Influence of Enzyme Activities on Stable Isotopes (δ13C and δ15N) and Nutrient Cycles in Semi-arid Agricultural soils

Abstract

The purpose of this study was to investigate the impacts of enzyme activities on stable isotopes (ä13C and ä15N) and nutrient cycles in Indian semi-arid agricultural soils. Three composite soil samples were collected from each of the organic management (ORG), inorganic management (IM), integrated crop management (ICM) and precision farming (PF) experimental plots during September 2017 to June 2019. Organically manage (ORG) soils had higher ä15N in both the analyzed years (2017-18 and 2018-19), compared to ICM, IM and PF. In contrast, PF soils had higher ä13C in both the years, compared to IM, ICM and ORG. Soils from ORG had significantly higher amount of organic carbon, total C, total nitrogen (N), total sulphur (S), available N, extractable phosphorus (P), soil organic carbon stock, exchangeable K and enzyme activities compared to IM, ICM and PF. Urease, â–glucosidase, acid phosphatase, alkaline phosphatase, invertase, cellulase and dehydrogenase activities were significantly influenced ä15N and ä13C in agricultural soils. Our results suggested that ORG had improved the soil enzyme activities, plant available nutrients. Stable ä13C and ä15N isotopes were good indicators for monitor the soil health and biogeochemical cycles in Indian semi-arid agricultural soils.