Study On Improvement Effect Of Fly Ash And Coal Gasification Fine Slag On Aeolian Sand Soil And Approach To Control Desertification

In order to study the improvement effect and defect of fly ash and coal gasification fine slag(CGFS)on aeolian sand soil,provide feasible approach for fly ash and coal gasification fine slag to control desertification.Two typical based-coal solid waste,fly ash and coal gasification fine slag were selected and applied at four levels of 0,60,120 and 240 t·hm2,cow dung was applied at one levels of 30 t·hm2.Study the effects of application of fly ash,coal gasification fine slag and application of fly ash,coal gasification fine slag and cow dung on the improvement of typical desert soil-aeolian sand soil.Furthermore,used fly ash,coal gasification fine slag and cow dung as raw materials,the nutrient planting pot which can holds water and supplies fertilizer was produced.According to the best application mode,the inner growth matrix of nutrient planting pot was compounded.Finally,the application effect of nutrient planting pot in desertification control was verified through experiments.The results show that:(1)After applied fly ash and coal gasification fine slag,the soil bulk density of aeolian sand soil decreased,the total porosity increased,and the water holding capacity increased.The natural water content,field water holding capacity and saturated water content of aeolian sand soil increased by 74.65%-99.74%,27.42%-82.10%,2.47%-25.56%,respectively,after the application of fly ash.After applied coal gasification fine slag,the natural water content,field water capacity and saturated water content of aeolian sand soil soil increased by 97.60%-131.52%,53.53%-85.70%and 6.43%-36.17%,respectively.The three moisture constants were increased with the increase of the application amount of fly ash and coal gasification fine slag.After application of fly ash,coal gasification fine slag,the electrical conductivity and alkali solution nitrogen,available phosphorus and available potassium content of aeolian sand soil increased,but the increase were small,overall,the single application of fly ash and coal gasification fine slag can not improve fertility level of aeolian sand soil.Because coal gasification fine slag has a lot of organic carbon,the coal gasification fine slag can increase the organic matter content of aeolian sand soil,significantly.In addition,the pH value of aeolian sand soil can be reduced by applying coal gasification fine slag alone.The plant height,overground fresh weight and tiller number of ryegrass were increased after the application of fly ash and coal gasification fine slag,and the contents of chlorophyll and photosynthetic pigment were increased,while the contents of proline,soluble sugar and malondialdehyde and the relative electrolyte exosmosis rate were decreased.Application of fly ash,coal gasification fine slag can improve the contents of cadmium,chromium,lead,arsenic of soil,but contents of four kinds of heavy metal element in soil did not over the risk screening value from standard,Soil environmental quality-farmland soil pollution risk control standards,not leaded to soil heavy metal pollution,the soil pollution levels is safety,and the potential ecological risk is low.(2)After the combined application of fly ash,coal gasification fine slag and cow dung,the soil bulk density of aeolian sand soil decreased and the total porosity increased.After the combined application of fly ash and cow dung,the natural water content,field water capacity and saturated water content of aeolian sand soil increased by 54.75%-76.67%,28.69%-85.24%and 8.57%-26.08%,respectively.After the combined application of coal gasification fine slag and cow dung,the natural water content field water capacity and saturated water content of aeolian sand soil increased by 88.15%-115.26%,59.04%-81.50%and 11.31%-37.16%,respectively.After the application of fly ash and coal gasification fine slag and cow dung,the fertility level of aeolian sand soil was significantly improved.After application of fly ash and cow dung,the electric conductivity and contents of alkali solution nitrogen,available phosphorus and available potassium of aeolian sand soil increased by 73.48%～106.16%,165.57%～300.88%,133.92%～165.84%,132.71%～175.68%,and organic matter content increased by 147.02%～244.37%,respectively.After combined application of coal gasification fine slag and cow dung,the electrical conductivity and the contents of alkali solution nitrogen,available phosphorus and available potassium of aeolian sand soil increased by 69.34%～133.69%,212.61%～336.19%,87.62%～181.93%and 135.36%～178.00%,respectively.The organic carbon content of aeolian sand soil increased greatly after the application of coal gasification fine slag and cow dung,which was 7.49 to 11.27 times of the original aeolian sand soil,because there is a mass of organic carbon in coal gasification fine slag and cow dung.The 60-day plant height,overground fresh weight and tiller number of ryegrass increased by 48.41%-75.52%,100.50%-171.14%and 96.30%-111.11%,respectively,after the application of fly ash and cow dung,increased by 74.98%-105.33%,260.51%-401.26%and 100.03%-114.81%after the application of coal gasification fine slag and cow dung.The contents of chlorophyll and photosynthetic pigment were increased significantly after application of fly ash and coal gasification and cow dung.The contents of proline,soluble sugar,malondialdehyde and relative electrolyte exosmosis rate decreased significantly.The combined application of fly ash,coal gasification fine slag and cow dung did not cause soil heavy metal pollution,and the soil pollution level was safety and the potential ecological risk was low.(3)Combined with the three indexes of water-holding capacity,fertility level and plant growth of aeolian sand soil,the improvement effect of fly ash,coal gasification fine slag and cow dung on aeolian sand soil was comprehensively evaluated.The evaluation results showed that the optimal combination of fly ash,coal gasification fine slag and cow dung to improve aeolian sand soil was 120 t·hm2 fly ash+30 t·hm2 cow dung,and 120 t·hm2 coal gasification fine slag+30 t·hm2 cow dung.Through comparative analysis,it is clear that fly ash and coal gasification fine slag are the main substances to improve the water-holding capacity of aeolian sand soil in this study,while cow dung is the main substance to improve the fertility of aeolian sand soil.Meanwhile,it is found that coal gasification fine slag has a stronger improvement effect on the water-holding capacity of aeolian sand soil compare with fly ash.(4)Used fly ash,coal gasification fine slag,cow dung as raw material to produce nutritional planting pot,the water absorb-water loss test found that compared with aeolian sand soil,the nutrition planting pot has the strong ability of holding water,through simulated rainfall experiment,found used the nutrition planting pot,the water content of inner soil of the nutrition planting pot is higher than external soil,nutrition planting pot has capacity of water retention.According to the preliminary test results,the modified aeolian sand soil with 120 t·hm2 fly ash,120 t·hm2 coal gasification fine slag and 30 t·hm2 cow dung was used as the inner filling growth matrix of the nutrient planting pot.The combination of the inner filling growth matrix and the nutrient planting pot can create inner micro environment that has sufficient water and nutrients.Different from the aeolian sand soil,the nutrient planting pot has a certain nutrient supply capacity.Compared with ryegrass grown on aeolian sand soil,the plant height,fresh weight of overground and tiller number of ryegrass planted in pot were significantly increased,the contents of chlorophyll and photosynthetic pigment were significantly increased,and the contents of proline,soluble sugar,malondialdehyde and relative electrolyte exosmosis rate of leaves were significantly decreased.