Long-term lowland rice and arable cropping effects on carbon and nitrogen status of some semi-arid tropical soils

Abstract

Samples of surface (0–30 cm) soils were collected from eight sites in the semi-arid tropical regions of India to evaluate and compare the long-term effects of lowland rice or paddy and non-rice or arable systems on soil organic C (SOC), soil inorganic C (SIC) and total N status. The results showed that soil samples from sites under lowland rice double cropping system had greater organic C and total N content than those from soils under rice in rotation with upland crop or under other arable systems. The SOC : N ratio was wider in soil samples from sites under lowland rice compared to those under other arable systems, which had lower C : N ratios. Samples from soils under lowland rice system tended to have a narrower SIC : N ratio than those under arable systems, indicating a better pedoenvironment under paddy rice. Our results support earlier findings that sites under continuous wetland rice cropping accumulate organic matter and contain higher soil organic matter compared to the sites under other arable systems.