Nitrogen oxides and CO₂ from an Oxisol cultivated with corn in succession to cover crops

Óxidos de nitrogênio e CO₂ de Latossolo cultivado com milho em sucessão a plantas de cobertura

Abstract

The objective of this work was to evaluate the effect of two legumes (Crotalaria juncea and Mucuna pruriens), as cover crops, and of natural fallow, as a control treatment, on the emissions of NO_x, N₂O, and CO₂ from an Oxisol cultivated with corn, under conventional and no-tillage systems, in the Cerrado region, in Central Brazil. Variations of CO₂ fluxes in the soil were explained mainly by soil humidity and, in the legumes, under conventional system, by soil NH₄⁺-N concentration. Plots with legumes under no-tillage system had higher annual emissions of CO₂, NO_x, and N₂O than natural fallow. Results show that the use of legumes as cover crops favors the emissions of NO_x-N + N₂O-N and CO₂-C. However, when considering the potential for mitigation of CO₂ and nitrogen oxide emissions from the soil, it is important to evaluate changes in soil carbon and nitrogen stocks.

Index terms:
Crotalaria juncea; Mucuna pruriens; carbon and nitrogen stocks; Cerrado; mitigating greenhouse gases