Effects of Pisha sandstone application rate and microbial agents on soil nutrient dynamics and microbial characteristics in sandy soil.

Sandy soils are characterized by rapid water loss, low nutrient availability, poor vegetation establishment, and high susceptibility to wind erosion. Although Pisha sandstone has been recognized as an effective amendment to improve the physical stability of sandy soils, its role in enhancing soil fertility and biological functioning-particularly when combined with microbial inoculants-remains poorly understood. This gap limits the development of integrated restoration strategies for desertified regions. To address it, a randomized field experiment was conducted in the Hobq Desert, China. Pisha sandstone was incorporated into native sandy soil at five volumetric ratios (0%, 30%, 50%, 80%, and 100%), with or without microbial inoculants. Indicators measured included soil organic carbon, available nitrogen and phosphorus, microbial populations (bacteria, fungi, actinomycetes), enzyme activities (urease, invertase, acid phosphatase), and licorice growth. Results showed that Pisha sandstone significantly improved soil nutrients and enzyme activities, with the greatest effect at the 50% mixing ratio. Microbial inoculation further enhanced these improvements, producing 1.5- to 2.0-fold increases in microbial populations and enzyme activities relative to uninoculated controls. The best licorice growth occurred in the 50% sandstone plus inoculant treatment, corresponding to the highest fertility and microbial activity. Correlation analysis revealed strong positive relationships among soil organic carbon, available nutrients, microbial densities, enzyme activities, and plant growth. These findings demonstrate that the co-application of Pisha sandstone and microbial inoculants effectively enhances the fertility and biological functioning of sandy soils, filling a key knowledge gap and offering a practical strategy for ecological restoration.