Phosphorus Uptake by Fescue from Soils Amended with Sewage Sludge Compost1

Abstract

AbstractThe value of sewage sludge compost as a source of P for plants has not been evaluated. The study reported is part of a series designed to assess benefits of amending soils with sewage sludge compost and deals specifically with P uptake by fescue grown in two soils amended with combinations of compost and N and P fertilizers. An Evesboro loamy sand (Typic Quartzipsamments) and a Fauquier silt loam (Ultic Hapludalfs) were amended with four rates of sewage sludge compost (0 to 6% equal to 0 to 134.4 metric tons/ha, dry weight), plus an additional lime control and two rates of N, (0 and 195 kg/ha) P, (0 and 390 kg/ha), or N plus P 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.All of the clippings and one replicate of roots and crowns grown in the Evesboro soil were analyzed for total P. Similar to the data on fescue yields, the cumulative fescue P grown in compost‐amended Evesboro soil was approximately double that from compost‐amended Fauquier. Cumulative P was not linearly related to compost amendment in either soil. Fertilizer N, P, or N and P additions resulted in greater P uptake by fescue grown in both compost amended soils. However, fescue grown in compost amended soils without fertilizer contained adequate P levels to satisfy the nutritional requirements of feed for ruminants. Highly significant regression equations were derived describing total P uptake and fescue P concentration as affected by compost amendment, fertilizer addition, and time. The percentage of total P added as compost that was taken up by fescue grown in Evesboro soil equaled 4.5, 3.0, and 2.5 for the 44.8, 89.6, and 134.4 metric tons/ha amendment rates, respectively.