sign in sign up
<<
Home , Compost, Sewage sludge, Soil conditioner

/ ê^ í^m

^^ United States Jjl Department of ^^ / Utilization of Agricultural Research Service as Agriculture Information Bulletin a Conditioner Number 464 and for Growth

.Co

: —Í

rT7 ABSTRACT

Hornick, S. B., L. J. Sikora, S. B. ornamentals, turfgrasses, field , Sterrett* and others. 1984. forage grasses, and the reclamation of Utilization of compost as marginal lands. Recommendations based a and fertilizer for on laboratory, , and field plant growth. U.S. Department of experiments provide methods, limita- Agriculture, Agriculture Information tions, and rates of compost application Bulletin No. 464, 32 p. for different management practices.

This bulletin presents information on KEYWORDS: Compost, compost application how sewage sludge compost can be used rates, field crops, greenhouse crops, most effectively. It includes discus- land reclamation, nursery crops and sions on the properties of sewage sludge ornamentals, content, plant compost as a soil conditioner and growth, root control, sewage fertilizer for plant growth and its use sludge, sod production, soil on vegetable crops, nursery crops and conditioner, turfgrass, vegetable crops. United States Department of Agriculture Utilization of Sewage Agricultural Research Service Sludge Compost as £r a Soil Conditioner Number 464 and Fertilizer for Plant Growth CONTENTS

Page Page Introduction 1 Uses for sewage sludge compost 19 Factors affecting sewage sludge Vegetable crops 19 compost use 3 Nursery crops and ornamentals— 20 Sludge quality • 3 Compost use in media 20 Regulations 4 Greenhouse crops and bedding Availability of macronutrients plant s 22 in compost 6 Turf grasses 2 3 Pathogen content 12 Establishment 2 3 Root disease control 14 Maintenance 24 Recent studies on the effects Sod production 24 of sewage sludge compost Field crops 25 on root • 15 Forage grasses 25 Future of sludge compost in Reclamation of disturbed and the control of soilborne marginal lands^ 26 diseases 16 Summary and conclusions 27 Economic benefits 16 Literature cited 27

This publication contains the results of research only. Mention of a chemical product does not constitute a recommendation for use by the U.S. Department of Agriculture. The use of trade names in this publication does not imply a guarantee or endorsement of the product by the Department over other products not mentioned.

This publication is a revision of and supersedes Agricultural Reviews and Manuals, Northeastern Series, No. 6, "Use of Sewage Sludge Compost for Soil Improvement and Plant Growth,"

Copies of this publication can be purchased from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

Microfiche copies can be purchased from the National Technical*Information Office, 5285 Port Royal Road, Springfield, Va. 22161.

Agricultural Research Service has no additional copies for free distribution.

Issued August 1984 Utilizaiion of Sewage Sludge Compost as a Soil Conditioner and Fertilizer for Plant Growth by S. B. Homick, L. J. Sikora, S. B. Sterrett, J. J. Murray, P. D. Millner, W. D. Bürge, D. Colacicco, J. F. Parr, human enteric and offensive R. L. Chaney, and G. B. Willsoni' .

INTRODUCTION In 1973, only a few composting operations in the United States were Composting is a process that converts known to be using sewage sludge as an organic Into a humuslike input material. Ten years later, at material, which can be used beneficially least 65 sludge composting were as a soil conditioner and fertilizer. in operation, 43 of which use the In composting practices in the United Beltsville method (Willson and Dalmat, States and other industrialized 1983). Another 20 plants are now either countries, such agricultural wastes as in final design or under construction. animal and residues have Most are in the densely populated areas been customarily utilized. However, of the Northeast and the Southwest (fig. since the 1970's, with the upgrading and 1). Several large sewage authorities construction of municipal sewage are now composting all or a significant treatment plants and the concomitant amount of their sludge output, including increase in the amount of sewage sludge Philadelphia, Los Angeles County, the generated, attention has focused on the District of Columbia, Columbus, Ohio, composting of good-quality for and El Paso, Tex. agricultural and horticultural use. Smaller conmiunities also have found that When sewage sludge and are composting their sludge into a useful mixed and composted, as by the and valuable resource is a viable Beltsville aerated pile method (Willson option, preferable to ultimate disposal et al., 1980),!/ a stabilized product by landfllling or incinerating. They results from the action of aerobic- include Old Beach, Maine, thermophilic , which Morgantown, N.C., Missoula, Mont., utilize a part of the organic material Bangor, Maine, Durham, N.H., and for their growth and activity. During Cambridge, Md., to mention a few. this , the composting heats to temperatures in the In addition to the aerated pile and range of 55*^ to 70^C, windrow methods of composting, several with resulting destruction of enteric types of enclosed vessel or reactor pathogenic microorganisms. The end systems are available commercially. result is a humuslike material useful as Mechanical aeration, mechanized material a soil conditioner and a source of plant handling, and automation are common . It is essentially free of features of these enclosed systems. The initial phase of the composting process, associated with rapid decomposition of J:/Agricultural Environmental Quality the organic materials, occurs in the Institute, except J. J. Murray, Plant reactor. However, composting is not Genetics and Germplasm Institute, carried to completion in the reactor, Beltsville Agricultural Research Center, since an increased number of units would Beltsville, Md. 20705; and S, B. be required. Thus, in most instances, Sterrett, Virginia Truck and Ornamentals the partially composted biomass is Research Station, Painter, Va. 23420. removed after a few days or several weeks and finished in windrows or 2/The year after the author's name aerated piles. A wide variety of refers to Literature Cited, p. 27. reactors has been developed, some

1 NUMBER OF SITES CZZ] 0 1 1 3 TO 5 I 6 TO 10

Figure 1.—Distribution of municipal sewage sludge composting facilities. resembling bottom-unloading silos, instances, especially when low others cement kilns, and still others sludges are used. Some bulking multiple hearth furnaces, ^Several materials might also contribute either systems have enclosed, open-top channels. plant nutrients or heavy to the Although few of these systems have been compost. used for composting sludge in the United States, there is considerable interest Sewage sludge compost can be used for in their potential application. many purposes, including the production of agronomic crops, vegetable crops, Most composting systems can yield a sod, and the reclamation of disturbed compost comparable in quality to that and marginal lands. Information on its produced at the U.S. Department of effective uses and specific limitations Agriculture's sewage sludge composting on soil pH, application rates, and metal facility in Beltsville, Md. The com- loadings is provided in this bulletin. position and quality of the compost, however, are dependent on process control, sludge composition, and FACTORS AFFECTING SEWAGE SLUDGE COMPOST selection of bulking material. Moni- USE toring of internal temperatures at critical locations in the composting Sludge Quality biomass is essential to insure that the compost has attained temperatures The sewage sludges produced in the necessary to kill pathogenic organisms United States differ markedly in their (Bürge et al., 1981). Ample curing time composition. (N), of at least 1 month is required to (P), and (K) contents of the produce a -stabilized compost. sludge can range from 3 to 7, 1 to 3, and 0.2 to 3 percent, respectively. Table 1 Periodic analysis is important so that shows the ranges and median values of the content of does not trace elements and heavy metals exceed acceptable levels mandated by contained in sludge and typical soil. Federal, State, or local governments. If high concentrations of heavy metals If compost is produced for or intended are found, it may be necessary to to be marketed for a wide variety of restrict the use of the compost or to uses, such as the production of regulate industrial discharges to the agricultural and horticultural crops, sewage system. reclamation and revegetation of disturbed lands, formulation of potting Selection of the bulking material, which media, and establishment and production is dictated somewhat by the composting of turfgrasses, only "good" sludges are method, may result in either dilution or recommended. The maximum recommended concentration of plant nutrients and levels of trace metals or other elements heavy metals. Most bulking materials, in good sludges acceptable for however, contain very low concentrations composting are shown in table 1 under of plant nutrients or heavy metals. the heading "Maximum domestic sludge." Thus, the bulking material remaining in the compost has, a diluting effect. Field research has shown that with proper Bulking materials such as woodchips and soil pH management (pH 6.5 or above) and shredded bark, which are partially the use of sewage sludges containing low recovered for in some composting levels of trace metals, metal uptake by processes, result in moderate dilution. crops is minimized. Use of or may also cause substantial dilution. If dry Since a wide variation in sludge con- compost is used as a bulking material, stituents to a wide variation in the concentration of heavy metals will the resulting compost, application rates increase proportionally. This should of different must be adjusted not pose a serious problem in most accordingly to assure beneficial results. Table !•—Concentrations of selected trace elements in dry digested sewage sludges

Reported Typical Typical "Maximum Elementl/ range median soil domestic sludge sludge" Mln. Max.

Arsenic (As)^ — 1.1 230 10.0 (Cd) 1.0 3,410 10.0 0.1 25.0 (Cr) 10.0 99,000 500.0 25.0 1,000.0 Cobalt (Co) 11.3 2,490 30.0 200.0 (Cu) 84.0 17,000 800.0 15.0 1,000.0 Fluorine (F) 80.0 33,500 260.0 200.0 1,000.0 Iron (Fe) .1 15 1.7 2.0 4.0 (Pb)^ 13.0 26,000 500.0 25.0 1,000.0 (Mn) 32.0 9,870 260.0 500.0 (Hg) .6 56 6.0 10.0 (Mo .1 214 4.0 25.0 (Ni) 2.0 5,300 80.0 25.0 200.0 (Se) 1.7 17 5.0 Tin (Sn) 2.6 329 14.0 (Zn) 101.0 49,000 1,700.0 50.0 2,500.0 Cadmium:zinc (Cd:Zn) .1 110 .8 1.5

1/Parts per million on dry weight basis except percent for iron and cadmium- to-zinc ratio.

Sources: Chaney and Giordano, 1977; Chaney, 1982.

Regulations of sewage sludge on -chain crops and leafy" vegetables were published by the The marketing and utilization of sewage Environmental Protection Agency (EPA). sludge compost are regulated by laws and Because crops differ in their ability to guidelines established at the Federal, absorb and accumulate cadmium (Cd) and State, and local levels. Generally the other heavy metals (see following list), provisions of these statutes tend to be specific criteria were issued to (1) more restrictive as one goes from maintain soil pH at 6.5 or above; (2) Federal to State to local jurisdictions. limit annual Cd application rates to 0.5 The State and local laws governing the kg per hectare when root crops, leafy use of sewage sludge compost are rather vegetables, or tobacco are grown for variable in their purpose and content. human consumption; and (3) for other Thus, in regard to specific questions food-chain crops, limit annual Cd concerning sludge compost utilization on applications per hectare to 2 kg until land, it is most important to consult June 30, 1984, 1.25 kg until December with municipal and county regulatory 31, 1986, and 0.5 kg after January 1, agencies and the State health depart- 1987. Criteria on ground-water and ments for existing laws and requirements surface-^ater contamination and on proper compost use and management management of dedicated sites were also procedures. specified (EPA, 1979).

