Food Waste Compost Effects on Fertilizer Nitrogen Efficiency, Available Nitrogen, and Tall Fescue Yield

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Composting of food waste is increasing as composting technologies improve and as social and environmental pressures demand alternatives to disposal in landfills. Few agronomic studies are available to document N availability following food waste compost application. The objectives of this study were (i) to determine food waste compost effects on N fertilizer uptake efficiency across a range of N fertilizer rates, (ii) evaluate the effect of food waste composts on grass yield and N uptake by tall fescue (Festuca arundinacea Schreb. ‘A.U. Triumph’), and (iii) estimate the residual effects of compost application on N fertilizer requirements. We used a split‐plot design with two compost treatments and a no‐compost control as main plots, and NH4NO3 (34‐0‐0) applied at rates of 0, 17, 34, 50, and 67 kg ha−1 per grass harvest as subplots. A food waste + yard trimmings + paper (FYP) compost and a food waste + wood waste + sawdust (FW) compost were applied at rates of approximately 78 Mg ha−1 (870–1000 kg N ha−1) before seeding tall fescue. Compost did not affect grass yield or N uptake in the first year of the study. Compost increased grass yield during the second and third seasons after application. Grass N uptake increased linearly with fertilizer N application rate in all years. Compost did not affect fertilizer N uptake efficiency (the linear slope describing grass N uptake vs. fertilizer N application). Nitrogen fertilizer requirements during the midseason growth period were reduced by 0.22 to 0.37 kg N ha−1 d−1 during the second season after compost application and by 0.13 to 0.26 kg ha−1 d−1 during the third season after compost application. Results of this study suggest that N mineralized from compost and N provided by fertilizer can be considered as additive components of N supply for crop growth.