Compost Science Complete scientific data on compost process control and end product quality

CURRENT RESEARCH PROJECTS

CSU Summer, 2004, Vol. 12, No. 3, p. 200

ENVIRONMENTAL IMPACT
Applying Composted Organic Residuals To New Highway Embankments
Investigators: T.D. Glanville, R.A. Persyn, T.L. Richard, J.M. Laflen, and P.M. Dixon, Department of Agricultural & Biosystems Engineering, Iowa State University, Ames, Iowa
Objectives: To compare runoff and soil erosion from compost-treated and conventionally prepared

highway embankments and also to evaluate water quality. Compost-treated test areas received 2- or 4-inch deep blankets (surface applied, no incorporation) of a biosolids, yard trimmings, or bioindustrial compost. Conventionally prepared embankment areas consisted of compacted subsoil, or subsoil amended with topsoil. Results are based on runoff samples collected during the first 30 minutes of rainfall applied at 4-inches/hour (equivalent to a 25-year return period storm in central Iowa) using a Norton-type rainfall simulator. All tests were replicated 6 times under both vegetated and unvegetated conditions. Much of the current thinking concerning the erosion control benefits of compost applications presume that they occur primarily as the result of increased soil organic matter content and improved vegetative growth. An important feature of the findings is that they are for unvegetated test plots, demonstrating that blanket applications of some types of composted organics can provide runoff and soil erosion control immediately upon application, a potentially important benefit at construction sites developed during late fall, winter, or early spring when establishment of vegetation may not be feasible.

Benefits And Costs Of Using Organic Waste Streams In Small-Scale Agriculture
Investigators: Craig Cogger, Marcy Ostrom, Andy Bary, Richard Carkner and Carol Miles, Washington State University; Alexandra Stone, Dan Sullivan and Del Hemphill, Oregon State University
Objectives: To work with small-scale farmers to develop management systems that utilize local inputs to produce high-quality, high-value crops efficiently and profitably in an environmentally sustainable manner. Supporting objectives include the following: 1) Identify locally available organic waste streams and assess farmer perceptions about using these materials; 2) Determine the nutrient value of locally available organic amendments and develop straightforward systems for farmers to estimate nutrient availability from these materials; 3) Evaluate the effects of local organic materials on disease suppression; 4) Assess overall costs and benefits to the farming system; and 5) Develop a participatory research and outreach team made up of farmers and faculty to design, conduct and evaluate research and disseminate results on an on-going basis.
Production research includes field, laboratory, and greenhouse experiments; and the collection of economic, labor, and social data. Field research will be done at OSU and WSU centers and at on-farm sites with farmer research partners. Producer surveys will be utilized to broadly assess farmer views and practices regarding soil amendments and disease control. In-depth farmer interviews will be conducted to gain more detailed farmer perspectives and develop case studies.

Effect Of Industrial By-Products Containing High Aluminum Or Iron Levels On Plant Residue Decomposition
Investigator: L. Sikora, USDA-ARS, Beltsville Agricultural Research Center, Beltsville, Maryland
Objectives: To study how problems from excess phosphorus in soils from manure and fertilizer additions can be avoided. One approach would be to treat manures or soils with by-products that contain iron (Fe), aluminum (Al), or calcium (Ca) that adsorb P readily. A study was conducted in which two industrial by-products and 14C-labeled soybean leaves and -stems were added to two soils and soil organic matter and residue decomposition were monitored. Water treatment residue (WTR) containing high Al content and iron-rich residue (IRR) were added to Sassafras and Matapeake soils at rates from 0.5 to 10.0 g kg-1 soil. Lime (CaO) was added as a treatment to determine the effect of increased pH. Additions of WTR to either soil did not affect decomposition of 14C-labeled soybean leaves and stems, soil organic matter decomposition recorded by total CO2 evolution or residual soil 14C. Addition of IRR affected decomposition of 14C-labeled soybean leaves and stems, soil organic matter decomposition recorded by total CO2 and residual soil 14C. Although no one factor explained the effects on decomposition, salinity may be a factor as well as pH. Lime addition corrected the low soil organic matter decomposition as a result of the 10 g kg-1 IRR amendment. Lime also reduced salinity about 20%. Remediation of high P soils or treatment of manure is beneficial, but additional tests on biological effects on industrial by-product addition may be necessary.

How Soil Microbiological Properties Are Affected By Long-Term Applications Of Biosolids Composts
Investigators: M. Zaman, M. Matsushima, S. X. Chang, K. Inubushi , L. Nguyen, S. Goto, F. Kaneko and T. Yoneyama, University of Tokyo, Japan
Objectives: To investigate the long-term effect of surface application of sewage sludge composts vs. chemical N fertilizer on total N, total C, soluble organic C, pH, EC, microbial biomass C and N, protease activity, deaminase activity, urease activity, gross and net rates of N mineralization and nitrification, CO2 evolution, and N2O production. Soil samples were taken from five depths (0-15, 15-20, 20-30, 30-40, and 40-50 cm) of a long-term experiment. Three fields have been receiving sludge composted with rice husks (RH), sawdust (SD), or mixed chemical fertilizer NPK (CF), applied at the rate of 240 kg N ha-1 each in split applications in summer and autumn since 1978. Significantly higher amounts of total N and C and soluble organic C were found in the compost than in the CF treatments up to the 40-cm soil depth, indicating improved soil quality in the former. In the CF treatment, soil pH values were significantly lower and electrical conductivity values were significantly higher than those of compost-treated soils of up to 50 cm depth. Soil microbial biomass C and N, CO2 evolution, protease, deaminase, and urease activities were significantly higher in the compost than in the CF treatments due to greater availability of organic substrates that stimulated microbial activity. Gross N mineralization rates determined by 15N dilution technique were eight and five times higher in the SD and RH treatments than in the CF treatment, respectively, probably due to high levels of microbial and enzyme activities. Net N mineralization rates were also significantly higher in the compost treatments and were negative in the CF treatment indicating immobilization. Net nitrification rates were higher in compost treatments and negative in the CF treatment. Nitrous oxide productions from compost treatments were higher than the CF treatment due to the greater availability of mineral N as a result of higher mineralization and nitrification rates and soluble organic C in the former. Most of the measured parameters were highest in the surface soil (0-15 cm) and were significantly higher in the SD treatment than in the RH treatment.

