Study On The Characteristics Of Soil Salinization And The Effect Of Different Pipe Diameters And Spacing Of Underground Pipes On Salt Removal In South Xinjiang Reclamation Area

Aiming at solving the severe salinization problems in the soil of the South Xinjiang Reclamation Area of the Corps,the first and second regiments of the Corps,the Hongqi Farm of the Third Division,and the 224 regiment of the Fourteenth Division were used as research areas to study the characteristics and soil salinization of the South Xinjiang Reclamation Area.The study of the effect of underground pipes with different pipe diameters and spacings on salt drainage provides a theoretical basis for formulating measures to improve saline cultivated land in the southern Xinjiang reclamation area according to local conditions.?1?There are differences in soil salinization types in different reclamation areas.According to the ratio of(CO₃^2-+HCO₃^-)/(CI^-+SO₄^2-)mmol in 0³0 cm soil layer,there is no sodic salinization.According to the ratio of Cl^-/SO₄^2-mmol,the second regiments of soil salinization are mainly chloride sulfate type and sulfate type,accounting for 49.04%and 48.41%respectively.The salinization types of 224 regiment were mainly sulfate chloride type and sulfate type,accounting for 32.31%and 28.85%respectively.The types of salinization in Hongqi farm are chloride sulfate type and sulfate chloride type,accounting for 40.35%and 36.84%without chloride.?2?The degree of soil salinization is different in each reclamation area.The second regiment non salinized soil is accounted for 47.77%,moderate salinized soil 29.30%,light and heavy salinized soil 22.93%.The 224 regiment non salinization is accounted for 84.95%,mild and moderate salinization is accounted for 8.85%,and severe salinization and saline soil is accounted for 5.77%.In Hongqi farm,the degree of soil salinization is more serious,including 19.30%of non salinization,15.79%of mild and moderate salinization,64.91%of severe salinization and saline soil.?3?The distribution characteristics of soil salt profiles in different reclamation areas are different,and they are epimeric and mesomeric.From the 0²00 cm soil layer,the salt content of the second regiment 40¹00 cm soil layer is high,accounting for 47.01%of the profile,which shows the middle aggregation type.The salt content in 0³0 cm soil layer of the 224 regiment and Hongqi farm was higher,accounting for 40.58%and 31.61%respectively.The distribution of different types of ions in soil profile is different.The contents of Ca²⁺and SO₄^2-were the most in soil cation and anion in second regiment and Hongqi farms,and the change trend was basically consistent with the salt content.The contents of Na⁺,Mg²⁺,K⁺,Cl^-and HCO₃^-did not change significantly with the increase of soil depth.The content of Na⁺,Cl^-,SO₄^2-in the soil of 224regiment was the most,the change trend was basically consistent with the salt content,and the surface content was high.The contents of Ca²⁺,Mg²⁺,K⁺and HCO₃^-did not change significantly with the increase of soil depth,while CO₃^2-was not detected in the experiment.?4?The soil salinization characteristics of different land use patterns were significantly different,and the salt content of cultivated land was lower than that of non cultivated land.The land use types of the 224 regiment are mainly salinized abandoned farmland,sand bag wasteland and jujube garden land,with the average salt content of 15.70 g·kg^-1,2.04 g·kg^-11 and 3.02 g·kg^-1respectively.There are many types of land use in Hongqi farm.The average salt content of uncultivated land is 48.13 g·kg^-11 in salt wasteland,46.09 g·kg^-11 in meadow land,32.16 g·kg^-11 in abandoned farmland and 9.98 g·kg^-11 in sandy land.For growing crops Corn fields 2.75 g·kg^-1,cotton fields 8.78 g·kg^-11 and grape fields 5.41 g·kg^-1.The main anion and cation composition of soil in different land use types of the 224 regiment were Cl^-,SO₄^2-,Na⁺,Ca²⁺,The soil of Hongqi farm is Ca²⁺,Mg²⁺,Na⁺and SO₄^2-,and the content changes greatly,while the content of HCO₃^-and K⁺is low,and the spatial distribution is uniform.?5?In different periods,the salinity and conductivity of the drainage in the concealed pipe were significantly higher than that of the irrigation water.In June,August and October,the salinity of the three irrigation water is 0.75 g/L,0.86 g/L and 0.63 g/L respectively,and the average salinity of the underground drainage is 6.427 g/L,7.382 g/L and 6.781 g/L respectively,which is8.57,8.58 and 10.76 times of the salinity of the irrigation water.The change of electrical conductivity of drainage and irrigation water is basically consistent with the change of salinity.Under the condition of the same spacing,the salinity and conductivity of the drainage with different diameters are significantly different.The salinity and conductivity of 60 mm pipe diameter were 1.4 times and 1.3 times respectively.Under the same pipe diameter,there are significant differences in the salinity and conductivity of the drainage with different spacing.1.5times,1.3 times and 1.3 times 1.2 times of that for the spacing of 10 m and the conductivity of 6 m and 8 m respectively.?6?The desalination rate of soil with different pipe diameters was significantly different.After two times of irrigation,One year later,the desalination effect of each soil layer is quite different.The desalting effect of pipe diameter 60 mm is better than that of 50 mm.The desalting rate of 0¹00 cm soil layer is between 25.88%⁴8.09%and 18.92%⁴0.52%respectively.The difference of soil desalination rate between different spacing was significant.The desalting effect of the 6 m spacing of the concealed pipe is better than that of the 8 m and 10 m spacing,and the desalting rate is 43.53%,36.91%and 26.82%respectively.When the distance between underground pipes is 6 m and the pipe diameter is 60 mm,the soil layer 0⁶0 cm after two times of irrigation has been reduced to the level of slight salinization(4⁸ g·kg^-1),and the efficiency of underground pipe drainage is higher,which is the optimal distance and pipe diameter layout parameters for the salinized soil of first division and the second regiment.