In 1979, regulations concerning the use The relative accumulation of heavy metals in edible plant parts by various crops Table 2.—Recommended maximum cumulative grown on acidic with Cd applica- sludge metal applications for privately tions of 5 kg per hectare was as owned cropland^' follows \èJ

Uptake Crops Maximum application at indicated soil cation exchange capacity High Beet greens, carrot, chard, 2/ cress, endive, escarole, Metal (meq/lQO g) lettuce, spinach, turnip greens. 0-5 5-15 15 Moderate- Beets, collards, kale, mustard, onion, potato, radish globes, turnip root. Kg/ha Kg/ha Kg/ha

Low Berry fruits, broccoli, brussels Cadmium 5 10 20 sprouts, cabbage, cauliflower, Nickel 50 100 200 celery, sweet corn. Copper 125 250 500 Zinc 250 500 1000 Very low- Eggplant, mellón family, peas, Lead 500 1000 2000 pepper, beans, tomato, tree fruits. 1/Annual Cd application should not The one soil property used to limit exceed 2 kg per hectare from dewatered or sewage sludge metal additions to land is composted sludge, or 1 kg per hectare the cation exchange capacity or CEC. It from liquid sludge; sludge should not is used as an index to predict the supply more crop available N than crop effects of certain soil components, such requires. Recommendations apply only to as , content, and soils adjusted to pH 6.5 when sludge is iron (Fe), aluminum (Al) and manganese applied and are to be maintained at no (Mn) hydrous oxides, on the solubility less than pH 6.2 thereafter. or availability of trace or heavy metals, such as zinc (Zn) and Cd, when sludge y^ov unamended soil. additions are made to soil (Logan and Chaney, 1983). Table 2 shows the Source: Chaney, 1982. recommended maximum cumulative sludge metal additions that should be made to express purpose of restricting excessive cropland. The CEC of most agricultural applications of high metal or industrial soils is reasonably well known and can sludges to cropland where disposal is the be obtained from the USDA Soil primary objective. When low metal sludges Conservation Service, USDA Cooperative or their composts are used, it is Extension Service, or State agricultural difficult to exceed maximum recommended experiment stations. application rates since the quantities of compost needed would be enormous and Some regulations were made with the economically impractical.

When good sewage sludges are composted, 3/From EPA, FDA, USDA (1981). the metal concentration is substantially Do not infer that crops with a higher diluted by the Inclusion of bulking uptake should never be grown on such a materials. This results in a low metal, soil or soils of higher Cd concentra- high organic matter material that can be tions. Such crops can be safely grown if safely and economically used as a soil the soil pH is 6.5 or greater at the time conditioner and low analysis fertilizer. of planting, since a crop's tendency to The ranges and limits in compost quality accumulate heavy metals is significantly on a dry weight basis observed in research reduced at a soil pH of 6.5 or higher. studies conducted by the Department at Beltsville, Md., are as follows: Availability of Macronutrients in Compost Elément!/ Percent The fertilizer value of sewage sludge Nitrogen 1.0-1.5 compost is dependent on the type of Phosphorus !•2-2.0 sludge and bulking material used in Potassium .2 making the compost. The chemical composition of sludges is variable Less than (mg/kg)— based on the industrial and treatment facilities of a given Iron 40,000 location (Chaney, 1978). Macronutrient Zinc 1,250 content is not so variable as the Copper 500 micronutrient content. Raw sewage Lead 500 sludge containing 3.0 percent total N, Nickel 200 3.0 percent total P, and 0.4 percent Cadmium 12.5 total K when mixed with woodchips and Mercury 5 composted will result in a finished compost containing 1.0 to 1.5 percent 1/Cadmium-to-zinc ratio was less than total N, 1.2 to 2 percent total P, and 1.5 percent, chlorinated hydrocarbons less than 0.2 percent total K. Most of were less than 5 ppm each, and this decrease results from dilution by alkalinity was greater than 10 percent the bulking material, but some N is as carbonate. also lost during the composting process. Sikora et al. (1983) showed If one uses the EPA annual loading rate that 10 percent of the total N was lost for Cd of 2 kg per hectare for this by volatilization and leaching during Beltsville compost, a cumulative annual composting of raw, limed sewage sludge application of 161 metric tons (mt) per and woodchips. Bulking materials, such hectare could be applied to farmland. as sawdust or refuse, generally cause However, application rates of this more compost dilution and subsequently magnitude are usually restricted result in a lower content. On to projects involving the reclamation the other hand, the use of unscreened and revegetation of soils disturbed by sewage sludge compost or other bulking surface mining. materials with a relatively high nutrient content will result in a final The fact that application of compost can compost containing proportionately markedly improve soil physical prop- higher levels of N and P. erties is evidenced by increased water content and retention, increased soil The ratio of bulking material to sewage aeration and permeability, Increased sludge in the final compost affects the water infiltration, and decreased bulk nutrient mineralization of the compost density and surface crusting (Epstein after application to soil. Tester et et al., 1976; Homick et al., 1980; al. (1979) studied the N mineralization Hornick, 1982). Such changes in soil rate of a compost made from raw, limed physical properties contribute signifi- sludge that had been screened to cantly to reducing soil erosion and produce different particle-size decreasing the loss of plant nutrients fractions ranging from 1.0 to 5.0 mm. by runoff. A major benefit from Analyses of these fractions indicated compost use can be achieved by that as more of the woodchips were relatively small additions of about 10 removed from the compost by screening, to 20 mt per hectare of compost to most the -to-nitrogen ratio (C:N) agricultural soils. Therefore, strong decreased and the N mineralization consideration should be given to using increased. However, extraetable P by low metal sewage sludge composts at Bray P-^1 (Olsen and Sommers, 1982) was considerably lower rates than the not significantly different in the fertilizer or N requirement of a crop. screened fractions. Most of the studies analyzing the N and abilities of 36 to 90 percent those of P availability in composts have been monocalcium (DeHaan, 1980). performed In the laboratory or green- With the addition of Fe and Al salt to house. Tester et al. (1982) found that the waste-water treatment process to 10 percent of the total N in composts remove P, the resulting sludges had P is as available as N in mineral ferti- availabilities ranging from 17 to 54 lizer for the first crop. Nitrogen percent. One composted sludge had a P mineralization rates for raw sludge availability of 50 percent. compost of 3.8 to 4.7 percent and for digested sludge compost of 7.0 to 9.3 Sikora et al. (1982) determined that P percent have been reported (Epstein et from raw sludge compost was 25 to 40 al., 1978). A greenhouse study showed percent as available as from triple that the availability of N in municipal superphosphate. Mays et al. (1973) refuse compost was 16 percent of that found P in municipal refuse compost to in ammonium nitrate (Mays et al., be 71 percent as available as super- 1973), whereas in another study, 20 phosphate. Phosphate from raw sludge percent of the organic N in - compost has been reported to be one- straw compost was available for plant third as available as triple super- uptake as determined by extraction phosphate at 500 kg of P per hectare or techniques (Kumada et al., 1977). higher (McCoy et al., 1982). In summary, the factor that affects the Recently two sewage sludge composts and availability of P in sludge composts to mineral were added to field plants is primarily Fe and Al content. plots and corn was grown. In the first year, the N mineralization rate for Compost usually contains 1.5 percent P compost was equal to 10 percent of the (3.5 percent P2O5) on a dry weight total N content (McCoy et al., 1983, basis equaling approximately 8 kg of unpub.) From these data, 10 percent total P per metric ton of compost. appears to be an adeqtiate approximation Research has indicated that the P in a of the availability of organic N in compost with a quality similar to that compost made from undigested sludge listed on page 6 is about 40 percent as with woodchips as the bulking material, available to crops as P in super- or a metric ton of compost contains phosphate fertilizers (Sikora et al., about 0.9 kg of available N on a wet 1982). The compost P recommendation weight basis. According to Epstein et is, therefore, equal to 2.5 times the al. (1978), the availability of N in commercial fertilizer P recommendations digested sludge composts may be higher for a specific crop and area. than that produced from undigested sludge. Recent evidenced' has indicated that composts made from sludges that are The availability of P from compost or lime-stabilized and contain iron- sludge is decreased as the Fe and Al precipitated phosphorus have lower content increases. Because the pH of percent availabilities than the composted organic materials is in a composts used to develop the recommen- narrow range of 6.5 to 7.5, the effect dations in table 3. Therefore, use of of pH on the plant available P forms in these composts as a P fertilizer will different composts is not so significant require higher application rates. as it is in different soils. Compost application rates to satisfy Pastene and Corey (1980) found that P availability of sludges was inversely proportional to the ratio of Fe plus Al i/McCoy, J. L. Availability of to P. The higher the ratio, the less P phosphorus in sewage sludge compost. was available to plants. Sludges from 1984. [Unpublished master's thesis. waste-water treatment plants not having Copy on file Dept. Agron., Univ. Md., specific P removal systems had P avail- College Park.] Table 3.—^Application rates for sewage sludge compost for various crops in 1st year based on N or P fertilizer recommendations^/

Compost rates2/ based on Crop and use recommendations for— Remarks

N fertilizer P fertilizer

Mt/ha Mt/ha Turfgrasses : Establishment : Soil incorporated 99-298 33-45 Incorporate with top 10-15 cm of soil. Use lower rate on relatively fertile soil and higher rate on infertile soil.

Surface - 29-38 N.R,1/ Broadcast uniformly on surface before seeding small seeded species (bluegrass) or after seeding large seeded species (fescues) .A'

Maintenance- 20-40 9-12 Broadcast uniformly on surface. On cool season grasses, apply higher rate in fall or lower rate in fall and again in early spring.

Sod production - mixed 150-298 33-45 Incorporate with top 10-15 cm of with soil. soil.

Vegetable crops: Establishment— 49-150 9-21 Rototill into surface 1-2 weeks before planting or In previous fallí

Maintenance- 49 Rate is for years after Initial establishment. Rototill into surface 1-2 weeks before planting or in previous fall. Field crops: Barley, oats, , 49-65 12 Incorporate into soil 1-2 weeks wheat. before planting or in previous fall.

See footnotes at end of table. Table 3.—Application rates for sewage sludge compost for various crops in 1st year based on N or P fertilizer recommendationsl:'—Con.

Compost ratest' based on Crop and use recommendations for— Remarks

N fertilizer P fertilizer

Mt/ha Mt/ha

Corn- 150-180 17-21 Incorporate into soil 1-2 weeks before planting. Supplemental potash may be required depending on results.

Legumes. 5/. N.R. 5 Legumes can be grown in rotation with corn, oats, or other nitrogen requiring crops.

Tobacco- 0 0 Sewage sludge materials should not be applied on acid land used in tobacco production.

Forage grasses: Establishment- 199-347 12-36 Incorporate with top 10-15 cm of soil. Use lower rate on relatively fertile soil and higher rate on infertile soil. Supplement during 1st year's growth with 28 kg per hectare of soluble nitrogen fertilizer when needed.

Maintenance- 49-65 12-15 Broadcast uniformly on surface in fall or early spring 1 year after incorporated application.

Nursery crops and 94-347 41-123 Incorporate with top 15-20 cm of ornamentals (shrubs and soil. Do not use composts made trees) - establishment. from limed, raw sludge or sludges containing free calcium carbonate where ericaceous plants (azalea, rhododendron, etc.) are to be grown. Broadcast uniformly on surface soil. Can be worked into soil or used as a mulch.

See footnotes at end of table. Table 3.—Application rates for sewage sludge compost for various crops in 1st year based on N or P fertilizer recommendationsi:/—Con.

Compost ratest' based on Crop and use recommendations for— Remarks

N fertilizer P fertilizer

Mt/ha Mt/ha

Reclamation: Conservation planting- Up to 457 N.R, Incorporate with top 15 cm of soil. Use maximum rate only where excessive growth for several months following establishment is desirable. For each 2.5 cm beyond 15 cm of incorporation, add 49 mt per hectare on soils where ground-water nitrogen will not be increased.

