Micronutrients availability in soil-plant system as influenced by long-term integrated nutrient management under rice-wheat cropping

The present field study was conducted on loamy sand soil at the Research Farm, Department of Soil Science, Punjab Agricultural University, Ludhiana, India under a rice-wheat cropping system to study the influence of long-term integrated nutrient management (INM) involving chemical fertilizers and organic amendments viz. farmyard manure (FYM), green manure (GM), and straw incorporation (SI) on the availability of micronutrients (Zn, Fe, Mn and Cu), yield and uptake of nutrients by crop in rice-wheat system. The experiment comprised 9 treatment combinations comprising control, 50% RDF (Recommended dose of fertilizer)+FYM, 50% RDF + GM, 100% RDF, 100% RDF (P to wheat), 100% RDF + FYM, 100% RDF + GM, 100% RDF + SI and 150% RDF. Results revealed that continuous use of chemical fertilizers along with organic amendments in rice-wheat cropping system (RWCS) for 19 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. The transfer coefficient (TC) value did not vary significantly among the treatments except for Cu in both rice and wheat crop. Low soil recovery coefficient (SRC) values of Zn, Cu, Fe, and Mn indicated that long-term INM can meet their plant nutritional requirement in rice-wheat cropping system. This study concludes that long-term integration of FYM with NPK fertilizers has an edge over GM and SI in regulating the supply of micronutrients in soil-plant system and correcting the micronutrients deficiencies in rice-wheat cropping system.