Soil microbial population dynamics as affected by organic residues and nitrogen gradients in wheat production

A two-year field experiment (Rabi 2023–24 and 2024–25) was undertaken at RCA, Udaipur to quantify the effects of crop residue incorporation and nitrogen levels on soil microbial populations following wheat (Triticum aestivum L.) harvest. The split-plot design comprised five crop residues (C₀–C₄) and four nitrogen levels (N₀–N₃), replicated thrice. Soil microbial populations-bacteria (10⁶ cfu g⁻¹), fungi (10⁴ cfu g⁻¹) and actinomycetes (10⁵ cfu g⁻¹)-responded significantly to both main factors in individual years and pooled analysis. Cluster bean stover @ 5 t ha⁻¹ (C₃) recorded the highest bacterial (66.02), fungal (20.54) and actinomycetes (14.98) counts, significantly surpassing the control. Among nitrogen treatments, 100% RDN (N₃) yielded the maximum microbial populations (bacteria 65.69, fungi 20.39, actinomycetes 14.89), indicating improved substrate availability and nutrient-driven microbial proliferation. Control plots consistently exhibited the lowest values. Interaction effects (C × N) remained non-significant, suggesting independent contributions of residue quality and nitrogen supply. The results demonstrate that integrating nutrient-rich crop residues with optimal nitrogen fertilization substantially improves soil microbial communities, which are essential indicators of soil fertility, nutrient cycling and long-term sustainability of wheat-based cropping systems.