Effects of rainwater harvesting on herbage diversity and productivity in degraded Aravalli hills in western India

Abstract

Over-exploitation and rural growth have severely damaged native vegetations of Aravalli hills in Rajasthan, India. This study was conducted to evaluate the effects of different restoration practices (i.e., rainwater harvesting (RWH) and planting of tree seedlings) on improvement in soil water and nutrients and growth and biomass of herbaceous vegetation. Contour trench (CT), Gradonie (G), Box trench (BT), V-ditch (VD) and a control were imposed on 75 plots (each of 700 m2) in natural slope gradient defined as 20% slopes in 2005. Each plot had three micro-sites of 1-m2 at up (USP), middle (MSP) and lower (LSP) part of the plot for observation in 2008. The existed gradient (due to soil texture and topographic features) of soil pH, EC, SOC, NH4-N, NO3-N and PO4-P in June 2005 between >20% to 20% slopes, compared with <10% slope. The highest diversity in CT treatment was related to herbage biomass, which was enhanced further by highest concentrations of SOC and PO4-P. Further, CT treatment was found to be the best treatment in minimizing biomass variance in different slopes. Conclusively, soil texture and topographic features controlled soil water and nutrients availability. Rainwater harvesting techniques increased soil water storage and nutrient retention and also enhanced vegetation status and biomass by minimizing the effects of hillslopes. Thus depending upon the site conditions, suitable RWH technique could be adopted to increase herbage biomass while rehabilitating the degraded hills.