Mulch ^ 16-36 N.R. Broadcast screened or unscreened compost uniformly on surface after seeding; unscreened is more effective.

1/Table based on sewage sludge compost with quality similar to that on p. 6.

2/Based on 1.27 cm mesh screened material at 40 percent moisture content, containing 1.5 percent total N and 1.5 percent total P on dry weight basis. Compost spread to depth of 1.27 cm equals 74 mt of moist, screened compost per hectare (33 wet tons per acre or 1,500 lb per 1,000 ft^, with approximate bulk density of 900 lb per cubic yard; to convert from metric tons per hectare to tons per acre, multiply by 0.45).

^'No recommendations.

A^See field crops section.

^'Maximum benefit of compost for legumes can be realized by growing legumes in rotation with other crops fertilized with compost or by applying compost at the P fertilizer requirement of the legumes, which equals approximately 6.7 kg of available N per hectare.

10 the N or P requirement are generally Tester et al. (1982) were recropped to insufficient to supply the K require- fescue (Festuca arundinacea Schreb.) ment of the crop. Soil test analyses after removing the roots of the first for K should be consulted and supple- crop. Nitrogen uptake by fescue was mental K added to satisfy the crop equal to 5 percent of the residual N requirement. (Tester et al., 1979). In the second year, availability of P from sewage Compost containing 6 to 10 percent lime sludge compost was estimated to be from will increase the pH of acid soils. 70 to 90 percent of the first year Soils below pH 4.5 will generally levels (McCoy et al., 1983). require additional lime when the compost is added at a rate equal to the Bunting (1963) summarized a series of N requirement of the crop. experiments on the yield response of vegetable crops to sewage sludge-straw Information in table 3 shows the sug- compost and other organic manures. gested application rates for different Yield increases for all crops were crops when a sewage sludge compost obtained when sewage sludge-straw similar in quality to that listed on compost was applied at an annual rate page 6 is used. The application rates of 27 wet mt per hectare (9 dry mt/ha). have been calculated to satisfy either After 4 consecutive years of compost the total N or the total P requirement application, the soil water content of of the crop. In arriving at these the compost-amended plots increased by values, the N availability for the 1 percent on a dry weight basis over first year following application was that in plots that received only assumed to equal 10 percent of the mineral fertilizer. total N content of the compost; the P availability of compost for the first An estimate of the amount of N avail- year was 40 percent that of mineral P able to the plant from one to several fertilizer; and the soils receiving the years is presented in table 4. A basic compost were of medium fertility. The assumption here is that the N minerali- other assumptions are listed in table 3. zation rates for the first, second through fifth, and succeeding years is The P requirement for most crops is 10, 5, and 2 percent, respectively, of usually less than the N requirement. the organic N remaining. Thus, when compost is applied at a rate to supply a crop's P requirement, O'Keefe^/ evaluated the plant uptake additional N fertilizer must be applied of residual N from plots amended with to provide the total amount of N sewage sludge compost for 3 to 4 con- required by the crop. secutive years. The average N uptake by corn for 3 years after amendment was The amount of inorganic N initially 5 percent. After several years of present in the compost was not used in applying compost at rates to fulfill calculating available N. Incubation the crop's N requirement, an data have shown that the inorganic N, equilibrium would be established. At which is primarily in the ammonium that time, the amount of available N form, is rapidly immobilized into the would be equal to the total N applied. organic N form because of the high The number of years of successive carbon-to-nitrogen ratios (C:N) that compost applications required to reach result from amending soil with compost (Tester et al., 1977). There are few data on the availability of residual N to crops in the second and subsequent 5./o*Keefe, B. E. Evaluation of nitrogen years from a single application of availability indexes on a sludge compost sewage sludge compost. amended soil. 1983. [Unpublished master's thesis. Copy on file Dept. Agron., Univ. Pots used in the study reported by Md., College Park,]

11 equilibrium has not been established mineral fertilizer are actually applied by research. The availability of P to in proper balance. Compost appears to plants in the second and remaining years increase the plant's efficiency in the from a single application of sewage use of mineral fertilizers (Bunting, sludge compost has not yet been deter- 1963; Sikora et al., 1980). Considering mined, either in the greenhouse or the the large amounts of compost that must be field. added to satisfy the N requirements of some crops like com, it may be more These application rates are examples of advantageous to apply a small amount of using compost alone as a source of compost to obtain the soil conditioning either N or P. In most agronomic benefits and then supplement the situations, it is unlikely that farmers remaining nutrient needs with mineral would be willing to apply the large bulk fertilizer. of compost necessary to furnish the entire N or P requirement for the crop. Application of sewage sludge compost can Certainly, a more acceptable rationale be accurately performed when the nutrient would be to apply compost at lower rates availability of the soil and the nutrient of 10 to 20 mt per hectare, primarily as requirement of the crop are known. Soil a soil conditioner, and to supplement tests should be performed annually or as the remaining N and P requirement as often as necessary to be certain of the mineral fertilizer. availability of nutrients.

Reports indicate that crop yields are Pathogen Content generally highest where compost and The adult forms of the helminths and Table 4.—Available N from single protozoans do not persist in the application of sewage sludge compost at environment outside their hosts. For indicated rates (derived from Willson reproduction, the helminths produce ova et al., 1980)1/ and the protozoans produce cysts. Both can persist to some extent in the environment and can continue the Sludge Total N Available N infection cycle when present in wastes. application applied 1st 2d- Beyond (wet mt/ha)l/ year 5th 5 Enteric and viruses do not year years produce resistant forms but are found in wastes. Of the bacteria, only the salmonellae seem capable of any sustained Kg/ha Kg/ha Kg/ha Kg/ha growth outside their hosts, and they have been reported to grow in sludge and 10 90 9 5 2 compost that have been sterilized to 20 180 18 8 3 eliminate competition from other organisms 50 450 45 19 7 (Brandon et al., 1977). Only limited and 100 900 90 38 13 occasional growth has been reported in 200 1800 180 78 26 unsterilized sludge or compost. The viruses, although capable of some persistence in the environment, are not 1/1.5 percent total N. Mineralization able to reproduce outside the cells of rates are 10, 5, and 2 percent for 1st, their hosts. 2d through 5th, and subsequent years, respectively. The most important enteric pathogens in human wastes that can also be found in ^./Moisture content equals 40 percent; sewage wastes, along with the diseases to convert metric tons per hectare to they cause, are as follows: tons per acre, multiply by 0.45.

12 Organism Disease Bacteria: Mycobacterlum tuberculosis Pulmonary tuberculosis. spp. Salmonellosls. Shlgella spp. Shigellosis. Helminthic parasites (Intestinal worms): Ancylostoma duodenale Hookworm Infection. Ascaris lumbrlcoldes Ascarlasls. Necator amerlcanus Hookworm Infection. Taenia saglnata ( tapeworm) Taenlasls. Trlchurls trlchlura (whlpworm) Trlchurlasls. - Entamoeba hlstolytlca Amoebic dysentery. Viruses : Adeno virus— Acute respiratory Infect .jL' Coxsacklevirus Aseptic meningitis, gastroenteritis.2,/ Echovirus Aseptic meningitis .2' Hepatitis virus infectious hepatitis. Poliovirus Poliomyelitis. Reovirus Mild respiratory infection, gastroenteritis. i/Other diseases include pharyngitis and infant pneumonia.

2./Two of the diseases caused by several serotypes of this virus; diseases caused range from trivial to lethal.

3/similar to diseases caused by coxsacklevirus.

Research by the Department has shown that values for f2 and other pathogens are under proper operating conditions for shown in table 5. aerobic-thermophlllc composting, sufficiently high temperatures are The much higher D value for f2 means that attained to Inactivate all these a temperature over a time period that pathogenic organisms (Bürge et al., would destroy this organism would insure 1978). This result has suggested that the destruction of any enteric pathogens time X temperature functions could be that might be present. A time period of used for monitoring pathogen Inactlvation 2.5 days at SS^C will Inactivate about during the composting process. However, 15 logs of f2 virus and has been chosen the time needed to inactivate any as a recommended criterion, because it is particular pathogen at a particular a goal that can be readily achieved under temperature varies considerably, and proper operating conditions and has temperatures can vary greatly throughout enough excess potential for destroying a composting pile. pathogens to result in a wide margin of safety. To overcome these problems of variability, a time X temperature monitoring program Unlike other enteric pathogens, salmo- was conducted utilizing the relatively nella bacteria can grow outside their heat-resistant bacterial virus f2 as a hosts. Thus, even though salmonellae may standard (Bürge et al., 1981). The rela- have been completely destroyed during the tive resistance of f2 to heat destruction composting process, regrowth is possible can be compared with that of other if the pile becomes contaminated with the organisms by using D values. A D value feces of salmonella-infected animals. is the amount of time required to cause a Although salmonellae do not compete well tenfold (one log) reduction in population. if other organisms are established, the The temperature must be specified. The D potential for regrowth exists; therefore.

13 Table 5.—D values for enteric pathogens provides an opportunity to achieve more and f2 bacteriophage enduring controls while conserving soil resources and improving .

D value at— The success in controlling soilbome Organism diseases through incorporating organic 550C 60OC residues has been attributed to the general increase in the antagonistic activity in soil during the micro- Minutes Minutes biological decomposition of organic substrates. Antagonistic activity Adenovirus, 12 11.0 0.17 includes (1) the production of growth Poliovirus, type 1 32.0 19.0 inhibitors or toxicants by saprophytic Ascans ova ~———— 1.3 microflora or plant roots, (2) nutrient Hlstolytica cysts 44.0 25.0 competition between pathogens and Salmonellal/ 80.0 7.5 saprophytes, and (3) parasitism of Bacteriophage, f2 267.0 47.0 pathogens by saprophytes. Enhancement of these activities by appropriate and timely application of organic residues 1/Serotype Senftenberg 775W, is one of the current approaches to biological control of soilbome diseases Source: Bürge et al., 1978. (Lumsden et al., 1983).

monthly assays of the finished compost Much work has been done on composts made should be run for salmonellae. Experi- from waste hardwood and pine bark and ence at Beltsville indicates that under used in container media for nursery and proper operation of the compost site, crops. These studies have salmonellae will not regrow. The salmo- shown that such composts suppress nella assay, therefore, is an additional soilbome diseases caused by plant check against improper site management. parasitic nematodes (Malek and Gartner, 1975) and by Corticium rolfsii, Fusarium In Maryland, the Department of Health spp., Pythium sp., several Phytophthora and Mental Hygiene is using these time X spp., and Rhizoctonia solani (Hong and temperature criteria and salmonella Ueyama, 1973; Chef et al., 1977; Hoitink assays as the standards to be met for et al., 1977; Daft et al., 1979; Hoitink release of the compost to the public for and Poole, 1980; Stephens et al., 1981; general use (Bürge, 1983). Other States Spencer and Benson, 1981, 1982). are considering adopting these criteria. Information on the effects of sewage Root Disease Control sludge or sludge compost on soilbome diseases is limited. Habicht (1975) Application of organic residues to soil reported that undigested sewage sludge has long been considered potentially compost was effective in reducing the useful for controlling some root rots amount of galling caused by the root- and seedling diseases caused by soil- knot nematode (Meloidogyne incognita borne plant pathogens (Baker and Cook, acrita Chitwood) on tomato roots. Raw 1974) and galling caused by plant sludge at a 2 percent amendment (dry parasitic nematodes (Linford et al., weight basis) was more effective than 1983). In the absence of organic sludge compost at a 4 percent rate in materials for soil amendment, crop reducing galling in comparison with the losses to soilbome diseases can unamended control. Habicht (1975) sometimes be reduced by periodic and suggested that , salts, or organic costly soil fumigation or by using acids produced during decomposition are -treated . The utilization more likely responsible for the observed of materials otherwise considered as activity than are antagonistic organisms organic wastes, in cropping practices. directly.

