Studies on Soil Phosphorus and Response of Sunflower to Applied Phosphorus on Some Soils of Haryana

An experiment was conducted in screenhouse on fourteen representative soils of Haryana to assess the suitability of some soil test methods of available P and different P fractions to predict the response of applied P and establish the critical limit of available P for sunflower (cv. Sungene 85). Multiple regression analysis showed that the variations in Olsen, Soltanpour and Schwab, AB-EDTA and Mehlich II P were accounted for by Al-P alone to the extent of 63.3, 67.9, 62.1 and 66.6 per cent, respectively. The critical limits of available P for sunflower were established as 18.2, 14.7, 20.1 and 16.2 kg ha⁻¹ for Soltanpour and Schwab, Olsen, AB-EDTA and modified Olsen soil tests, respectively.