Nitrogen Utilization by Tall Fescue from Sewage Sludge Compost Amended Soils1

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Abstract
The agronomic value of sewage sludge compost as an N source for tall fescue (Festuca arundinacea Schreb. ‘Kentucky 31’) was evaluated in a greenhouse pot study. An Evesboro loamy sand (mesic, coated Typic Quartzipsamments) and a Fauquier silt loam (fine, mixed, mesic Ultic Hapludalfs) soil were amended with four rates of sewage sludge compost (0 to 6% on a dry weight basis) equal to 0 to 135 metric tons/ha, a lime treatment, two rates of N (0 and 195 kg/ha), P (0 and 390 kg/ha), and N plus P in a factorial design. Kentucky 31 tall fescue was grown and harvested at 40, 76, 120, and 167 days. The clippings and one replicate of roots and crowns grown in the Evesboro soil were analyzed for total N.Total N uptake by fescue grown in compost amended Evesboro soil was significantly greater than with Fauquier soil treated similarly. Fescue N content was linearly related to the compost amendment for both soils and was significantly increased by the addition of N and P singly or in combination. The largest fescue N increase was obtained by the addition of N and P. Nitrogen uptake was limited by the mineralization rate of compost organic N. Regression equations describing total N uptake and fescue N concentration as affected by compost amendment, fertilizer addition, and time, required, in most cases, a quadratic term for compost amendment to explain the variation in Fescue N.During 167 days of growth the fescue utilized approximately 8% of the compost N and 80% of the fertilizer N. Based on the N content of fescue grown in Evesboro soil an equivalent fertilizer value of 166 kg N/ha was obtained for the 135 metric tons/ha compost amendment compared with the fertilizer treatments.