Food waste compost effects on fertilizer nitrogen efficiency, available nitrogen, and tall fescue yield

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.