Growth parameters, nutrient uptake and soil fertility under wheat (Triticum aestivum) as influenced by levels of phosphorus and phosphate-solubilizing micro-organisms

A field experiment was conducted during the winter season of 1998–99 and 1999–2000, to study the effect of phosphorus levels and phosphate-solubilizing micro-organisms on growth parameters, nutrient uptake and soil fertility under wheat (Triticum aestivum L emend. Fiori & Paol.) crop. The treatments consisted of 4 levels of phosphorus (0, 30, 60 and 90 kg P₂O₅/ha) and of phosphate-solubilizing micro-organisms (no inoculation, Pseudomonas striata, Aspergillus awamori and Pseudomonas striata + Aspergillus awamori). The growth parameters like dry-matter production, root dry weight yield and nitrogen and phosphorus uptake were significantly improved with application of 60 kg P₂O₅/ha. Similarly, all these parameters were significantly increased owing to combined inoculation with Pseudomonas striata + Aspergillus awamoriover individual and no inoculation. Nitrogen and phosphorus uptake of wheat crop increased significantly only up to 60 kg P₂O₅/ha. Though increasing levels of phosphorus (up to 90 kg/ha) left the soil rich significantly in respect of post-harvest status of phosphorus. However, successive higher levels of phosphorus declined the available soil nitrogen status, though significant depletion was observed only up to 60 kg P₂O₅/ha. Inoculation with phosphate-solubilizing micro-organisms also reduced the post-harvest status of available soil nitrogen and phosphorus pool. Highest deciine was observed due to combined inoculation with Pseudomonas striata + Aspergillus awamori.