 51. Martin, ¥. P.,Taylor, G. G., Engibous, J. C., Burnett, E., 1952, Soil and crop responses from field applica tions of soil conditioners. Soil Sci. 75*455-471. 52. ______, 1955j Status report on soil condition ing chemicals. I. Soil Sci. Soc. Amer. Proc. 17*1-9. 55. Mort'eilsen, J. L. and Martin, ¥. P., 1954, Decomposi tion of the soil conditioning polyelectrolytes, HPAN and VAMA in Ohio soils. Soil Sci. Soc. Amer. Proc. 18:595-598. 54. , 1955# The effect of synthetic poly electrolytes on certain biochemical and biophysical properties of some Ohio soils. Ph. D. Thesis, Ohio State University. 55. ______and Martin, ¥. P., 1955, Effect of soil conditioner-fertilizer interactions on soil structure, plant growth, and yield. Soil Sci. (In press). 56 . Moser, P., 1959, The influence of cropping practices on some physical and chemical properties of soil. Soil Sci. 48:421-451. t> 98 57. Myers, H. E. and McCalla, T. M., 1941, Changes in soil aggregation in relation to bacterial numbers, hydrogen-ion concentration and length of time soil was kept moist. Soil Sci. 51:189-200. 58. Nielsen, Kenneth P., 1952, The influence of alfalfa green manure on the availability of phosphorus to plants. Ph.D. Thesis, Ohio State University. 59. Oberholzer, P. C. J., 1956, The decomposition of organic matter in relation to soil fertility in arid and semi-arid regions. Soil Sci. 42:559-577* 60. Olmstead, L. B., 1946, The effect of long-time crop ping systems and tillage practices upon soil aggre gation at Hays, Kansas. Soil Sci. Soc. Amer. Proc. 11j89-92. 61. Page, J. 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W., 1952, Mechanism of clay aggregation by polyelectrolytes. Soil Sci. 75:485-492. 99 69 . Rynasiewicz, J., 1945* Soil aggregation and. onion yields. Soil Sci. 60:287. 70. Sayre, C. B., 1942* Starter solutions for tomato plants. Bulletin No. 706. New York State Agri. Expt. Sta. 71. Sherwood, L. V. and Engibous, J. C., 1955* Status report on soil conditioning chemicals. IT. Soil Sci. Soc. Amer. Proc. 17:9-16. 72. Stanford, G. and Pierre, W. H., 1947* The relation of potassium fixation to ammonium fixation. Soil Sci. Soc. Amer. Proc. 11:155-160. 72. Swaby, R. J., 1950, Influence of humus on soil aggre gation. Jour. Soil Sci. 1:182-194. 74. Swanson, D. L. W. and Jacobson, H. G. M., 1955* Effect of aqueous solutions of soil conditioner chemicals on corn seedlings grown in nutrient solu tions. Soil Sci. 79:122-146. 75. Taylor, G. S. and Baldrige, P. E., 1954, The effect of sodium carboxymethylcellulose on some physical properties of Ohio soils. Soil Sci. Soc. Amer. Proc. 18:282-285. 7 6 . Van Bavel, C. H. M., 1950, Ude of volatile silicones to increase water-stability of soil. Soil Sci. 70: 291-297. 77. Walkley, A. and Black, I. A., 1954, An examination of the Degtjareff method for determining soil organic matter,and a proposed modification of the chromic acid titration method. Soil Sci. 27:29-58. 7 8 . Weeks, L. E. and Colter, W. G., 1952, Effect of syn thetic soil conditioners on erosion control. Soil Sci. 75:475-484. 79. Wester, R. E., 1955* Response of vegetable crops to soil conditioners. Agri. Chem. 8 , 7:48-50. 80. Woodruff, C. M., 1929* Variations in the state and stability of aggregation as a result of different methods of cropping. Soil Sci. Soc. Amer. Proc. 4:12-18. 100 81. Worsham, W. E. and Sturgis, M. B., 1942, Factors affecting the availability of K in soils of the lower Mississippi Deltas. Soil Sci. Soc. Amer. Proc. 6:342-347. 82. Wright, C. H., 1934, Soil Analysis, Thomas Murby and Co., London. 83 . Yoder, R. E., 1936, A direct method of aggregate analysis and a study of the physical nature of erosion losses. Jour. Am. Soc. Agron. 