Sowing wheat earlier can help increase yields in India

ANN ARBOR—Yield gaps in wheat production in India can be countered with an earlier sowing date, says a University of Michigan researcher.

Using a new way to measure wheat yields using satellite data, Meha Jain, assistant professor at the U-M School for Environment and Sustainability, found that the wheat production in eastern Indo-Gangetic Plains, India’s main wheat growing region, can grow by 110 percent if the best farm management practices like earlier sow dates are implemented.

“Identifying the causes of gaps will provide actionable information to enhance food security,” said Jain, adding that food security will be increasingly challenged by climate change, natural resource degradation and population growth over the coming decades.

Changes in the production of major world crop like wheat impacts food prices, food security and land use decisions. For wheat, there is a clear connection to increased temperatures, says the researcher. “Wheat is one crop that is highly impacted by heat during grain filling stage,” she said. “Moving the sow date earlier, even by a couple of weeks, can make a big difference to the yield.”

India is the world’s second-largest producer of wheat after China. Previous studies have suggested that wheat yields have stagnated and rising temperatures could reduce yields by up to 30 percent by mid-century.

Jain’s research looked at some of the top wheat producing states—Haryana, Punjab, Uttar Pradesh and Bihar—from 2001 to 2015. This includes millions of fields distributed over a range of management, soil and climate regimes.

Understanding how different climate factors interact and impact food production is essential to understanding global crop production. Researchers often use crop models as an essential tool for assessing yields and the impacts of climate change.

Instead of using crop models to simulate yield gaps, in their study, Jain and colleagues used the Scalable Crop Yield Mapper to map wheat yields using satellite data empirically at fine spatial resolutions. They then used these estimates to quantify existing yield gaps within each district across the Indo-Gangetic Plains.

Meha Jain

“This new method gave us much more granularity,” Jain said. “We were able to estimate yields at 30-meter resolutions instead of using typically available coarse scale, district-level census statistics.”

According to the study, the yield gaps were low in the northwestern states of Haryana and Punjab—India’s main bread basket—but it could be increased by another 10 percent by improving managing, including shifting sow dates earlier.

In the northern and eastern states of Uttar Pradesh and Bihar the gaps were much higher—yields could be increased by up to 32 percent if farmers adopted best management practices within a given district. By improving management practices to those adopted in Punjab, the highest yielding state, yields in eastern plains could be doubled.

“One of the most important factors we found for closing yield gaps was earlier sowing,” Jain said.

The researchers also examined the impact of other factors like the impact of sow dates, and irrigation use. They found that sow date was the biggest factor in the wheat yield gap across all states. Access to irrigation was the second-largest factor leading to a yield gap.

“Strategies to reduce the negative impacts of heat stress, like earlier sowing and planting heat-tolerant wheat varieties, are critical to increasing yields in this globally important agricultural region,” Jain said. “Agriculture is the primary livelihood for over 50% of India’s population, and in heavy wheat producing regions like the Indo-Gangetic Plains, a loss in wheat yields in not only a matter of food security but also for household welfare.”

The study, “Using satellite data to identify the causes of and potential solutions for yield gaps in India’s wheat belt” was published in September in Environmental Research Letters. Other researchers on the study are Balwinder Singh, A.K. Srivastava, R.K. Malik, A.J. MacDonald of International Maize and Wheat Improvement Center, and D.B. Lobell of Stanford University.

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Meha Jain