Journal of the Indian Society of Soil Science

A field experiment was conducted during 1993–94 On a Vertisol with two sources of phosphatic fertilizers viz. single superphosphate (SSP) and rock phosphate (RP) with or without different strains of phosphate solubilizing microorganisms on rainfed soybean. Results showed that the application of SSP @ 60 kg P₂O₄ ha⁻¹ was superior, but it was at par with 30 kg P₂O₅ ha⁻¹ as SSP along with Pseudomonas striata (single inoculant) or Pseudomonas striata +Aspergillus mamori (composite inoculant) with regard to seed and straw yield, and N, P and K uptake (seed + straw). Similarly, application of rock phosphate @30 kg P₂O₅ ha⁻¹ with single or composite inoculants of phosphate solubilizers was also equivalel]l to SSP @30 kg P₂O₅ ha⁻¹ (alone) with regard to all the recorded parameters. Among the inoculants, composite inoculant of P. striata and A. awamori was proved superior than single inoculant of P. striata. Maximum phosphorus use efficiency of 21.6 kg ha⁻¹ was noted with the use of SSP @ 30 kg P,0, ha⁻¹ + composite inoculant. Fertility status after soybean harvest indicate that available soil III, was improved from 7.7–30.0 kg N ha⁻¹ whereas P and K got depleted over the initial values. Significant correlations between shedded residues and residual soil N, available N with total Nand P uptake were also observed..