Assessment of soil fertility status for sustainable crop production in a watershed of Semi-Arid Tropics in Southern India

Assessment of the soil fertility status in a watershed was carried out for efficient soil management and cropping systems for sustainable yields. Composite soil samples in surface soil (0–15 cm) from 253 locations were collected from the watershed by considering their physiographic units. Samples were analyzed for pH, electrical conductivity, organic carbon, available N, P₂ O₅ and K₂ O and micronutrients i.e. Zn, Cu, Fe and Mn. Results revealed that Nutrient Index of organic carbon (g kg⁻¹), available N (kg ha⁻¹) and zinc (mg kg⁻¹) were very low and nutrient index was medium for available P₂ O₅ and K₂ O in the watershed. The extent of deficiency of organic carbon, nitrogen and zinc was 63%, 86% and 58%, respectively. The study indicated that the low organic carbon and nitrogen in soils were attributed to low application rates of organic material, high temperature and low rate of application of N fertilizers, especially in the rainfed areas. To build up organic matter and native nitrogen and maintain nutrient balance in the soil, farmers are advised to adopt FYM and ZnSO₄ application, crop rotation of groundnut with bajra, intercropping of groundnut with redgram in the rainfed areas, whereas in irrigated areas, crop rotation along with application of farm yard manure, SSP and ZnSO₄ can enhance crop production and soil fertility.