I 9 9 6 N u m her 1 Now Inc I uding Intern ationa I Topics

m Ji ; 1

In This Issue

Aglime Benefits C O IN T E N T S BETTER Spring-Applied Aglime Can Provide 3 Immediate Soybean Response (Midsouth) CROPS C.S. Snyder, J.H. Muir and G.M. Lessman WITH PLANT FOOD Short-term Soil Chemical and 6 Crop Yield Responses to Aglime Vol. LXXX (80) 1996, No. 1 Applications (Virginia) Our Cover: Spreading aglime — an important management M.M. Alley practice for crop production. Photos: J.C. Allen & Son, Inc. Time to Re-Apply Lime to Orchards 8 Design: Design RT in Washington? (Washington) Timothy J. Smith Editor: Donald L. Armstrong Assistant Editor: Kathy A. Hefner Editorial Assistant: Katherine P. Griffin Aglime: A Low-Cost Alternative Source 10 Circulation Manager: Carol Mees of Calcium for Peanuts (Georgia) Gary J. Gascho Potash & Phosphate Institute (PPI) J.U. Huber, Chairman of the Board Kalium Chemicals Liming Acid Soils for Ryegrass 14 CO. Dunn, Vice Chairman of the Board Production (Texas) Mississippi Chemical Corporation Vincent A. Haby, Jeff B. Hillard and Greg Clary HEADQUARTERS: NORCROSS, GEORGIA, U.S.A. D.W. Dibb, President Lime Needs under No-till Conditions 16 B. C. Darst, Executive Vice President (Pennsylvania) R.T. Roberts, Vice President Douglas B. Beegle CV. Holcomb, Asst. Treasurer S.O. Fox, Executive Secretary W.R. Agerton, Communications Specialist International Soil Fertility Manual 18 S.K. Rogers, Statistics/Accounting Now Available

MANHATTAN, KANSAS L.S. Murphy, Senior Vice President Fun with the Plant Nutrient Team 19 North American Programs Activity Book Available

REGIONAL DIRECTORS-North America Foliar Boron Application Enhances 20 T.W. Bruulsema, Guelph, Ontario P.E. Fixen, Brookings, South Dakota Almond Yield (California) A.E. Ludwick, Mill Valley, California Patrick Brown, Hening Hu, H.F. Reetz, Jr., Monticello, Illinois Agnes Nyomora and Mark Freeman T.L. Roberts, Saskatoon, Saskatchewan C. S. Snyder, Conway, Arkansas N.R. Usherwood, Norcross, Georgia Bahiagrass Response to Dolomitic 23 Limestone (Florida/Research Notes) INTERNATIONAL PROGRAMS Saskatoon, Saskatchewan, Canada M.D. Stauffer, Senior Vice President, International Research Tracks Nitrogen Dissipation 24 Programs (PPI), and President, Potash & Patterns in Rice Production (Texas) Phosphate Institute of Canada (PPIC) Garry N. McCauley J. Gautier, Dir., Admin. Serv.

INTERNATIONAL PROGRAM LOCATIONS Information Agriculture Conference 26 Brazil-POTAFOS T. Yamada, Piracicaba Planned for July 30 - August 1, 1996 China S.S. Portch, Hong Kong J. Wang, Hong Kong Jin Ji-yun, Beijing Conversion Factors for 27 Wu Ronggui, Beijing Metric and U.S. Units India G. Dev, Dundahera, Gurgaon Latin America J. Espinosa, Quito, Ecuador 28 Mexico I. Lazcano-Ferrat, Queretaro Liming Tropical Soils — A Management Southeast Asia E. Mutert, Singapore Challenge (South America) Jose Espinosa BETTER CROPS WITH PLANT FOOD (ISSN:0006-0089) is published quarterly by the Potash & Phosphate Institute (PPI). Second-Class Dr. R.L. Yadav Receives 1995 31 postage paid at Norcross, GA, and at additional mail­ PPIC-FAI Award for Research ing offices (USPS 012-713). Subscription free on request to qualified individuals; others $8.00 per year Plant and Human Nutrition 32 or $2.00 per issue. POSTMASTER: Send address changes to Better Crops with Plant Food, 655 Engineering J. Fielding Reed Drive, Suite 110, Norcross, GA 30092-2843. Phone (770) 447-0335; fax (770) 448-0439. Copyright 1996 by Potash & Phosphate Institute

Members: Agrium Inc. • Cargill, Incorporated • CF Industries, Inc. • Farmland Hydro, Inc. • Great Salt Lake Minerals Corporation • IMC Global Inc. • Kalium Chemicals )i Chemical Corporation • New Mexico Potash • Potash Company of Canada limited • Potash Corporation of Saskatchewan Inc. • Western Ag-Minerals Company M I D S O U T H Spring-Applied Aglime Can Provide Immediate Soybean Response

By C.S. Snyder, J.H. Muir and G.M. Lessman

"aintaining proper soil pH is the eral months. Even larger particles within foundation of a good soil fertility the range of 10 to 60 mesh may require a .and nutrient management pro­ year or longer to neutralize soil acidity. gram. Agricultural limestone (aglime) use Other liming materials include fluid where needed remains a good investment or suspension lime and pelletized lime. and is a critical best management practice Fluid lime is a mixture of fine lime (often (BMP) in crop produc­ 200 mesh or finer), water, tion. With increased Research in the Midsouth and a suspending agent in nitrogen (N) use for rota­ shows that application of about a 50:50 mix of water tional crops, larger good quality agricultural and fine lime particles. amounts of crop residues limestone can have benefi­ Pelletized lime is fertilizer associated with reduced cial effects on soybean granule-sized pellets made tillage practices, and yields even when applied from relatively fine lime­ higher yields, soil acidity immediately prior to planting stone particles. As much as and aglime needs should 50 to 70 percent of the be monitored through soil testing. aglime used to make the pellets is 100 Many farmers believe that if they mesh or finer. The finalpelle t size is com­ don't apply aglime at least six months parable to fertilizers so that pelletized ahead of the crop, they won't see a bene­ lime may be spread by conventional fer­ fit. While it is best to apply aglime and tilizer spreaders. incorporate it well in advance of the tar­ In central Arkansas, aglime costs geted crop, university research in the range from $12 to $24 per ton spread. The Midsouth U.S. indicates good crop price of pelletized lime often ranges from responses can be experienced when it is $90 to over $100 per ton spread. Fluid or applied as late as planting time. suspension lime may be priced near $30 per ton spread. This equates to about $60 Liming Materials per ton of dry, high quality aglime. High quality aglime has a calcium Transportation distance is one of the carbonate equivalence (purity) of 90 per­ major factors affecting the price of the cent or more. It also has a desirable dis­ various sources. tribution of effective particle sizes. In quality aglime, 90 percent of the particles Comparison of Liming Materials pass a 10 mesh sieve, 40 percent pass a Applications of 250 to 300 lb/A of 60 mesh sieve, and 25 percent pass a 100 pelletized lime have been suggested as a mesh sieve. Each ton may contain 500 lb substitute for one ton of aglime. At a 250 or more of fineparticle s that begin to neu­ to 300 lb/A rate of pelletized lime, costs tralize soil acidity immediately. Larger might range from $11 to $15 per acre. particles (60 to 100 mesh) react over sev­ Lower rates are normally intended only to

Better Crops/VoL 80 (1996, No. 1) 3 maintain soil pH at present levels, or to prevent further pH decline. Arkansas research with aglime and pelletized lime was recently conducted on a Loring silt loam soil 250 lb/A with a 3 to 8 percent slope and a 4.8 pelletized 500 lb/A water pH, using no-till soybeans pelletized 1,000 lb/A (nonirrigated) doublecropped after pelletized wheat. Liming materials were 14 18 22 26 applied in early July and a disk was Soybean yield, bu/A used to very lightly scratch the soil FIGURE 1. Doublecropped soybean responses to surface to help ensure the materials aglime and pelletized lime. stayed in place on the slope. The Source: Muir et al., Arkansas results indicate that it would take about 500 to 700 lb/A of pelletized • Low rates (250 lb/A) of pelletized lime to equal the soil reaction and soy­ lime are not an agronomic or economic bean yield response from one ton of good substitute for one ton of good quality quality aglime (Figure 1). Both were aglime. effective in increasing no-till soybean • It may take 1,000 lb/A or more of yields even with minimal incorporation. fluid lime (50 percent water: 50 percent Similar work with soil-incorporated 100 to 200 mesh fine limestone) or 500 to fine lime (100 mesh) and aglime has been 900 lb/A of pelletized lime to provide the conducted in Tennessee. The fine lime material was suspended in 0) water and applied as fluid lime. g Check Figure 2 illustrates the pH S= 300 lb/A £» 400 lb/A response measured within 100 days "O 500 lb/A of application. Little change in soil 75 1,000 lb/A 3 1 ton/A pH was noted until lime rates were aglime O 2 tons/A 1,000 lb/A or greater. aglime First-year soybean lime 5 5.2 5.4 5.6 5.8 6 responses in Tennessee (Figure 3) Soil pH were about 6 bu/A and peaked at the FIGURE 2. Soil pH 100 days after lime application. recommended rate of 2 tons/A of Source: Lessman, Tennessee aglime. A rate of about 500 lb/A of fine lime was required to produce a significant yield response. Responses same short-term response as one ton of over a five-yearperio d (Figure 4) of con­ good quality aglime. tinued aglime application rose to about 14 • Use of low rates of pelletized lime or bu/A with a net application of 4 tons/A. fluid lime will probably result in a need to Summing up, here are several re-lime sooner than if recommended rates guidelines. of aglime are used. • Recommended rates of good quali­ • If pelletized lime is used, it should ty aglime can significantly change soil pH be allowed to "melt-down" with rain or within 100 days of application, and fre­ irrigation before soil incorporation. quently within 45 to 60 days, if properly Subsurface banding of lime has failed to incorporated. show any practical yield benefits com-

