Nitrous oxide emission from animal manures applied to soil under controlled conditions

Animal manures may differ strongly in composition and as a result may differ in the emission of N^sub 2^O following application to soil. An incubation study was carried out to assess the effects of type of mineral N fertilizer and manure, application technique and application rate on N^sub 2^O emission from a sandy soil with low organic matter content. Fluxes of N^sub 2^O were measured 30 times over a 98-day period. The total N^sub 2^O emission from mineral N fertilizer ranged from 2.1 to 4.0% of the N applied. High emissions were associated with manures with high contents of inorganic N, easily mineralizable N and easily mineralizable C, such as liquid pig manure (7.3-13.9% of the N applied). The emission from cattle slurries ranged from 1.8 to 3.0% and that of poultry manures from 0.5 to 1.9%. The total N^sub 2^O emission during the experimental period tended to increase linearly with increasing N application rate of NH^sub 4^NO^sub 3^ and liquid pig manure. The N^sub 2^O emission from surface-applied NH^sub 4^NO^sub 3^ was significantly smaller than that following the incorporation of NH^sub 4^NO^sub 3^ in the soil. The N^sub 2^O emission from pig manure placed in a row at 5 cm depth was significantly higher than from surface-application and other techniques in which manure was incorporated in the soil. The results show that modification of the composition and application technique may be tools to mitigate emission of N^sub 2^O.[PUBLICATION ABSTRACT]