Effect of Different Levels of Phosphorus, Phosphorus Solubilising Bacteria and Farmyard Manure on Nutrient Content and Uptake by Bt-Cotton

Aim: To determine the effect of integrated use of inorganic phosphorus along with phosphorus solubilising bacteria and farmyard manure on nutrient Content and uptake in Bt-Cotton.

Study Design: The experiment was laid out in randomized block design with three replications.

Place of Study: At College Farm, Agricultural College, Bapatla, Guntur district.

Methodology: After the preliminary layout, the Tulasi-BG II hybrid of cotton was used as a test crop, with a spacing of 90 cm x 60 cm in the experimental site. Plant samples were collected at 45, 90 DAS, and harvest. Plant samples were shade dried and kept in hot air oven at 75°C until a constant weight was obtained. Samples were powdered and then analysed using standard chemical procedures.

Results: The uptake of macronutrients viz., N, P, and K was markedly influenced by the treatments with maximum values recorded by the treatment that received 60 kg P2O5 ha-1 + FYM + PSB. Their uptake significantly differed with increase in dose of phosphorus applied at all growth stages. Combined use of 60 kg P2O5 ha-1 + FYM + PSB resulted in a significant increase in uptake of all micronutrients (Zn, Cu, Mn, and Fe) at all stages except Cu at 90 DAS.

Conclusion: Application of phosphorus combined with FYM and PSB not only reduce inorganic phosphorus fertilization but also enhance the uptake of nutrients and plant nutrient content by providing favourable conditions for plant growth. Application of 30 kg P2O5 ha-1+ PSB + FYM was found to be on a par with addition of only 60 kg ha-1P2O5. Hence the P dose can be reduced to half by integrating with PSB and FYM.