4 Better Crops/Vol 80 (1996, No. 1) pared to broadcast, soil-incor­ porated aglime at recom­ mended rates. Recommended rates of aglime applied ahead of soy­ bean planting have resulted in yield increases of 4 to 10 bu/A or more the first year, and also for the next three to seven years. One of the major benefits from liming is an increase in the availability of soil molybdenum (Mo) when SOYBEAN DEVELOPMENT suffered in this field area with soil pH of the soil pH is increased. If the 4.1. Manganese toxicity also affected the plants, with "crinkle decision is made not to lime leaf" symptoms. acid soybean land, then a Mo seed treatment should be con­ sidered. When soils are strongly

£ Check acidic and Mo is not used, response = 300 lb/A to applied phosphorus (P) and potas­ 400 lb/A sium (K) may be limited. Maximum •° 500 lb/A efficiency in nutrient uptake by 75 1,000 lb/A plants will not be realized unless the £ 1 ton/A

tS aglime root environment is maintained in 2 tons/A < aglime 22 26 the desirable pH range, usually 5.8 Soybean yield, bu/A to 6.5 for southern soybeans. 03

FIGURE 3. Aglime effects on soybean yields Dr. Snyder is Midsouth Director, PPI, P.O. -first year. Drawer 2440, Conway, AR 72033-2440. Dr. Source: Lessman, Tennessee Muir is Associate Professor of Soil Fertility, School of Agriculture, Arkansas State University, P.O. Box 2340, State University, E Check AR 72467. Dr. Lessman is Professor of Soil 300 lb/A Fertility, Dept. of Plant and Soil Sciences, 400 lb/A 375 Plant Science Bldg., Knoxville, 77V 500 lb/A 37996. 75 1,000 lb/A 3 1 ton/A +* aglime 2 tons/A 3 agli 18 22 26 30 Soybean yield, bu/A

FIGURE 4. Annual aglime application effects on soybean yields - five-year average. Source: Lessman, Tennessee

Better Crops/Vol 80 (1996, No. 1) 5 V 11 R G 11 N m Short-term Soil Chemical and Crop Yield Responses to Aglime Applications

By M.M. Alley

rop yields are reduced on acid soils ent that increases in availability as soil due to toxic concentrations of alu­ pH increases. Moreover, other soil organ­ C minum (Al) and, in some soils, isms that decompose organic matter and manganese (Mn). The availability of contribute to the general health of soils applied and residual soil phosphorus (P) are most active at soil pH levels of 6.0 to in mineral soils is maximized when soil 7.0. Finally, many herbicides lose pH levels are between 6.0 effectiveness as soils and 6.5, as is the reten­ Recommendations for become acid. tion and availability of aglime use generally call for Recommendations for applied potassium (K). application at least 2 to 6 aglime use generally call For legume crops, the months prior to planting due for an application at least to the slow rate of soil-lime nitrogen (N) fixing capac­ 2 to 6 months prior to plant­ reaction. Virginia studies ity of Rhizobia bacteria is ing due to the supposedly show that soil chemical slow rate of soil-limestone maximized at pH levels properties change rapidly between 6.0 and 7.0. and that crop yields increase reaction. In practice, much Rhizobia need high levels with aglime applications aglime is applied immedi­ of available calcium (Ca) made immediately prior to ately prior to planting and magnesium (Mg), as planting on acid soils. because of soil and crop well as adequate supplies conditions, or the applica­ of molybdenum (Mo), the only micronutri tion is delayed because of the belief that

TABLE 1. Liming affects soil pH, exchangeable soil Ca and Mg. It also decreases exchangeable Al and lowers Al saturation of the soil's exchange complex. Goldsboro sandy loam Pacolet sandy clay loam Exchangeable Exchangeable Lime rate, Ca Mg Al Al sat.1, Ca Mg Al Al sat.1, tons/A pH meq/100 g % PH meq/1001J % 0.0 4.1 0.21 0.08 1.66 76 5.3 1.94 0.89 0.27 8

0.5 4.6 0.38 0.24 1.15 56 - - - - -

1.0 4.6 0.53 0.40 0.56 33 5.9 2.06 1.01 0.04 1

2.0 5.0 0.74 0.54 0.32 18 5.9 2.30 1.12 0.02 1

3.0 - - - - - 6.2 2.40 1.19 0.02 1

4.0 5.2 1.01 0.78 0.04 2 6.2 2.40 1.20 <0.01 <1

6.0 5.5 1.20 0.95 0.02 1 6.5 2.80 1.33 <0.01 <1 8.0 - - - - - 6.4 2.80 1.40 <0.01 <1

Sampled 16 weeks after liming. Virginia 1 Percent Al saturation = Exchangeable Al x100 Exch. Ca + Exch. Mg + Exch. K + Exch. Al

6 Better Crops/Vol. 80 (1996, No. 1) little benefit will be obtained by TABLE 2. Good quality aglime soil incorporated the initial crop. This article immediately prior to planting can reports on studies that were con­ significantly increase crop yields. ducted to quantify initial crop Goldsboro soil Pacolet soil Frederick soil yield benefits as well as soil Lime rate, Corn yield, Barley yield, Alfalfa yield, chemical changes that occur soon tons/A bu/A bu/A lb/A after aglime applications. 0.0 21 49 303 0.5 87 Virginia Studies 1.0 105 61 1,229 Three acid soils on growers' 2.0 104 56 1,674 3.0 56 1,817 farms were used for these studies: 4.0 110 65 2,191 a Goldsboro sandy loam (Coastal 6.0 121 60 2,262 Plain region), a Pacolet sandy 8.0 59 2,369 clay loam (Piedmont region), and Virginia a Frederick silt loam (Valley region). A commercially-available dolo- yields were related to increases in soil pH mitic aglime, containing 54 percent calci­ and exchangeable Ca and decreases in um carbonate and 43 percent magnesium exchangeable Al. Barley responses to carbonate, was utilized for these studies. limestone on the Pacolet soil were limited The particle size distribution of this by severe winter-kill which resulted in aglime was 88, 60 and 50 percent passing variable yield data. 20, 60 and 100 mesh sieves, respectively. The aglime was applied at various rates Summary and incorporated with tillage immediately Soil pH and exchangeable soil Ca prior to planting each crop. Corn was and Mg increased, and exchangeable Al planted on the Goldsboro soil, barley on levels decreased during the 16-week the Pacolet, and alfalfa on the Frederick. (continued on page 9)

Results Lime treatments increased surface soil pH at all locations within 16 weeks of application (Table 1), and other observa­ tions showed measurable increases in soil pH two weeks after aglime application. Exchangeable Ca and Mg levels were increased and exchangeable Al levels decreased with aglime application. These effects are reasonable responses because the aglime particles passing a 100 mesh sieve can be expected to be almost imme­ diately reactive in acid soils. Corn, barley and alfalfa yields were all increased with aglime applications GOOD QUALITY aglime can have immediate effects (Table 2). Regression analyses indicated on crop growth and yield. Corn plants in the fore­ that corn yield increases were strongly ground are growing on an unlimed area. Liming associated with reductions in exchange­ produced the growth difference shown by plants able Al levels, while first-cutting alfalfa in background.

Better Crops/Vol 80 (1996, No. 1) 7 WASHINGTON Time to Re-Apply Lime to Orchards in Washington?