14 Information from W-124 studies on the rate of amendment was used in all optimum utilization of sewage sludge on studies. agricultural land in Oregon (Anonymous, 1981) indicated that a reduction in In the greenhouse tests, sandy and crown gall disease caused by Agro- loamy soils that were naturally or bacterium tumefaciens on cane berries artificially Infested with the pathogens was observed in soils amended with were amended with compost and incubated anaerobically digested sewage sludge. from 1 to 14 weeks to allow an active The effect was associated with the microflora to develop. After planting presence of antagonistic micro- and appropriate incubation, the disease organisms and decreases in numbers and incidence or severity was evaluated at kinds of Agrobacterium in amended suitable periods, 3 to 6 weeks, soils. In the same studies, sewage depending on the host. From these sludge applications to soil also tests, it was concluded that root rots Immediately eliminated Cercosporella caused by Aphanomyces euteiches, foot rot of wheat. In contrast, Phytophthora capsicl, Rhizoctonia take-all root rot of wheat caused by solani, and Sclerotinia minor on such Gaeumannomyces graminls var. tritici crops as peas, pepper, lettuce, beans, developed after 2 years of wheat cotton, and radish were reduced signifi- culture. The disease was more severe cantly in comparison with disease in where sewage sludge rather than ferti- unamended control soils. However, root lizer was used as a soil amendment, and rots and damping-off caused by Fusarium it was further enhanced where soils had solani, Pythium aphanidermatum, P. been previously limed. ultlmum, and Thielaviopsis basicola on peas and beans were unaffected or Recent Studies on the Effects of Sewage increased in comparison with disease in Sludge Compost on Root Diseases—A the unamended controls. combination of greenhouse and field studies has been used in studying the Based on these results, as well as effects of sewage sludge compost on root considerations of climate, host, and diseases. With turfgrass and tall pathogen factors, disease caused by S_. fescue, greenhouse results indicated minor and R. solani was studied in 24 that brown patch and preemergent and field plots (2.5 by 4.0 m) at Beltsville. postemergent damping-off caused by R. An indigenous population of P. ultlmum solani were reduced by topdressing or was also present in the plots; however, amending soil with sewage sludge R. solani did not become established. compost, respectively (O'Neill, 1982). During the 3-year study, test plots were The inoculum size and concentration amended with compost at a 10-percent affected the amount of postemergent rate (dry weight basis) for the first 2 damping-off. In field trials comparing years; control plots were amended with sewage sludge compost with several lime and fertilizer to bring the pH and turfgrass fertilizers as a topdressing, N-P-K levels to equivalence with those the incidence and severity of fusarium available in the compost-amended plots. blight caused by Fusarium spp. were less No compost was used the third year. on plots receiving compost (J. J. Lettuce seedlings (Lactuca sativa var. Murray, unpub. data). longifolia 'Paris White') were planted in the spring and fall in £. minor Both greenhouse and field studies on infested plots and bean (Phaseolus sewage sludge compost have been completed vulgaris 'Tendercrop') were planted in on a few vegetable crops (Lumsden et the summer. Pea seeds (Pisum satlvum al., 1982; Miliner et al., 1982). The 'Perfected Freezer' and 'Early Alaska*) greenhouse results were used to select were planted in the spring and fall in the host-pathogen systems that were P. ultimum infested plots, and cotton studied in the field. Based on results seed (Gossypium hlrsutum 'Acala') was from previous tests (J. A. Lewis, planted in the summer. Pea and cotton unpub.), a 10 percent (dry weight basis) seed were treated with thiram, PCNB, or untreated. 15 Typical examples of results are shown in compost from the previous applications table 6. In general, leaf drop of was present. lettuce was controlled in the cropping season immediately after the first Future of Sludge Compost in the Control application of compost and each season of Sollbome Diseases—The potential is thereafter, including seasons when no great for using sewage sludge compost to additional compost was added. Damping- enhance or Induce biological control of off of peas in the resistant cultivar soilbome diseases. The success reported *Early Alaska' was never enhanced by with bark and hardwood composts in compost. In the susceptible cultivar containerized potting media systems and 'Perfected Freezer,' disease was not the greenhouse and field trials using reduced during the first growing season sewage sludge compost with several major after amendment but was in the second diseases support the general principles and third. When only residual effects of biological control. At present, with of previous compost applications were only limited data available, it is present, no control was evident. In difficult to generalize about possible contrast, damping-off of cotton was effects with other host-pathogen systems. enhanced in fungicide-treated However, the various and encouraging seed-compost trials during the first results obtained thus far indicate the season after compost amendment, not in need to continue to coordinate activities the second, and control was regained in among plant pathologists, microbiolo- the third year, when only residual gists, and environmental scientists involved in the applications of sewage Table 6.—Typical suppressive effects of sludge compost in agricultural systems. compost amendment on leaf drop of lettuce As more users develop and communicate caused by Sclerotinia minor and on their results with different compost- damping-off of peas and cotton caused by crop-pathogen systems, the pathologist Pythium ultimum will be better able to assess the effect of future applications.

Healthy plants with— Economic Benefits Disease Seed treatment Compost No compost The economic benefit to a grower from using sewage sludge compost in plant production may result from an increase Percent Percent in profit due to increased prices from improved plant quality, increased Lettuce None—- - 92 62 quantity of crop for sale, decreased drop. costs of inputs, or combinations of these. The actual profitability of Damping-off: using compost will vary with the quality of the compost, the price of the compost Peas None - 24 0 as compared to its substitutes, the value of the crop, and other variables. Thiram- - 58 0 The simplest method to estimate the PCNBI/-- 73 2 worth of the compost is to assume that it is a N, P, and K substitute for Cotton— None - 38 28 commercial nutrients in plant production that would otherwise have to be pur- Thiram- - 52 42 chased. By this method, the Beltsville sewage sludge compost described on page PCNB " 58 43 6 would be worth $59.45 per metric ton of dry material when prices for N, P, and K are $0.55, $1.28, and $0.35 per i'PCNB =* pentachloronitrobenzene. kilogram, respectively. However, this

16 must be considered a rough estimate for Two generalizations concerning the several reasons. Some of the nutrients, relative value of sewage sludge compost particularly N, are predominantly in an can be made that are important in organic form in the compost and will not analyzing the profitability of using be as available to the plant as the compost. First, the plant response due nutrients in mineral fertilizers. The to the material is subject to dimin- relative quantity of nutrients in the ishing returns. The per unit value of compost may not be in optimum balance the material is reduced as more units of for some crops, and some nutrients may compost are utilized. Often the plant be applied at too high or low a rate. response, and hence value, can even Thus, the yield response may not be as become negative if too much material is reliable per unit of nutrient as with applied. Second, the economic value of commercial mineral fertilizers. the material may extend over several growing seasons because of its charac- Sewage sludge compost contains many teristic as a slow-release fertilizer. constituents other than N, P, and K that The benefits of the nutrients and affect the yield and quality of crops organic matter are evident for years and ultimately the profits. The compost after application to the soil. Several contains micronutrients and organic studies have shown that most of the matter that may be substitutes for benefits from compost are obtained after required inputs to production and the first year of application (Barbarika increase the worth of the material. On and Colacicco, 1980; Colacicco, 1982). the other hand, some composts may contain soluble salts, toxic metals, or The cumulative quantity of sludge have a high C:N ratio, all of which compost applied to cropland is usually would reduce the profitability of the limited by regulations based on its material. The assumption that the content of heavy metals. The user must nutrients in the compost are only then decide on the quantity of compost substitutes for the nutrients in ' applied in any year until the limit is commercial fertilizers is suspect reached. The per hectare returns from because o£ data that Indicate sewage farming can be significantly affected by sludge compost is a complement to the application strategy selected. commercial N (Sikora et al., 1980). The results of an economic analysis A better estimate of the worth of sewage showing the expected effects on yield sludge compost comes from yield response and profit from alternative application experiments designed to analyze how much strategies is presented in table 7. compost can substitute for another input, This analysis utilized a yield response such as or fertilizer, to achieve a function estimated from the data of Mays desirable plant growth response. et al. (1973) and Duggan and Wiles (1976). It was determined that a farmer Compost has been found to substitute for who applied a refuse-sludge compost to topsoil and peat in certain horti- meet the N requirement of a com grain cultural applications. In this case, crop would make annually about $12 per the compost would be worth $35 to $50 hectare per year more than a farmer who per metric ton. For comparative applied the entire permitted amount of purposes, a metric ton of digested compost, based on metal limitations, in sewage sludge, which has higher concen- 1 year. Application based on the crop's trations of nutrients than when in the N requirement specified that the compost form of compost, was found to provide be spread over two consecutive cropping the same yield response as $16 of seasons. It was further determined that commercial fertilizer in com production. lower than N requirement application The value of the compost as a substitute rates would Increase net returns. The for another input can vary considerably present value of net return was and, therefore, few generalizations can maximized when the limited amount of be made unless a specific use for the compost was spread over a 7-year period compost is included in the discussion. with supplemental N added. The present 17 Table 7.—Example of effect of alternative strategies for applying compost on application rates, nitrogen, yield, and return above variable cost to grow corn

Year Compost N added Yield Net Present value added return of net return

Mt/hai/ Kg/ha Mt/ha Dol/hal/ Dol/ha¿/

Strategy 1: All permitted compost spread 1st year; no constraint on N

1 362 130 11.4 679 679 2 0 130 9.6 491 459 3 0 130 7.2 261 228 5 0 130 6.0 143 109 7 0 130 5.9 133 89 10 0 130 5.9 133 72

10-year total- 362 1300 69.9 2,420 2,034

Strategy 2: Compost and N applied to meet N requirement; constraint on Nz'

1 217 0 10.4 624 624 2 118 0 10.0 585 547 3 27 59 7.7 336 293 5 0 94 5.9 148 113 7 0 95 5.6 128 85 10 0 97 5.6 128 70

10-year total- 362 720 68.8 2,539 2,144

Strategy 3: Compost and N added to maximize profits^'

1 122 130 9.7 501 501 2 70 130 9.4 469 438 3 60 130 9.0 435 380 5 36 130 8.1 348 265 7 5 130 6.8 227 151 10 0 130 5.9 133 72

10-year total- 362 1300 77.2 3,112 2,522

1/Cumulative application of compost was limited to 362 mt/ha by restriction that cumulative zinc = 170 kg/ha (Maryland Guidelines at CEC = 8 meq).

^'Annual net return is defined as revenue less variable cost (VC); VC = 358 + 0.44 X nitrogen; price of com = 94.50/mt; compost free in field.

3,/Discount rate = 7 percent.

4/N requirement was 143 kg/ha/yr, which is the profit maximizing N application if no compost is applied.

