Abstract

A field experiment was conducted for 2 years (2013-14 and 2014-15) during winter (Rabi) season at Research Farm of ICAR-Indian Agricultural Research Institute, New Delhi, India with an objective to study the significance of two microbial consortia inoculations, zinc (Zn) fertilization (5 kg Zn ha^-1 through ZnSO₄∙7H₂O soil application in each crop at sowing) and three rates of nitrogen (N) and phosphorus (P) fertilization on potassium (K) concentration, uptake and as well as ammonium acetate (NH₄OAC)-extractable K content in soil at different growth stages in wheat. The microbial consortia used were Anabaena sp. (CR1) + Providencia sp. (PR3) and Anabaena-Pseudomonas biofilmed bio-fertilizer; while rate of fertilization were 0, 75% and 100% of recommended rate of nutrients (RDN) (120 kg N ha^-1 and 25.8 kg P ha^-1). The concentration and uptake of K was significantly higher in zero tillage wheat (ZTW) than conventional drill-sown wheat (CDW) and system of wheat intensification (SWI) at all observations except at 30 days after sowing. The application of 100% RDN and Zn fertilization have significant and positive effect on K uptake. The microbial consortia increase K concentration and uptake by 0.09-0.12 mg kg^-1 and 9.9-12.7 kg ha^-1 in straw and 0.08-0.11 mg kg^-1 and 3.8-5.6 kg ha^-1 in grain. The soil ammonium acetate (NH₄OAC)-extractable K decreased by 87-108 kg ha^-1 and 19-44 kg ha^-1 in first and second year, respectively over initial soil K even after application of recommended rate of K (49.8 kg ha^-1). Our study concludes the significant increase in K uptake due to ZTW and use of microbial consortia and there is the need for redeciding K fertilization in wheat for sustained productivity.

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