By Timothy J. Smith

The Problem move into the soil by irrigation and winter pre­ n the mid-1980s, fruit growers of north cipitation. central Washington realized that soil Local studies carried out in the 1970s IpH had dropped to dangerously low showed that orchard soil pH would even­ levels in a band about 10 feet wide and 3 tually be affected by aglime application, feet deep under tree rows. Many growers even two or three feet deep. The top foot tested blocks in their of soil, however, was most orchards and applied 2 to Liming orchards in north rapidly affected and its pH 4 tons/A of high quality central Washington often was increased the most. aglime where pH was visibly improves tree growth For example, pH of the top found to be too low. Soils within a year of applica­ foot in one experiment are primarily sandy loam tion...even when aglime is went from 4.5 to 6.5 after in texture, ranging from surface applied. eight years, while pH in sand to loam. the second foot increased from 5 to 6. The Solution The rapid tree response common in In orchards where aglime was spread, treated orchards apparently happens tree growth often visibly improved within a when aglime raises the soil pH in only the year of application. Nitrogen (N) fertilization top few inches. There is a high level of was halted or greatly cut back for a few sea­ tree root activity in the surface 6 inches. sons to control tree vigor. Symptoms of man­ That means trees can take advantage of ganese (Mn) toxicity (bark measles), which is the benefits of topdressed aglime, such as common on spur-type Red Delicious apples enhanced nutrient release, before much growing in low pH soil, was reduced or totally pH correction has taken place in the cured. Leaf size and upper 6 to 12 inch­ color were also es. Although im­ improved. proving the pH All of these posi­ throughout the soil tive effects occurred profile will have a despite the fact that less dramatic effect aglime was surface and will take applied, although decades to accom­ incorporation is rec­ plish, it is neces­ ommended for most sary for long-term rapid benefit. Aglime tree health. dissolves very slowly AGLIME application in a pple orchards of At the time the in water and may Washington state can offer several benefits to 1980s liming boom require many years to improve production. took place, univer-

8 Better Crops/VoL 80 (1996, No. 1) sity and Extension personnel advised Assessing pH trends at the three depths growers that surface applied aglime will indicate the progress of the aglime worked slowly and that high rates were no application. If the pH of the surface 6 more effective than 2 to 4 tons/A. The rec­ inches is well above 7.0, then there is still ommended approach was to apply 2 tons, free aglime present and applying more wait a couple of years, apply 2 more tons, will not necessarily speed the correction then give the aglime a number of years to of pH at lower depths. On the other hand, become fully effective. if the surface pH is near or below 7.0, and About 6 to 10 years have passed the second foot is 6.0 or less, the orchard since liming was emphasized in area is probably ready for more lime. orchards, and it may be time for assess­ ment and possible re-treatment. Most Summary orchards have built up a "lime debt" of The positive effect of proper soil pH for at least 8 to 10 tons/A over the past 20 fruit production is too important to overlook. years, so we will need to continue com­ Trees pick up important nutrients...especially ing back to this issue for another decade N, calcium (Ca) and phosphorus (P)...much or so before we can return to a mainte­ more efficiently when pH is above 6.0. Since nance mode. considerable time and money can be spent Soil pH can be sampled any time the improving the nutrient status of trees by apply­ soil is not frozen. Samples should be ing various fertilizer products, it makes sense taken from the top 6 inches, 6 to 12 inch­ to maximize their potential benefit with a es, and 12 to 24 inches, taking care to proper liming program. 09 prevent cross contamination between the samples (e.g., sluffing of surface soil into Mr. Smith is Washington State University Area the sampling hole may result in an artifi­ Cooperative Extension Agent for Chelan, Douglas, cially high pH for the deeper samples). and Okanogan counties, Wenatchee, WA.

Responses to Aglim • • • continued from page 7 period following dolomitic aglime appli­ sieve, will react immediately with soil cation to three acid soils typical of the acidity and increase crop yields. mid-Atlantic region. More importantly, Finally, one of the most difficult sit­ crop yields were increased, and these uations for a grower is to suffer yield increases were directly associated with losses due to acid soils, and then face the changes in soil chemical properties the prospect of a large cost per acre for from aglime applications made at plant­ liming. Regular soil testing and aglime ing. Data clearly indicate that crops use must be a part of the farm manage­ planted into acid soils do respond ment program each year so that costs immediately to aglime applications. are not too great in any one year, and Aglime applications should never be soil pH values do not fall to levels that postponed because of the belief that result in crop yield reductions. Liming aglime reaction will be slow. Aglime acid soils is the foundation for an effi­ with a relatively high calcium carbonate cient crop production program. 09 equivalency (85 percent or greater) and a significant portion (30 percent or Dr. Alley is Professor of Agronomy, Virginia more) of particles passing a 100 mesh Polytechnic University, Blackshurg, VA.

Better Crops/Vol. 80 (1996, No. 1) 9 G E R G Aglime: A Low-Cost Alternative Source of Calcium for Peanuts

By Gary J. Gascho

alcium is often considered the deficiency are blackened plumules, high essential element most commonly incidences of pod rot, and unfilled pods C deficient for peanuts in noncalcare- (termed "pops") resulting in low yield and ous soils. The need for Ca in peanuts is substandard grade. Seed peanuts produced exceptionally high and its uptake by the in Ca-deficient conditions will exhibit peanut plant is unique. The fruit develops much poorer germination than those by absorbing nutrients produced with an adequate directly from the soil as Farmers are looking for meth­ Ca supply. opposed to nutrients ods to decrease their input being absorbed by roots, costs for peanuts due to the Soil Effects transported to shoots and decreasing support prices. In Peanuts are most often back to the fruit. It is this many instances, using aglime grown on sandy soils which unique aspect that has in the pegging zone to supply have limited ability to sup­ required much research calcium (Ca) for fruit develop­ ply Ca to replenish that in and which guides the ment as well as to provide the soil solution. Further, application of Ca for the proper soil pH for both such soils are often rela­ greatest yield, quality and peanuts and the rotational tively droughty. Since seed germination. crops will help them meet peanuts are relatively their objective. drought tolerant in compar­ Deficiency Symptoms ison to most plants grown in It is rare that Ca is deficient to the semi-humid regions, they are often grown point where peanut vine growth is stunt­ in locales with limited rainfall during ed. However, the growth of peanuts with­ some portion of pod and seed develop­ out supplemental Ca visibly suffers com­ ment. The problem of limited soil mois­ pared to peanuts with adequate Ca sup­ ture in the developmental period adds to plied by preplant-incorporated dolomitic the Ca deficiency problems of peanuts lime. The normal consequences of Ca since added Ca compounds will not dis-

Virginia-Type 1,087 lb 2,000 1,703 lb 1,500 1,439 lb 1,443 lb

1,000

500

0

Legend: I Calcite I Calcite/ I Dolomite I Dolomite/ & Gypsum No Gypsum & Gypsum No Gypsum

FIGURE 1. Increased yields of two types of peanuts due to calcite or dolomitic lime application preplant and gypsum at bloom.

10 Better Crops/Vol. 80 (1996, No. 1) Data combined from the literature for 168 experiments conducted in Alabama and Georgia with small-seeded, runner-type peanuts showed that 95 percent of maximum yield was obtained when soil test Ca (Mehlich 1 extractable) was 200 parts per million (ppm). For the larger-seeded Virginia-type, soil test Ca is less valuable since supplemen­ tal Ca is normally recommended regardless of the soil test level. Recently, data fromexperi ­ ments conducted in Alabama, Georgia, North Carolina and Virginia were combined to show the effect of soil Ca on relative yield of GROWTH of peanuts without supplemental Ca (on left) suf­ Virginia-type peanuts. Maximum yield was fers compared to peanuts with adequate Ca supplied by attained at about 525 ppm Mehlich 1 Ca. preplant-incorporated dolomitic lime (on right). Calcium Sources solve or move to the pod without soil mois­ Getting soluble Ca into the pegging ture. Calcium in droughty soils is, therefore, zone and maintaining a supply to replen­ not rapidly replenished in the soil solution ish depletion by crop uptake and leaching close to the developing pod due low solu­ can be especially difficult in sands. Very bility of Ca sources and an inability to main­ soluble Ca sources such as calcium chlo­ tain a diffusion gradient toward the pod. The ride (CaCl2) are generally expensive and result is Ca deficiency. short-lived due to leaching losses.

Gypsum (calcium sulfate, CaS04) is much Predicting Calcium Needs less soluble, but its application on the soil Soil analysis is the most useful diag­ surface at first bloom is generally appro­ nostic tool for determining the need for priate for supplying Ca over the 60-day supplemental Ca fertilization. Samples period when there is a great requirement taken from the surface 6 to 8 inches prior for available Ca. to planting are often used. Soil test Ca in In addition to mined gypsum, byprod­ the pegging zone (top 3 inches), 10 to 14 uct and phosphogypsum are also available days following planting, has been an in many places at lower cost. When soil important diagnostic tool for determining Ca is less than the chosen threshold level, needs for supplemental Ca in the form of gypsum is either broadcast or banded over gypsum applied at bloom (BG) in Georgia. the peanut row at first bloom. Most prod-

Runner-Type Virginia-Type 400 ) r $564 350 0) T3 300 •S 250 200 150 S « 100 §•§ 50 II III

Legend: • Calcite I Calcite/ • Dolomite • Dolomite/ & Gypsum No Gypsum & Gypsum No Gypsum

FIGURE 2. Increased gross value of two types of peanuts due to calcite or dolomitic lime application preplant and gypsum at bloom.

