APPLICATION OF AZOTOBACTER AND CHEMICAL FERTILIZER FOR IMPROVING GROUNDNUT YIELD IN INCEPTISOLS

Abstract

The overuse of chemical fertilizers poses environmental concerns and economic burdens, highlighting the need for sustainable alternatives. Azotobacter chroococcum (AC), a nitrogen-fixing bacterium, offers a promising strategy to enhance soil fertility while reducing chemical fertilizer dependency. This study aimed to evaluate the effects of AC liquid inoculant combined with reduced doses of NPK fertilizer on nitrogen availability, uptake, nodulation, growth, and yield of groundnut cultivated in Inceptisols. A field experiment was conducted using a Randomized Block Design (RBD) with eight treatment combinations of AC (2 and 3 L ha⁻¹) and NPK fertilizer (75, 150, and 300 kg ha⁻¹). Duncan’s Multiple Range Test (DMRT) was applied to assess treatment significance. Results showed that the combination of AC 2 L ha⁻¹ + NPK 300 kg ha⁻¹ increased soil NO₃⁻ levels by 37–53% compared to individual treatments. While plant height was unaffected, this combination significantly enhanced nitrogen uptake (up to 169 mg plant⁻¹). The highest shoot dry weight (44.27 g) was observed with AC 2 L ha⁻¹ + NPK 75 kg ha⁻¹. Notably, the combination of AC 2 L ha⁻¹ + NPK 150 kg ha⁻¹ produced the highest nodule dry weight (0.49 g) and yield (2.62 kg plot⁻¹), outperforming the full NPK dose (300 kg ha⁻¹). This study demonstrates that inoculation with A. chroococcum can enhance groundnut yield by up to 40% while enabling a 50% reduction in NPK fertilizer use, supporting more sustainable and cost-effective groundnut cultivation in Inceptisols.