^'Present value of profit for 20 years was used to solve for optimal annual N and compost application rates. 18 value of profit over a 10-year period borne vegetable diseases (Rhizoctonia would be almost $500 per hectare higher solani, Phytophthora capsici, and than a one-time application. The annual Sclerotinia minor) by the incorporation profit in this case would average $69 of compost has been reported (Lumsden et per hectare per year more than the al., 1981). one-time large compost application. Numerous studies have been conducted to The optimal number of years of determine the availability and uptake of application of compost and the resultant sludge- or compost-applied heavy metals increase in net return are expected to by vegetable crops (Bingham et al., be highly variable and dependent on many 1975; Dowdy and Larson, 1975; CAST, factors. However, the fact that waste 1976, 1980; Chaney et al., 1978, 1982; composts contain many constituents, such Giordano et al., 1979). These studies as organic matter and micronutrients have generally shown that leafy vege- that are complements to conimercial tables, particularly lettuce and chard, fertilizers, implies that the most accumulate greater levels of Cd and Zn effective use of the material can be than crops grown for fruits or tubers. made by applying the compost with The accumulation of Cd and Zn is also fertilizer over a longer period than if affected by the concentration of these the compost were used as a substitute metals in the sludge or compost, the for commercial fertilizer. total cumulative application of these materials, and the pH of the amended soil over time (CAST, 1976, 1980; Mahler USES FOR SEWAGE SLUDGE COMPOST et al., 1978; Chaney et al., 1982).

Vegetable Crops As mentioned previously, the quantity of composted material that can be safely The benefits of applying sewage sludge spread is directly related to the quality compost to vegetable cropland are derived of that sludge or compost. Sludges or from improved soil physical properties, composts made from sludges originating such as enhanced aggregation, lower bulk from sources without excessive industrial density, increased water infiltration waste contamination have low metal and retention, and increased cation concentrations and are therefore of exchange capacity (Epstein et al., 1976). greater value for land application. Compost also provides P, micronutrients, and some slowly available N (Homick et Federal guidelines have been developed al., 1980; Parr and Wlllson, 1980). that provide for the use of high-quality However, because of the high N require- sludges or composts and the approprikte ments of many vegetable crops, the management practices to assure the ! application of sewage sludge compost as maintenance of the current high standard a N fertilizer may not be feasible. The of good quality (EPA, 1979). The guide- greatest potential value is obtained lines were formulated to maximize the when compost is used in combination with benefits of sludges or composts to food- inorganic fertilizers, as the compost chain cropland while minimizing the fulfills part of the nutritional accumulation of these metals. When requirements of the crop (Parr and State or local regulations are more Willson, 1980). This is particularly stringent than Federal guidelines, the; true in succession cropping systems former take precedence. In certain (Parr, 1982). areas, the use of sewage sludge or compost may also be limited by policies A major advantage of compost over sludge of the food processors. is the ease of spreading the material. Compost has a lower moisture content and To further assure safe and wholesome has a more friable structure than most food products, a Joint Statement of sewage sludges (Epstein et al., 1976). Federal Policy recommended the use of Also, the suppression of certain soil- only high-quality sludges or composts.

19 with the concentrations of contaminants quality at pH 7.0 (Sterrett et al., limited to £25 mg per kilogram of Cd, 1982, 1983). 1,000 mg per kilogram of Pb, and 10 mg per kilogram of polychlorinated Where available, sewage sludge compost biphenyls (PCBs). This level of PCB can be used as a fertilizer and soil assumes that carrots receive appropriate conditioner in the home garden. For processing, including scrubbing and best results, it should not be applied peeling. Other restrictions include a in excess of the crop*s N requirement. maximum cumulative Pb application of 800 Supplemental P fertilization is not kg per hectare; applications of sludge necessary when compost is applied as a N directly to soil, never to growing fertilizer. Because of the low K levels crops; crops grown on sludge- or in compost, additional K may prove compost-amended soils, particularly root beneficial to such crops as com and crops and low growing fresh fruits and melons. vegetables, processed in accordance with established industry practices; and As in commercial production and in the annual monitoring of pH (EPA, FDA, USDA, production of vegetable transplants, the 1981). use of low metal sludge composts is recommended to achieve the maximum In some geographical locations, benefit of compost as a soil conditioner particularly those with warm, humid and fertilizer, and to minimize the climates, planting may need to be delayed acctunulatlon of Cd and Pb in food-chain for 36 months until crops can be consumed crops. Additionally, soil pH should be raw or without sufficient blanching for maintained at 6.5 to 7.0 whenever vege- adequate pathogen destruction. However, tables are to be grown. Periodic soil crops that are cooked or will receive testing and pH monitoring are advisable appropriate heat processing may be used to Insure proper soil fertility. These in normal rotation during the 36-month services can be obtained through the waiting period. USDA Cooperative Extension Service.

Another aspect to be considered is the Nursery Crops and Ornamentals potential toxicity due to compost composition. Temporary soluble salt Compost Use In Media—Mixing compost in toxicity may occur with composts made container media, nursery soils, or soils from sludges where ferric chloride where trees and shrubs are to be planted (FeCl3) has been used for improved P can improve soil fertility, pH, soil removal in the flocculation dewatering structure, and the water-holding capac- process (Chaney et al., 1980). Boron ity. However, the physical attributes toxicity may limit the use of some of a particular compost reflect the composts when municipal refuse is used treatment process employed In the pro- as the bulking agent (Purves and duction of the sewage sludge to be MacKenzie, 1973). Also, when limestone composted. Sludges resulting from is used in the treatment of raw sewage, dewatering techniques using polymers the pH of the resulting compost will be have a lower, less buffered pH than substantially higher than that of limed, raw sewage sludges. Since compost made from digested sludge. optimal plant growth occurs at pH 5.0 to 6.5 (lower for ericaceous plants), the Sewage sludge composts made with low use of composts made from limed, raw metal sludges can be used in the growing sewage sludges may be limited. This is media of vegetable transplants without particularly true when the lime content an increase of the metal concentrations of the sludge exceeds 10 percent lime- in the edible parts (Sterrett et al., stone by weight (pers. commun., F. R. 1983). However, the use of a compost Gouln, Mar. 1983). The utilization of containing an industrially contaminated ferric chloride (FeClß) in the treat- sludge resulted in severe phytotoxlclty ment process can result in excessive at pH 6.5 and inferior transplant soluble salt levels in the compost, so

20 that thorough initial leaching of the Plnus strobus (white pine), and Quercus growing media is essential to avoid root rubra (red oak) (Gouin and Walker, 1977; injury (Chaney et al., 1980). Gouin, 1977a; Lepp and Eardley, 1978; Korcak et al., 1979). Stem length was Although woodchips are the most commonly increased and winter die back reduced by used bulking agent (Willson et al., the incorporation of 112 to 224 dry mt 1980), sludge composts containing per hectare (2,300 to 4,600 lb per 1,000 municipal leaves or municipal refuse ft^) of digested sludge compost into have also been evaluated for use in the the . However, incorporation of production of nursery or greenhouse 448 dry mt per hectare has resulted in crops. Media containing municipal leaf reduced plant populations and less stem compost were well aerated and had elongation in some species (Gouin and optimal pH, as well as adequate magne- Walker, 1977; Gouin, 1977a). Azaleas, sium (Mg), P, and K concentrations for rhododendrons, and Japanese hollies have plant growth (Sawhney, 1976; Gouin, also been grown in silt loam soils 1977b). However, excessive media amended with 112 to 168 dry mt per shrinkage (loss of one-half of total hectare of screened sewage sludge volume within the first year due to compost (Gouin and Link, 1977, 1982). oxidation) limits the acceptance of municipal leaf sludge compost as a media Sludge compost has also been used in the component for container production production of container-grown woody (Gouin, 1976). Municipal refuse-sludge ornamentals. The pH of compost made compost has compared unfavorably with from lime-dewatered sludge will be 6.8 peat moss-based media in the production to 7.2. Plant growth will be improved of both greenhouse crops and container by incorporating 1.19 to 1.78 kg per nursery stock (Sanderson, 1980). The cubic meter (2 to 3 lb per cubic yard) poor growth of chrysanthemums, snap- of wettable . Ericaceous plants dragons, geraniums, and various woody that grow best in media with low pH ornamental species has been attributed include Ilex crenata (Japanese holly), to various combinations of high pH, Kalmia (mountain laurel), Leucothoe excess soluble salts, and N deficiency spp., Pieris spp. (Japanese Andromeda), caused by incomplete stabilization, Quercus coccínea (scarlet oak), Quercus boron toxicity, or both (Sanderson, palustris (pin oak), and Rhododendron 1980). spp. Because of inadequate root development and poor growth after The total number of composted materials transplanting into the landscape, limed, that have been evaluated as growing raw sludge compost is no longer media components is limited. Therefore, recommended for use in the media for any recommendation must be of a general container-grown ericaceous plants (pers. nature and growers are strongly urged to commun., F. R. Gouin, Apr. 1983). The conduct small-scale screening tests with presently recommended growing medium locally available products prior to containing lime-dewatered sewage sludge making major changes in the composition compost consists of equal parts of of their growing media. Only screened compost, coarse sharp sand, and peat compost (particle size <1.27 cm dia- moss (Gouin, 1982a, 1982b). meter) should be used in the production of horticultural crops (Gouin, 1982a, Composts made from polymer-dewatered, 1982b). digested sewage sludge appear to have more potential as a growing media Sewage sludge compost has been used component, particularly for ericaceous effectively in the production of tree plants. Good-quality plants have been seedlings, such as Acer pseudoplatanus grown in media containing 33 to 50 (sycamore or planetree maple), Cornus percent (by volume) polymer-dewatered, florida (dogwood), Juglans nigra (black digested sludge compost, 25 to 33 walnut), Liriodendron tullpifera (tulip percent peat moss, and 25 to 33 percent poplar), Picea abies (Norway spruce), coarse sharp sand. For production of

21 species that grow best at pH 5.0 or been grown in media containing 33 or 50 below, 1.19 kg per cubic meter of percent compost by volume particularly wettable sulfur should be added to the when peat moss (25 to 33 percent) was media (Gouin, 1982a). included in the media (Sterrett et al., 1984)• Both papermill sludge compost (Gouin, 1982a; Sterrett et al.l^) and com- For short-term crops (those ready for posted gelatin waste (Gouin and Shanks, market in 2 months or less), media 1981) have been evaluated as growing containing compost, peat moss or media components. Problems with fine-milled pine bark, and incomplete stabilization, high pH, high are appropriate. Media containing soluble salts, and low fertility compost, peat moss or finely milled pine (gelatiu wastes) may limit the useful- bark, and perlite or Styrofoam beads are ness of these products. preferred for long-term greenhouse crops (Gouin, 1982a). Plants grown in compost Another advantage of composted sewage should be watered thoroughly immediately sludge as an ingredient in potting media after planting to avoid soluble salt is reduced fertilizer requirements injury (Chaney et al., 1980; Gouin, (Chaney et al., 1980). Resin-coated 1982a; Sterrett et al.l/). fertilizers have been applied at 75 percent of the recommended rate with no Greenhouse crops should be fertilized 2 observable differences in plant growth to 3 weeks after planting (Gouin, 1982a). (Gouin, 1982a). Media containing 33 percent compost will provide adequate P for most short-term Where available, sludge composts may be bedding plants. Optimum plant quality a beneficial, economical media component has been obtained with either weekly (Sterrett et al.^/). However, sludge applications of 250 mg per kilogram of N composts will vary in pH, soluble salts, (Sterrett et al., 1984) or biweekly and nutrients, particularly N, depending applications of 500 mg per kilogram of N on the treatment employed in the (Gouin, 1982a). production of sludge. Therefore, each sludge must be tested and evaluated Preliminary results indicate a definite prior to large-scale use. For beneficial response of chrysanthemum and consistent production of good quality poinsettia cuttings rooted in media plants, the compost must be uniform both containing equal parts of compost, within and between delivered batches. vermiculite, and perlite (Gouin, 1982a). The naturally occurring in Greenhouse Crops and Bedding Plants— composted hardwood bark (Hoitnik and Media containing 33 to 50 percent sewage Poole, 1976) may also be in sewage sludge compost by volume have produced sludge composts and would account for satisfactory growth of poinsettias, the suppression of root rots reported by chrysanthemums, and lilies (Shanks and Gouin (1982b). Gouin, 1984). Since many greenhouse crops will tolerate higher soil pH Compost stockpiles destined for green- without an adverse effect on growth, pH house use should be covered to avoid adjustment with sulfur is less critical. introduction of windbome weed seed. Good-quality bedding plants have also Also, stockpiles should be constructed so that aerobic conditions prevail within the pile. The development of i/sterrett, S. B., C. W. Reynolds, F. strong odors is an indication of D. Schales, and R. L. Chaney. Influence anaerobic conditions and can be used as of soilless media on transplant quality an indicator that the piles need to be and crop yield of tomato, cucumber, turned or aerated. The utilization of eggplant, and cabbage. 1983. compost stored under anaerobic conditions [Unpublished. Copy on file USDÂ, ARS, may result in poor root development and Bldg. 007, Beltsville, Md.] delayed plant growth. This is especially