Better CropsAbl. 80 (1996, No. 1) 11 ucts have a range of particle sizes that sol- ubilize over time to provide Ca. Gypsum has been a very successful source of Ca for peanuts; however, its application can add considerable cost to peanut produc­ tion. Dependent on source and recom­ mended rate of application, the applied costs may range from about $15 to $30/A. Aglime is an important source of Ca for peanuts grown in the acidic soils of the south­ eastern U.S. and other regions. The main response of peanuts to aglime is due to the ability to supply Ca, whether it was applied for that purpose or to increase soil pH. : J _ Field experiments conducted with run­ POD DEVELOPMENT in peanuts with adequate Ca is ner-type peanuts in Alabama prior to 1980 shown at left, in contrast with Ca-deficient indicated that aglime appeared to do little peanuts on the right. more than serve as a source of Ca and that spring-applied aglime provided all of the Ca rates required to increase pH to the rec­ needed for maximum yield and grade when it ommended value, did not supply ade­ was properly incorporated into the pegging quate Ca for the larger-seeded Virginia- zone. Since good farmers will lime their soils type peanut. A comparison of increased for their chosen crop rotation, they should yields of pods resulting from preplant- attempt to apply aglime in a manner that will incorporated calcite and dolomite (1,000 supply Ca to their peanut crop and thereby lb/A) with and without gypsum applica­ reduce or eliminate the expense of a gypsum tion at bloom (1,000 lb/A) is presented in application. When aglime was applied to the Figure 1. The BG application did not soil prior to planting and incorporated to a increase yield of pods above the increase shallow depth of 2 to 5 inches, adequate Ca provided by the aglime alone for runner- was usually available for runner-type peanuts type peanuts, indicating that the Ca since yield responses to gypsum applied at requirements for top yield were satisfied bloom were rare following such applications. by the aglime. Dolomite was superior to calcite for the runner-type peanuts on Georgia Studies sandy soils in Georgia only because soil Similar results were recently record­ magnesium (Mg) was very low. However, ed in Georgia for runner-type peanuts, but dolomite at 1,000 lb/A did not supply preplant-incorporated aglime, applied at enough Ca for Virginia-type peanuts as

Runner-Type

llll

Legend: • Calcite • Calcite/ • Dolomite • Dolomite/ & Gypsum No Gypsum & Gypsum No Gypsum

FIGURE 3. Effect of Ca source on germination of seed peanuts.

12 Better Crops/Vol. 80 (1996, No. 1) indicated by their additional response to aglime is applied prior to plowing, it will BG after receiving the dolomite. Most rota­ remain far below the zone of nut develop­ tional crops have a greater Mg requirement ment and not provide Ca needed by the than peanuts, and their needs must also be peanut. We found no benefit to runner- considered in a liming program. type peanuts for preplow application The gross value received for peanuts (turned under). Benefits were equal for is also dependent on quality (grade), gypsum at bloom and preplant-incorpo­ which includes several factors. Relations rated aglime (Figure 4). Postplant incor­ among Ca sources for runner-type peanuts poration to a depth of 3 inches was effec­ are similar for yield and value (Figure 2), tive in increasing gross value, but not as but value of the Virginia-type is increased effective as preplant incorporated. greatly by BG following preplant-incorpo­ rated aglime. Summary Germination of seed produced from Aglime preplant-incorporated for fields with inadequate Ca supplying runner peanuts is effective for reducing power is poor. Preplant-incorporated pod rot, for increasing pod yield and aglime is effective in increasing the ger­ increasing value per acre on sandy soils mination of seed produced (Figure 3), with pH less than 6 and a low Ca soil test. but gypsum applied at bloom increased Calcite and dolomite are both effec­ germination percentage even when tive for runner-type peanuts. Dolomite aglime had been applied preplant. For should be the material of choice for fields that reason, gypsum at bloom is always with low or medium soil test Mg and cal­ recommended for peanuts which will be cite the choice for soil with high Mg. used for seed. When soil pH is less than 6 and aglime is recommended, preplant incor­ Lime Placement poration also appears to be a good means Lime placement is critical. Most of applying Ca prior to planting Virginia- aglime applications are incorporated type peanuts. However, on sands, greatest much deeper than the peanut pegging yield, grade and value for the Virginia- zone either by harrows or plows. Nearly type peanut will be attained by applying all peanut fields in the southern U.S. gypsum at bloom, regardless of the lime peanut belt are turned by moldboard application. OH plowing in order to bury trash and provide a loose bed for fruit development and Dr. Gascho is Professor of Soil Fertility at the removal. The modern moldboard plow University of Georgia, Coastal Plain Experiment essentially inverts the top foot of soil. If Station, Tifton, GA.

Yield Value

$ „ 1,000 r 940 lb $ m 400 r s<3 mm 350 - i£L *J 800 " 692 1b §3 300 -

i| 600 - If 250 - $238

I§ 200 - 100-

Legend: • Turned • Preplant • Postplant under Incorporated Incorporated

FIGURE 4. Yield and gross value of runner-type peanut as affected by aglime placement.

Better Crops/Vol. 80 (1996, No. 1) 13 Liming Acid Soils for Ryegrass Production

By Vincent A. Haby, Jeff B. Hillard and Greg Clary

nnual ryegrass is an important (Mn). Ryegrass forage production the fol­ cool-season forage crop that may lowing year was 4,523 lb/A due to this Ai.b e seeded into a prepared seedbed treatment. An application of 1.7 tons/A of or overseeded into grass sods in the fall to aglime increased ryegrass forage yields to extend grazing into late fall, winter, and 5,379 lb/A. The unlimed soil produced spring in the southern and southwestern only 2,783 lb of forage per acre. U.S. In the Coastal Plain After three years of nitro­ area of Louisiana and Liming an acid soil for rye­ gen (N) treatments totaling Texas more than one mil­ grass production increased 1,214 lb/A for ryegrass and lion acres are planted to forage yields over a four-year Coastal bermudagrass, pH ryegrass each year. period. The value of in the soil treated with 1.7 Studies at the Texas increased forage yield for the tons of aglime/A had A&M University Agri­ 1986 season was estimated declined to 4.6, but rye­ cultural Research and to exceed $400 per acre. grass yield was still 5,415 Extension Center at lb/A. Extractable Al in soil Overton found that ryegrass is relatively treated with 0.3 ton of aglime/A was 23.4 intolerant to soil acidity. Strongly acid compared to 13.1 ppm at the 1.7 ton/A Coastal Plain soils, pH 4.0 to 5.0, normal­ aglime rate. Extractable Ca was 296 ppm ly have low levels of extractable calcium in soil treated with the high rate compared (Ca) and magnesium (Mg) and high levels to 162 and 169 ppm for the control and of extractable aluminum (Al). 0.3 ton/A rate of aglime, respectively. The Annual ryegrass is relatively intoler­ decreased extractable Al and increased ant to soil acidity. Marshall ryegrass level of extractable Ca appeared to relate response to incorporation of 1.7 tons/A of better to ryegrass yield than did soil pH. 62 percent effective calcium carbonate Figure 1 shows the greater neutral­ equivalent (ECCE) aglime into an acid izing effect of aglime with ECCE 100 as (pH 4.7) Lilbert loamy fine sand two years compared to ECCE 62 aglime on a Darco earlier is shown in the photo. Application of TABLE 1. Soil pH and Marshall ryegrass response to aglime aglime at a rate of 0.3 incorporated into a Lilbert loamy fine sand. ton/A on July 1 raised Aglime Fall of Dry matter Dry matter Dry matter soil pH from 4.7 to 4.8 rate. application 1984, pH, 1986, pH, 1987, by fall (Table 1). It tons/A year, pH lb/A 1985 lb/A 1987 lb/A decreased extractable soil Al from 23.4 to 19.6 0 4.7 2,783 4.5 3,434 4.5 633 parts per million (ppm), 0.3 4.8 4,523 4.7 4,576 4.5 981 1.7 5.7 5,379 6.2 7,422 4.6 5,415 and had no effect on soil extractable manganese Texas

14 Better Cwps/Vol 80 (1996, No. 1) FIGURE 1. Impact of aglime rate and effective APPLICATION of 1.7 tons of aglime per acre to a Lilbert

CaC03 equivalent (ECCE) on pH in soil with pH 4.7 increased forage yields an average the 0 to 6 inch soil depth two and a of 3,785 lb/A over three production seasons in a half years after treatment. Texas Agricultural Experiment Station study. loamy sand. One ton of ECCE 100 aglime Summary raised pH higher than did 2 tons/A of Recent Texas research on treatment ECCE 62. of acid, Coastal Plain soils with aglime for Economic estimates of the value of ryegrass production emphasizes the the ryegrass response to aglime applica­ improvement in forage yield that can be tions projected that had the increased for­ obtained. Producers need to think of age been grazed by stocker cattle weigh­ aglime as an investment that provides ing 450 lb each, the added monetary excellent returns over multiple years from return over the cost of the lime in 1986, increased ryegrass production. El three years after application, could still exceed $400/A. The response curve pre­ Dr. Haby and Dr. Clary are located at the Texas A&M dicted that the marginal rate of return may University Agricultural Research and Extension Center, have occurred beyond 2 tons of aglime per Overton, TX. Dr. Hillard is with Louisiana Tech University. acre (Table 2).

TABLE 2. Economic evaluation of estimated livestock gains from increased yield of annual ryegrass in 1986 due to liming.

Aglime Ryegrass yield. Yield increase. Added Added application, dry matter dry matter incremental return2, tons/A lb/A lb/A cost1,$/A $/A

0 3,233 — — — 0.5 5,148 1,915 12 186.00 1.0 6,503 1,355 12 132.00 1.5 7,298 795 12 77.00 2.0 7,533 235 12 23.00

Marshall variety. 1Aglime cost estimated at$24/ton applied. 2Forage consumption and rates of gain estimated using a computerized simulation program. Based on $85.00/cwt steers.

