Soil Organic Carbon Pools and Indices under Different Land Use Systems in Vertisols of Central India

Soil organic carbon (SOC) plays an important role in soil fertility and productivity. It occurs in soil in labile (i.e. easily decomposable) and non-labile (i.e. resistant to microbial decay) forms that help in maintaining the soil health. Different pools of organic carbon were studied under dominant land use systems in a Vertisol of Central India. Various SOC pools viz., water soluble carbon, labile carbon, easily oxidizable carbon and soil microbial biomass carbon were the highest under forest land use system [eucalyptus (Eucalyptus globules) mahua (Madhuca longifolia) and tendu (Diospyros melanoxylo) and horticulture [mango (Mangifera indica)] plantation. Among agriculture land use systems, the continuous application of 6 t farmyard manure (FYM) ha⁻¹ per annum to soybean-wheat cropping system significantly increased various pools of carbon. Under agri-horticulture system aonla (Emblica officinalis) and guava (Psidium guajava) plantations along with gram as rabi season companion crop improved the carbon pools over riverine land adjoining the river bed. As compared to no-fertilizer and no-manure application (control), the carbon management index (CMI) was 1.31 fold higher when only organic source of nutrients were applied. The perennial crops registered significantly higher CMI of 4.02 (mango), 3.28 (eucalyptus) and 3.88 (mahua and tendu) fold over control under agriculture land use.