Micronutrient availability in soil–plant system as influenced by 47 years long application of chemical fertilizers, organics and lime under maize–wheat cropping in an acid Alfisol

The present field study was conducted on silty loam soil at ‘long-term fertilizer experiment’ Research Farm, Department of Soil Science, CSK HPKV, Palampur (HP), India under a maize–wheat cropping to study the influence of long-term integrated nutrient management (INM) involving chemical fertilizers, organics and lime on the availability of micronutrients (Zn, Fe, Mn and Cu) in soil, yield and uptake of these micronutrients by maize and wheat. Ten fertilizer treatments comprising different amounts of NPK fertilizers, farmyard manure (FYM) and lime, and Natural Farming and control, were replicated thrice in a randomized block design. Soil availability of micronutrients and their plant concentrations were estimated in grain and stover/straw of both the crops. Soil recovery coefficient (SRC) was calculated to find out micronutrients availability in relation to their plant uptake. The continuous use of chemical fertilizers along with organics and lime in maize–wheat cropping system for 47 years has resulted to an increase in the availability of micronutrient cations (Zn, Fe, Mn and Cu). Build-up of soil organic carbon and decrease in soil pH has resulted in the increase of bio-available forms of micronutrients. Low SRC values of Zn, Cu, Fe, and Mn indicated that long-term INM can meet their plant nutritional requirement in maize–wheat cropping system. This study concluded that long-term integration of FYM with NPK fertilizers has an edge over chemical fertilizers alone in regulating the supply of micronutrients in soil–plant system and correcting the micronutrients deficiencies in maize–wheat cropping system.