22 true with bedding plants and vegetable conditioner. When compost is incorpor- transplants. ated with the top 12 to 15 cm of the soil or is applied as a mulch to the Turfgrasses soil surface before or after seeding, seedling establishment is more rapid Sewage sludge compost can be used eco- than with conventional fertilizer nomically and beneficially in turfgrass practices (Murray, 1978; Duell, 1982). production for various areas, including home lawns, parks, institutional grounds, Best results for germination, establish- athletic fields, golf courses, and road- ment, and initial growth rate of turf- sides. It can also be used in the pro- grass are obtained with an application duction of cultivated sod. The benefits of 99 to 298 mt per hectare of compost from utilizing compost are derived from (wet weight equivalent to 40 percent its content of plant nutrients, organic moisture).Z/ The lower rate is matter, and liming properties. generally used on fertile soils and higher rates on sandy soils or subsoils On many soils with poor physical prop- low in organic matter. These rates will erties, compost used correctly will provide sufficient N and P for optimum produce better turfgrass than mineral plant growth. Potassium must be added fertilizers (Murray, 1978; Murray et if the soil is naturally low in this al., 1980; Duell, 1982). The use of element. The K fertility level of a compost as a source of organic matter soil should be verified by a soil test. takes on added significance as more Additions of less than 99 mt per hectare marginal lands are being used for con- of compost are beneficial but should be struction of homes and other developments supplemented with commercial N and P and as good topsoil becomes increasingly fertilizers. Where compost applications expensive. are based on the nutrient requirements of the turfgrass, rather uniform and The plant nutrient content of sludge favorable growth rates can be expected compost, especially its N content, and for 5 to 6 months after seeding or the mineralization rate are very impor- sodding. Excessive growth occurs with tant when compost is utilized in turf- additions greater than 298 mt per grass production. Nitrogen affects the hectare, even on infertile soils. rate of turfgrass growth more than other nutrients. Unlike the production of Research has shown (Patterson et al., many crops, maximum growth or production 1981) that on many disturbed sites where of vegetative material in turfgrass topsoil would be needed to grow production is generally undesirable. acceptable turf, the judicious use of The desirable rate of growth is one that sewage sludge compost can improve the is sufficient to maintain a healthy, existing soil for turfgrass establish- uniform turf during the growing season ment and maintenance. Higher rates can without excessive production of be used on sites where the compost can vegetation. be incorporated deeper than 15 cm and where ground-water contamination is not Sludge compost can be used as (1) a soil a potential problem. Since the plant amendment for establishment of turf- nutrients in compost are slowly grass, (2) a fertilizer source for released, a heavy single application maintenance of established turfgrass, could supply the fertilizer requirements and (3) a soil amendment or growth of the turf for several seasons medium for commercial turfgrass sod depending, on the quality desired. production.

Establishment—Establishment of turf- Z'l yd3 of screened compost at 40 grass from seed or sod can be signifi- percent moisture will weigh about 1,000 cantly increased on many soils by using lb and will cover a l,000-ft2 area to sludge compost principally as a soil a depth of one-third inch.

23 Compost applied at 29 to 38 mt per general-purpose turf and most home lawns. hectare to the soil surface as a mulch However, higher quality turf of cool- before or after seeding can markedly season grasses can be obtained by increase the establishment of cool- applying compost in the fall and winter season grasses. The greatest benefits at rates that would supply one-half of from its use as a mulch have been on the total N requirement. A water- late fall or early spring seedings of soluble source of N would then be cool-season grasses when air temper- applied when needed for added color, atures are relatively cool. When used probably during late spring or early as a mulch with soiall seeded grasses, summer• such as Kentucky bluegrass and bent- grass, the compost should be applied Growth response of cool-season grasses before seeding. With larger seeded can usually be detected within 72 hours grasses, such as tall fescue, red after the compost is applied. Response fescue, and perennial ryegrass, the is poor during periods of high air compost can be applied uniformly after temperatures. Low rates of application seeding. in summer have also increased dollar spot disease, and application in late Root growth of conventionally produced spring or early summer has increased sod is increased when the sod is laid on leaf spot disease on Kentucky bluegrass. soil previously amended with compost. The use of compost on close cut, highly Applications of 99 to 198 mt per hectare, maintained turf, such as golf-course depending on the soil and incorporated greens and tees, may be objectionable to a depth of 12 to 15 cm, will signifi- because of a black residue. cantly Increase root growth and develop- ment and provide near optimum growth for Warm-season grasses, such as bermuda- 2 to 4 months after the sod is laid. grass and zoysia, respond well to Root growth is not increased appreciably compost applications of 40 to 60 mt per with higher compost rates; however, hectare applied when new growth is excessive grass growth can be expected starting in the spring while temper- with rates higher than 298 mt per atures are still relatively cool. hectare. During the first 2 years of compost use, additional N from a water-soluble source Maintenance—Sewage sludge compost can may be needed to provide acceptable substitute for conventional fertilizer turfgrass quality. After the second in the maintenance of established turf- year, the application of compost in the grasses. The extent to which compost spring will provide acceptable turfgrass can be used to supply the total N quality for general-purpose turf without requirement depends on the maintenance supplemental fertilizers. Midsunmier level desired. For turf under a low to applications of 20 to 40 mt per hectare moderate maintenance level, compost can are beneficial. Maximum response is be used to supply the total N require- obtained when the compost is "watered-in" ment. For higher maintained or higher immediately after application. quality turf, compost can be used to supply a part of the N requirement, with Sod Production—The greatest potential the additional N supplied from other use for compost in the turfgrass sources. industry is probably in commercial sod production. If compost is managed The response of cool-season grasses, properly, large quantities could be used such as tall fescue and Kentucky on a relatively small land area. It can bluegrass, is best with compost appli- be used in sod production as a soil cations of 40 mt per hectare in the fall amendment, as discussed under establish- or split applications of 20 mt per ment of turfgrasses, or as a growth hectare in the fall and again in the medium. spring (March). These treatments will provide acceptable turfgrass quality for When used as a soil conditioner, 149 to

24 298 mt per hectare (wet weight of 40 Compost applications in the field can be percent moisture) incorporated to a made by using a calibrated manure depth of 12 to 15 cm will provide good spreader. Rates for field crops are plant growth. Incorporating the compost given in table 3. It is not a good is essential if is not practice to plant a legume crop the same practiced. Further research is needed year that compost is applied because to evaluate the optimum usage of compost most legumes do not need N fertilizer under different production practices. and thus the compost would be inefficiently used. Sewage sludge compost is an ideal growth medium for most turfgrass sod. The only Sewage sludge composts should not be essential plant nutrient that has to be applied on soils used in tobacco added is K. Kentucky bluegrass-red production, either as fertilizers or fescue and tall fescue-Kentucky blue- soil conditioners. Composts would have grass mixtures seeded into a 5- to 13-cm a liming effect on most soils and might layer of 298 to 894 mt per hectare of enhance the incidence of root diseases compost on the soil surface can produce of tobacco. Also, tobacco grown on a harvestable sod within 7 months after soils amended with sewage sludges or fall seeding compared with 12 to 18 sludge composts will contain increased months normally required when compost is levels of Cd, which may jeopardize the not used. Sprigging or plugging marketing of this crop both domestically bermudagrass or zoysia into a layer of and abroad. Cadmium in cigarettes compost in early spring results in a already contributes to the body burden rapid production of a harvestable sod or of Cd in humans, and increased Cd in sprigs. tobacco must be avoided.

When seeding or sodding into a layer of Forage Grasses compost on the soil surface, irrigate to leach salts and prevent of the Compost can be used successfully to upper part. Although frequent mowing is establish and maintain forage grasses. required with the use of compost as a For establishment, an initial or one- growth medium, the total ntmiber of time application of 199 to 347 mt per mowings would be about the same as with hectare of compost should be thoroughly conventional sod production because the incorporated with the top 15 cm of soil. sod can be harvested sooner. Other The lower rate should be used on rather advantages of surface applications are fertile or already productive soils and that little or no and commer- higher rates on unproductive soils. cial mineral fertilizers are required. Additions of compost at these rates Moreover, compost sod weighs about 30 to should produce a rapid rate of growth. 40 percent less than mineral soil sod. Later applications of 28 kg per hectare of a soluble N fertilizer will be needed Field Crops to sustain a high rate of growth.