Better Crops/Vol. 80 (1996, No. 1) 15 PENNSYLVANIA Lime Needs under No-till Conditions

By Douglas B. Beegle

onservation tillage is becoming study included four aglime rates (0, more and more common in North 3,000, 6,000, 9,000 lb CCE/A) and lim­ C America. It is usually accompanied ing programs ranging from applying by an increase in surface acidity from the aglime every year to once every five long-term surface application of ammoni­ years. Each year the soil was sampled in um-containing fertilizers and manures. the spring in 2-inch increments to a This lower surface pH depth of 6 inches. No-till can result in aluminum Pennsylvania studies show corn was grown for the first (Al) toxicity which can that surface applications of seven years, no-till soy­ limit root growth and lead aglime in no-till systems pri­ beans for next two years, to reduced effectiveness marily affect the surface 2 oats for one year and wheat of triazine herbicides. inches of soil. Still, this for one year. The effects of liming change in soil pH can bene­ are limited in the short fit crops and affect herbicide Results term to soil in close prox­ performance. Soil samples were collect­ imity to the limestone ed in the spring of each particles. For maximum effectiveness, year for the first nine years of the study. recommendations call for limestone to be The recommended liming program, 6,000 mixed thoroughly with the soil. But, in lb CCE/A every third year (Figure 1), reduced tillage systems, mixing is very changed the soil pH in the surface 2 limited. That raises the question for con­ inches within the first year after applica­ servation tillage systems, particularly no- tion. Most of the change occurred within till crop production, "Can aglime be the first two months after spring liming. applied to the soil surface and effectively That sort of change was expected change the soil pH?" because the aglime used was high qual­ ity with 90 percent passing a 100 mesh Penn State Studies sieve. Spot checks indicated that most A study was initiated at Penn State to of the pH change actually occurred in look at the effects of surface application of the surface half inch of soil. There was lime on a very acid, long-term no-till soil. little change in the soil pH below the For the preceding eight years, the field surface 2 inches until about the fourth had been in no-till corn production with year of the study following subsequent no aglime applied. The initial pH of the lime applications. plow layer was 5.1 and the pH of the sur­ A second program, 6,000 lb CCE/A face 2 inches was 4.5. The lime recom­ initially and 3,000 lb CCE/A per year mendation, based on the SMP buffer pH after two years, was of substantial interest and a target pH of 6.5, was 6,000 lb/A because of speculation that more fre­ calcium carbonate equivalent (CCE). The quent, smaller applications of lime may

16 Better Crops/Vol 80 (1996, No. 1) be necessary in no-till systems. Soil pH TABLE 1. Wheat yield response due to liming. values (Figure 2) indicated little differ­ ence between the standard program...lim­ Aglime rate, Wheat yield, ing every third year...and the annual lime lb/A bu/A 0 52 applications. 3,000 69 Aglime applications resulted in slight 6,000 71 increases in corn yield. Yield increases 9,000 may have been limited by compaction TABLE 2. Effects of liming on corn ear leaf from the liming operation, especially in Ca and Mn in the first year after the more frequent liming programs. application. Wheat showed the greatest yield response Aglime rate, Calcium, Manganese, in the tenth year of the study (Table 1). lb/A % ppm Corn ear leaf samples were analyzed 0 0.51 198 in several years of the study. There were 3,000 0.58 159 significant effects on plant tissue nutrient 6,000 0.57 133 concentrations immediately after liming 9,000 0.58 122 even though the pH effect was limited to the surface in a high residue system. the soil surface. Data indicated a signifi­ A triazine weed control evaluation cant increase in calcium (Ca) concentra­ was included in the early years of this tions and a decrease in manganese (Mn) study. This work showed that the initial (Table 2). The Ca levels in all of the plots liming which only affected the pH at the were in the sufficient range. The Mn lev­ soil surface did improve the efficacy of the els in the check and 3,000 lb CCE/A triazine herbicides. This was expected treatments were in the high range and the since many of the herbicides work in this other two treatments were in the sufficient shallow layer near the soil surface. range for com. Still, the rapid effect on nutrient availability, when the pH change Summary was limited to the soil surface, was a little This study indicated that surface surprising. However, this could be application of aglime will rapidly change explained by increased root growth near the pH of surface soil. It also indicated

Lime applied - every third year 6,000 lb/A

Sample depth a • 0-2 in. • 2-4 in. • 4-6 in.

O 12 24 36 48 60 72 84 96 108 Time (months)

FIGURE 1. Soil pH versus time for a no-till soil limed at 6,000 lb/A every third year.

Better Crops/Vol. 80 (1996, No. 1) 17 Initially 6,000 lb/A then 3,000 lb/A every year 8 Initial Limed every year @ 3,000 lb/A 7 liming 6 Sample 5 depth i * • 0-2 in. 3 • 2-4 in. 2 • 4-6 in. 1 0 0 12 24 36 48 60 72 84 96 108 Time (months)

FIGURE 2. Soil pH versus time for a no-till soil limed at 6,000 lb/A initially and then at 3,000 lb/A annually after the second year. that even this shallow pH improvement program is followed and soil pH is not could affect herbicide activity and nutri­ allowed to drop to very low levels, further ent availability. The study showed that a incorporation of aglime applications very long time is required for aglime to should not be necessary. Where incorpo­ have much effect on the soil pH below the ration is not possible, there are beneficial surface 2 inches in a no-till system. effects of surface application of aglime to Finally, there seems to be little justifica­ acid no-till soils even though the immedi­ tion for more frequent liming in ate effect will only be near the soil sur­ no-till systems. face. Surface liming approximately every The current recommendation for lim­ three years based on a regular soil testing ing no-till systems is effective. On an acid program should be adequate for soil, aglime should be incorporated to no-till systems. 09 adjust the soil pH to the desired level in the entire plow layer before no-till crop Dr. Beegle is Professor of Agronomy, Department of production is initiated. If the soil pH is in Agronomy, Pennsylvania State University, University the desired range initially, it can be main­ Park, PA 16802. tained by surface applications of lime­ stone in no-till systems. If a regular liming International Soil Fertility Manual Now Available Since 1978, PPI has distributed over To order a single copy, send $30.00 in U.S. 75,000 copies of the Soil Fertility Manual. In funds ($15.00 for PPI member companies) recent years, there has been growing payable to "Potash & Phosphate Institute." interest in a version of the manual adapted U.S. and Canada orders add $4.00 shipping, all to international audiences and presented other countries add $7.00. If ordering multiple in metric units. Now, PPI is pleased to copies contact: Potash & Phosphate Institute, announce that the 114-page International 655 Engineering Dr., Ste. 110, Norcross, GA Soil Fertility Manual is available. 30092-2843; phone (770) 447-0335, ext. 213 or 214; fax (770) 448-0439. II in Better Cmps/VoL 80 (1996, No. 1) FUN WITH THE

n education­ gen (N), phosphorus (P) al activity and potasssium (K) as Abook for use characters in a variety in kindergarten of activities such as through third grade dot-to-dot, word puz­ is now available. zles, coloring, mazes, The book, a project matching pictures and of PPI and FAR, experiments. Princi­ encompasses infor­ ples such as soil con­ mation about the servation and science importance of plant as part of modern agri­ nutrients and basic culture are included. concepts of food and A sample copy of fiber production. Fun with the Plant "Because so NUTRIENT | Nutrient Team can be many children to­ TEAM purchased for $3.00. day don't grow up j Additional copies are on farms, they may $1.00 each, plus not realize how shipping/handling. A plants grow and where food and fiberprod ­ teachers guide with additional information, ucts originate," said Dr. David W. Dibb, experiments, facts and resources is also President of PPI. "Our challenge was to available on request. produce an activity Send orders to: book that will be Potash & Phosphate entertaining but also Institute, 655 Engi­ educational for neering Drive, Suite young children. We 110, Norcross, GA believe we have met 30092-2843. Phone the challenge with 770-447-0335, ext. Fun with the Plant 213 or 214; fax 770- Nutrient Team." 448-0439. The 24-page book features nitro-

Better Crops/Vol. 80 (1996, No. 1) 19 CALIFORNIA Foliar Boron Application Enhances Almond Yields

