Nitrogen Management in Conservation Agriculture-based Cropping Systems

Abstract

The conversion of conventional agriculture to conservation agriculture (CA) affects the nitrogen (N) availability to crop plants. During the initial 2-3 years of CA-based management practices, more N immobilization is associated with the added crop residue retention and incorporation. This increase in N immobilization decreases the nitrogen use efficiency (NUE) in crops and cropping systems. After three years of organic residues buildup in soil under CA improved significantly the soil organic carbon (SOC) content and physical properties of soils; this improvement in physical and chemical soil health enhanced the NUE. This review article focuses on the impacts of CA principles namely, zero tillage (ZT), residue management, and crop diversification on N availability and its dynamics in the CA-based system, and their efficient N management strategies. Here, the impact of major N management tools and techniques, namely, chlorophyll meter, leaf color chart (LCC), GreenSeeker (GS), Nutrient Expert (NE), band placement, coated fertilizer application, fertigation etc. on the N availability and crop yields under the CA-based system is reviewed. It is concluded, that the adaptive N management with modern tools and techniques, and better agronomic management can enhance the N availability to crop plants in the CA-based systems, which can scale-up the areaunder CA. The judicious N management in CA can enhance: soil health by 50-100% depending on the residue load, crop productivity by 5-10%, NUE by 20-30%, and offer innumerable environmental benefits. The fertigation through subsurface drip irrigation saved about 40% of irrigation water and 20% of N in rice-wheat and maize-wheat cropping systems, respectively.