Closing yield gaps in South Asian wheat production (Bihar, India and Terai of Nepal)

Rising wheat consumption and recurring climate extremes threaten food security in the Eastern Indo-Gangetic Plain. Closing wheat yield gaps in this region through agronomic practices currently available to farmers can contribute to a more secure future in this region. In Nepal and Bihar, India, a set of complementary management practices were associated with higher yields, namely: 1) early sowing with long maturing varieties, 2) higher rates of N, P and particularly K application, 3) transitions to zero-till for crop establishment, and 4) encouraging more frequent irrigation. Financial and policy support for infrastructure and agricultural inputs, extension, research and development of private service networks made a marked improvement in yield outcomes in Bihar. Nepal is at a crossroads of diminishing farm-labor and inadequate investment into farming operations that, among other factors, have stagnated domestic wheat yield. Cultural and economic constraints have hindered the widespread adoption of more expensive precision agriculture technologies like zero-till that have the capacity to improve labor and farm input efficiencies. To capture the benefits from added precision of application but with the ability to fit within the current semi-mechanized seed bed preparation and tillage system, we introduced a low-cost, chest mounted seed and fertilizer. We found that simple mechanization caused yield efficiencies to be positive and significant for nitrogen and phosphate. Seed rates using this method were positively associated with seedling density. This led to both yield and profit being more predictable for farmers. Conversely, hand-applied inputs caused a disassociation between inputs and end of season yield and therefore added a large measure of risk to their farming operations. Nepali farmers endure many types of risks in producing wheat. Some, such as those affiliated with socioeconomic and demographic pressures, they have little control over. Other sources of risk, such as stresses associated with particular agronomic practices, can be mitigated through better management. In this research, we found that waterlogging stress early in wheat phenology reduced yield. This was attributed to farmers applying flood irrigation to the crop to the point of ponding at early wheat growth stages when the plants were more vulnerable. Waterlogging stress was exacerbated by the common practice of applying seed and fertilizer by hand which created in-field heterogeneity of nutrient distribution, thereby reducing individual plant access to nutrients and making them less resilient to waterlogging stress. Two different solutions, one a technological intervention and the other a change in irrigation practices, reduced this stress. The first was the introduction of a chest-mounted spreader that added a greater measure of uniformity to input application and reduced the impact that waterlogging stress had on crop productivity by ensuring greater availability of nutrients across fields. The second was a delay in the timing of flood irrigation to coincide with greater crop maturity. Plants at the tillering development stage (zadoks stage 20) demonstrated a greater resilience to waterlogging stress and promoted greater yield. At the policy level, increasing the availability of diesel pumps on the landscape, and splitting irrigations, would offer farmers greater flexibility in their management to reduce crop stresses and overall risk