Soil and Water Conservation Measures Improve Soil Microbial Activity and Carbon Sequestration: A Study on High Density Cashew in West Coast Region of India

Abstract

A 13-years study was conducted from 2001 to 2013 to assess the effect of soil and water conservation (SWC) measures on soil microbial activity and carbon sequestration under high density (4 m × 4 m) cashew nut on 19% sloping land in the west coast region of India. Five SWC measures namely, continuous contour trenches + vegetative barrier (CCT+VB), staggered contour trenches + vegetative barrier (SCT+VB), crescent shape trench + vegetative barrier (CST+VB), vegetative barrier (VB), and control with no SWC measures were evaluated. The CCT+VB showed the best performance with significantly higher soil organic carbon (SOC) (1.41 to 2.02%) and SOC stock (SOCS) (44.9-57.8 Mg C ha-1) compared to control up to a depth of 0-0.9 m. The same treatment had significantly higher SOC sequestration rate (SOCSR) of 1.5 Mg C ha-1 yr-1 with significantly (p<0.05) lower SOCSR (0.9 Mg C ha-1 yr-1). Compared to other SWC measures and control, the highest average soil microbial biomass carbon (33.9 mg kg-1) and lowest metabolic quotient (qCO2) (0.52 mg CO2-C g-1 h-1) was obtained in CCT+VB indicating better soil biological activity and alleviation of environmental stress on microbes. The study indicated that SWC measures in cashew could be adopted as a strategy to improve microbial activity and soil carbon sequestration alongside advantages of reduced soil loss, runoff, and nutrient loss.