UTILIZATION OF MUNICIPAL AND INDUSTRIAL BYPRODUCTS IN AGRICULTURE

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0110	2000	75%
102	0210	2000	25%

Progress 03/01/02 to 09/30/07

Outputs
OUTPUTS: This project developed guidance for land application of byproducts via research, and disseminated information on current technologies via Extension workshops, publications and other outreach activities. Project publications and outreach activities delivered CSREES research findings in a format that is useful to a variety of clientele audiences, including: wastewater treatment facility managers, state environmental agencies and USEPA, NRCS, farm supply and allied industries, farmers (row crops, fruit, pasture, nursery), irrigation water districts, agricultural professionals that assist farmers, agricultural testing laboratories, composters, gardeners, water quality professionals. Over the course of this project (2003 to 2007), 7 graduate students were trained. The project PI (Sullivan) presented project findings at approximately 60 workshops, meetings, webconferences, or other outreach events, directly reaching over 1800 participants. For example, recent findings in biosolids management are presented annually at the Clackamas Short Course and the Northwest Biosolids Management Association Conference, reaching over 200 participants each year. This project contributed to three CSREES multistate projects: SERA-17, WERA-103 and W-1170. Project findings were incorporated into 6 Pacific Northwest Extension publications, 5 Oregon Extension publications, and 13 refereed papers. Project outreach is provided via the following websites: Nutrient management and water quality (WERA-103): cropandsoil.oregonstate.edu/wera103/ Participatory organic potato project (Ospud):ospud.org Northwest Biosolids Management Association: nwbiosolids.org Integrated Soil, Nutrient and Pest Management Education Project: isnap.org Organic Nutrient Management and Water Quality. puyallup.wsu.edu/soilmgmt/Index.htm TARGET AUDIENCES: wastewater treatment facility managers, state environmental agencies and USEPA, NRCS, farm supply and allied industries, farmers (row crops, fruit, pasture, nursery), irrigation water districts, agricultural professionals that assist farmers, agricultural testing laboratories, composters, gardeners, water quality professionals

Impacts
Changes in knowledge: This project developed new applied knowledge to guide beneficial use of byproducts from municipal, industrial and agricultural sources. Specifically, the project contributed knowledge in these key areas: 1. Improved predictions for N availability from organic amendments (manures, composts, biosolids). 2. Improved methods for quantifying compost stability. 3. Standardized method for evaluating phosphorus solubility in biosolids and manures. 4. Validation of agronomic soil testing method as an indicator of P loss to surface runoff from Oregon soils. Adoption of knowledge by clientele: Study findings have been used to formulate guidance for agronomic rates for land application of biosolids and other municipal, industrial and agricultural byproducts. Scientifically-based guidance provides economic benefits for byproduct generators and farmers, and assists in the protection of the environment from excessive nutrient applications. 1. Nitrogen: A new tool for estimating available nitrogen in organic farming, the Organic Fertilizer Calculator, was released for public use by OSU Extension (Andrews, 2007). The Calculator is based on research conducted in Oregon and Washington under CSREES funding. The Calculator compares the cost, nutrient value and nitrogen availability of organic fertilizers. The Calculator assists organic farmers in choosing a fertilizer source and rate that supplies sufficient N, saving dollars and protecting groundwater quality. 2. Biosolids: Two Extension publications on biosolids management (PNW Extesnion publications 508 and 511) are used by Oregon and Washington State environmental agencies as guidance for land application of biosolids. Permitted application rates of biosolids in OR and WA are based on these publications. 3. Phosphorus: The laboratory method for water soluble phosphorus has been incorporated into a national manual, Methods of phosphorus analysis for soils, sediments, residuals, and waters, found at www.sera17.ext.vt.edu. Agronomic soil testing for phosphorus has been incorporated into a risk assessment tool used by Oregon NRCS, the Oregon/Washington Phosphorus Index.

