Determinants and Impacts of Conservation Agriculture in South Asia: A Meta-Analysis of the Evidences

Rice-wheat cropping system in the Indo-Gangetic plains is pivotal in ensuring food and livelihood security in South Asia. However, the productivity of the system is threatened by factors like climate change, urbanisation and excessive resource use. Conservation agriculture (CA) practices provide the scope for curbing the consequences of climate change by its resource saving and carbon emission as well as cost reducing potential. To analyse the effectiveness of CA under different crops, soil, and climatic conditions, a meta-analysis was conducted by synthesising the results of various experimental studies. Adoption of only zero/minimum/reduced tillage without integrating it with mulching and crop rotation in CA provided lesser yield as compared to conventional tillage. In contrast, crop yields were higher in CA when all the three practices, viz., conservation tillage practices, mulching and crop rotation were followed as compared to the conventional tillage. Crop yields were higher under reduced/minimum tillage as compared to zero tillage for all the crops considered for the study. Wheat, maize and pulses performed better in CA system as compared to rice in terms of water saving and yield. It was found that irrigation, soil cover and application of nitrogen were the crucial inputs in improving the performance of conservation tillage. Further, adoption of CA practices lead to significant reduction in the cost and at the same time provided better returns as compared to the conventional system. Training, targeting to irrigated, sub-tropical regions and fiscal incentive are critical for the successful implementation of CA in the region.