Response of soybean (Glycine max) to phosphorus with or without biofertilizers

A field experiment was conducted in kharif 2008 and 2009 to assess the effect of phosphorus fertilization in conjunction with biofertilizers, viz. Phosphorus solubilizing bacteria (PSB) i.e.Pseudomonas striata and vesicular arbuscular mycorrhizae (VAM) on soybean (Glycine max (L.) Merrill). The 10 treatments comprised of combinations of 50% and 100% of recommended dose of P, 2 sources of P, viz. [di-ammonium phosphate (DAP) and rock phosphate (RP) in conjunction with PSB and VAM, one absolute control and another control (no P) with PSB+VAM were tried in a randomized block design and were replicated thrice. Maximum yield (1.56 t/ha) was obtained with RP application at recommended dose along with biofertilizers. Yield attributes and yield were at par when full dose of P was applied in conjunction with biofertilizers irrespective of the source of P fertilization indicating increased efficiency of RP when supplied in conjunction with biofertilizers even in neutral soils. Soil application of biofertilizers showed the highest protein content in soybean seed (38.89%), which signified the fact that qualitative improvement is possible with combined application of fertilizers and biofertilizers. Higher nutrient uptake by the crop was also recorded in biofertilizer applied plots. Maximum net returns (15,953) was obtained with full dose of DAP with biofertilizers.