Effects of fly ash with different mesh sizes on the physicochemical properties of aeolian sandy soil and the growth of Pakchoi

To rationalize the application of fly ash for aeolian sandy soil improvement, this study used 0-180 mesh, 180-325 mesh, and >325 mesh fly ash as amendments in a pot experiment, determining soil physicochemical properties and pakchoi growth indices to evaluate improvement effects. All fly ash treatments reduced soil bulk density. 180-325 mesh fly ash increased soil permeability coefficient, while >325 mesh fly ash performed best in enhancing water absorption and holding capacity but significantly elevated soil pH, making it unsuitable for large-scale application. 180-325 mesh fly ash mainly improved available nitrogen and total phosphorus, while >325 mesh fly ash enhanced available phosphorus and total potassium. All treatments promoted pakchoi growth, with the most significant effect observed at 10% 180-325 mesh fly ash application (p < 0.01).