AUTHOR=Bhardwaj Ajay Kumar , Malik Kapil , Chejara Sukirtee , Rajwar Deepika , Narjary Bhaskar , Chandra Priyanka 

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

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1075011

DOI=10.3389/fpls.2022.1075011

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>The contrasting soil management in flooded-transplanted rice (<italic>Oryza sativa</italic>) and dry-tilled wheat (<italic>Triticum aestivum</italic>) 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 <italic>via</italic> changes in growing conditions and soil responses.</p></sec><sec><title>Materials and methods</title><p>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 <italic>via</italic> (i) including a legume crop (<italic>Vigna radiata</italic>) in the sequence and its biomass incorporation (LE), (ii) green manuring with <italic>Sesbania aculeata</italic> (GM), (iii) farmyard manure application (FYM), (iv) 1/3 wheat stubble <italic>in situ</italic> retention (WS), and (v) 1/3 rice stubble <italic>in situ</italic> retention.</p></sec><sec><title>Results and Discussion</title><p>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 <inline-formula><mml:math display="inline" id="im1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow><mml:mtext>NH</mml:mtext></mml:mrow><mml:mn>4</mml:mn><mml:mo>+</mml:mo></mml:msubsup><mml:mo>−</mml:mo><mml:mtext>N</mml:mtext></mml:mrow></mml:math></inline-formula> 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.</p></sec><sec><title>Conclusion</title><p>The results showed that these INM strategies can immensely benefit the rice-wheat system <italic>via</italic> improvement in biological health along with electrochemical changes for flooded rice, and labile-C-assisted improvement in soil conditions for wheat.</p></sec>