Objective This study aims to investigate the impact of varying quantities of cotton straw returned to the soil on soil physical and chemical properties, cotton growth, and nitrogen fertilizer utilization rate, with the objective of providing a theoretical foundation for the rational use of straw resources and sustainable agricultural development.

Methods The experiment comprised four treatments: no straw return (N300), half-straw return (50%ST), full-straw return (100%ST), and double-straw return (200%ST).

Results In comparison to the N300 treatment, both 100%ST and 200%ST treatments significantly increased soil porosity, water content, organic matter, total nitrogen, available phosphorus, and available potassium content while notably reducing soil bulk density and pH value. As the quantity of straw returned to the soil increased, cotton plant height, Chlorophyll value, biomass production, seed cotton yield, nitrogen uptake showed an initial increase followed by a decrease. Relative to N300 treatment, the 100%ST treatment led to a 29.23% increase in total biomass production, a 15.38% increase in seed cotton yield, and a 45.89% improvement in nitrogen fertilizer utilization rate.

Conclusion Returning straw to the soil enhances its physical and chemical properties, augments soil nutrient levels, stimulates cotton growth and nutrient absorption, thereby elevating both cotton yield and nitrogen fertilizer utilization rate; among all treatments tested, full-straw return exhibits superior efficacy.