Soil microbial responses as influenced by Jatropha plantation under rainfed condition in north-west India

Abstract

The use of Jatropha curcas L. (Jatropha) as biofuel is currently increasing in tropical and sub-tropical regions. Jatropha species are well known for synthesizing various toxicants. However, the effects of Jatropha plantation on soil microbiota have barely been investigated. Hence, in current experiment, we had investigated the effects of Jatropha cultivation on soil microbial and biochemical properties in winter, summer and wet seasons after 9 years of plantation with different plant population densities. A nearby uncultivated area was included as the control site. Soil organic carbon was found to increase, while carbon: nitrogen ratio (C:N) decreased under Jatropha plantation as compared to control. Irrespective of seasons, mean microbial biomass C (MBC) and microbial biomass N increased under Jatropha plantation. The microbial quotient calculated as the percentage of MBC to soil organic carbon was lowest in summer and relatively constant in other two seasons. There was a significant increase in urease and dehydrogenase enzyme activities due to Jatropha plantation. The rate of decomposition of soil organic matter was faster under Jatropha cultivation compared to the control. The study revealed that irrespective of population density of Jatropha, there was improvement of soil health in terms of biochemical and microbial characteristics. These findings suggest that Jatropha can be used in the bunds of agricultural lands or in the degraded lands without any harmful effects on the soil microbial community.