By Patrick Brown, Hening Hu, Agnes Nyomora and Mark Freeman

oron deficiency occurs widely in boric acid formulations are both rapidly the fruit-growing regions of absorbed by almond when leaves are pre­ BCalifornia and is more common in sent and will effectively increase leaf B the lighter textured soils supplied with concentrations. However, since B is high quality irrigation water. Severe B required for effective nut set it is also deficiency, however, resulting in charac­ necessary to ensure that flower buds have teristic leaf symptoms, is adequate B supplies to relatively uncommon and A three-year study in carry them through flower­ can be effectively con­ California shows that foliar ing, fertilization and nut trolled with soil applica­ boron (B) applications can set. Given the highly vari­ tion of B fertilizers. increase yield in almonds able nature of soil B uptake There is mounting even where there are no vis­ that results from changes in evidence in the fruit ible leaf symptoms of B defi­ water availability, tempera­ growing regions of ciency. Data suggest that ture and organic matter California, Oregon and foliar applications act specif­ content, it is suggested that Washington (pistachio, ically to enhance the num­ a supplemental foliar B almond, apple, pear) that ber of flowers that set fruit. application may be benefi­ alleviation of foliar symp­ cial. In comparison with the toms of B deficiency may not be sufficient high value of crops such as almond, the to bring the plant to full yield. Indeed, cost of foliar B is low. Since the number there are many examples in which yield of nuts set is critical to productivity, foliar has been increased by foliar B application application of B is worthwhile whenever to plants with no visual signs of B defi­ B levels are moderate or low. ciency. This observation and the well doc­ umented role of B in pollen growth and California Almond Studies fertilization suggest that flowering and Trials were conducted in a low B fruit set may have a higher demand for B region of Fresno County. Though almond than does leaf growth. This phenomenon trees in this area did not show distinctive was investigated over a three-year period B deficiency symptoms in vegetative in a commercial almond orchard in parts, B concentration measured in July Fresno County, CA. leaf samples were <30 ppm and nut pro­ Extensive experimentation with duction was very low. The following many different crop species demonstrates symptoms were observed: trees flowered that both soil and foliar applications of B early and were very prolific, but within can effectively increase tissue B levels two weeks of flowering large numbers of above the critical value of 30 to 60 parts flowers and small nuts had fallen from the per million (ppm) for vegetative growth of tree; after an additional two weeks, essen­ almond. Sodium borate (Solubor) and tially all nuts had been aborted with less

20 Better Crops/Vol. 80 (1996, No. 1) ALMONDS on the bottom row demonstrate a EXCESSIVE production of gum produces boron deficiency. unsuitable almonds. than 5 percent of the initial flowers result­ centration sampled the following spring ing in a viable nut. In many cases these (Figure 1). Boron concentrations trees then became excessively vigorous as increased from 20 to 90 ppm as B a result of the lack of carbon demand from increased from 0 to 5 lb sodium the developing fruit. At maturity, nuts on borate/100 gallons. Leaf B concentrations some varieties had excessive production sampled during the summer (Figure 2) of gum and were unsuitable for consump­ also increased in direct proportion to tion. Yield was less than 20 percent of the B application. county average for trees of this age in sim­ Increased concentrations of B in ilar climatic conditions. Reports of similar flower buds (Figure 1), flowers and symptoms in pear and pistachio suggested pollen (data not shown) resulted in a sig­ this may be the result of a marginal defi­ nificant increase in the viability of almond ciency of B. Based on the success of our pollen from 55 percent to >75 percent work in pistachio, a series of experiments (Figure 3). was established to develop an effective B foliar spray program for almond.

Foliar Boron Application Foliar B sprays were applied at 0, 1, 2, and 5 lb/A sodium borate (20.5 percent B) in 100 gallons of water to a 15-year old almond orchard. Applications were made at three different times over a one-year period. Treatments were applied to 15 replicate trees. Number of flowers, per­ cent flowers setting fruit, leaf, bud and m flower B concentrations, as well as total yield were determined. The experiment B rate, was repeated for three consecutive lb sodium borate/100 gal. years. The results of the 1994 season presented here are representative of the FIGURE 1. Effect of foliar B application on entire experiment. concentration in bud (February Applications of foliar B two weeks sample). Foliar B applied the after nut harvest (September 1993) result­ previous September. ed in a significant increase in bud B con-

Better Crops/Vol. 80 (1996, No. 1) 21 rates were used. It is likely that the increase in nut set in response to B appli­ cation was the result of the observed increase in pollen viability. To determine the optimum time for B applications, trials were performed apply­ ing 1 and 2 lb sodium borate/100 gal. in September 1993, December 1993, or February 1994, to almond. Yields were collected in August 1994. Boron applica­ 15" ' ' ' ' ' ' tion in September 1993 (Figure 5) 1 2 3 4 5 6 enhanced fruit yield by 67 percent. No B rate, other application date significantly affect­ lb sodium borate/100 gal. ed yield in this or any other year. The need for B in flower buds may require that FIGURE 2. Effect of foliar B application on it be applied during bud formation, which concentration in leaves (July occurs in late summer in almond. Foliar B sample). Foliar B applied the application appears to be the most effec­ previous September. tive way to supply B at this critical stage of development. Foliar B sprays also dramatically improved nut set, which is the primary Summary determinant of yield (Figure 4) and prof­ The results of this and similar itability. Nut set increased from 45 per­ research with pistachio suggest that foliar cent to 75 percent with the application of B application can increase yield in nut 1 or 2 lb sodium borate/100 gal., but crops even in the absence of any visible decreased to 55 percent when higher B (i.e. vegetative) signs of B deficiency. The

B rate, B rate, lb sodium borate/100 gal. lb sodium borate/100 gal.

FIGURE 3. Effect of foliar B on pollen ger­ FIGURE 4. Effect of foliar Bon almond mination rate in almond. Foliar yield. Foliar B applied the B applied the previous previous September. September.

22 Better Crops/Vol. 80 (1996, No. 1) application rates below 30 ppm, utilized in these 100 September while foliar B foliar trials are low December applications in comparison to should be benefi­ normal soil applica­ cial in areas of tion rates and when moderate B status provided in even (30 to 50 ppm). slight excess can •u Boron toxicity is reduce yields. In a possibility in both pistachio and > much of California almond there is a and should be specific brief period monitored closely. at which foliar B Leaf tissue B in sprays are effective. B rate, excess of 50 ppm B These observations lb sodium borate/100 gal may indicate suggest that foliar B potential B toxicity applications act FIGURE 5. Effect of foliar B application on and can be con­ specifically to yield at three times of firmed by sampling enhance the num­ application. almond hulls in ber of flowers that July. A hull value set fruit. Soil applications that enhance in excess of 200 ppm suggests B toxicity. whole tree B levels may not have this Under these conditions no application of same specific effect. B is warranted. 03 Soil applications of B effectively cor­ rect chronic B deficiency and should be Dr. Brown is Associate Professor, Dr. Hening Hu and used in programs where soil and water B Dr. Nyomora are Postdoctoral Researchers, levels are low. A combination of soil Department of Pomology, University of California- application plus foliar B application is Davis, and Mr. Freeman is Farm Advisor, University of recommended when leaf B levels are California Cooperative Extension, Fresno, CA.

Florida: Bahiagrass Response to Dolomitic Limestone Bahiagrass is an which ranged from 3.1 to 3.3 tons/A in important forage crop 1989, 3.4 to 3.9 tons/A in 1990, 3.7 to in the southeastern U.S. A four-year 4.9 tons/A in 1991 and 3.4 to 4.3 tons/A field study on a Pomona fine sand in in 1992. Data indicate that part of the Florida demonstrated the importance of yield response is due to addition of dolomitic lime for bahiagrass production magnesium (Mg) from the dolomite. on low pH soils. Year to year variation in yields was also Four rates of dolomitic lime (0,1,2, affected by rainfall differences. and 3 tons/A) were compared in 1989 through 1992. Dolomitic lime increased Source: J.E. Rechcigl, P. Mislevy and H. Ibrikci. soil pH and reduced exchangeable alu­ Journal of Production Agriculture, 8:249-253 minum (Al). It also increased yields, (1995).

Better Crops/Vol. 80 (1996, No. 1) 23 Research Tracks Nitrogen Dissipation Patterns in Rice Production

By Garry N. McCauley

itrogen is the primary fertilizer Twenty producers in a four-county area nutrient in rice and other crop pro­ (Colorado, Jackson, Matagorda and N duction. Because it is highly Wharton) were recruited by county mobile in most soils, it is easily leached Extension agents to participate in the study. and has the potential to reach and pollute Producers took a water sample at the inlet groundwater if not properly managed. and outlet of each test field following each Further, excess nitrate-N rain and flush irrigation. (NO3-N) in surface water Nitrogen (N) is the nutrient After flood establishment, can contribute to algal most often associated with inlet and outlet samples were blooms and result in water quality. Since most taken when the flood reduced oxygen for aquat­ Texas rice production is reached the bottom of the ic life. Nitrate-N is the N concentrated in areas near field and at three day inter­ form that is of greatest the Gulf Coast, N in flood vals until four samples were concern because of its waters leaving rice fields taken or at least 12 days after relationship to human can impact surrounding flood establishment. health, particularly in­ areas, including coastal The 20 producers took fants, unborn babies and waters. This study was a total of 220 samples at the elderly. The U.S. established to evaluate the 116 different times. There Environmental Protection environmental impact of N, were 104 matched inlet and Agency (EPA) has set a phosphorus (P) and potassi­ outlet samples, with 12 out­ safe drinking water stan­ um (K) fertilization of rice let samples being taken dard of 10 parts per mil­ grown under flood manage­ when no inlet water was lion (ppm) NO3-N. ment. Earlier articles (Better available. Historical data and Crops, Vol. 79, No. 3,1995 Figure 1 shows the recent studies have shown and Vol. 79, No. 4,1995) concentration distribution that movement of chemi­ dealt with P and K. This one of the 220 samples. Most of cals in groundwater is not discusses N. the samples ... 94 percent...

