Soil microbiological and biochemical changes as a consequence of land management and water erosion in a semiarid environment

Abstract

Three sites were selected for the present study: native forest (FR), anagricultural land subjected to minimum water erosion by terracing farming (ARMN), and an agricultural land subjected to moderate water erosion without terracing farming (ARMD). Conversion of forest to agricultural land significantly affected soil physicochemical properties.The lowest contents of both humic and fulvic acids were registered in the ARMD site, while the highest was observed in FR. The site withmoderate water erosion showed a decrease of total microbial activityas estimated by fluorescein diacetate activity (FDA), but an increase ofdehydrogenase activity. Both C-related enzyme activities glucuronidaseand glucosidase as estimated by fluorogenic methylumbelliferil (MUF)-substrates were also reduced in ARMD, with moderate values in ARMNsite, and high values in FR. Our study revealed that ARMD had the meanmicrobial biomass estimated by phospholipid fatty acid (PLFA) profiles.Furthermore, the ARMD site showed the highest Gram-positive to Gramnegativeratio, suggesting that moderate water erosion may also affectsoil microbial community structure. The results of the present researchhave important implications for the study of deforestation under sitessubjected to water erosion, which is one of the most significant ecologicalchanges facing in central Argentina and the world.