When sewage sludge compost is used as a To maintain the pasture after the first fertilizer as well as a soil conditioner year, apply compost after the grass is for agronomic row crops or pasture, cut. A rate of 49 to 65 mt per hectare yearly application rates should be should be sufficient to maintain growth determined by the N or P requirement of and produce quality forage. Animals can the specific crop to be grown. This be allowed to graze after regrowth has information can be obtained from a local occurred. After repeated applications cooperative extension agent. For of sludge compost (5 to 10 years), a example, an oat variety requiring about substantial amount of compost probably 45 kg of N per hectare would need 50 mt will have accumulated on the surface per hectare of sludge compost. A com from topdressing. If so, the pasture variety requiring 157 kg of N per should be renovated by tilling the hectare would need 174 mt per hectare of compost into the soil. Tilling and sewage sludge compost. 25 replanting best utilize the soil condi- plants are difficult because of (1) tioning properties of the compost and extremely low pH, (2) extreme droughti- minimize ingestion of the compost by the ness from lack of organic matter, (3) animals while grazing. very high surface temperature, (4) lack of nutrients, and (5) very poor soil Heavy applications of over 67 mt per physical conditions. hectare of sludge compost to the surface of established pastures can cause an Research by the Department has shown increased consumption of compost by that through the proper use of sludge grazing livestock if improper animal and compost and dolomitic limestone forage management practices are used. agronomic crops can be grown on such Consumption of high levels of compost lands (Hornick, 1982). With proper can interfere with Cu availability in management, disturbed lands can be cattle and sheep, and high Fe levels in restored to a high level of productivity the compost can further reduce Cu in a surprisingly short time of 3 to 5 availability (Standish et al., 1969). years. Often, the use of compost in the When liquid digested sludge containing reclamation process is more economical 11 percent Fe was sprayed on tall fescue, than the use of mineral fertilizers, grazing cattle developed high levels of primarily because the very poor chemical Fe in tissues (Decker et al., 1980). and physical properties of these lands However, when cattle grazed tall fescue must be improved before optimum plant pasture topdressed with 227 mt per growth and response to fertilizer can hectare of a compost containing 4 percent occur. Fe, the Fe content of tissues did not increase. Compost applications for marginal lands should be based on soil characteristics Based on these findings and in the and the cover crop to be grown. For absence of any research on composts with disturbed soils, up to 400 wet mt per Fe over 4 percent, users who topdress hectare could be applied, with even established pastures with compost having higher rates where the compost is mixed a higher content of Fe should consider with more than 15 cm of surface soil and the following precautions: (1) Graze where ground-water contamination is not livestock alternately on compost- a potential problem. Since compost fertilized and noneompost-fertilized functions as a slow release N ferti- pastures; (2) after topdressing with lizer, a single heavy application of compost, wait at least 3 weeks for compost could supply the fertilizer forage regrowth or apply in the fall for requirements for several seasons. spring regrowth; (3) avoid overgrazing Research has shown that on very droughty pastures because it increases compost or acid soils, the deeper the compost is consumption; (4) apply at rates lower incorporated in the soil, the better are than required for N fertilization; (5) the crop yields. Special equipment may mechanically harvest the first forage be required for deep placement of the crop after compost application for use compost. as stored hay or silage; and (6) consider using feed supplements that contain Cu In general, the establishment of grasses but no Fe. on disturbed or marginal lands has been best with a fall application of sludge Reclamation of Disturbed and Marginal compost and subsequent seeding. For Lands both grassland and agronomic crops, the compost should be thoroughly plowed and Applying sewage sludge compost can aid disked Into the soil before the crop is significantly in the revegetation and planted. On acid soils, with crops reclamation of lands disturbed by sur- requiring less than 75 wet mt per hectare face mining, removal of topsoil, and of sludge compost for their N require- excavation of gravel deposits. On these ment, 1 to 2 mt per hectare of dolomitic lands the establishment and growth of limestone may be needed. On soils where

26 the pH is lower than 4,5, more lime may as decreased bulk density and surface be necessary for maximum crop yields. crusting, and increased water infil- tration, permeability, aeration, and Compost can be used beneficially as a water-holding capacity. * Economic mulch after conservation seeding. With analyses have also shown that small the woodchips present (unscreened), it additions annually are more profitable will more effectively control erosion for the farmer than a single one-time, and water loss by evaporation. From 14 large application. Land reclamation to 35 mt per hectare can be applied. projects on disturbed and marginal land are exceptions, since one-time, large applications of 100 to 200 mt per SUMMARY AND CONCLUSIONS hectare are necessary to overcome the inherent, adverse, chemical and physical Composts made from sewage sludges that conditions that prevent the establish- are low in their content of heavy metals ment and growth of plants. and toxic organics can be used safely and beneficially as soil conditioners Although substantial research data are and fertilizers. These benefits are available on the use of sewage sludge largely dependent on the quality of the compost, several areas need to be sludge, the bulking material used, and further researched, such as the residual the degree of stabilization achieved fertilizer value of compost, long-term during the composting process. Research effects on soil physical properties, has shown that good-quality sewage sludge ability of composts to suppress soil- compost can be used as a valuable amend- borne diseases, availability of ment in the production of agricultural organically bound heavy metals with and horticultural crops; in the estab- time, development of suitable analyses lishment, maintenance, and production of or bioassays to monitor composts for turfgrasses; in the formulation of harmful constituents, improvement of potting media for nursery production; in composting technology to insure a vegetable ; and in the recla- uniform, stable product, and more mation of marginal and disturbed soils. accurate estimates of the long-term Since State and local laws governing the economic benefits of using sewage sludge use of sewage sludge compost are vari- compost. Although further research is able, specific details concerning its needed, the information to date demon- utilization should be obtained from strates the many benefits that can be appropriate municipal, county, or State derived from using good-quality sewage regulatory agencies. sludge composts in agriculture, horti- culture, and land reclamation. This bulletin provides information on how sewage sludge compost can be used most effectively. Recommendations are LITERATURE CITED based on a decade of research involving many laboratory, greenhouse, and field Anonymous. 1981. Optimum utilization experiments. Because the type of sewage of sewage sludge on agricultural land sludge and bulking material affects the (W-124). Oreg. Rpt. 1980 (Jan. 5-8), quality of the final product, it is 6 p. Cincinnati, Ohio. (Oreg. Proj. essential that the source and composition 42,324, EPA.) of these materials be known prior to composting and certainly before using Baker, K. F., and R. J. Cook. 1974. the product. Biological control of plant pathogens. 433 p. W..H. Freeman & Co., San The greatest benefit from compost Francisco, Calif. usually can be achieved at relatively low applications of 10 to 20 mt per Barbarika, A., and D. Colacicco. 1980. hectare, a level that generally would The value and use of organic wastes. improve soil physical properties, such 5 p. Md. Agri-Economics, Md. Coop. Ext. Serv., College Park.

27 Bingham, F. T,, A. L. Page, R. J. Mahler, compost on cropland. In Conf. Sludge and T. J, Ganje, 1975. Growth and Mangt. Alternatives; WEat Will We Do cadmium accumulation of plants grown on After the 1981 Ocean Disposal Ban?, a soil treated with a cadmium enriched Proc. 1978, p. 54-59, 115-127. Scien- sewage sludge. J. Environ. Qual. tists Com. Pub. Inform., New York. 4:207-211. Chaney, R. L. 1982, Fate of toxic Brandon, J. R., W. D. Bürge, and N. K. substances in sludge applied to cropland. Enkiri. 1977. Inactivation by ionizing In Internatl. Symp. Land Appl. Sewage radiation of Salmonella enteritidis, Sludge, Tokyo, Japan, Proc, 1982 (Oct. serotype montevideo grown in composted 13-15), p. 259-324. sewage sludge. Appl. Environ. Microbiol, 33:1011-1012. Chaney, R. L., and P. M. Giordano. 1977. Microelements as related to plant Bunting, A. H. 1963. Experiments on deficiencies and toxicities. In Elliott, organic manures 1942-49. J. Agr. Sei. L. F., and F. J. Stevenson, eds.. Soils 60:121-140. for management and utilization of organic wastes and waste waters, p. Bürge, W. D. 1983. Temperature and 233-280. Soil Sei. Soc. Amer., Madison, salmonella monitoring as criteria for Wis. pathogen inactivation during composting. BioCycle 24:48-50. Chaney, R. L., P. T. Hundemann, W. T. Palmer, and others. 1978. Plant Bürge, W. D., D. Golacicco, and W. N. accumulation of heavy metals and phyto- Cramer. 1981. Criteria for achieving toxicity resulting from utilization of pathogen inactivation during sewage sewage sludge and sludge composts on sludge composting. J. Water Pollut. cropland. In 1977 Nati. Conf. Com- Control Fed. 53:1683-1690. posting Munie. Residues and Sludges Proc. 1978, p. 86-99. Inform. Transfer, Bürge, W. D., D. Golacicco, W. N. Inc., Spring, Md. Cramer, and E. Epstein. 1978. Criteria for control of pathogens during sewage Chaney, R. L., J. B. Munns, and H. M. sludge composting. In Nati. Conf. Cathey. 1980. Effectiveness of digested Design Munie. Sludge Compost Facilities sewage sludge compost in supplying Proc. 1978, p. 124-129. Hazardous nutrients for soilless potting media. Mater. Control Res. Inst., Silver J. Amer. Soc. Hort. Sei. 105:485-492. Spring, Md. Chaney, R. L., S. B. Sterrett, M. C. Bürge, W. D., and P. B. Marsh. 1978. Morella, and C. A. Lloyd. 1982. Effect Infectious disease of land- of sludge quality and rate, soil pH, and spreading sewage wastes. J. Environ. time on heavy metal residues in leafy Qual. 7:1-9. vegetables. In 5th Ann. Madison Conf. Munie, and Indus. Waste, Madison, Wis., CAST. 1976. Application of sewage Proc. 1982, p. 444-458. sludge to cropland: Appraisal of potential hazards of the heavy metals to Chef, D., H. A. J. Hoitink, and H. A. plants and animals. Council Agr. Sei. Poole. 1977. Suppression of Fusarium and Tech. Rpt. 64, 63 p. oxysporum f. sp. *ehrysanthemi* in composted hardwood bark. Amer. CAST. 1980. Effects of sewage sludge Phytopath. Soc. Proc. 4:174. on the cadmium and zinc content of crops. Council Agr. Sei. and Tech. Rpt. Golacicco, D. 1982. Economic aspects 83, 77 p. of composting. BioCycle 23(5):26-31.

Chaney, R. L. 1978. Heavy metal Daft, G. C., H. A. Poole, and H. A. J. limitation in use of sludge and sludge Hoitink. 1979. Composted hardwood

28 bark: A substitute for steam sterili- Epstein, E., J. M. Taylor, and R. L. zation and fungicide drenches for Chaney. 1976. Effects of sewage sludge control of poinsettia crown and root and sludge compost applied to soil on rot. HortScience 14:185-187. some soil physical and chemical properties. J. Environ. Qual. 5:422-426, Decker, A. M., R. L. Chaney, J. P. Davison, and others. 1980. Animal Giordano, P. M., D. A. Mays, and A. D. performance on pastures topdressed with Behel, Jr. 1979. Soil temperature liquid sewage sludge and sludge compost. effects on uptake of cadmium and zinc by In Nati. Conf. Munie, and Indus. Sludge vegetables grown on sludge-amended Util, and Disposal Proc. 1980, p. 37-41. soil. J. Environ. Qual. 8:233-236. Inform. Transfer, Inc., Silver Spring, Md. Gouin, F. R. 1976. Marked growth response of woody plants with screened DeHaan, S. 1980. Sewage sludge as a composted sewage sludge. In Internatl. phosphorus fertilizer. Phosphorus Agr. Plant Propagators* Soc. Proc. 26:195-201. 78, p. 33-41. Gouin, F. R. 1977a. Conifer tree Dowdy, R. H., and W. E. Larson. 1975. seedling response to nursery soil The availability of sludge-borne metals amended with composted sewage sludge. to various vegetable crops. J. Environ. HortScience 12:341-342. Qual. 4:278-282. Gouin, F. R. 1977b. Using sludge to Duell, R. W. 1982. Sludge composting improve the soil. Amer. Nurseryman and utilization: For turfgrass estab- CXLVI(5):15, 110-115. lishment and maintenance. 57 p. N.J. Agr. Expt. Sta., Cook Col., Rutgers The Gouin,.F.R. 1982a. Compost sludges State Univ., New Brunswick, N.J. for potting mixes. Md. Nurserymen's News 1982 (Mar.-Apr.), p. 3-5. Duggan, J. C, and C. C. Wiles. 1976. Effect of municipal compost and nitrogen Gouin, F. R. 1982b. Using composted fertilizer on selected soils and plants. waste for growing horticultural crops. Compost Sei. 17:24-31. BioCycle 22(l):45-47.

