Integration of organics in nutrient management for rice-wheat system improves nitrogen use efficiency via favorable soil biological and electrochemical responses

Ajay Kumar Bhardwaj; Kapil Malik; Sukirtee Chejara; Deepika Rajwar; Bhaskar Narjary; Priyanka Chandra

doi:10.3389/fpls.2022.1075011

Integration of organics in nutrient management for rice-wheat system improves nitrogen use efficiency via favorable soil biological and electrochemical responses

Front Plant Sci. 2023 Jan 5:13:1075011. doi: 10.3389/fpls.2022.1075011. eCollection 2022.

Authors

Ajay Kumar Bhardwaj¹, Kapil Malik¹, Sukirtee Chejara¹, Deepika Rajwar¹, Bhaskar Narjary¹, Priyanka Chandra¹

Affiliation

¹ Division of Soil and Crop Management, Central Soil Salinity Research Institute, Karnal, HR, India.

Abstract

Introduction: The contrasting soil management in flooded-transplanted rice (Oryza sativa) and dry-tilled wheat (Triticum aestivum) poses a challenge for improving low nitrogen use efficiency (NUE) of the rice-wheat system. Integration of organics in nutrient management can bring in changes favoring efficient N uptake via changes in growing conditions and soil responses.

Materials and methods: This study reported the results of a 15-year-long experiment on integrated nutrient management (INM) systems for rice-wheat cropping. The INM included substituting ~50% of chemical fertilizers via (i) including a legume crop (Vigna radiata) in the sequence and its biomass incorporation (LE), (ii) green manuring with Sesbania aculeata (GM), (iii) farmyard manure application (FYM), (iv) 1/3 wheat stubble in situ retention (WS), and (v) 1/3 rice stubble in situ retention.

Results and discussion: The INM strategies resulted in improved NUE compared to 100% chemical fertilizers (F). The INM had significantly higher net N mineralization and improved biological activity aligning with the NUE trends. The reductions in redox potential (Eh) and pH during rice season improved NUE under integrated management. Highly reduced conditions favored N mineralization and plant availability in form of ${NH}_{4}^{+} - N$ resulting in enhanced uptake efficiency, in rice crop. The soil organic carbon (C) significantly increased in INM, and an effect of the active C fractions was evident on the NUE of the wheat crop.

Conclusion: The results showed that these INM strategies can immensely benefit the rice-wheat system via improvement in biological health along with electrochemical changes for flooded rice, and labile-C-assisted improvement in soil conditions for wheat.

Keywords: Nitrogen use efficiency; Sustainable nitrogen management index; crop residue; green manure; legumes; redox potential; soil carbon.