28:337-351. APPENDIX 102 Table I. Analysis of variance for the effect of apply ing soil conditioners at various rates by different methods on soil aggregate stability. Variation D.F. S.S. M.S. F Spray method Soils and Conditioners 8 2,458.39 307.3 7.28 Rate 5 11,505,00 3,835.0 50.4 Error 24 1,826.50 76.1 Total 35 15,789.89 Hedrick's method Soils and Conditioners 8 6,043.06 755.38 7.58 Rate 3 11,486.33 3,828.77 38.46 Error 24 2,369.17 99.55 Total 35 19,918.53 Pouring method Soils and Conditioners 8 2,699.5 337.4 15.28 Rate 3 3,051.88 1,729.33 78.35 Error 24 529.62 22.07 Total 35 6 ,281.00 Bartlett's test of homogeneity D.F. M,,S. error log s2 „ -2 24 99 1.9956 m e a n o f s « 62.3 24 76 1.8808 log s _ 2 = 1.7945 24 22 1.3424 n log s = 3(1.7945) O = 5.3835 L log sfc = 5.2188 72 187 5.2188 difference.1647 X 2 = loge 10 (D.F. of individual s2)(no. of variances compared) -1 = 2.3 (24)(.1647) =9.1017 degrees of freedom for7f= 2. Probability value lies between .05 and .02. 103 Table II. Analysis of variance for ammonium extracted with acid-sodium chloride. Variation D. F. S.S. M.S. F Treatments 7 325,611.5 46,515.93 2 4 .7^ Error 24 45,092 1,878.33 Total 31 370,703.5 Table III. Analysis of variance for potassium extracted with ammonium acetate. Variation D. F. S.S. M.S. F Replications 3 103.68 34.56 Treatments 9 309,354.53 34,372.725 382. 47 ^ Conditioner 1 29,539.23 29,539.23 328.69** Fertilizer 4 262,474.15 65,618.537 730.15** Interaction 4 17,341.15 4,335.288 48.23** error 27 2,426.57 89.87 Total 39 311,884.78 ♦♦Significant at 1 per cent level. 104 Table IV. Analysis of variance fdr corn yield-Miami Silt Loam-greenhouse. Variation D.F. S.S. M.S. F Replications 3 22.43 7.477 2.69 Treatments 8 200.17 25.021 9.00^ Fertilizer 2 3.76 1.88 Conditioner 2 169.78 84.89 30.53** Interaction 4 26.63 7.66 2.75 Error 24 66.76 2.78 Total 35 289.36 ♦♦Significant at the 1 per cent level. Table V. Analysis of variance for tomato yields - starter solution treatments Northwest Substation 1953. Variation D.F. S.S. M.S. F Replications 11 158.17 14.379 .38 Fertilizers 3 114.24 38.08 4.22# Error (a) 33 297.51 9.01 Conditioners 2 1.58 .79 .09 Interaction 6 50.85 8.475 1.23 Error (b) 88 603.16 6.854 Total 143 1,225.51 ♦Significant at the 5 per cent level. 105 Table VI. Analysis of variance for corn yields Horticulture Farm, Ohio State University 1952. Variation D.F. S.S. M.S. F Treatments 5 145.0625 47.687 2.27 Error 20 419.71875 20.9859 Total 25 562.781 Table VII. Analysis of variance of aggregation on Trumbull clay - Agnew Farm - October 5# 1952. Variation D.F. S.S. . M.S. F Treatments 2 2,675.76 1,557.88 16.28^ Error 27 2 ,218.76 82.176 Total 29 4,894.52 ♦♦Significant at the 1 per cent level. Table VIII. Analysis of variance for tomato stands. Crust control treatments-Northwest Substation- 1954. Variation D.F. S. S. M. S. F Replications 4 8,855.75 2,213.95 3.43* Treatments 7 23,280.775 5,525.825 5.I5** Error 28 18,085.85 645.92 Total 39 50,222.38 Orthogonal comparisons among treatments Variation D.F. S. S. £3. S. F Spray vs. Jet 1 4,750.625 4,750.625 7.52* Water (sprayed) vs. Cond. (sprayed) 1 7,548.267 7,548.267 11.38** Water (jet) vs. Cond.(jet) 1 11,016.150 11,016.150 17.05** HPAN (sprayed) vs. IBMA & SMA (sprayed) 1 80.035 80.035. IBMA (sprayed) vs. SMA (sprayed) 1 4.900 4.900 HPAN (jet) vs. IBMA & SMA (jet) 1 43.200 43.200 IBMA (jet)vs. SMA (jet) 1 57.600 57.600 Treatments Total 7 23,280.775 ♦Significant at the 5 per cent level. ** Significant at the 1 per cent level. AUTOBIOGRAPHY I, Milton Bennion Jones, was born in Cedar City, Utah, January 15, 1926, and received my secondary school educa tion in the public schools of that city. I obtained my undergraduate training at Arizona State College, Flagstaff, Arizona, in 1944-45 in the Navy V-12 training program; Branch Agricultural College, Cedar City, Utah, in 1947-48, and Utah State Agricultural College, Logan, Utah, in 1948-49 and 1951-52, from which I received the degree Bachelor of Science in March, 1952. From July 1944 until June 1947# I served in the U. S. Navy. In April, 1952, I received an appointment as Research Fellow at the Ohio Agricultural Experiment Station, where I specialized in the Department of Agronomy. I held this position and consecutively the positions of Research Assistant, Assistant Instructor, and Research Assistant during a three-and-a-half year period while completing the requirements for the degree Doctor of Philosophy.