Effect of hybrids and fertilizer levels on urease and dehydrogenase activity in cotton soils under high density planting system in medium black soils

Soil enzymatic activity plays a crucial role in nutrient transformation and availability in agricultural systems. This study evaluates the impact of cotton hybrids and different fertilizer regimes on urease and dehydrogenase activity in soil during the 2021 and 2022 cotton-growing seasons. Among the fertilizer levels, the highest urease activity was observed in the STCR-based fertilizer application targeting a yield of 32 q ha⁻¹, with values of 88.671 µg NH₄⁺ g⁻¹ 2 hrs⁻¹ in 2021 and 96.612 µg NH₄⁺ g⁻¹ 2 hrs⁻¹ in 2022 at flowering. Similarly, dehydrogenase activity was highest under the same fertilizer regime, reaching 7.513 µg TPF g⁻¹ day⁻¹ in 2021 and 8.384 µg TPF g⁻¹ day⁻¹ in 2022 at flowering. Among the hybrids, NCS-2778 exhibited superior enzymatic activity compared to RCH-665, indicating its better suitability for enhancing soil microbial function. The results underscore the importance of optimized fertilization strategies for maintaining soil microbial activity and nitrogen transformation efficiency.