Conservation Agriculture Effects on Dynamics of Soil C and N under Climate Change Scenario

Anthropogenic release of greenhouse gases is fast affecting climate change and global warming. This will increase soil organic matter decomposition and soil water deficits in future. Greater frequency of high intensity rainfall events, runoff, and flooding in future would cause high soil erosion losses unless offsetting conservation measures are taken. Mitigation strategy of diverting CO2 from atmosphere to soil as SOC by adopting conservation agricultural practices of reduced or no-tillage, crop residue retention, and diverse cropping system is now a recognized such method which has the potential of offsetting a significant portion of the future atmospheric increase in CO2 concentration. Cropping intensification combined with no-tillage or reduced tillage systems and optimum fertilizer management targeted to production level of the system affects favorably the SOC and N stocking. Such a stocking is more pronounced in the surface soil layer which fosters productivity and regulates terrestrial water flow, high infiltration rate, and higher amount of water storage in soil profile. Increased soil profile stored water, by facilitating increased cropping intensity, helps in overcoming the problem from keeping the soil fallow, a management system which is responsible for rapid loss of SOC and N and soil erosion in dry land and rain fed conditions. Conservation tillage practice also reduces the relative quantity of residual soil NO3-N available for leaching and/or denitrification even under situations of higher fertilizer N applications, thus preventing their possible leakage to the environment. Some residual NO3 may be denitrified to N2O gas especially in SOC-rich heavy soils prone to excessive wetness after several years of no-till practice.