Department of Soil Science and Water Management, Himachal Pradesh Agricultural University, Palampur, Himachal Pradesh
*A part of Ph. D. thesis submitted by the first author to Himachal Pradesh Agricultural University, Palampur, Himachal Pradesh
Response of 2 leguminous (peas and berseem) and 2 non-leguminous (wheat and potato) crops to ground Mussoorie rock phosphate alone and along with superphosphate, farmyard manure and low grade pyrites or its partial acidulation with H3PO4 @10% in an acidic soil (pH 5.7) is reported. The yield and phosphorus uptake in all the crops, except berseem, increased significantly with rock phosphate application, but it proved only 41.6% as effective as superphosphate for potatoes, 32.7% for peas, 23.7% for wheat and 3.2% for berseem. The effectiveness of rock phosphate, however, increased greatly when it was used in conjunction with small amounts of superphosphate or farmyard manure or was partially acidulated with H3PO4, the effect of later treatment being highest and comparable to an equal dote of superphosphate both on the basis of direct and residual effect on crop yields and phosphorus uptake. The results, however, envisage the use of low grade pyrites to be undesirable in acid soils with pH less than 6.0. All the phosphatic treatments exhibited considerable residual effect which proportionately higher than their direct effect. The residual effect of rock phosphate (alone) was found to be 48.7 to 74.1% as effective as that of superphosphate for corn and it was highest under berseem and lowest under potatoes.
Rock phosphate, direct and residual effect, pyrites, acid soil, acidulation
