| The mobility,aridity and infertility of aeolian sandy soil in wind-eroded desertification areas are the fundamental factors affecting the development of the ecological industry of sand prevention and control and the improvement of productivity.Sand fixation and soil improvement are the key ways to improve the biological yield,production and ecological functions of the aeolian sandy soil.In the existing engineering sand control materials,straw materials are perishable,soil and rock materials are not easy to obtain,chemical materials are expensive,economical,rainwater is not easy to infiltrate,and the impact of materials on environmental quality,etc.,develop low-cost,easy-to-obtain,Environmentally-friendly physical sand-fixing materials The deployment of belt-like flat sand barriers is of great significance for sand fixation,soil improvement and vegetation restoration in wind-eroded desertified areas.Based on this,this article takes the mobile sandland of Shengmu High-tech Eleven Pasture in Dengkou County on the northeastern edge of the Ulan Buh Desert as the research object,and selects three solid waste materials: fly ash,gypsum,and cow dung to develop indoor 15% and 25%.% Ratio of compound soil,the best ratio was selected through soil quality evaluation of its physicochemical and heavy metal characteristics,field flat sand fixation and sand barrier combined application test,combined with field investigation,indoor test analysis and other methods,determined the initial ratio After the application(May)and after the growing season(October),the soil physical and chemical properties and metal element properties were evaluated using principal component analysis and minimal data set induction to evaluate the soil quality index after the application of physical sand-fixing materials,combined with the concept of high efficiency and low cost,and finally Screen out the combination of materials and their proportions in the field.The main findings are as follows:(1)Mechanical composition characteristics of indoor compound soil and field sand barrier soilThe mechanical composition of the indoor composite soil is the same as that of CK,and it is still mainly fine and medium sand,but the volume fraction of medium sand,coarse sand,very fine sand and silt sand in the composite soil has increased,and the volume fraction of fine sand has decreased Trend.The average particle size of the sand-barrier soil in the field has an overall upward trend during the initial application and after the growing season;the sorting tends to be moderate,improving from dispersion to concentration;the overall skewness is nearly symmetrical;except for 15% F kurtosis,which is very high Except for the sharp and narrow,the remaining kurtosis is basically medium;the single fractal dimension increases;the particle size shows a trend of increasing at both ends and decreasing in the middle,and the distribution of soil particle size becomes wider.Medium sand,coarse sand and very fine sand,which are not easy to start,With the increase of powder composition,the volume fraction of fine sand that is easy to be blown and eroded decreases,which helps increase the starting wind speed of sand particles and achieve the purpose of sand fixation.(2)Nutrient characteristics of indoor compound soil and sand barrier soil in the fieldIndoor compound soil organic matter content and each nutrient content in the F,N and FS combinations have the same changing trends,and all show an increasing trend.The S soil sample is close to CK and the difference is not significant(P>0.05),and the overall distribution is N>F >CK≈S.The soil nutrient content of the sand barrier in the field increased overall,with SOC increasing the most,and N was the best,followed by F.The trends of TN and TK were consistent with SOC,and 15%F was the best for TP;15%F and 25 The p H and conductivity of %FS decrease.(3)Characteristics of metal elements in indoor compound soil and sand barrier soil in the fieldThe overall trend of the metal element content of the composite soil.The N composite soil sample increases the metal content and is higher than CK,and the S composite soil sample reduces the metal content and is lower than the Mn,Zn,and Al content of the CK,F composite soil sample Close to CK,Cr and As are lower than CK,Fe and Cu are higher than CK;FS mixed composite soil samples show a trend of Cu,Zn,Al close to CK,and Cr,Mn,Fe,As are significantly lower than CK.The content of Cr,Mn,and Fe in the soil with sand barrier after the growing season is the highest in all plots.The content of Cu and Al in the plots is the highest with 15% N,followed by CK;the content of Zn is the highest with 25% FS,and CK Second;As content,15% S is the highest,CK is the second.Adding physical sand-fixing materials and applying sand-barrier soils can reduce the content of heavy metals to a certain extent,and there is a tendency to increase trace elements such as Zn and Mn,and the heavy metals Cr and As are lower at 15%F.(4)Screening of the ratio of indoor compound soil materials and the ratio of sand barriers in the fieldUsing principal component analysis and summarizing the minimum data set indicators,the soil quality index of indoor composite soil samples from large to small is finally 15% F(0.545)>15%S(0.537)>15%N(0.506)>25% F(0.484)=25%FS(0.484)>25%S(0.478)>15%FS(0.395)>CK(0.385)>25%N(0.335),reaching the middle level of Grade III,15%F is determined according to the cost,15% N,15% S,25% FS four schemes for field application.In the same way,the soil quality index of the soil samples after the growth season of the sand barrier soil is 15%F(0.515)>15%S(0.492)>15%N(0.462)>25%FS(0.445)> CK(0.265),CK was grade IV barren level,and the plots with physical sand fixation materials all rose to grade III medium level.Comprehensive analysis of physical and chemical and heavy metal characteristics shows that the volume fraction of clay,silt,and coarse sand in the 15% F plot increases;the effect of increasing SOC and TP is better;the effect of sand fixation and soil improvement is obvious;and the content of heavy metals Cr and As is the lowest,and the vegetation grows.The density is the best and the price is the cheapest.Therefore,among the several physical sand-fixing materials and their proportions in this study,15% F can be used as the best material and proportion of the field physical materials for sand barrier application. |
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