Publications

Andrews, N. and J. Foster. 2007. Organic Fertilizer Calculator: A New Planning Tool for Comparing the Cost, Value and Nitrogen Availability of Organic Materials. Oregon State University Extension Publication EM 8936-E. Oregon State University. Corvallis, OR. http://smallfarms.oregonstate.edu/organic-fertilizer-calculator.
Buamscha, M. G., J.E. Altland, D.M. Sullivan, D.A. Horneck, and J. Cassidy. 2007. Chemical and Physical Properties of Douglas Fir Bark Relevant to the Production of Container Plants. HortScience 42:281-1286.
Buamscha, M.G., J.E. Altland, D.M. Sullivan, and D.A. Horneck. 2007. Micronutrient availability in fresh and aged Douglas fir bark. HortScience 42:1-5.
Kleinman, P. D. Sullivan, A. Wolf, R. Brandt, Z. Dou, H. Elliott, J. Kovar, A. Leytem, R. Maguire, P. Moore, A. Sharpley, A. Shober, T. Sims, J. Toth, G. Toor, H. Zhang, T. Zhang. 2007. Selection of a water extractable phosphorus test for manures and biosolids as an indicator of runoff loss potential. J. Envir. Qual. 36:1357-1367.
Horneck, D.A., J.W. Ellsworth, B.G. Hopkins, D.M. Sullivan, and R.G. Stevens. 2007. Managing Salt-Affected Soils for Crop Production. PNW 601-E. Oregon State Univ. Extension Service. Corvallis, OR.
Sullivan, D.M., J.P.G. McQueen, and D.A. Horneck. 2007. Estimating Nitrogen Mineralization in Organic Potato Production. Oregon State University Extension, Corvallis, OR.
Cogger, C.G. and D.M. Sullivan. 2007. Worksheet for calculating biosolids application rates in agriculture. Pacific Northwest Extension Publ. 511-E. Washington State University Cooperative Extension, Pullman, WA.
Sullivan, D.M., C.G. Cogger, and A.I. Bary. 2007. Fertilizing with biosolids. Pacific Northwest Extension Publ. 508-E. Oregon State University Extension, Corvallis, OR.
Downing, T., D. Sullivan, J. Hart and M. Gamroth. 2007. Manure application rates for forage production. EM8585-E. Oregon State Univ. Extension. Corvallis, OR.
Hopkins, B.G., D.A. Horneck, R.G. Stevens, J.W. Ellsworth, and D.M. Sullivan. 2007. Managing Irrigation Water Quality for Crop Production in the Pacific Northwest. PNW 597-E. Oregon State Univ. Extension. Corvallis, OR.

Progress 03/01/02 to 09/30/06

Outputs
This project contributed to the development of guidance for beneficial use of byproducts from municipal, industrial and agricultural sources. The project validated a low-tech computer simulation model (DECOMPOSITION) that predicts first-year mineralization of nitrogen from a variety of organic soil amendments: composts, manures, biosolids and specialty products. Inputs for this simulation model are relatively simple and can be readily adapted to any organic material. The project also investigated longer-term N mineralization and found that the quantity of N-mineralized per unit of total amendment N applied in Years 2 and 3 after land application was similar for amendments ranging with initial C:N ratios of 5 to 30. Second and third year N mineralization was similar for materials composted prior to application, or for uncomposted materials. The project also investigated compost stability as an indicator of compost quality. Compost stability measurements corresponding to stable compost suitable for most horticultural uses was approximately 2 mg CO2-C per g compost C per day at 22 oC for a variety of feedstocks and composting methods. We also demonstrated that compost stability is a key indicator of the ability of the compost to suppress some soil borne pathogens (Pythium spp.) but not Rhizoctonia spp. Several studies investigated amendment testing procedures for phosphorus in an effort to better predict risks of P loss to surface waters. In one study, the agronomic Bray P1 soil test was found to be a reasonable indicator of water soluble or labile P for western Oregon soils. Another study, done in collaboration with ten other laboratories in North America, developed a common protocol for testing amendments to determine water-soluble P. Research findings from our studies have been incorporated into regional Cooperative Extension guidance and have been featured in clientele workshops.

Impacts
Study findings are used to formulate guidance for agronomic rates for land application of biosolids and other municipal, industrial and agricultural byproducts. Scientifically-based guidance provides economic benefits for byproduct generators and farmers, and assists in the protection of the environment from excessive nutrient applications.

Publications

Gale,E.S., D.M. Sullivan, D. Hemphill, C.G. Cogger, A.I. Bary and E.A. Myhre. 2006. Estimating Plant-Available Nitrogen Release from Manures, Composts, and Specialty Products Journal Environmental Quality 35:2321-2332.
Sullivan, D.M. and T.L. Matteson. 2006. Stability of mixed food waste composted with low-technology methods. Compost Sci Util. 14(3):170-177.
Larney, F.J., Sullivan, D.M., Buckley, K.E. and Eghball, B. 2006. The role of composting in recycling manure nutrients. Can. J. Soil Sci. 86:597-611.

