A climate-friendly transformation of rice-wheat cultivation in South Asia is urgently needed – CIMMYT

South Asia, a climate change hotspot region that features both smallholder and intensive agriculture, embodies the crushing pressure on land and water resources from global agriculture to feed a populous, warming world. For example, the continuous irrigated cultivation of rice and wheat across northern India is depleting and degrading soils, draining a major aquifer and creating a steady drain of greenhouse gases.

Through decades of Asian and global partnerships, the International Maize and Wheat Improvement Center (CIMMYT) has helped research and promote resource-efficient, climate-friendly solutions for South Asian agriculture. Innovations include more precise and efficient use of water and fertilizers, conservation agriculture that mixes reduced or tillage, use of crop residues or mulching as soil cover, and more diverse cover crops and crop rotations. Partners are recently researching regenerative agriculture approaches – a set of integrated farming and grazing practices to rebuild soil organic matter and biodiversity.

Along with their environmental benefits, these practices can significantly reduce operating costs and maintain or increase crop yields. Their widespread acceptance depends in part on enlightened policies and dedicated promotion and testing, in which farmers are directly involved. Below we highlight promising results and policy directions from a collection of recent scientific studies by CIMMYT and partners.

Down in the dirt

A recent scientific review examines the potential of a range of improved practices—reduced or zero tillage with residue management, use of organic fertilizer, the balanced and integrated application of plant nutrients, land leveling, and precise water and pest control—to capture and soil carbon on smallholder farms hold in South Asia. The results show a potential 36% increase in topsoil organic carbon, equivalent to approximately 18 tonnes of carbon per hectare of land, and a potential 12% reduction in methane emissions across all crops and environments. Policies and programs are needed to encourage farmers to adopt such practices.

Another study of soil quality in India’s sprawling breadbasket region found that conservation farming practices could increase wheat yields per hectare by nearly half a ton and soil quality indices by nearly a third over conventional practices, and reduced greenhouse gas emissions by more than 60%.

Ten years of research in the Indo-Gangetic Plains using rice-wheat-mungbean or corn-wheat-mungbean rotations with flooded versus subsurface drip irrigation showed that earthworms – which are essential contributors to soil health – are absent from soils among typical farmer practices. However, large earthworm populations were present and active under climate-friendly practices, resulting in improved soil carbon sequestration, soil quality, and nutrient availability to plants.

The field of farmer Ram Shubagh Chaudhary, Pokhar Binda village, Maharajganj district, Uttar Pradesh, India, who tested zero tillage to sow wheat directly into the unplowed paddy fields, leaving crop residues after the rice harvest. Chaudhary is one of many partner farmers in the Cereal Systems Initiative for South Asia (CSISA) led by CIMMYT. (Photo: P. Kosina/CIMMYT)

Scheduled restart of marginal farms

Using the FarmDESIGN model to assess the realities of small marginal farmers in North West India (approximately 67% of the population) and redesign their current practices to increase agricultural profits, soil organic matter and nutrient yields while reducing pesticide use, demonstrated by an international team of agronomists that the integration of innovative cropping systems can help improve agricultural performance and household livelihoods.

More than 19 gigatonnes of groundwater are extracted each year in northern India, much of it to flood the region’s puddled, transplanted rice crops. A recent experiment calibrated and validated the HYDRUS 2D model to simulate water dynamics for puddle rice and for rice sown in non-flooded soil with zero tillage and irrigated with subsurface drip irrigation. It was found that the yield of rice grown using the methods of conservation agriculture and subsurface drip irrigation was comparable to that of rice transplanted from puddles, but required only half the irrigation water. Subsurface drip irrigation also reduced water losses through evaporation and deep drainage, meaning this innovation coupled with conservation agriculture offers an ecologically viable alternative for sustainable rice production.

Given that yield gains from the use of conservation agriculture in northern India are widespread but generally small, a nine-year study of rice-wheat cultivation in the eastern Indo-Gangetic Plains using the Environmental Policy Climate (EPIC) Models performed, in this case combining data from long-term experiments with regionally-scaled crop modeling, documented the need to flexibly adapt conservation agriculture to local conditions while building the ability of farmers to test and adapt appropriate conservation agriculture practices. The study found that conservation agriculture could increase rice-wheat productivity by up to 38% with optimal management.

Key partner organizations in this research include: Indian Council of Agricultural Research (ICAR); Central Soil Salinity Research Institute (CSSRI), Indian Agricultural Research Institute (IARI), Indian Institute of Farming Systems Research (IIFSR), Agriculture University, Kota; Agricultural University CCS Haryana, Hisar; Punjab Agricultural University, Ludhiana; Sri Karan Narendra Agricultural University, Jobner, Rajasthan; the Borlaug Institute for South Asia (BISA); the Trust for the Advancement of Agricultural Sciences, Cornell University; University of Damanhour, Damanhour, Egypt; UM6P, Ben Guerir, Morocco; the University of Aberdeen; the University of California, Davis; Wageningen University and Research; and IFDC.

Generous funding for the cited work comes from the Bill & Melinda Gates Foundation, the CGIAR Research Programs on Wheat Agri-Food Systems (WHEAT) and Climate Change, Agriculture and Food Security (CCAFS), supported by CGIAR Fund Donors and through bilateral funding agreements ) , the Indian Council for Agricultural Research (ICAR) and USAID.

Cover photo: A shortage of farm workers is driving serious consideration by farmers and policymakers to replace traditional, labor-intensive puddle rice cultivation (shown here), which results in significant methane emissions and wasteful use of irrigation water, with the practice of growing rice in non-flooded soils , using conservation agriculture and drip irrigation practices. (Photo: P. Wall/CIMMYT)

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