Greenhouse gas emissions under conservation agriculture compared to traditional cultivation of maize in the central highlands of Mexico

摘要

Laboratory of Soil Ecology, ABACUS, Cinvestav, Avenida Institute Politecnico National 2508, C.P. 07360 Mexico, D.F., Mexico;Laboratory of Plant Biotechnology, Institute Tecnologico de Tuxtla-Gutierrez, Tuxtla-Cutierrez, Chiapas, Mexico;Laboratory of Soil Ecology, ABACUS, Cinvestav, Avenida Institute Politecnico National 2508, C.P. 07360 Mexico, D.F., Mexico;Departamente de Mkrobiologia, Escuela Nacional de Ciencias Biologkas-IPN, Av. Prolongation de Carpio y Plan de Ayala, C.P. 11340 Mexico, D.F., Mexico;International Maize and Wheat Improvement Centre (CIMMYT), Apdo. Postal 6-641, 06600, Mexico D.F., Mexico;Laboratory of Soil Ecology, ABACUS, Cinvestav, Avenida Institute Politecnico National 2508, C.P. 07360 Mexico, D.F., Mexico;Laboratory of Soil Ecology, ABACUS, Cinvestav, Avenida Institute Politecnico National 2508, C.P. 07360 Mexico, D.F., Mexico;Laboratory of Plant Biotechnology, Institute Tecnologico de Tuxtla-Gutierrez, Tuxtla-Cutierrez, Chiapas, Mexico;Laboratory of Plant Biotechnology, Institute Tecnologico de Tuxtla-Gutierrez, Tuxtla-Cutierrez, Chiapas, Mexico;Departamente de Mkrobiologia, Escuela Nacional de Ciencias Biologkas-IPN, Av. Prolongation de Carpio y Plan de Ayala, C.P. 11340 Mexico, D.F., Mexico;International Maize and Wheat Improvement Centre (CIMMYT), Apdo. Postal 6-641, 06600, Mexico D.F., Mexico;%In 1991, the 'International Maize and Wheat Improvement Center' (CIMMYT) started a field experiment in the rain fed Mexican highlands to investigate conservation agriculture (CA) as a sustainable alternative for conventional maize production practices (CT). CT techniques, characterized by deep tillage, monoculture and crop residue removal, have deteriorated soil fertility and reduced yields. CA, which combines minimum tillage, crop rotations and residue retention, restores soil fertility and increases yields. Soil organic matter increases in CA compared to CT, but increases in greenhouse gas emissions (GHG) in CA might offset the gains obtained to mitigate global warming. Therefore, CO_2, CH_4 and N_2O emissions, soil temperature, C and water content were monitored in CA and CT treatments in 2010-2011. The cumulative GHG emitted were similar for CA and CT in both years, but the C content in the 0-60 cm layer was higher in CA (117.7 Mg C ha~(-1)) than in CT (69.7 Mg C ha~(-1)). The net global warming potential (GWP) of CA (considering soil C sequestration, GHG emissions, fuel use, and fertilizer and seeds production) was -7729kg CO_2ha~(-1)y~(-1) in 2008-2009 and -7892 kgCO_2 ha~(-1) y~(-1) in 2010-2011, whereas that of a was 1327 and 1156 kg CO_2 ha~(-1) y~(-1). It was found that the contribution of CA to GWP was small compared to that of CT.