Progress 01/01/05 to 12/31/05

Outputs
As interest in food waste composting grows, so does the need for proven low-technology composting methods. Stability testing has been proposed as a compost quality assurance tool to verify that finished compost will not serve as a substrate for human pathogen regrowth. We conducted this study to: (i) to evaluate the efficacy of low-technology, outdoor composting methods in producing a compost with a low, stable decomposition rate, and (ii) to determine the reliability of simple, 4-h compost stability evaluation methods. Composting was conducted outdoors in winter and spring in Eugene, Oregon without moisture addition. Mixed food waste was combined with screened dairy solids and ground yard trimmings. Sawdust was used to cover windrows for the first 27 d of composting. Compost windrow temperatures remained above 55 oC for 30+ d. Carbon dioxide evolved with several 4-h test methods was strongly correlated (r2 > 0.7) with CO2 evolved using a 48-h test. A limited-turn windrow (LTW) composting system produced compost with slightly greater stability than a passively aerated windrow (PAW) composting system. Food waste compost samples had a low CO2 evolution rate after 71 to 99 d using either system. Compost CO2 evolution rate at 25 oC decreased with composting time, reaching approximately 1 to 4 mg CO2-C g compost C-1 d-1 for the PAW method and 0.5 to 2 mg CO2-C g compost C-1 d-1 for the LTW method. Putrescible organic matter in food waste was effectively decomposed by low technology composting methods. Several 4-h stability tests showed promise for implementation as quality assurance tools.

Impacts
Improved compost testing procedures provide better management of the composting process, thereby improving product quality and reducing composting costs. Effective, reliable, composting methods for putrescible materials like food waste assist solid waste managers in reaching recycling goals, provide valuable soil amendments for soil improvement, and provide business opportunities for local entrepreneurs.

Publications

Scheuerell, S.J., D.M.Sullivan, and W.F. Mahaffee. 2005. Suppression of Seedling Damping-Off Caused by Pythium ultimum, P. irregulare, and Rhizoctonia solani in Container Media Amended with a Diverse Range of Pacific Northwest Compost Sources. Phytopathology, 95(3): 306-315.
Bary, A.I., C.G. Cogger, D.M. Sullivan, and E.A. Myhre. 2005. Characterization of fresh yard trimmings for agricultural use. Bioresource Technol. 96:1499-1504.

Progress 01/01/04 to 12/31/04

Outputs
Land application of yard trimmings from urban landscapes on farmland is an emerging recycling alternative in the Pacific Northwest (USA). Estimates of the plant-available nitrogen provided by yard trimmings are needed to meet grower demands and environmental regulations. Our objectives were to: (i) estimate available N provided by yard trimmings containing grass clippings and woody plant materials (ii) evaluate the impact of aging on available N supplied by grass clippings, and (iii) identify laboratory analyses that are correlated with N mineralized from yard trimmings in soil. Yard trimmings were mixed with sandy loam soil and incubated at 25 oC to determine N availability and CO2 loss. Mixed grass clippings + woody trimmings with typical C:N ratios of 15 to 19 had available N equivalent to 10 to 14% of total N; grass clippings alone had available N equivalent to 21 to 37% of total N. Aging of grass clippings for 14 to 28 d in unmanaged piles increased NH4-N, ash, and lignin concentrations. Aging also reduced N and C mineralized from grass clippings in soil. Nitrogen mineralized from yard trimmings in soil was correlated (R2 = 0.64 to 0.78) with yard trimmings total N, C:N, lignin, carbohydrate + hemicellulose concentrations, and with CO2 evolution during a 7-d incubation in soil. Based on the present study, it appears unlikely that excess N will be provided by typical application rates of mixed yard trimmings. Mixed yard trimmings with typical moisture of 600 g kg-1, total N of 17 g kg-1 (dry matter basis), and N availability equal to 15% of total N, supplied approximately 1 kg available N per metric ton.

Impacts
Land application of yard trimmings from urban landscapes on farmland is an emerging recycling alternative in the Pacific Northwest. This research, which determined typical amounts of plant-available nitrogen provided by yard trimmings, has been incorporated into Extension guidance for Oregon and Washington State. The use of yard trimmings as a soil amendment and nitrogen source is of particular interest to farmers interested in non-chemical sources of nitrogen for crop production.

