/ ê^ í^m ^^ United States Jjl Department of ^^ Agriculture / Utilization of Sewage Agricultural Research Service Sludge Compost as Agriculture Information Bulletin a Soil Conditioner Number 464 and Fertilizer for Plant Growth .Co : —Í rT7 ABSTRACT Hornick, S. B., L. J. Sikora, S. B. ornamentals, turfgrasses, field crops, Sterrett* and others. 1984. forage grasses, and the reclamation of Utilization of sewage sludge compost as marginal lands. Recommendations based a soil conditioner and fertilizer for on laboratory, greenhouse, 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, pathogen content, plant compost as a soil conditioner and growth, root disease 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 diseases • 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 pathogens and offensive R. L. Chaney, and G. B. Willsoni' odors. 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 wastes Into a humuslike input material. Ten years later, at material, which can be used beneficially least 65 sludge composting plants 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 manures and crop 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 sludges for and El Paso, Tex. agricultural and horticultural use. Smaller conmiunities also have found that When sewage sludge and woodchips 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 Orchard Beach, Maine, thermophilic microorganisms, 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 decomposition, the composting biomass heats to temperatures in the In addition to the aerated pile and pasteurization 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 nutrients. 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 metal 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 metals 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. Nitrogen (N), phosphorus of at least 1 month is required to (P), and potassium (K) contents of the produce a well-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 heavy metals 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