Soil management for Sustained and Higher Productivity in the Adarsha Watershed

Kothapally watershed is a typical representative of rain-fed (800 mm rainfall) semi-arid tropics (SAT) with varying soil depth in the watershed and widespread soil degradation as the major challenge coupled with low crop yields and family incomes. Before the onset of initiative during 1999, soil health mapping and baseline surveys showed varying soil depth in fields at different topo-sequence, macro-/micronutrient deficiencies along with low soil carbon (C) levels and heavy soil loss through erosion that compromised with crop production in the watershed. Inappropriate fertilizer management decisions leading to negative budget for primary nutrients in major crops/cropping systems highlighted suboptimal fertilizer use. Unawareness about micro-/secondary nutrient deficiencies like sulphur (S), boron (B) and zinc (Zn) and lack of addition of such fertilizers contributed to low crop yields and declining fertilizer and water use efficiency. Farmers participatory trials highlighted yield loss of 13–39% in crops like sorghum and maize in the absence of deficient micro-/secondary nutrient fertilizers. Recycling of on-farm wastes through vermicomposting and biomass generation using N-rich Gliricidia on farm boundaries were promoted for fertilizer savings and crop yield benefit alongside soil carbon building for developing resilience. The impact of integrated soil health management practices cumulatively observed over 13 years was demonstrated during 2012 soil health mapping that showed improved mean level of soil organic C; available nutrients, viz. phosphorus (P), B, Zn and S; and significantly reduced number of fields with low nutrient/C levels. Along with yield advantage, soil loss was significantly reduced from 3.48 t ha in untreated area to 1.62 t ha in treated watershed area