From CO2Science: Over the period 1980 to 2016, wheat production in India experienced a positive trend, increasing at a rate of 1.17 Mt per year. And although India ranks third in the world in terms of total wheat production, in the words of Gahlot et al. (2020), “domestic production is barely sufficient to meet the country’s demand for food and livestock feed.” Hence, they add, “there is an urgent need to address this yield gap by developing better land management practices under different environmental conditions.” And so it was that they set out to explore just what are the major environmental and land management factors that influence wheat production in India, hoping that such knowledge could be utilized to boost future grain production.
Paper reviewed: Gahlot, S., Lin, T.-S., Jain, A.K., Roy, S.B., Sehgal, V.K. and Dhakar, R. 2020. Impact of environmental changes and land management practices on wheat production in India. Earth System Dynamics 11: 641-652.
To accomplish their objective, the team of six researchers examined the influence of two environmental factors (CO2 and temperature) and two management practices (irrigation and nitrogen fertilizer application). This they did at a field site at the Indian Agricultural Research Institute’s campus in New Delhi during two growing seasons (2014-2015 and 2015-2016). Data gathered during the field study was then incorporated with other observational records into an Integrated Science Assessment Model, a state-of-the-art land model capable of simulating production at the country scale. Several model runs were then conducted that both included and withheld the four production-influencing factors (temperature, CO2, irrigation and nitrogen application) in an effort to evaluate the individual effects of each variable on country-wide wheat production over the period 1980-2016.
In the words of the authors, “results show that the increase in atmospheric CO2 concentration has a positive impact on wheat production due to the CO2 fertilization effect.” More specifically, the CO2 increase of 1.82 ppm per year raised wheat production in India by 22 Mt since the 1980s, representing a 30% increase. The next most significant factor was the nitrogen fertilizer. Its application increased at a rate of 2.71 kg N ha-1 yr-1, leading to a 10.63 Mt (15%) increase in wheat production over the study period. Coming in third was irrigation, which likely increased country-wide wheat production by 12% since 1980. And lastly, the model suggested that rising temperatures during the growing season of 0.026 °C per year had a negative effect on yields, equivalent to an approximate 10% decline over the period under investigation. Nevertheless, the negative influence of rising temperatures was more than overcome and compensated for by the positive influence of rising CO2, nitrogen fertilizer application and irrigation such that overall annual wheat production increased by approximately 43 Mt over the 37-year period.
In light of the above, it would appear that wheat production in India will continue to benefit from rising atmospheric CO2 and land management practices in the future. And by selecting more heat-tolerant cultivars, production should increase even more, allowing this highly populated country to meet its wheat production needs in the years and decades to come.