Publications

Sullivan, D.M. T.J. Nartea, A.I. Bary, C.G. Cogger and E.A. Myhre. 2004. Nitrogen Availability and Decomposition of Urban Yard Trimmings in Soil. Soil Science 169:697-707.
Cogger, C.G., A.I. Bary, D.M. Sullivan and E.A. Myhre. 2004. Biosolids processing effects on first and second year available nitrogen. Soil Sci. Soc. Am J. 68: 162-167.

Progress 01/01/03 to 12/31/03

Outputs
Reliable methods of compost quality assessment are needed for the development and expansion of high-value markets for compost. The objective of this research was to evaluate a variety of stability and maturity indices for yard trimmings compost. We collected compost samples periodically during a 133-d composting cycle at a commercial composting facility. We found that indices of compost respiration rate were sensitive indicators of compost quality. All respiration rate indices identified a period of high respiration rates during active composting (first 27 d), and a period of relatively stable respiration rates during the latter part of curing (70 to 133 d). Chemical tests of compost solids showed less promise as maturity indicators, but provided valuable information on final compost quality. Mature yard trimmings compost had a C:N of 12, an NH4-N to NO3-N ratio of less than 4, a cation exchange capacity (CEC) of 400 cmol per kg of compost-C, and a pH between 6.5 and 7.0. Seed germination tests and sensory tests (color and odor) were of limited value in assessing compost maturity. Fully-cured compost produced with forced aeration had a Solvita CO2 test value of 6 to 7 and a respiration rate via the alkaline trap method of 2 mg CO2-C g compost-C-1 d-1. It reheated less than 2oC in an insulated Dewar flask in a 7 d incubation. We recommend further evaluation and calibration of respiration test protocols for compost quality assurance testing programs.

Impacts
Composting of organic wastes provides an alternative to landfilling and incineration, produces a value-added product, and provides a source of nutrients and organic matter for small scale farmers. Successful compost marketing depends on product consistency and freedom from human pathogens. Quick and reliable measurements of organic matter stability have not been widely used in the compost industry. Composts with stable organic matter decompose slowly in soil and do not provide a suitable substrate for human pathogen (e.g. E. coli, Salmonella) regrowth. We have developed a quick and reliable method for measurement of compost stability. The method is suitable for on-site use by compost facility operators with minimal training or scientific expertise. The method uses a widely available carbon dioxide measurement technology. Test results are available in four hours. Cost per test is less than $10. The method uses a large sample size, thereby minimizing problems with collection of a representative sample. We recently collaborated with the Oregon Dept of Environmental Quality to evaluate our stability quick test method in a pilot food-waste composting project. Study data showed that our stability test method was suitable as a replacement for the standard laboratory stability test method. Oregon DEQ is in the process of revising its composting regulations, including stability test requirements. Our compost stability test method also shows promise in helping organic farmers comply with requirements of recently adopted USDA National Organic Program (NOP).

Publications

Bell, N., D.M. Sullivan, L.J. Brewer, and J. Hart. 2003. Improving garden soils with organic matter. EC 1561. Oregon State University Extension Service. Corvallis, OR.
Brewer, L.J. and D.M. Sullivan. 2003. Maturity and stability evaluation of composted yard trimmings. Compost Sci. Util. 11(2): 96-112
Gilmour, J.T., C. Cogger, L.W. Jacobs, G.K. Evanylo, and D.M. Sullivan. 2003. Decomposition and plant available N in biosolids: laboratory studies, field studies and computer simulation. J. Environ. Qual. 32:1498-1507.
Staben, M.L., J.W. Ellsworth, D.M. Sullivan, D. Horneck, B.D. Brown and R.G. Stevens. 2003. Monitoring soil nutrients using a management unit approach. PNW 570-E. Oregon State University Extension Service. Corvallis, OR.
Sullivan, D.M and C.G. Cogger. 2003. Post-harvest soil nitrate testing for manured cropping systems in west of the Cascades. EM 8832. Oregon State University Extension Service. Corvallis, OR
Sullivan, D.M and R.G. Stevens. 2003. Agricultural phosphorus management using the Oregon/Washington Phosphorus Indexes. EM 8848-E. Oregon State University Extension Service. Corvallis, OR
Sullivan, D.M., A.I. Bary, T.J. Nartea, E.A. Myrhe, C.G. Cogger, and S.C. Fransen. 2003. Nitrogen availability seven years after a high-rate food waste compost application. Compost Sci. Util. 11(3): 265-275.

