Validation of Bio-stimulant Seed Treatment, Soil and Foliar Application of Nano DAP, Urea, K, Zn, Cu, B Formulations in a Flood Affected Bt Hybrid Cotton

Abstract

Bt hybrid cotton faced 30-60% excess rains in 70% years since its release and four times water logging in 2021, in a deep and shallow Vertisols with Calcareous sub-strata forced to confirm all the agronomical advices to it. Water logging reduced the biomass, boll number and cotton lint yields to more than 50 percent except the fibre quality. Prevailing runoff and leaching losses of  soil applied fertilizer nutrients were accumulated at downstream, which increased the soil test values. Water logging caused reduction of index leaf N, P, K, Zn and B nutrient status below the threshold levels. Soil application of Zn and B once in three years alone or seed treatment formulation with N, P, K Bio-inoculant consortia along with nano ZnO  0.0004% + CuO 0.0001% as  seed treatment  at the time of sowing with or without foliar application of  NPK WSF 2%,  Zn 0.5%, B 0.3% or 0.04% nano formulations of DAP alternated with Urea alongwith ZnO and K with common insecticides and fungicidal sprays significantly improved index leaf nutrient status, biomass, boll number and seed cotton yields in both the soils.   Validation of these results in station trials during 2022-24 found the need for atleast two foliar application of nano nutrients each DAP + ZnO + K  followed by nano Urea+ ZnO + K 0.004% alternately at the mid and end September and October months.  This increased N, P, K, Zn, B content in index leaves and seeds with additional cotton lint yield 209 kg ha-1 worth 174 US $ ha-1 net profit by soil application ZnSO4 20 and  Borox 5  kg ha-1  yr -3   in Vertisols and three times foliar application at squaring, flowering and boll formation stage with nano ZnO 0.004%+ B 0.3% or ZnSO4 0.36% +Boron 0.2% in Vertisols with calcareous sub-strata.