A Review of Carbon Sequestration through Conservation Agriculture

摘要

This review aims at developing a clear understanding of the impacts and benefits of the prevalent types of agriculture with respect to soil organic carbon (SOC) sequestration and carbon (C) pools, and examining if there are any misleading findings at present in the scientific literature. Most of the world's agricultural soils have been depleted of organic matter and soil health over the years under tillage-based agriculture (TA), compared with their state under natural vegetation. This degradation process can be reversed and the review identifies conditions that can increase soil organic matter (SOM) content and improve soil health under conservation agriculture (CA) practices which involve minimum soil disturbance, maintenance of soil cover and crop diversity. The review also discusses the need to refer to specific C pools when addressing C sequestration, as each C category has a different turnover rate. With respect to greenhouse gas emissions (GHG), sustainable agricultural systems based on CA principles are described which result in lower emissions from farm operations as well as from machinery manufacturing processes, and that also help to reduce fertilizer use. The review concludes that terrestrial sequestration of carbon can be achieved efficiently by changing the management of agricultural lands from high soil disturbance TA practices to low disturbance CA practices and by adopting effective nitrogen (N) management practices to provide a positive nitrogen balance forC sequestration. However,full advantages of CA in terms of C sequestration can usually be observed only in the medium- to longer-terms when CA practices and associated C sequestration processes in the soil are well established.