The downpour that floods an entire landscape and searing heat that drains water in every form. Such weather variations in Kerala are impacting its food platter too, with the yield from crops falling up to 33% in the past few decades.
This was revealed in a study done by the Kozhikode-based Centre for Water Resource Development and Management between 2014 and 2019. It covered Kozhikode district of Kerala and Tikamgarh district of Madhya Pradesh and Gujarat. Twenty farms covering all the agro-ecological units in Kozhikode were chosen for the purpose.
The increase in the maximum temperature ranged from 0.43 degrees Celsius to 1.92 degrees Celsius. The minimum temperature showed an increase of 0.66 degrees Celsius to 2.17 degrees Celsius. Rainfall was reported to have gone up by 166 mm to 1,434 mm. The main reasons for these are what scientists call “anthropogenic activities” that include deforestation, industrial pollution, soil erosion, and land degradation.
The yield from rice, banana, rubber, coffee, black pepper, coconut, and arecanut, all rain-fed crops, showed a decline of 0.3% to 33% under different scenarios. The total crop water requirement of major crops such as coconut, paddy, and banana increased with a rise in temperature, enhancing the irrigation water demand. Since a rise in the mean temperature above a threshold level will cause a reduction in agricultural yield, an increase in maximum temperature by one, two, and three degrees Celsius could reduce the grain yield of rice by 6%, 8.4% and 25.1%, respectively, if all other climatic variables remain constant. The grain yield of rice declined by 10% for each one degree Celsius increase in the minimum temperature during the growing season. Crop climate suitability is also changing abruptly because of climate change, says the study. As much as 81% and 64% of growing areas of coffee and black pepper may not be suitable for these crops in future unless effective management strategies are adopted.
The study suggests that the yield can be sustained or improved in the case of coconut, coffee, arecanut and black pepper if the crop is irrigated. Since about 80% of the land is under rain-fed farming in Kerala, it is essential to manage every drop of water received through rain, especially during summer, by effective implementation of soil and water conservation steps. Mulching with green and dry residues of crops is important for reducing the higher soil temperature as well as for conserving available soil moisture, it says.
The study was in research collaboration with International Institute of Applied Systems Analysis, Austria; National Institute of Hydrology, Roorkee, Uttarakhand; and the Institute of Rural Management, Anand, Gujarat. It was funded by the Government of India think-tank Technology Information, Forecasting and Assessment Council of the Department of Science and Technology.