The contribution of agricultural practices to nitrous oxide emissions in semi-arid Mali

Abstract

The yield and flux of nitrous oxide (N2O) emitted from continuous cereals (with and without urea), legumes ⁄ cereal in rotation and cereal ⁄ legume in rotation all with or without organic manure was monitored from January 2004 to February 2005. All treatments except continuous cereals had phosphate added. The cereal grown July–October in 2003 and 2004 was pearl millet (Pennisetum glaucum) and the legume was a bean (Phaseolus vulgaris). The 10 m · 10 m plots were established in a semi-arid climate in Mali. The addition of organic manure and both inorganic fertilizers increased yield and N2O emissions. Continuous cereals treated with both organic manure and urea emitted significantly less N2O (882 g N⁄ ha per year) than plots receiving no organic manure(1535 g N⁄ ha per year). Growing N-fixing crops in rotation did not significantly increase N2O emissions. This study supports the new practice of growing cereal and legumes in rotation as an environmentally sustainable system in semi-arid Mal