Progress 01/01/02 to 12/31/02

Outputs
Repeated application of biosolids (municipal sewage sludge that meets USEPA criteria for land application) to cropland results in accumulation of total P in soil. Runoff of P from cropland into surface waters may degrade water quality by inducing undesirable algae growth. We evaluated the effect of biosolids application on labile P in soils in the Willamette Valley of Oregon at 20 field sites. Biosolids application sites had 2 to 5 previous biosolids applications with cumulative P loading of approximately 200 to 1000 kg P ha-1. Soil samples were collected from biosolids application sites and adjacent field areas that did not receive biosolids application. Soil was analyzed for P via an agronomic method (Bray P1) and via environmental methods. Biosolids application increased average soil test P (0-5 cm depth) from 46 to 75 mg kg-1 Bray P, from 35 to 53 mg kg-1 anion-exchange resin-P, from 583 to 950 mg kg-1 ammonium oxalate extractable P, from 1.8 to 2.3 mg kg-1 dilute salt (0.01 M CaCl2) extractable P. The molar ratio of P/(Al + Fe) from increased from 0.08 to 0.13 with biosolids application. Agronomic soil test P (Bray) was strongly correlated with other indices of water soluble P. Results suggest that biosolids are a significant source of soluble P after application to western Oregon soils. Our findings support the use of agronomic soil test P (Bray P1 method) in risk assessment tools such as the Oregon NRCS Phosphorus Index.

Impacts
Study findings are used to formulate guidance for agronomic rates for land application of biosolids and other municipal, industrial and agricultural byproducts. Scientifically-based guidance provides economic benefits for byproduct generators and farmers, and assists in the protection of the environment from excessive nutrient applications.

Publications

Jacobs, LW., J.T. Gilmour, C.G. Cogger, G.K. Evanylo and D.M. Sullivan. 2002. New N mineralization factors for estimating plant-available N in biosolids. In: 2002 Agronomy Abstracts, SSSA, Madison, WI.
Sullivan, D.M. 2002. Biological stability assessment methods for compost. In: 2002 Agronomy Abstracts, SSSA, Madison, WI.
Sullivan, D.M., A.I. Bary, D.R. Thomas, S.C. Fransen, and C.G. Cogger. 2002. Food waste compost effects on fertilizer nitrogen efficiency, available nitrogen, and tall fescue yield. Soil Sci. Soc. Am J. 66:154-161.
Bary, A.I., D.M. Sullivan, S.C. Fransen and C.G. Cogger. 2001. Supercow: a liquid manure applicator for small-plot research. Agron. J. 93:1344-1345.

Progress 01/01/01 to 12/31/01

Outputs
Application of uncomposted yard trimmings to farmland is an alternative to composting; it provides an option for compost facilities in dealing with high volumes of incoming yard trimmings in spring months. Reliable estimates of the plant-available nitrogen provided by uncomposted yard trimmings are needed to meet grower demands and environmental regulations. Our objectives were to (i) estimate available N provided by yard trimmings containing variable proportions of grass and woody plant materials (ii) evaluate the impact of aging on available N supplied by grass clippings, (iii) identify laboratory analyses that are correlated with cumulative net N mineralized from yard trimmings in soil. Available N (sum of NH4-N in yard trimmings + net N mineralized after 98 d in soil) was 21 to 37 % of total N for grass clippings alone, and 1 to 19 % for mixed yard trimmings (grass + woody plant material). Aging of grass clippings for up to 28 d in unmanaged piles increased NH4-N concentration and reduced mineralization of organic N and C compounds in soil. The changes observed in grass N and C fractions with aging were similar to those reported for a Maillard reaction, a non-enzymatic browning reaction that reduces the digestibility of forages. Net N mineralized from yard trimmings in soil was correlated (R2 = 0.69 to 0.79) with total N, C:N, lignin, carbohydrate + hemicellulose concentrations in yard trimmings and 14 d CO2 evolution in soil. Dynamic simulation models that predict C and N mineralization in soil based on yard trimmings analytical characteristics (proportions of labile and recalcitrant C compounds, total N and NH4-N) are promising tools for further refinement of agronomic rate estimates.