Soil Response To Different Stabilization Degrees Of Treated Biosolids Following Land Application
Investigators: M.A. Sánchez-Monedero and A. Roig, Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafología y Biología Aplicada del Segura, CSIC, Murcia, Spain; C. Mondini and L. Leita, Istituto Sperimentale per la Nutrizione delle Piante, Sezione di Gorizia, Gorizia, Italy; M. de Nobili, Dipartimento di Produzione Vegetale e Tecnologie Agrarie, Università degli Studi di Udine, Udine, Italy
Objectives: To study the effect of land application of biosolids on an agricultural soil during a two-month incubation experiment. The soil microbial biomass and the availability of heavy metals in the soil was monitored after the application of four different composting mixtures of sewage sludge and cotton waste, at different stages of composting. Land application caused an increase of both size and activity of soil microbial biomass that was related to the stabilization degree of the composting mixture. Sewage sludge stabilization through composting reduced the perturbance of the soil microbial biomass. At the end of the experiment, the size and the activity of the soil microbial biomass following the addition of untreated sewage sludge were twice those developed with mature compost. For the mature compost, the soil microbial biomass recovered its original equilibrium status (defined as the specific respiration activity, qCO2) after 18 days of incubation, whereas the soil amended with less stabilized materials did not recover equilibrium even after the two-month incubation period. The stabilization degree of the added materials did not affect the availability of Zn, Ni, Pb, Cu, Cr and Cd in the soil in the low heavy metal content of the sewage sludge studied. Stabilization of organic wastes before soil application is advisable for the lower perturbation of soil equilibria status and the more efficient C mineralization.

Water Retention Capacity And Crop Variables Following Applications Of Yard Trimmings Compost And Soils
Investigators: Rob Malone, Jeremy Singer and Mark Tomer, USDA-ARS, National Soil Tilth Lab, Ames, Iowa; Wayne Petersen, USDA-NRCS, Coralville, Iowa; and Jennifer Welch, Urban Resources & Borderland Alliance Network (URBAN), Ankeny, Iowa
Objectives: To investigate the water retention and plant variables of yard waste compost amended soil on plots planted with turfgrass and native grasses. Research suggests that compost application to soil reduces erosion and runoff, increases crop yield, and improves soil quality. However, if compost application reduces runoff, an undesired effect may be higher water tables in residential and commercial areas. Alternatively, compost application to soil may retain more rainfall within the soil root zone where it is beneficial to plants and reduces peak stream-flow rates. This research is complemented with a detailed lab study investigating the water retention characteristics of yard waste compost. Preliminary data suggest that amending the soil with 5 cm of yard waste compost results in 1 cm more rainfall retained in the soil root zone after storms compared to unamended soil and the plant density and nutrient status appear greater on the compost amended plots.
Materials and Methods
Replacing peat with compost for growing
vegetable transplants
Investigators: B.A. Kahn, J.K. Hyde, J.C. Cole, P.J. Stoffella and D.A. Graetz; Oklahoma State University and University of Florida Institute of Food and Agricultural Sciences
Objectives: To explore growth impacts of different media comprised of commercial peat mix and a yard trimmings/biosolids compost. The specific objective was to test the compost mix as a partial or total replacement for a peat medium to produce cauliflower transplants.

Composting residuals generated in the wine industry
Investigators: T. Gea, A. Artola, X. Sort and A. Sanchez, University of Barcelona, Spain and C/Comerc, Barcelona, Spain
Objectives: To study the compostability of such wine residuals as stalks and sludge to ensure complete sanitation of feedstocks and the stability and maturity of the final compost. Researchers also sought to monitor the properties of ground stalks during storage to evaluate their influence on optimum ground stalk: sludge volumetric ratio for composting.
Microbial Ecology
Optimization of windrow food waste composting
to inactivate pathogenic microorganisms
Investigators: Deniz Cekmecelioglu, Ali Demirci, Robert E. Graves, Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, Pennsylvania; Nadine H. Davitt, Organic Materials Processing and Education Center, The Pennsylvania State University, University Park, Pennsylvania
Objectives: To evaluate optimization of windrow composting of food waste, manure, and bulking agents for maximum pathogen inactivation (Salmonella and E. coli O157:H7). Seasonal effects on reductions of Salmonella and E. coli O157:H7 related to the compost temperatures were studied (90-150 days). Fecal coliforms and fecal streptococcus were also monitored during composting in order to determine their appropriateness as indicator microorganisms.