Wednesday, 9 November 2005
14

Nitrogen Management and Soil Microbial Health Following Application of a Class Α Biosolid Fertilizer.

Whitney O'Hanian and W. Michael Sullivan. University of Rhode Island, 9 East Alumni Avenue, Suite 7, Kingston, RI 02881

Class A “Exceptional Quality” (EQ) biosolids are recycled from municipal sewage sludge through a high temperature based treatment process and transformed into a fertilizer product regulated by the USEPA and state agencies. The product is readily available within the Northeastern USA and appears to be underutilized in agricultural and horticultural industries. The primary objective of this study was to monitor the rate of decomposition for the biosolid-based fertilizer pellets, track concurrent nitrogen mineralization and the effects of pellet application on the size, activity, and structure of the soil microbial community under a low-input, sustainable vegetable crop production system. Five different nitrogen applications: 0, 33.61, 67.24, 100.86 and 134.47 kg ha -1 were made via appropriate biosolid applications on a well-drained Bridgehampton silt loam (coarse-silty, mixed, mesic Typic Dystrochrept) in Kingston, RI, based on pre-plant soil tests and anticipated crop needs. Soil nitrate and pH levels were measured every 10 to 14 days throughout the growing season. Phospholipid fatty acid analysis (PLFA) was conducted to measure total microbial biomass, community structure and physiological status. Preliminary results indicate a negative correlation between total soil microbial biomass and biosolid application rates.

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