Carbon Stocks in Different Soil Types under Diverse Rainfed Production Systems in Tropical India

Abstract

Soil carbon (C) pool plays a crucial role in the soil’s quality, availability of plant nutrients, environmental functions, and global C cycle. Drylands generally have poor fertility and little organic matter and hence are candidates for C sequestration. Carbon storage in the soil profile not only improves fertility but also abates global warming. Several soils, production, and management factors influence C sequestration, and it is important to identify production and management factors that enhance C sequestrations in dryland soils. The objective of the present study was to examine C stocks at 21 sites under ongoing rainfed production systems and management regimes over the last 25 years on dominant soil types, covering a range of climatic conditions in India. Organic C stocks in the soil profiles across the country showed wide variations and followed the order Vertisols . Inceptisols . Alfisols . Aridisols. Inorganic C and total C stocks were larger in Vertisols than in other soil types. Soil organic C stocks decreased with depth in the profile, whereas inorganic C stocks increased with depth. Among the production systems, soybean-, maize-, and groundnut-based systems showed greater organic C stocks than other production systems. However, the greatest contribution of organic C to total C stock was under upland rice system. Organic C stocks in the surface layer of the soils increased with rainfall (r 5 0.59*), whereas inorganic C stocks in soils were found in the regions with less than 550mm annual rainfall. Cation exchange capacity had better correlation with organic C stocks than clay content in soils. Results suggest that Indian dryland soils are low in organic C but have potential to sequester. Further potential of tropical soils to sequester more C in soil could be harnessed by identifying appropriate production systems and management practices for sustainable development and improved livelihoods in the tropics.