Soil Carbon in Agro-Ecosystems of India

Abstract

A large proportion of soils of agroecosystems of India are degraded and depleted of their soil organic carbon (SOC) stock. Soils of arid and semi-arid regions have a relatively higher soil inorganic C (SIC) content. Whereas SOC content decreases with plowing, crop residues removal or burning and intensive grazing, SIC stock is vulnerable to acidification by use of nitrogenous fertilizers. Thus, degraded and depleted soils of India have a large soil C deficit and a high soil C sink capacity. Land use and agricultural practices which enhance SOC content are conservation agriculture, residue retention, elimination of in-field burning of residues, controlled grazing and use of organic amendments. Increasing SOC content in the root zone has a positive impact on crop yield and increase in over all agronomic productivity, and sequestering C through sustainable soil management can be a solution to climate change mitigation. However, gain in SIC content may have a little if any impact on crop yield. Farmers can be incentivized for enhancing soil C stock through payments for ecosystem services (PESs) at the rate of US $50 per credit (INR ~4600) or an appropriate social value of soil C. There is a strong need for Soil Health Act at district, state and national level. The Bharat Soil Protection Policy (BSPP) being developed by ICAR is a useful start in promoting carbon farming and recarbonization of soils of India.