Critical Limit of Available Phosphorus for Soybean in Vertisols of Chambal Command Area of Rajasthan

Field trials on soybean with three phosphate levels were conducted on farmers fields at twenty six locations on Vertisols of Chambal Command Area of Rajasthan to evaluate the critical limit of available phosphorus. A significant and positive correlation was observed between soil phosphorus extracted by Olsen's method and Bray's per cent yield. The critical limit of Olsen's P₂O₅ determined by scatter diagram as well as statistical procedure was 37.5 kg ha_-1 below which pofitable responses to phosphate application can be expectedfrom soybean.