Nitrogen availability and leaching from soil amended with municipal solid waste compost

Beneficial use of municipal solid waste compost depends on identifying a management strategy that supports crop production and protects water quality. Effects of compost and N fertilizer management strategies on corn (Zea mays L.) yield and NO₃^--N leaching were evaluated in a 3-yr study on a Hubbard loamy sand soil (sandy, mixed, Udorthentic Haploboroll). Two composts were each applied at either 90 Mg ha^-1 yr^-1 from 1993 to 1995, or at 270 Mg ha^-1 in one application in 1993. The compost and non-amended plots were sidedressed annually with N fertilizer as urea at 0, 125, and 250 kg ha^-1. Biochemical properties of the compost as well as compost management strongly affected crop response and fate of N. Compost increased grain yield with no significant yield response to N fertilizer with the single compost application in Year 1 and the annual compost application in Year 3. Plant N uptake increased with N fertilizer rate, except in the 270 Mg ha^-1 compost treatments in Year 1. Over the 3-yr period, NO₃^--N leaching with the 270 Mg ha^-1 compost application was 1.8 times greater compared to that with the annual application. The estimated N mineralization ranged from 0 to 12% and 3 to 6% in the annual and single compost addition, respectively. Under the conditions of this study, annual compost application with reduced supplemental N fertilizer was the best management strategy to reach optimum crop yield while minimizing NO₃^--N leaching losses.