Nitrous Oxide and Carbon Dioxide Emissions Following Green Manure and Compost Fertilization in Corn

Abstract

Alternative N fertilizers that stimulate low greenhouse gas emissions from soil are needed to reduce the impact of agriculture on global warming. Corn ( Zea mays L.) grown in a calcareous silt loam soil in northwestern Italy was fertilized with a municipal solid waste compost and vetch ( Vicia villosa Roth.) green manure. Their potential to reduce N 2 O and CO 2 emissions was compared with that of urea (130 kg N ha −1 ). Gaseous fluxes were measured for 2 yr in the spring (after soil incorporation of fertilizers) and in summer. In spring, the slow mineralization of compost reduced N 2 O emissions (0.11% of supplied N) relative to urea (3.4% of applied N), without an increase in CO 2 fluxes. Nitrous oxide (2.31% of fixed N) and CO 2 emissions from rapid vetch decomposition did not differ from urea. When N 2 O and CO 2 fluxes were combined, compost reduced by 49% the CO 2 equivalent emitted following urea application. Vetch did not show such an effect. In summer, no fertilizer effect was found on N 2 O and CO 2 emissions. Compost proved to be potentially suitable to reduce the CO 2 equivalent emitted after soil incorporation while vetch did not. For a thorough evaluation, net greenhouse gas emissions assessment should be extended to the entire N life cycle. Differences between calculated N 2 O emission factors and the default Tier 1 value of the Intergovernmental Panel on Climate Change (1%) confirmed the need for site‐ and fertilizer‐specific estimations.