Micronutrients and field crop production in India: A review

The crucial role played by micronutrients in enhancing food/crop production in India is now a well recognized fact. Widespread micronutrient deficiencies in crops, now being recorded all over the country, have resulted in severe losses in yield and nutritional quality. It is estimated that nearly half of the soils on which food crops are grown, are deficient in zinc (Zn). Next to Zn, boron (B) (33%) and iron (Fe) (15%) deficiencies are also limiting the crop production to a large extent. Extensive manganese (Mn) (6%) deficiency is now being manifested in the most widely spread ‘rice-wheat’ cropping system in northern India, particularly in Punjab (18%) and Haryana (12%). Intensive agriculture in north India and soils rich in organic matter in southern part of the country also exhibited copper (Cu) (8%) deficiency. Extensive micronutrient deficiencies lead to decline in factor productivity even with balanced NPK fertilization. Although the crop response to micronutrients application varies with soil type, crops and genotype, agro-climatic conditions and severity of deficiency, an enormous response to micronutrient fertilization has been reported in a wide variety of crops including horticultural crops across the country. It has been estimated that proper Zn management contributes about 18.4 million tonnes (with economic value of 2,11,619 million) for major food grain crops, and it may further enhance the contribution up to 24.85 million tonnes (with an economic value of 2,32,119 million) if sugarcane, cotton and potato are included. The contribution of B is estimated about 4.02 million tonnes assuming 10% of cultivated area is receiving B fertilization. Number of crops also exhibited a sizeable response to Mn, Cu and Fe application under deficient situations. Oilseeds and pulses productivity could be enhanced substantially by Mo application as evidenced from scattered studies in Andhra Pradesh, Madhya Pradesh and Maharashtra. Micronutrient nutrition in relation to crops, optimization of doses, sources and methods of application; nutrient interactions, behaviour in cropping system, delineation of deficient areas, identification and cataloguing of micronutrient disorders, development of micronutrients fertilizers have been researched extensively under aegis of All India Coordinated Research Project (AICRP) on micronutrients. Micronutrient deficiencies/malnutrition in animal and human being are becoming increasingly important globally including India. The crops grown in micronutrient deficient soils contain low level of micronutrients to meet the demand of animal and human being. Thus, research on enriching the food grains and fodder with micronutrients through agronomic and genetic biofortification and their bioavailability in animal and human should be taken up in soil-plant animal/human continuum. Micronutrient research provides invaluable information highly useful in sustaining food security and wellbeing of animals and human being without harming the environment.