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CURRENT RESEARCH PROJECTS

Compost Science & Utilization, (2006), Vol. 14, No. 1, 4

Crop Response

Compost maturity effects on nitrogen and carbon mineralization and plant growth
Investigators: T.S. Griffin and M. Hutchinson, USDA-ARS New England Plant Soil and Water Laboratory, Orono, Maine
Objectives: To establish the basis for predicting relationships between compost maturity and N

availability by collecting samples from a single windrow over a three-month period. Compost samples were assessed using standard chemical analyses (total C and N, Mineral N, total volatile solids) and other methods.

Characterization of compost maturity
Investigators: M. Hutchinson and T.S. Griffin, USDA-ARS New England Plant Soil and Water Laboratory, Orono, Maine
Objectives: To assess the relationship between duration of the composting period and compost characteristics associated with stability and maturity. Understanding changes in composition that occur during the composting process are important for proper utilization. If compost is to be useful in crop management as a soil conditioner and nutrient source, relationships between nutrient availability, plant growth and maturity needed to be predictable to enable growers to make appropriate decisions.

Environmental Impact

Leaching potential of heavy metals, nitrogen, and phosphate from compost amended medium columns
Investigators: Y.P. Xia, Zhejiang University, China; P.J. Stoffella, Z.L. He, D.V. Calvert, and S. Wilson, University of Florida. Fort Pierce, Florida; M.K. Zhang and X. Yang, Zhejiang University, China
Objectives: To assess leachable concentrations of heavy metals - Cd, Cr, Cu, Mn, Pb, Zn- as well as the available N and P in peat-based medium amended with various proportions of compost, and to identify factors that influence the leaching potential. Although the extractability of heavy metals from MSW compost and sewage sludge has been assessed, few studies have focused on direct leaching of heavy metals from biosolids and yard trimmings as a whole or partly for growth media.

Materials And Methods

Composting of ferric chloride and organic polymers treated hog wastewater excess sludge amended with sawdust
Investigators: J. Hong and K. Park, Sunchon National University, Sunchon, Korea
Objectives: To develop a full-scale composting of separated solid manure mixed with biosolids from the livestock wastewater biotreatment and manure compost biofiltration system during agitated and aerated bed composting. Effects of turning frequency on compost temperature and ammonia emission were also investigated using compost reactors and biofilter vessels. Reducing pH of initial composting mixture seemed to be a more effective means of increasing thermophilic composting temperature.

Composting olive-mill pomace and other residues from rural Spain
Investigators: R. Canet, F. Pomares, B. Cabot, E. Ferrer, M. Ribo and M.R. Albiach, Instituto Valenciano de Investigaciones Agrarias, Moncada. Spain
Objectives: To determine if composting would be a solution for the wide range of organic residues generated in the areas of small olive oil production in Mediterranean areas of Spain and their value to agricultural soils. Another objective was to lower costs for disposal of semisolid residual pomace generated in the two-phase extraction used in modem olive-mills

Microbial Ecology

Nitrogen dynamics in vineyard soils from applications of mature biowaste compost
Investigators: C. Nendell, Institute of Vegetables and Ornamental Crops, GroBeeren, Germany; and S. Reuter, Institute of AgroEcology, Neustadt, Germany
Objectives: To investigate the effect of compost applications on soil biology at four different sites. For three years, soil mineral N, microbial biomass and soil respiration would be observed. In the past decade, use of biowaste compost was promoted as a substrate for soil melioration. Winegrowers favor compost because of its ability to increase water holding capacity along with structure and elasticity. Nutritional value of compost is of particular importance when it comes to calculating fertilizer recommendations. Field monitoring was also established.

Structure of the microbial community in a livestock manure-based composting process
Investigators: H. Sasaki, J. Nonaka, T. Sasaki, Y. Nakai, Tohoku University, Miyagi, Japan
Objectives: To investigate microbial succession in four different manure-based composts and determine the dominant species using polymerase chain reaction-denaturing gradient gel electrophoresis. This method may contribute to the understanding of the complex nature of the microbial community in manure treatment.