Applying bio-organic fertilizer improved saline alkaline soil properties and cotton yield in Xinjiang

Bio-organic fertilizers have demonstrated significant potential in enhancing saline-alkali soil properties, boosting crop yield, and reducing chemical fertilizer dependency. However, the extent of improvement and optimal application rates for varying saline-alkali soil conditions remain unclear. We conducted a 2-year field experiment (2022-2023) to evaluate the effects of different bio-organic fertilizer application rates on soil properties, nutrient availability, and cotton yield across three saline-alkali cotton fields with varying salinity levels 4.58, 9.07, and 12.76 g·kg⁻¹ (T1-T3). Four treatments were implemented, involving chemical fertilizer reductions of 0% (CK), 20% (F1), 40% (F2), and 60% (F3). Results indicated that, compared to CK, bio-organic fertilizer application reduced soil bulk density, salinity, and pH by an average of 15.84%, 53.86%, and 7.5%, respectively. Concurrently, soil moisture content, organic matter, nitrogen, phosphorus, potassium, and cotton yield increased by 36.72%, 58.4%, 59.4%, 77.9%, 88.7%, and 50.32%, respectively. Notably, the improvements in soil properties and cotton yield were more pronounced in 2023 compared to 2022. Principal component analysis revealed that a 60% bio-organic fertilizer application rate was optimal for mild, moderate, and severely salinized cotton fields. These findings provide a scientific basis for reducing chemical fertilizer use while improving the productivity and sustainability of saline-alkali soils.