Heatwave takes a toll on north India’s wheat yield

A cultivated wheat field in the Rohtak district of Haryana. Photo by Kapil Kajal.
  • The heatwave in Punjab has reduced the yield and quality of wheat this year.
  • Punjab’s wheat yield this year has reduced to 43 quintals per hectare, which is the lowest since the year 2000.
  • The heatwaves and particularly their early onset have resulted in an estimated 10-35 percent reduction in crop yields in Punjab, Haryana and Uttar Pradesh.

Hardeep Kaur, 36, and her husband Chamkaur Singh, 39, owned two acres of agricultural land in the Bathinda district of Punjab, a northern Indian state. With a fierce heatwave in March and April, the yield of wheat crop on their land reduced. At the time, the couple had a loan of Rs. 800,000 and with reduced income from the low wheat yield, the stress to repay the loan kept mounting. Kaur and Singh died by suicide in April 2022.

Sarup Singh Sidhu, general secretary of the Bathinda chapter of Bhartiya Kisan Union (BKU), a farmer’s organisation, told Mongabay-India, that since mid-March this year, nine farmers in Bathinda had died by suicide. In another district, Mansa, seven farmers had died the same way. Sarup Singh Sidhu attributes these deaths to the stressful situation that overcame them because of the low wheat output, which in turn is linked to the heatwaves.

Bathinda and Mansa districts have recorded the highest decline in wheat yield this season in Punjab, said M.S. Sidhu, head of the Indian Society for Agricultural Development and Policy, an agricultural journal. “Punjab registered the lowest wheat harvest this year in two decades,” he told Mongabay-India. “In the 1980s, Punjab wheat yield used to be 27 quintals per hectare which increased to 35 quintals in the 1990s and crossed 45 quintals per hectare in the year 2000.” After the year 2000, wheat yield in Punjab continued to stay above 45 quintals per hectare. From 2016 to 2020, the wheat yield crossed 50 quintals per hectare every year. Then last year, in 2021, it came down to 48 quintals per hectare.

“But this year, in 2022, the wheat yield is reduced to 43 quintals per hectare,” M.S. Sidhu claimed. Until now, the lowest wheat yield had been in 2015 when it touched 45.83 quintals per hectare.

March was the hottest in India since records began 122 years ago. This has resulted in an estimated 10-35 percent reduction in crop yields in Punjab, Haryana and Uttar Pradesh. These states are collectively known as India’s “wheat bowl” because of their high production of wheat.

Increasing temperatures impact agriculture

The Global Food Policy Report 2022 by the International Food Policy Research Institute has warned that climate change may push 90 million Indians towards hunger by 2030 due to a decline in agricultural production and disruption in the food supply chain.

Climate change increases the likelihood and intensity of heatwaves, which in turn impact the agricultural sector as is seen in the case of Punjab.

A 2016 government report on the impact of climate change on agriculture in India, says that it has been projected that under the scenario of a 2.5 degrees Celsius to 4.9 degrees Celsius temperature rise, rice yields will drop by 32-40 percent and wheat yields by 41-52 percent.

This has been the hottest March in Punjab since 1970, according to Pavneet Kaur Kingra, head, of the Department of Climate Change and Agricultural Meteorology, Punjab Agricultural University, who attributes it to global warming and climate change impacts. The average minimum temperature in some regions of Punjab rose by 3.9 degrees Celsius while the average maximum increased by 4.1 degrees Celsius, this year, Kingra said.

“Since the beginning of March, India is encountering radical heatwaves. So, the early onset of heatwaves shrivelled the wheat grain by 20 percent in Punjab. The wheat reaping is usually done in April but this year, when the grain was in the maturing process, the temperature increased drastically in March. This led to the harvesting in March itself and shrivelling of wheat grains,” Kingra explained.

Umashanker Singh, Joint Director of the Union Ministry of Agriculture and Farmer’s welfare, told Mongabay-India that India stopped the export (of wheat) as a precautionary measure to maintain the buffer stock. He attributes the problem to the poor coping strategies in India and the world for climate change and global warming issues. Singh blamed inaction by politicians and the India Meteorological Department for what he claims are poor weather predictions.

Read more: The Arabian Sea faces an increased frequency and duration of marine heatwave days, finds study

Heat reduces grain yield as well as quality

According to Rajesh Kumar Sharma, the senior researcher at the Indian Institute of Wheat and Barley Research (IIWBR), there are three phases of wheat harvesting which are sowing, flowering and maturing. The high temperature at any of the one phases adversely impacts the wheat grain yield as well as the quality, Sharma said.

