A six-year study by scientists of the Indian Council of Agricultural Research (ICAR) has found that climate change and the unbalanced use of chemical fertilisers are significantly reducing soil organic carbon levels across India’s farmlands. The decline, researchers warn, threatens long-term soil fertility, crop productivity, and the country’s carbon balance.
The study, coordinated by the Indian Institute of Soil Science in Bhopal, examined more than 2.5 lakh soil samples collected from 620 districts across 29 States. The findings have been published in the international journal Land Degradation & Development.
According to the project coordinator, Arvind K. Shukla, organic carbon plays a central role in soil health because it affects its physical structure, chemical nutrient balance, and biological activity. “If organic carbon is low, micronutrient deficiency increases. High organic carbon means better nutrient availability,” he said, adding that this is closely linked to climate and geography.
The study found that areas at higher elevations generally retain more soil organic carbon, while lowland regions and regions with high temperatures show severe depletion. States such as Rajasthan and Telangana recorded low organic carbon due to prolonged heat. In contrast, regions with rice and pulse-based cropping systems showed relatively better levels, as these systems promote microbial activity and carbon sequestration in the soil.
The research also highlighted the impact of fertiliser practices. Haryana, Punjab, and parts of western Uttar Pradesh showed declining soil organic carbon because of heavy and uneven application of urea and phosphorus-based fertilisers. Meanwhile, States like Bihar, where fertiliser use is more balanced, recorded healthier soil conditions.
Scientists noted that rising temperatures due to climate change will accelerate the decline of soil organic carbon in the coming years. Lower carbon in soil means less heat absorption and more heat reflection from the ground, contributing to greenhouse effects and potentially worsening local warming.
The team has prepared an agri-ecological map to guide policy decisions on land degradation and carbon credit planning. They recommend that governments support carbon-sequestering agricultural practices, including maintaining continuous crop cover, expanding plantation drives, improving irrigation access, and encouraging crop rotations that restore soil carbon.
They also suggested introducing carbon credit incentives for farmers who adopt practices that increase carbon storage in soil. “We must promote crop management systems that can mitigate climate change impacts. Farmers who help trap carbon should be supported for their contribution,” Mr. Shukla said.
The study warns that without immediate corrective measures, declining soil carbon may undermine India’s food security and climate mitigation efforts in the decades ahead.