Assessment of soil organic and inorganic carbon stock at different soil depths after conversion of desert into arable land in the hot arid regions of India

Abstract

Soil organic carbon (SOC) and inorganic carbon (SIC) are important carbon reservoirs in terrestrial ecosystems. But, little attention was paid to carbon dynamics in hot arid regions of India. In order to assess the carbon stock after conversion of desert into irrigated arable land in arid regions, the variability of SOC and SIC concentrations in the Suratgarh block of Rajasthan, India were analyzed using geostatistics. Soil samples were collected from depths of 0–15 cm, 15–30cm, 30–60cm and 60–90cm at 150 sampling sites in the study area over an area of 3000 km2. The coefficient of variation (CV) for SOC and SIC was high for all depths (> 35%). Geostatistical analysis showed that spherical, circular, Gaussian and exponential models were the best-fit models for soil carbon stocks. The average stock of SOC and SIC were 4.55 and 10.9Mg ha 1 in the 0–15cm soil layer, and 3.02Mg ha 1 SOC and 12.42Mg ha 1 SIC in the 15–30cm soil layer, respectively. Our results showed that SOC and SIC stocks over 0–90cm were 15.54 and 76.71Mg ha 1, respectively. There was significantly positive correlation (r¼0.33, p<0.01) between SOC and SIC stock in 0–90cm depth. Our study suggested that increasing SOC might lead to an increase in SIC stocks after conversion of desert into irrigated arable land. Thus the study highlights the importance of SIC in the carbon cycle of India’s arid region.