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, 15–30 cm, 30–60 cm and 60–90 cm 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 10.9 Mg ha⁻¹ in the 0–15 cm soil layer, and 3.02 Mg ha⁻¹ SOC and 12.42 Mg ha⁻¹ SIC in the 15–30 cm soil layer, respectively. Our results showed that SOC and SIC stocks over 0–90 cm were 15.54 and 76.71 Mg ha⁻¹, respectively. There was significantly positive correlation (r = 0.33, p < 0.01) between SOC and SIC stock in 0–90 cm 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.

摘要

土壤有机碳（SOC）和无机碳（SIC）是陆地生态系统中重要的碳库。但是，很少有人关注印度炎热干旱地区的碳动态。为了评估在干旱地区将沙漠转变为灌溉耕地后的碳储量，使用地统计学方法分析了印度拉贾斯坦邦苏拉特加尔地区的SOC和SIC浓度的变化。在3000 km ²的区域内，在150个采样点的0-15 cm，15-30 cm，30-60 cm和60-90 cm深度采集了土壤样品。SOC和SIC的变异系数（CV）在所有深度都很高（> 35％）。地统计分析表明，球形，圆形，高斯和指数模型是土壤碳储量的最佳拟合模型。在0–15 cm土层中，SOC和SIC的平均存量分别为4.55和10.9 Mg ha ^-1，在15–30 cm土层中分别为3.02 Mg ha ^-1 SOC和12.42 Mg ha ^-1 SIC。我们的结果表明，在0-90 cm处的SOC和SIC储量分别为15.54和76.71 Mg ha ^-1。呈显着正相关（r  = 0.33，p < 0.01）在SOC和SIC料之间，深度为0-90 cm。我们的研究表明，将沙漠转化为灌溉耕地后，SOC的增加可能会导致SIC库存的增加。因此，该研究突出了SIC在印度干旱地区碳循环中的重要性。