Impacts
Study findings are used to formulate guidance for agronomic rates for land application of residuals. Scientifically-based guidance provides economic benefits for byproduct generators and farmers, and assists in the protection of the environment from excessive nutrient applications.

Publications

Sullivan, D.M., C.G. Cogger, A.I. Bary, E.A. Myhre, and J. Choate. 2001. Predicting N availability from yard debris. In: Proc. Western Nutrient Mgmt. Conf., Vol. 4. Mar 8-9, 2001. Salt Lake City, UT. Potash and Phosphate Institute, Brookings, SD.
Gilmour, J.T., C.G. Cogger, L.W. Jacobs, S.A. Wilson, G.K. Evanylo and D.M. Sullivan. 2000. Nitrogen management protocols for biosolids beneficial reuse. Final report. Water Environment Federation Project 97-REM-3. WEF stock no. D00307. Water Environment Federation. Alexandria, VA.
Shearin, T.E., Sullivan, D.M., S. Macnab, E. Jacobsen, D.J. Wysocki, and R.S. Karow. 1999. Agronomic rates of biosolids for soft white winter wheat. p. 49-58. In: 1999 Columbia Basin Agricultural Research Annual Report. Special Report 999. Oregon St. Univ. Agric. Expt. Sta. and USDA-ARS. Columbia Basin Agric. Res. Ctr. Pendleton, OR.
Cogger, C.G., D.M. Sullivan, A.I. Bary and S.C. Fransen. 1999. Nitrogen recovery from heat-dried and dewatered biosolids applied to forage grasses. J. Envir. Qual. 28:754-759.
Cogger, C.G. and D.M. Sullivan. 1999. Worksheet for calculating biosolids application rates in agriculture. Pacific Northwest Extension Publ. 511. Washington State University Cooperative Extension, Pullman, WA.
Sullivan, D.M., A.I. Bary, C.G. Cogger and E.A. Myhre. 1999. Field microplot estimates of soil N mineralization for manured and non-manured soils. p. 193-200. In: Proc. Western Nutrient Management Conference. Salt Lake City, UT. 4-5 Mar. 1999. Potash & Phosphate Institute. Manhattan, KS.
Cogger, C.G., D.M. Sullivan, A.I. Bary, and J.A. Kropf. 1998. Matching plant-available nitrogen from biosolids with dryland wheat needs. J. Prod. Agric. 11:41-47.
Sullivan, D.M., S.C. Fransen, A.I. Bary, and C.G. Cogger. 1998. Fertilizer nitrogen replacement value of food residuals composted with yard trimmings, paper, or wood wastes. Compost Sci. Util. 6(1): 6-18.
Sullivan, D.M., S.C. Fransen, A.I. Bary and C.G. Cogger. 1998. Slow-release nitrogen from composts: the bulking agent is more than just fluff. p. 319-325. In: S.L. Brown, J.S. Angle, and L.W. Jacobs (ed.) Beneficial Co-Utilization of Agricultural, Municipal and Industrial By-Products. Kluwer Academic Publishers, Dordrecht, The Netherlands.
Sullivan, D.M. 1998. Fertilizing with biosolids. Pacific Northwest Extension Publ. 508. Oregon State University Extension, Corvallis, OR.
Sullivan, D., S. Macnab, E. Jacobsen, D. Wysocki, and R. Karow. 1998. Optimum biosolids application rates for soft white winter wheat. p. 41-45. In: 1998 Columbia Basin Agricultural Research Annual Report. Special Report 989. Oregon St. Univ. Agric. Expt. Sta. and USDA-ARS. Columbia Basin Agric. Res. Ctr. Pendleton, OR.
Sullivan, D.M., S.C. Fransen, C.G. Cogger, and A.I. Bary. 1997. Biosolids and dairy manure as nitrogen sources for prairiegrass on poorly drained soil. J. Prod. Agric. 10:589-596.
Cogger, C.G., A.I. Bary, S.C. Fransen and D.M. Sullivan. 2001. Seven years of biosolids vs. inorganic nitrogen applications to tall fescue. J. Environ. Qual 30: 2188-2194.
Sullivan, D.M. and R.O. Miller. 2001. Compost quality attributes, measurements and variability. p. 95-120. In: P.J. Stofella and B.A. Kahn (eds.). Compost utilization in horticultural cropping systems. CRC Press. Boca Raton, FL.