Phosphorus Status in Soils of Eastern Dry Zone, Karnataka, India

Abstract

Phosphorus (P) deficiency is second to nitrogen (N) and its deficiency is widespread. Soil based site specific P recommendation for sustainable crop productivity mainly relies on status, and availability of phosphorus. Representative soil samples (250) from different agro-ecological regions of Eastern Dry Zone (EDZ) of Karnataka were analysed for P status and randomly collected samples were analysed for P fractions. Results revealed that, AvP (Available phosphorus) ranged 12.74 to 94.70; 11.21 to 49.55; 10.70 to 98.32 and 10.22 to 64.05 kg ha-1 in Bangalore Rural, Tumkur, Kolar and Chikkaballapura districts, respectively. Among P fractions, total-P (range: 1218.90-3383.08 mg kg-1), organic-P (range: 624.95-3461.85 mg kg-1), reductant soluble-P (range: 132.56-364.55 mg kg-1), occluded-P (range: 7.38-49.69 mg kg-1) and Ca-P (range: 6.21-38.76 mg kg-1) content increased as the P fertility of soil increased and decreasing trend was recorded for Saloid-P (range: 38.31-63.23 mg kg-1), Al-P (range: 61.49-164.31 mg kg-1) and Fe-P (range: 35.23- 109.87 mg kg-1) fractions. Total account of phosphorus is necessary tool for soil based P recommendation under both irrigated and rainfed agriculture.