Available macronutrient status of soils in various cropping systems of Thotapalli irrigation project ayacut of North coastal Andhra Pradesh

Assessment of macronutrient status of soils under five major cropping systems namely, rainfed mango/cashew orchards, rainfed groundnut/mesta cropping, irrigated rice followed by pulses, irrigated rice followed by maize and irrigated sugarcane in Thotapalli irrigation project ayacut area of north coastal Andhra Pradesh was carried out. A total of 125 random soil samples were collected from five different cropping systems from five villages of five Tehsils (mandals) namely, Cheeprupalli, Therlam (both tehsils from Vizianagarm district), Ranasthalam, Regidiamadalavalasa and Laveru (from Srikakulam district). The results of the study revealed that the soil organic carbon (OC), available nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) contents of the irrigated land was higher than adjacent rainfed upland, however the exchangeable calcium and magnesium were higher in rainfed uplands and relatively lower in irrigated cropping systems. Significant positive correlation was noticed between percent clay content with available N (r = 0.311**), available P2O5 (r = 0.232*), available K2O (r = 0.473**), available Sulphur (r = 0.249*), likewise organic carbon content also positively correlated with available N (r = 0.456**), available P2O5 (r = O.578**), available K2O (r = 0.211*) and available sulphur (r = 0.298*), while available phosphorous, was negatively correlated with soil pH, EC and CaCO3 contents. The variations in soil properties and nutrient status among cropping systems indicate need for employing integrated and soil test based nutrient management in sustainable manner.