Influence of organic and inorganic nutrient sources on root nodulation in mungbean (Vigna redita. L) under citrus (Citrus sps. L.) based Agri-horti systems

Abstract

The present investigation was undertaken to assess the influence of integrated nutrient management (INM) on root nodulation in mungbean (Vigna radiata L. Wilczek), a vital short-duration pulse crop grown extensively in India, under a citrus-based agri-horti system. Conducted during the Kharif season of 2023-24 at the College of Forestry, SHUATS, Prayagraj, this study aimed to determine the most effective combination of organic and inorganic nutrient sources for enhancing biological nitrogen fixation (BNF) through root nodulation. Thirteen nutrient management treatments were evaluated, incorporating different ratios of recommended dose of fertilizers (RDF) with organic amendments, including farmyard manure (FYM), vermicompost, press mud, and poultry manure, under two cropping conditions: agroforestry (AF) and open-field environments. The treatments showed significant variation in their influence on nodule formation at multiple growth stages — specifically at 20, 40, and 60 days after sowing (DAS). Among all, the treatment T9 (50% RDF + 50% poultry manure) consistently recorded the highest number of root nodules across all growth stages, under both AF and open-field settings. The enhancement in nodulation under T9 suggests a synergistic interaction between readily available nutrients from poultry manure and chemical fertilizers, which likely promoted better root development, rhizobial activity, and nodulation efficiency. Furthermore, the open-field condition exhibited slightly higher nodule counts as compared to agroforestry plots, possibly due to less competition for light, nutrients, and space, as well as better microclimatic conditions conducive to root and microbial growth. The integration of organic and inorganic nutrient sources demonstrated a substantial improvement in root nodulation, which is a proxy for enhanced nitrogen fixation. This indicates improved soil microbial activity, nutrient cycling, and soil health, critical factors for sustainable pulse production in agri-horti systems. These findings underscore the importance of INM in maintaining ecological sustainability while optimizing crop productivity, especially in diversified land-use systems like citrus-based agroforestry.