Fescue Yield Response to Sewage Sludge Compost Amendments1

Abstract

AbstractThe agronomic benefits of applying sewage sludge compost to land have yet to be defined. The study reported is part of a series designed to assess the benefits. It deals specifically with fescue yield response to sewage sludge compost and fertilizer. An Evesboro loamy sand (Typic Quartzipsamments) and a Fauquier silt loam (Ultic Hapudalfs) soil were amended with four rates of sewage sludge compost (0 to 6% equal to 0 to 134.4 metric ton/ha, dry weight), plus an additional lime control and two rates of N, P or N plus P (0 and 195 kg/ha) in a factorial greenhouse study. —Kentucky 31― tall fescue (Festuca arundinacea Schreb.) was grown and harvested at 40, 76, 120, and 167 days and the clippings were dried and weighed. A significantly greater grass yield was obtained from the compost amended Evesboro than the compost amended Fauquier which contained a vermiculite clay fraction. Yields were linearly related to compost amendment for both soils. Yields were significantly increased by the addition of N, P, or N plus P to compost amended soils. The largest yield increase was obtained by the addition of N plus P. The mineralization of compost organic N was the limiting factor in grass yield. Regression models were derived from the data using compost and days as independent variables for each soil, N, and P combination. In most cases, a quadratic term for compost amendment was necessary for explaining the variation in yield. Regression model equations based on cumulative yield data contained similar terms for each soil, N, and P combination except for the Fauquier soil with N and P added for which no model was obtained.