According to a study by the Indian Institute of Wheat and Barley Research (IIWBR), the best temperature regime for optimum growth and yield of the wheat crop is 20–22 degrees Celsius at sowing, 16–22 degrees Celsius at tillering to grain filling and the slow rise of temperature to 40 degrees Celsius at harvesting.

The high temperatures in one stage, may reduce the duration of another stage which in turn have a negative effect on grain yield and size.

“As the global temperature is increasing, the winters are shrinking. Winters are needed for wheat growth. The heatwaves in March had a considerable impact on wheat yield and growth as the temperature rose suddenly. But ever since November, the temperature was more than what is needed for wheat growth and it is increasing every year,” said Sharma.

A depressed farmer in his field in Pataudi district in Haryana after a low yield of wheat this year. Photo by Kapil Kajal.
A farmer in his field in Pataudi district in Haryana after a low yield of wheat this year. The heatwave in north India has resulted in an estimated 10-35 percent reduction in crop yields in Punjab, Haryana and Uttar Pradesh. Photo by Kapil Kajal.

A vulnerability assessment of Indian agriculture to climate change, undertaken by the Indian Council of Agricultural Research (ICAR), assessed 573 rural districts of India for their climate change risk. Risk, as per the assessment, is the result of interaction among exposure, vulnerability and hazard. Based on the vulnerability analysis, 109 districts out of 573 rural districts (19 percent of total districts) were categorised as ‘very high-risk’ districts, while 201 districts were categorised as ‘high risk’ districts.

The assessment notes that the maximum temperature is expected to increase by 1 to 1.3 degrees Celsius in 256 districts and by 1.3 to 1.6 degrees Celsius in 157 districts, for the period 2020-2049.  The increase ranged from less than 1.3 degrees Celsius in 199 districts and greater than 1.6 degrees Celsius in 89 districts. The cultivation of wheat in these districts is likely to be affected by heat stress.

Read more: Climate change hits home as increasing heatwave days scorch India

Not the first time for India

Kharif crops like paddy, maize, cotton, and groundnut, also known as monsoon crops, are sowed in June and harvested in October. The increased instances of erratic monsoon is impacting kharif crops, an occurrence which is well documented. This year, however, climatic factors also emerged as an influence on rabi crops – wheat, barley, and mustard which are sown around mid-November and harvested in April or May.

A Reserve Bank of India (RBI) report published in January 2022 mentioned that climatic factors continue to have a significant impact on the agricultural productivity in India. The rising temperature along with increased occurrences of extreme weather conditions have made climate change a major threat to Indian agriculture and productivity loss, RBI noted.

A season-wise analysis by the RBI shows that rabi season months have recorded maximum changes in rainfall and temperature. “Long-term co-movements show that the change in different climatic variables has different implications for rabi and kharif crops. While the maximum temperature anomalies, in both seasons, depict a significant negative relationship with respective yields. For minimum temperature anomalies, the correlation turned out to be negative but statistically significant in case of rabi season only.”

Overall, the preliminary findings of the RBI analysis indicate that maximum temperature impact is more prominent during kharif season while minimum temperature anomalies impact rabi crop yields more.

Devinder Sharma, food and policy analyst, told Mongabay-India, “The heat is unusual this time. But this is not the first time when such an impact of a heat wave on crops is noticed. In 2010 as well, such heatwaves impacted the crop yield in Punjab.” The wheat in 2010 decreased by 4.9 percent, 4.1 percent and 3.5 percent in Punjab, Haryana and Uttar Pradesh, respectively, according to a 2019 study.

“The impact was historic this time because heatwaves started at the beginning of March. We have faced heatwaves before, but this time it was more extreme than ever,” added Devinder Sharma.

Farmers showing the shrivelled wheat grain this year. Photo by Kapil Kajal.
Farmers showing shrivelled wheat grain. the early onset of heatwaves shrivelled the wheat grain by 20 percent in Punjab. Photo by Kapil Kajal.

In its latest report, the Intergovernmental Panel on Climate Change (IPCC) alerted that the rise in global average temperature will have substantial threats to agriculture in India. Rising warmth will push the agrarian workforce exhausted, IPCC noted.  It counted that climatic conditions like intense rainfall and heatwaves will negatively influence crop yields. “Increased temperatures will cause yields to significantly reduce. rice production by 10 percent to 30 per cent, and maize production by 25 percent to 70 percent.”


Banner image: A cultivated wheat field in the Rohtak district of Haryana. Photo by Kapil Kajal.

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