Abstract: 【Objective】To understand the characteristics of coal slime and its impact on the physical properties of sandy soil,and to explore the utilization of coal slime in agriculture.【Methods】On the basis of examining the features of coal slime,using unplanted simulation culture experiments with varying application rates of 0（CK）,15 t/hm²（L-1）,45 t/hm²（L-2）,75 t/hm²（L-3） and 135 t/hm²（L-4）,the changes in physical properties of sandy soil following the application of coal slime were examined.【Results】The content of cadmium,mercury,lead,chromium,and arsenic in coal slime was low,accounting for only 0.32% to 11.55% of the standard values,with up to 73.43% of clay and powder particles. It was rich in plant growth promoting beneficial elements,SiO₂ and Al₂O₃（with a relative content of 71.17%）,contained essential macroelements K₂O and P₂O₅（with a relative content of 2.02%）,essential medium elements CaO,SO₃,MgO（with a relative content of 18.00%）,and essential trace elements Fe₂O₃,MnO,ZnO,CuO,NiO（with a relative content of 6.73%）,all of which were beneficial for plant growth. At 240.5 g/kg,the content of total organic carbon was high. The ratio of light and heavy fraction organic carbon was around 1 ∶ 4. Applying coal slime optimized the particle size composition of sandy soil and increased the content of clay particles（d<2 μm）and powder particles（2~50 μm）with increases of 1.01-4.95 percentage points and 0.21-0.71 percentage points respectively. The proportion of capillary pores in sandy soil increased by 2.29% to 16.46%. The non capillary pore ratio of sandy soil reduced by 1.12% to 45.42%. The available water content of sandy soil increased by 1.04% to 18.89%. Compared with CK,both L-3 and L-4 treatments significantly（P<0.05）increased the content of clay and powder particles in sandy soil and significantly reduced the bulk density of sandy soil. L-3 treatment had the highest proportion of soil capillary pores of 24.90%,lowest proportion of non capillary pores of 6.31% and the highest proportion of soil available water to water loss of 75.27%.【Conclusion】Coal slime had low levels of heavy metals and met the safety index criteria of Soil Quality for Land Improvement of Urban Sewage Treatment Plant Sludge Disposal,with high water retention capacity,rich in various elements,and could provide sufficient organic carbon. It had good improvement effects on the physical properties of sandy soil. Within the scope of the experiment,the best effect achieved when the amount of coal slime applied at 75 t/hm².

Key words: Coal slime, Sandy soil, Physical properties, Water retention capacity