Impact of best management practices on sustainable crop production and climate resilience in smallholder farming systems of South Asia

A host of best water and soil management practices (BMPs) hold promise in addressing water scarcity and land degradation to enable sustainable crop intensification in smallholder farming systems. This study quantifies the effect of BMPs on crop productivity, income, water saving and water balance components and identifies gaps for future research. This paper synthesizes the performance of BMPs and the existing data gap by reviewing 108 published studies from the Indian subcontinent which capture a diverse range of rainfall and cropping systems. In situ conservation measures helped enhance crop yields by 200–1000 kg/ha, reduced cost of cultivation and enhanced incomes by US$ 10–200/ha/year. The BMPs were helpful in enabling annual water saving in the range of 50 mm to 300 mm by either conserving residual soil moisture or saving irrigation water resulting in enhanced water productivity. Interventions such as direct seeded rice and laser land leveling were found most effective in terms of water saving and in reducing cost of cultivation. On the other hand, ex situ rainwater harvesting interventions helped enhance groundwater recharge by harvesting an additional 50–150 mm of surface runoff which helped increase crop yields, led to sustainable crop intensification and strengthened the number of ecosystem services. Most of the published literature on in situ conservation measures are studies that were carried out at research stations, which show promise of sustainable intensification. However, greater efforts are needed to document learnings from farmer/community scale interventions for effective scaling up. There is also a gap in data availability that hampers a clear understanding of the impact of ex situ rainwater harvesting interventions and ecosystem trade-offs; moreover the data available covers short periods and only covers an area of up to 10 km2. We recommend the monitoring of long-term system-level impact indicators to realize the potential of ex situ rainwater harvesting interventions in a systems perspective and better grasp the ecosystem trade-offs. More importantly, the review revealed the ample scope of integrating in situ and ex situ interventions to build system-level resilience in smallholder farming systems in order to accelerate progress towards achieving the United Nations Sustainable Development Goals (SDGs).