a problem in Texas rice contained 2.0 ppm N03-N soils. These soils have clayey layers with or less. Only two exceeded the drinking high cation exchange capacities and hold water limit of 10 ppm. These results sup­ charged chemicals, slowly releasing them port earlier research (1992-93) which back to the soil solution as needed. showed that NO3-N concentrations in flood Nitrate-N moves downward very slowly in water are low most of the time. these soils. Its leaching into the groundwa­ To allow for detailed interpretation, ter is not considered a problem. samples were broken into seven groups This study was designed to measure (Table 1). the environmental impact of N, P and K fer­ Studying the seven groups reveals tilization of rice under flood management. that A through E can only be interpreted

24 Better Crops/Vol. 80 (1996, No. 1) TABLE 1. Seven water sample groups used to have a neutral or positive environmen­ to determine potential effects of tal impact. Group F would be a negative N fertilization. environmental factor, the magnitude

A = No inlet—outlet non-detectable depending on the amount of concentra­ B = Concentration declined to non-detectable tion increase. The impact of G group can C = Concentration declined, still detectable not be determined because there was only

D = Inlet and outlet samples non-detectable one sample taken, but it is assumed to be E = Detectable levels—no change negative (conservative interpretation). F = Concentration increased Only three of the 55 samples in groups G = No inlet sample—detectable level in outlet F and G should be of environmental con­ cern (Figure 2). They were the ones of the 104 matched sample

pairs that showed N03-N concen­ trations high enough to create a potential environmental problem, as shown in Figure 3. Nine of the 55 samples could not be evaluat­ ed, however, because there was

Sample concentration groupings, ppm not a matching inlet sample. The above results support ear­ FIGURE 1. Concentration distribution of 220 N0 -N rice 3 lier research which showed that in field water quality samples. (ND=Non- only a small percentage of the detectable, <0.1 ppm)

cases would N03-N in a rice field cause problems if discharged into waterways. The key to water purifi­ cation in a vegetative lagoon (such as a flooded rice field) is retention or flow time. In summary, there are few

instances where N03-N concen­ Sample groupings trations in rice field runoff may be high enough to be an environ­ FIGURE 2. Distribution of inlet-outlet sample change mental concern. In those individ­ in N0 -N concentration for 116 rice field 3 ual cases where concentrations water samples. do pose a potential threat to water 5 quality, they should be evaluated 25 r 20 to determine how N management Ea ra 3 o 15 can be modified to eliminate 10 10 7 1 the problem. 03 4 5 3 2 0 0 0 0 0 0 0 0 E 1 1 1 1 L I 1 0 in q q q 0 q q q 0 0 q q Dr. McCauley is Associate Professor, Texas 6 6 f s ? 6 >80.o | A&M University System, Eagle Lake, TX. 1.0-2. 0 2.0-3. 0 8.0 -S

3.0 - 4 4 .0-5. 0 6 .0 - 7 0 0.5- 1 in q >.0-20. 0 ).0-30. 0 q q 0 - n 50.0 -6 C r» Sample concentration groupings, ppm

FIGURE 3. Distribution of N03-N concentration increases from inlet to outlet for 55 rice field water samples that increased. (ND=Non-detectable, <0.1 ppm)

Better Crops/Vol 80 (1996, No. 1) 25 Information Agriculture Conference PLANNED FOR JULY 30 - AUGUST 1, 1996

ates for the 1996 Information Agriculture Conference are now Dset for Tuesday, July 30 through Thursday, August 1. The event will take place at the Krannert Center for the Performing Arts, University of Illinois, Urbana. Plans were announced by Dr. David W. Dibb, President of PPI. Dr. Harold F. Reetz, Jr., PPI Midwest Director, Monticello, IL, will serve as chairman of the coordinating committee THE CYBERFARM demonstration area will feature for the conference. Sponsors will include more on electronic information and record systems PPI, the Foundation for Agronomic at the 1996 Information Agriculture Conference. Research (FAR), National Center for Supercomputer Applications (NCSA), For registration and lodging informa­ University of Illinois College of Agricul­ tion, contact: tural, Consumer and Environmental Mary Hughes, PPI Sciences and others to be announced. 2805 Claflin Road, Suite 200 The conference will focus on site-spe­ Manhattan, KS 66502 cific crop and soil management technolo­ Phone (913) 776-0273 gy and computer communication systems Fax (913) 776-8347 for agriculture. Program features will E-mail: 72253.114 @ compuserve.com include yield mapping and interpretation, For more information on exhibit variable rate systems, data management, arrangements, contact: remote sensing, global positioning system Bill Agerton, PPI potential, geographic information sys­ 655 Engineering Drive, Suite 110 tems, and communication developments. Norcross, GA 30092-2843 An exhibit hall will allow space for Phone (770) 447-0335, ext 209 companies and organizations to display Direct line: (770) 825-8074 products and services related to modern Fax (770) 448-0439 crop production and information. An area E-mail: 73074.3713 @ compuserve.com will also be available for volunteer Potential co-sponsors and those interest­ "poster" presentations where researchers ed in supporting the conference may contact and others can share results of studies and Dr. Larry S. Murphy at the PPI Manhattan, field experience. KS, office: (913) 776-0273 El Registration fees are $200 per individ­ Additional details will be available on the Information ual before July 15, 1996 (students $100). Agriculture Conference Home Page on the Internet at: Exhibitor fee is $300 for a standard booth http://w3ag.uiuc.edu/INF0AG/ area. The fee includes conference registra­ or the PPI Home Page at: tion for one person. http://www.agriculture.com/contents/ppi/ppiindex.html.

26 Better Crops/Vol. 80 (1996, No. 1) Conversion Factors for Metric and U.S, Units

To convert To convert column 1 column 2 into column 2, into column 1, multiply by: Column 1 Column 2 multiply by:

LENGTH

0.621 kilometer, km mile, mi 1.609 1.094 meter, m yard, yd 0.914 0.394 centimeter, cm inch, in 2.54

AREA

0.386 kilometer2, km2 mile2, mi2 2.590 247.1 kilometer2, km2 acre, acre 0.00405 2.471 hectare, ha acre, acre 0.405

VOLUME

0.00973 cubic meter, m3 acre-inch 102.8 3.532 hectoliter, hi cubic foot, ft3 0.2832 2.838 hectoliter, hi bushel, bu 0.352 0.0284 liter, 1 bushel, bu 35.24 1.057 liter, 1 quart (liquid), qt. 0.946

MASS

1.102 tonne (metric) ton (short) 0.9072 2.205 quintal, q hundredweight, cwt (short) 0.454 2.205 kilogram, kg pound, lb 0.454 0.035 gram, g ounce (avdp), oz 28.35

YIELD OR RATE

0.446 tonne(metric)/hectare ton (short)/acre 2.240 0.891 kg/ha lb/acre 1.12 0.891 quintal/hectare hundredweight/acre 1.12 1.15 hectoliter/hectare,hl/ha bu/acre 0.87

TEMPERATURE

(1.8xC) + 32 Celcius, C Fahrenheit, F 0.56 x (F-32) -17.8° 0°F 0°C 32°F 20°C 68°F 100°C 212°F

METRIC PREFIX DEFINITIONS

mega 1,000,000 deca 10 centi 0.01 kilo 1,000 basic metric unit 1 milli 0.001 hecto 100 deci 0.1 micro 0.000001

TO CONVERT U.S. CROP YIELDS FROM BUSHELS PER ACRE (bu/A) TO METRICS

Corn-bu/A x 0.063 - tonnes/ha Wheat-bu/A x 0.067 = tonnes/ha Soybeans-bu/A x 0.067 = tonnes/ha Grain Sorghum-bu/A x 0.056 = tonnes/ha

Better Crops/VoL 80 (1996, No. 1) 27 SOUTH AMERICA Liming Tropical Soils — A Management Challenge

By Jose Espinosa

oils that are dominated by 2:1 clays nent charge clays are based on buffered (montmorillonite, vermiculite, illite) solutions. The most popular of these Sare usually found in temperate zones methods is the SMP method developed to of the globe. However, they also occur in determine lime needs in acid soils of the tropical and subtropical areas. These soils temperate zones of the U.S. The equilibri­ behave differently than the typical tropi­ um pH value of a suspension made of soil cal red soils (Ultisols and - water - buffer solution is Oxisols) which are domi­ Research in several South correlated with the amount nated by kaolinite and by American countries has of lime needed to increase iron (Fe) and aluminum emphasized the importance soil pH to a certain value, of lowering exchangeable (Al) oxides and hydrox­ using a CaC03 incubation ides. And they are not the aluminum (Al) through lim­ procedure, in the same soil same as soils developed ing. Objectives of lime appli­ sample. In this way, recom­ from volcanic ash cations for temperate and mendations can be devel­ (Andisols) that are widely tropical or ash derived soils oped to indicate the amount spread over the world. are quite different. of time required to bring These important differ­ soil pH to a particular ences determine the approach used to value. Table 1 presents an example of evaluate lime requirements. liming recommendations based on cali­ In soils dominated by 2:1 clays, the bration of a SMP buffer solution. reduction in base saturation from loss of potassium (K), calcium (Ca), and magne­ Liming Tropical and Ash Soils sium (Mg) leads to increasing acidity. This However, the approach for liming increased acidity in turn leads to the sub­ tropical red soils and soils derived from sequent breakdown of the clay material volcanic ash is quite different. In Ultisols and to the release of structural Al, which and Oxisols, Al and Fe are present in occupies the exchange sites left by the lost mineral clays that are stable at pH values bases. This is the reason why these soils as low as 5.0. In this case, Al is buried in can be easily limed to a pH of near 7.0, the clay particle. It is not a threat to plant which is optimal for the production of many growth until soil pH reaches a value crops. During the liming process there is where the oxides and kaolinite dissolve, little change in cation exchange capacity bringing Al...sometimes in toxic quanti­ (CEC)...soils of permanent charge. ties...into the soil solution. When this sit­ uation arises it is advisable to raise soil Determining Lime Needs — pH to about 5.5. This will allow Al pre­ Temperate Soils cipitation and appreciable increase in Common methods for determining CEC (soils of variable charge), Table 2. lime needs in soils dominated by perma­ In this pH range, crop growth and yield

