Effects Of Coal Gangue Mulching On Soil Moisture-Nutrient-Salinity Characteristics In Mining Areas

The reclaimed soil in mining area was mainly raw soil,which has poor performance in water and fertilizer conservation and lack of organic matter,and the accumulation of a large number of coal gangue cause serious environmental problems.In order to explore the influence of coal gangue mulching on soil moisture-nutrient-salinity characteristics in mining area so as to achieve the effect of water retention and improve soil physical and chemical properties.four types of coal gangue mulching thickness(4cm,8cm,12cm,16cm)and grain size(0-0.5cm,0.5-1cm,1-2cm,2-4cm)were respectively set by means of laboratory simulation test in this study,and the treatment of uncovered coal gangue was used as the control,with a total of 17 treatments.The effects of different coal gangue mulching thickness and grain size on the process of soil water infiltration and evaporation,as well as the changes characteristics of soil nutrient content and salt ion concentration in mining area were studied.The results showed that:(1)Coal gangue mulching can change soil water infiltration capacity and reduce water evaporation.When the thickness of coal gangue was 4cm and the grain size was 0.5-1cm,the cumulative infiltration amoumt of soil was the largest.When the thickness of coal gangue was relatively large(8cm,12cm,16cm in this test)and the grain size was 1-2cm,the cumulative infiltration amoumt of soil was the largest.When the thickness of coal gangue was 16cm,and the grain size was 1-2cm,the cumulative evaporation of soil was the smallest,which was significantly lower than that of the untreated treatment,and reducd by 35.63%.According to the cluster analysis,The best water retention performance was obtained when the coal gangue mulching thickness was 16cm,and the grain size was 0.5-1cm,1-2cm and 2-4cm.(2)Coal gangue mulching can effectively improve soil nutrient content.The contents of total organic carbon,easily oxidized carbon,water-soluble carbon,total nitrogen,water-soluble nitrogen and available potassium in soil increased significantly,while the content of available phosphorus decreased.A two-way ANOVA demonstrated that the thickness and grain size of coal gangue can significantly affect the soil nutrient content.The cluster analysis showed that the influence of soil physical and chemical properties were greatest when the thickness of coal gangue was 16cm and the grain size was0-0.5cm,and the contents of easily oxidized carbon,water-soluble carbon,total nitrogen and water-soluble nitrogen were the highest.(3)Effects of coal gangue mulching on soil salt ion concentration.According to the soaking test of coal gangue,the cations and anions in the leaching solution were mainly Na⁺and SO₄²⁺.As the quality of coal gangue increased and the particle size decreased,the salt ion concentration significantly increased.Coal gangue mulching significantly affected the salt ion concentration in soil,and the salt ion concentration in soil was also dolinated by Na⁺and SO₄²⁺.The cluster analysis showed that the Na⁺and SO₄^2-concentrations of gangue were the highest when the thickness of the coal gangue was 16cm and the grain size was 0-0.5cm,and the Na⁺and SO₄^2-concentrations of the treatment was significantly increased by 83.1%and 363.47%respectively compared with the uncovered treatment.In summary,the treatment of coal gangue with the thickness of 16cm and the grain size of 1-2cm has a better effect on improving soil water retention.The treatment of coal gangue with the thickness of16cm and the grain size of 0-0.5cm has a good effect on improving soil nutrient content.Therefore using coal gangue as a mulch material can effectively improve the water retention and nutrient content of the soil in mining area and providee practical reference for the reuse of coal gangue resources.