Eco-friendly nitrogen fertilizers for sustainable agriculture

Abstract

Agriculture meets two great sustainability challenges: first one is ability to provide nutrition to the world population and another one is to improve ecosystem services to maintain clean air, water, and other benefits to humanity. Appropriate nitrogen management is one of the primary challenges in agricultural production. Its application to agricultural and horticultural crops in conventional chemical forms causes significant increase in crop yield. Generally, farmers apply overdoses of chemical fertilizers in their agriculture field in order to maximize the crop productivity and about 50-70% of the applied conventional chemical fertilizers get lost in the environment due to leaching, runoff, emissions and volatilization in soil, water, and air. It causes agronomical, economic, environmental concerns, and health threats. Organic manures (OM) and bio-fertilizers are considered as possible alternatives for eco-friendly, economic, and organic agriculture, however, due to problems of limited availability and bulk transport of manures and low efficacy of OM and microbial bio-fertilizers, the use of conventional chemical fertilizers is still in practice in main stream agriculture. Slow (controlled) release fertilizers (SRFs) that release the nutrients slowly or synchronized with the growth rate and physiological need of plants increase the nutrient recovery to a great extent and minimize the nutrient losses and the resultant environmental hazards caused by the excessive use of soluble chemical fertilizers. The SRFs are new type of eco-friendly plant nutrient providers that can be used as a feasible alternative to the chemical fertilizers. However, the cost effectiveness of the commercial SRF formulations and lack of awareness on ill effects of chemical fertilizers are major limitations for replacing the conventional chemical fertilizers by slow release fertilizers and other customized fertilizers especially in the developing world. We have developed organic matrix based slow release fertilizers using biodegradable non-toxic and locally available agro-waste/ agroproducts which are low cost, highly efficient, and eco-friendly that enhance crop productivity as well as soil fertility in the applied fields. It is evident from the earlier reports and our own work that during consistent supply of exogenous N either through the split doses or through the SRFs, accumulation of inorganic N occurs in aerial sinks of plants, i.e., mature leaves and grains increases. A manipulation of source-sink relationship, transport and remobilization of the nutrients, and enhanced assimilation of accumulated inorganic N in plants during reproductive phases, in addition to application of the customized fertilizers, will lead to alleviate yield and improved food quality. Present chapter critically review the potentiality of N based SRFs and genetic manipulations for enhanced NUE for sustainable plant productivity as a viable alternative to the green revolution based nutritional packages.