Environmental Protection Agency. 1979. Gouin, F. R., and C. B. Link. 1977. Criteria for classification of solid Growth response of broadleaf evergreens waste disposal facilities and practices; to soils amended with screened composted final, interim final, and proposed sewage sludge. Md. Nurserymen's News regulations. Fed. Register 44(179): 1977 (Sept-Oct.), p. 4-7. 53438-53468, Sept. 13. Gouin, F. R., and C. B. Link. 1982. Environmental Protection Agency, Food Sulfur tested for lowering pH of media and Drug Administration, and U.S. amended with sewage sludge. Amer. Department of Agriculture. 1981. Land Nurseryman 156(2):71-79. application of municipal sewage sludge for the production of fruits and Gouin, F. R., and J. B. Shanks. 1981. vegetables. A statement of Federal Composted gelatin waste aids crops. policy and guidance. 21 p. Environ. BioCycle 22(4):41-45. Protect. Agency Joint Policy Statement SW-905. Gouin, F. R., and J. M. Walker. 1977. Tree seedling response to nursery soil Epstein, E., D. B. Keane, J. S. amended with composted sewage sludge. Meisinger, and J. 0. Legg. 1978. HortScience 12:45-47. Mineralization of nitrogen from sewage sludge and sludge compost. J. Environ. Habicht, W. A., Jr. 1975. The Qual. 7:217-221. nematicidal effects of varied rates of

29 raw and composted sewage sludge as soil amended with sewage sludge. J. organic amendments on a root-knot Environ. Qual. 7:413-416. nematode. Plant Dis. Rptr. 59:631-634. Linford, M. B., F. Yap, and J. M. Hoitink, H. Â. J., and H, A. Poole. Olivera. 1983. Reduction of soil 1976. Composted bark media for control populations of the root-knot nematode of soil-borne plant pathogens. In during decomposition of organic matter. Internat1. Plant Propagators' Soc. Proc. Soil Sei. 45:127-141. 26:261-263. Logan, T. J., and R. L. Chaney. 1983. Hoitink, H. Â. J., and H. A. Poole. Utilization of municipal wastewater and 1980. Factors affecting quality of sludges on land - metals. ^ Colo. composts for utilization in container Sludge Mtg., Denver, Colo., Proc. 1983, media. HortScience 15:171-173. p. 235-326.

Hoitink, H. A. J., D. M. Van Doren, Jr., Lumsden, R. D., J. A. Lewis, and P. D. and A. F. Schmitthenner. 1977. Sup- Millner. 1982. Composted sludge as a pression of Phytophthora cinnamomi in a soil amendment for control of soilborne composted hardwood bark potting medium. plant diseases. In Kerr, H. W., Jr., Phytopathology 67:561-564. and L. Knutson, eds., Research for small farms. Spec. Symp. Proc. U.S. Hong, D. Y., and A. Ueyama. 1973. An Dept. Agr. Misc. Pub. 1422, p. 275-277. example of utilization of wood waste deposit: Manufacture of fortified bark Lumsden, R. D., J. A. Lewis, and G. C. compost having a decreased ability to Papavizas. 1983. Effect of organic support an outbreak of soil-borne plant amendments on soilborne plant pathogens diseases. Stockholm Skogshogskolan and their antagonists. In Lockertz, W., Inst. Virkeslära Rap. 83:1-13. ed.. Environmentally sound agriculture, p. 51-70. Praeger Press, New York. Homick, S. B. 1982. Organic wastes for revegetating marginal land. Lumsden, R. D., J. A. Lewis, R. E. BioCycle 23(4):42-43. Werner, and P. D. Millner. 1981. Effect of sludge compost on selected Hornick, S. B., J. J. Murray, and R. L. soil-borne diseases. Phytopathology Chaney. 1980. Overview on utilization 71:238. of composted municipal sludges. In Nati. Conf. Munie, and Indus. Sludge McCoy, J. L., R. R. Weil, and L. J. Composting Proc. 1980, p. 15-22. Inform. Sikora. 1982. Availability of Transfer, Inc., Silver Spring, Md. phosphorus in composted sewage sludge. Northeast Agron. Abs, 1982, p. 10. Korcak, R. F., F. R. Gouin, and D. S. Fanning. 1979. Metal content of plants McCoy, J. L., R. R. Weil, and L. J. and soils in a tree nursery treated with Sikora. 1983. Plant availability of composted sludge. J. Environ. Qual. phosphorus from composted sewage 8:63-68. sludge. Agron Abs. 1983, p. 35.

Kumada, K., K. Yoshida, A. Takei, and N. Mahler, R. J., F. T. Bingham, and A. L. Shumada. 1977. Some characteristics Page. 1978. Cadmium-enriched sewage of various composts with special sludge application to acid and reference to nitrogen. In Internatl. calcareous soils; Effect on yield and Seminar Soil Environ, and Fert. Mangt. cadmium uptake by lettuce and chard. J. Intensive Agr. Proc. 1977, p. 677-682. Environ. Qual. 7:274-281.

Lepp, N. W., and G. T. Eardley. 1978. Malek, R. B., and J. B. Gartner. 1975. Growth and trace metal content of Hardwood bark as a soil amendment for European sycamore seedlings grown in suppression of plant parasitic nematodes

30 on container-grown plants. HortScience Ann. Conf. Appl. Res. and Munie, and 10:33-35. Indus. Waste, Madison, Wis., Proc. 1980, p. 63-74. Mays, D. A., G. L. Terman, and J. C. Duggan. 1973. Municipal waste compost: Patterson, J. C, J. J. Murray, and J. Effects on crop yields and soil R. Short. 1981. The impact of urban properties. J. Environ. Qual. 2:89-92. soils on vegetation. In 3d Metrop. Conf., "Urban Trees and Their Soils," Millner, P. D., R. D. Lumsden, and J. A. Proc. 1981 (June 18-29), p. 33-56. Lewis. 1982. Controlling plant disease Sponsored by State Tree Impr. Alliance, with sludge compost. BioCycle 23:50-52. N.J. State Univ., New Brunswick.

Murray, J. J. 1978. Use of composted Purves, D., and E. J. MacKenzie. 1973. sewage sludge in turfgrass production. Effects of applications of municipal In Wastewater Conf. sponsored by Amer. compost on uptake of copper, zinc, and Soc. Golf Course Architects Found., boron by garden vegetables. Plant and Green Sect., U.S. Golf Assoc, Nati. Soil 39:361-371. Golf Found., and Golf Course Supts. Assoc. Amer., Chicago, 111., Proc. 1978 Sanderson, K. C. 1980. Use of sewage- (Nov. 12-14), p. 132-146. refuse compost in the production of ornamental plants. HortScience Murray, J. J., S. B. Homick, and J. C. 15:173-178. Patterson. 1980. Use of sewage sludge compost in urban lands. In 2d Conf. Sawhney, B. L. 1976. Leaf compost for Sei. Res. Nati. Parks sponsored by Nati. container-grown plants. HortScience Park Serv. and Amer. Inst. Biol. Sei., 11:34-35. San Francisco, Calif., Proc. 1979 (Nov. 26-30), p. 116-128. Shanks, J. B., and F. R. Gouin. 1984. Suitability of composted raw sewage Olsen, S. R., and L. E. Sommers. 1982. sludge as a component of the root medium Phosphorus. In Page, A. L., R. H. for several containerized ornamental Miller, and D. R. Keeney, eds.. Methods species grown in the greenhouse. of soil analysis, pt. 2, p. 403-430. BioCycle 25(l):42-45. Amer. Soc. Agron., Madison, Wis. Sikora, L. J., M. A. Ramirez, and T. A. O'Neill, N. R. 1982. Plant pathogenic Troeschel. 1983. Laboratory composter fungi in compost soil mixtures. In for simulation studies. J. Environ. Kerr, H. W., Jr., and L. Knutson, eds., Qual. 12:219-224. Research for small farms. Spec. Symp. Proc. U.S. Dept. Agr. Misc. Pub. 1422, Sikora, L. J., C. F. Tester, J. M. p. 285-287. Taylor, and J. F. Parr. 1980. Fescue yield response to sewage sludge compost Parr, J. F. 1982. Composting sewage amendments. Agron. J. 72:79-84. sludge, a potential resource for small farms. In Kerr, H. W., Jr., and L. Sikora, L. J., C. F. Tester, J. M. Knutson, eds.. Research for small farms. Taylor, and J. F. Parr. 1982. Spec. Symp. Proc. U.S. Dept. Agr. Misc. Phosphorus uptake by fescue (Festuca Pub. 1422, p. 90-99. arundenacea Schreb.) from soil amended with sewage sludge compost. Agron. J. Parr, J. F., and G. B. Willson. 1980. 74:27-33. organic wastes to improve soil productivity. HortScience 15:162-166. Spencer, S., and D. M. Benson. 1981. Root rot of Acuba japónica caused by Pastene, A. J., and R. B. Corey. 1980. Phytophthora cinnamomi and P. citricola Forms and availability of phosphorus in and suppressed with bark media. Plant a sewage sludge amended soil. In 3d Dis. 65:918-921.

31 Spencer, S., and D. M. Benson, 1982, grown in media containing sewage sludge Pinebark, hardwood bark compost, and compost, J. Amer. Soc, Hort, Sei. peat amendment effects on development of 108:36-41. Phytophthora spp, and lupine root rot. Phytopathology 72:346-351. Tester, G. F., L. J. Sikora, J. M, Taylor, and J. F. Parr, 1977. Standish, J. F., C. B. Ámmerman, C. F. Decomposition of sewage sludge compost Simpson, and others. 1969. Influence in soil. I. Carbon and N transfor- of graded levels of dietary iron, as mations. J. Environ, Qual. 6:459-463. ferrous sulfate, on performance and tissue mineral composition of steers. Tester, C. F., L, J. Sikora, J. M. J. Anlm. Sei, 29:496-503. Taylor, and J, F, Parr. 1979. Decomposition of sewage sludge compost Stephens, C. T., L. J. Herr, H. Â. J. in soil. III. Carbon, nitrogen, and Hoitink, and A. F. Schmitthenner. phosphorus transformation in different 1981. Suppression of Rhizoctonia sized fractions. J. Environ. Qual. damping-off by composted hardwood bark 8:79-82. medium. Plant Dis. 65:796-797, Tester, C. F., L. J, Sikora, J, M. Sterrett, S. B., R. L. Chaney, and L. W. Taylor, and J, F. Parr, 1982. Nitrogen Douglass. 1984. Management of limed- utilization by tall fescue (Festuca raw sludge compost as a growing medium arundenacea Schreb. 'Ky 31') from sewage component. HortScience (In press). sludge compost amended soils. Agron. J, 74:1013-1018. Sterrett, S. B., R. L. Chaney, C. W. Reynolds, and others. 1982. Transplant Willson, G. B,, and D. Dalmat. 1983. quality and metal concentrations in Sewage sludge composting in the U.S.A. vegetable transplants grown in media BioCycle 24(5):20-33. containing sewage sludge compost. HortScience 17(6):920-922. Willson, G. B,, J. F. Parr, E, Epstein, and others, 1980, Manual for composting Sterrett, S. B., C. W. Reynolds, F. D. sewage sludge by the Beltsville aerated- Schales, and others, 1983. Transplant pile method. EPA-600/8-80-022, 65 p. quality, yield, and heavy metal accumu- (Available from Nati. Tech. Inform. lation of tomato, muskmelon, and cabbage Serv., Springfield, Va.)

32 ^ U.S. Government Printing Office : 1984 -421-227/10107