Laboratory of Soil Ecology, ABACUS, Cinvestav, Avenida Instituto Politécnico Nacional 2508, C.P. 07360 Mexico, D.F., Mexico.
Sci Total Environ. 2012 Aug 1;431:237-44. doi: 10.1016/j.scitotenv.2012.05.029. Epub 2012 Jun 9.
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(2)O 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 -7729 kg CO(2) ha(-1) y(-1) in 2008-2009 and -7892 kg CO(2) ha(-1) y(-1) in 2010-2011, whereas that of CT 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.
1991 年，国际玉米和小麦改良中心（CIMMYT）在墨西哥高地的雨养区开始了一项田间试验，以研究保护性农业（CA）作为传统玉米生产实践（CT）的可持续替代方法。CT 技术的特点是深耕、单一栽培和作物残茬清除，这导致了土壤肥力的恶化和产量的降低。CA 结合了浅耕、轮作和残茬保留，恢复了土壤肥力并提高了产量。与 CT 相比，CA 增加了土壤有机质，但 CA 中温室气体（GHG）的增加可能会抵消缓解全球变暖所获得的收益。因此，在 2010-2011 年，监测了 CA 和 CT 处理中的土壤有机碳（SOC）、土壤温度、C 和水分含量、CO2、CH4 和 N2O 排放。在这两年中，CA 和 CT 的累积 GHG 排放相似，但 CA（117.7 Mg C ha-1）的 0-60 cm 土层中的 C 含量高于 CT（69.7 Mg C ha-1）。CA 的净全球变暖潜势（GWP）（考虑土壤 C 封存、GHG 排放、燃料使用以及肥料和种子生产）在 2008-2009 年为-7729 kg CO2 ha-1 y-1，在 2010-2011 年为-7892 kg CO2 ha-1 y-1，而 CT 的为 1327 和 1156 kg CO2 ha-1 y-1。结果发现，与 CT 相比，CA 对 GWP 的贡献较小。
