Soil Organic Carbon (SOC) refers to the carbon stored in the soil, derived from the decomposition of plants, animals, and microorganisms. It plays a vital role in maintaining soil fertility, water retention, and microbial activity.
Example: In a healthy paddy field, decomposed straw and roots enrich the soil with carbon, enhancing productivity and resilience to drought.
SOC determines a soil’s capacity to retain nutrients and moisture, supports beneficial microbes, and improves crop yield. When SOC levels decline, soils become nutrient-poor and increasingly dependent on synthetic fertilizers.
Example: Regions with high SOC, such as the Indo-Gangetic plains, sustain better crop productivity compared to arid areas like Rajasthan.
Excessive use of urea and phosphorus-based fertilizers without adding organic matter reduces microbial activity and accelerates carbon loss. Balanced fertilizer application helps restore soil structure and preserve organic carbon.
Example: In Haryana and Punjab, overreliance on chemical fertilizers has reduced organic carbon levels, resulting in declining soil fertility.
Rising global temperatures increase the rate of organic matter decomposition, releasing carbon dioxide and lowering SOC levels. This cycle not only degrades soil quality but also contributes to greenhouse gas emissions.
Example: In Rajasthan and Telangana, prolonged heat and low rainfall have significantly reduced organic carbon compared to cooler hilly regions.
Major factors influencing SOC include rainfall, temperature, altitude, and cropping patterns. Elevated regions with cooler climates tend to retain more carbon than dry, low-lying plains.
Example: Hilly terrains of Himachal Pradesh have higher SOC levels than the plains of western Uttar Pradesh.
The Indian Council of Agricultural Research (ICAR) recommends region-specific soil management practices such as promoting organic manure, ensuring balanced nutrient use, and creating carbon maps to support sustainable agriculture.
Example: ICAR’s Agri-Ecological Base Map helps states restore soil carbon through organic farming and effective crop residue management.
The ICAR study reveals that rising temperatures and imbalanced fertilizer use have severely depleted soil organic carbon across India. Based on over 2.5 lakh soil samples from 620 districts, researchers established a strong correlation between temperature, rainfall, and carbon content. Unscientific fertilizer application — especially of urea and phosphorus — has worsened soil degradation in Haryana, Punjab, and western Uttar Pradesh. Climate change further threatens soil health, making sustainable soil management essential for India’s long-term food security.
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