28 Better Crops/VoL 80 (1996, No. 1) TABLE 1. Liming rates determined using SMP The primary goal of this approach buffer solutions. is to neutralize all Al, but there are Al-tolerant crops that can SMP Desired pH after liming grow and yield satisfactorily at Index1 5.5 6.0 6.5 Lime rate, t/ha moderate to high Al saturation of 4.4 15.0 21.0 29.0 the exchange complex. Since not 4.6 10.9 15.1 20.0 all Al needs to be precipitated, a 4.8 8.5 11.9 15.7 lower amount of lime can be 5.0 6.9 9.7 12.9 used...to reduce Al saturation to 5.2 5.5 8.0 10.6 the desired level. In most of these 5.4 4.4 6.5 8.7 5.6 3.3 5.1 7.0 cases, the lime applied is used to 5.8 2.3 3.9 5.5 overcome Ca and Mg deficiencies 6.0 1.4 2.8 4.1 which can be limiting to plant 6.2 0.6 1.7 2.7 growth in weathered soils of low 6.4 0.0 0.0 1.5 CEC. Coffee, banana, oil palm, 1 pH of the suspension soil-water-buffer solution. pineapple, and a number of trop­ ical grasses and legumes are are excellent, Table 3. among the crops that tolerate high In tropical soils, the determination of Al saturation. lime requirements using buffered solu­ Plant breeding has developed culti- tions does not work adequately. Using this vars of certain crops that are also tolerant approach, large amounts of lime are rec­ of high soil Al saturation. Examples are ommended to force soil pH to values in Orizyca sabana 6 (upland rice) and the 6.0 to 7.0 range. However, only a Sorghica real 60 (sorghum) developed for moderate amount of lime is needed to Oxisols from the eastern savannas of raise soil pH to val­ ues high enough to TABLE 2. Effect of lime application to a red Ultisol from Panama. precipitate Al in the top layer in this type Treatment pH Ca Mg K Al Effective CEC of soil (around pH cmol/kg

5.5). A better No|ime 49 1.79 1.11 0.11 2.15 5.18 approach to develop Lime (4 vha) 5 8 7.90 6.73 0.14 0.09 14.85 liming recommen­ dations is to take into account the amount of exchangeable Colombia. Lime recommendations for Al present in the topsoil. Following this Orizyca sabana 6 upland rice range from concept, lime requirements for most trop­ 250 to 500 kg/ha of dolomite, with the ical soils can be predicted applying the only purpose of providing Ca and Mg to following equation: the crop. Another common method used to cal­

CaC03 (t/ha) = Factor x cmol Al/kg soil culate lime requirements, related to Al saturation, is based on soil base satura­ The factor used can vary from 1.5 to tion. Though it has been determined that 3.0 depending on the crop characteristics base saturation does not influence yield in and the soil type and can be fine tuned by soils dominated by 2:1 clays, this param­ the agronomist or farmer working at any eter is very important in highly weathered specific site. soil (Ultisols and Oxisols) of low CEC and

Better Crops/Vol. 80 (1996, No. 1) 29 low Ca and Mg content. As indicated above, lime is used not only as an amendment in these types of soils, but also as a source of Ca and Mg. Research has demonstrated that, within certain limits, higher base saturation in weath­ ered soils improves fertility and increases crop yields. A method for determining lime requirement was developed taking into account a targeted soil base saturation which is attained by lime application. Brazilian experience indicates, for exam­ ple, that the best coffee yields are obtained at 60 percent saturation. In other words, coffee can grow satisfactorily in a soil with up to 40 percent Al satura­ tion. According to these criteria, lime requirements can be calculated using the following equation:

(BS2 BS xCEC CaCQ3(t/ha) = - i) 3 100 THE EFFECT of soil pH on growth of faba bean BSj = Initial base saturation plants is shown in this comparison on an

BS2 = Required base saturation Andisol in Ecuador.

The liming approach for soils derived weathering. For this reason, there is no from volcanic ash (Andisols) is somewhat simple rule to evaluate lime requirement different. The high buffering capacity in these soils. The use of the exchange­ (resistance to pH change) of Andisols able Al criterion, in certain cases, under­ complicates lime requirement evaluation. estimates lime needed, as illustrated by The intensity of the buffering capacity the data presented in Table 4. varies from one place to another accord­ Clay particles resulting from volcanic ing to altitude, rainfall and temperature, ash weathering (allophane, imogolite, which are factors that control volcanic ash humus-Al complexes, etc.) have very

TABLE 3. Liming effects on soil pH and the yield of various crops in Oxisols from Brazil.

Corn Wheat Soybeans

CaC03, Soil Yield, CaC03, Soil Yield, CaC03, Soil Yield, t/ha pH kg/ha \ t/ha pH kg/ha j t/ha pH kg/ha

0 3.9 1,150 0 4.7 1,320

2 4.5 4,090 3.5 5.0 2,364

4 4.7 4,420 7.0 5.2 3,031

6 5.3 5,340

30 Better Crops/VoL 80 (1996, No. 1) TABLE 4. Effect of lime application on soil chemical properties and crop yield in an Andisol of the highlands of Ecuador.

Lime, Soil Ca Mg K Al CEC Faba beans Barley Oats t/ha pH cmol (+)/kg Yield, t/ha

0 4.9 2.54 0.36 0.30 2.1 6.0 13.9 2.2 3.6 3 5.2 3.30 0.39 0.29 1.6 6.6 17.1 2.9 4.3 6 5.3 4.69 0.40 0.28 0.6 7.2 19.2 3.9 4.7 12 5.4 5.59 0.40 0.30 0.2 8.4 21.6 4.1 4.8

15 5.8 8.60 0.42 0.29 0.1 10.4 21.0 4.3 4.7 reactive surfaces. When lime is applied to lime applications. Usually this happens these soils it reacts with the clay surfaces, when such soils are limed to neutrality. creating charge (increase in CEC) while Tropical soils should only be limed to failing to increase pH or to precipitate Al. neutralize exchangeable Al, which gener­ The amount of lime needed to precipitate ally brings soil pH to values in the 5.5 to Al varies with the age and weathering of 6.0 range. Overliming leads to soil struc­ the volcanic ash. For this reason, it is ture deterioration, reduced boron (B), zinc necessary to conduct simple field trails (Zn) and manganese (Mn) availability, and which can indicate precisely the amount lower yields. 03 of lime needed at a specific site. Regardless of the method used to Dr. Espinosa is Director of INPOFOS, the determine lime requirement in tropical PPI/PPIC program in northern Latin America. soils, it is advisable to avoid excessive He is located in Quito, Ecuador.

Dr. R.L. Yadav Receives 1995 PPIC-FAI Award for Research

he 1995 award for best research Dr. Yadav obtained his Ph.D. on Management and Balanced degree from GBPUA&T, Pantnagar and TUse of Inputs in Achieving started his research career as Sr. Maximum Yield went to Dr. R.L. Scientist at IISR, Lucknow, where he Yadav, Project Directorate for worked for about 18 years. He has 276 Cropping Systems Research, papers to his credit and nine awards, Modipuram, Uttar Pradesh, India. The including the FAI Silver Jubilee Award award is presented annually by the in 1988. His main research interests PPIC-India Programme and The are integrated use of chemical fertiliz­ Fertiliser Association of India (FAI). ers and organic manures, particularly recycling of organic farm wastes. C3

Better Crops/Vol. 80 (1996, No. 1) 31 Often, soil and plant scientists overlook the important relationship between chemical composition of plants and human nutrition and health. But the public is aware of this. People recognize the need for potassium, phosphorus, calcium and proteins in their diet, and know that bananas and citrus are good sources of potassium. They see the value of beta carotene and vitamins C and E, and can tell you what plants supply them. They have definite opinions about margarine pro­ duced from corn oil, or canola or sunflower oil. Soil and plant scientists have concerned themselves with yield, pesticide resistance, weather tolerance and pollution control. Great! But do they con­ nect soil properties and treatment with human nutrition? Are plant breeders associating plant properties with human health? The agronomist of the future will take into account the health needs of people, which means getting adequate and balanced levels of nutrients into the plant. Soil properties, plant nutrient levels, and other plant properties will assume greater importance. What an interesting field in which to be involved.

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