Optimizing Row Arrangements in Maize-legume Intercropping Systems for Improved Soil Chemical and Microbial Properties in Alfisols of Eastern India

Abstract

A field experiment was conducted during the kharif season of 2022 at the ICAR-Indian Agricultural Research Institute, Jharkhand, to evaluate the effects of row arrangements in maize-based intercropping systems on soil properties in Eastern India. The randomised complete block experiment comprised nine treatments: sole maize, sole green gram, sole cowpea, and maize intercropped with green gram or cowpea under additive (1:2) and replacement (1:1 and 1:3) row arrangements, with five replications. Soil chemical properties, available nutrients, microbial biomass carbon (MBC), and dehydrogenase activity (DHA) were measured before and after harvest. Intercropping significantly improved soil fertility and biological activity compared with sole maize. Sole cowpea recorded the highest soil organic carbon (0.35%) and available nitrogen (158.7 kg ha⁻¹), phosphorus (6.45 kg ha⁻¹), potassium (125.3 kg ha⁻¹), and sulphur (20.2 kg ha⁻¹). Maize + cowpea under replacement stand II (1:3) recorded the highest soil pH (5.77), MBC (192.5 µg MBC g⁻¹ soil), and DHA (74.8 µg TPF g⁻¹ soil day⁻¹). Sole green gram recorded higher Zn, Fe, and Cu availability, whereas Mn availability was highest under sole cowpea. Sole maize recorded the lowest values. The improvements were attributed to biological nitrogen fixation, greater carbon inputs from roots and residues, and stimulated microbial processes. Overall, maize + cowpea under replacement stand II (1:3) was the most promising arrangement for improving soil quality and supporting sustainable maize-based production in the Eastern Plateau region of India.