Study On The Regulation Of Soil Water And Salt Movement By Smashing Ridge Tillage And Subsurface Pipe Drainage Technology

Object:Xinjiang is short of water resources,and the saline-alkali soil is widely distributed.Soil salinization control is accompanied by agricultural development,which is a persistent and urgent problem that needs to be solved.The technical of drip irrigation under mulched can only control salt locally,but cannot discharge salt,and the accumulation of salt over the years causes soil consolidation and secondary salinization.The smashing ridge tillage can break the soil compaction layer and the clay layer,and increase the soil water retention and permeability.The subsurface pipe drainage technology can collect water and salt below the plough layer,and discharge the salt outside the farmland.At present,there is no research on how the smashing ridge tillage and the subsurface pipe drainage technology can produce better drainage and salt washing effect through the coupling effect.Methods:This paper carried out the experiment in 2021 in the 4th Company of the 51st Regiment,Tumushuke City,the third division of typical saline-alkali land in southern Xinjiang.Three depth levels of the smashing ridge tillage(20 cm,F1;40 cm,F2;60 cm,F3),three subsurface pipe combination(burial depth+spacing)modes(0.6 m+12 m,A1;0.8 m+16 m,A2;1.0 m+20 m,A3)and conventional tillage control treatment(CK)were set.Results:The effect of the combination of the smashing ridge tillage and the subsurface pipe drainage on the movement and distribution of soil water and salt in the 0～120 cm soil layer was explored.Taking the soil desalination rate,crop yield and economic benefit as the goal,a multivariate regression fitting analysis was performed based on the least squares method,and a suitable combination of smashing ridge tillage and subsurface pipe drainage model was selected to regulate soil water-salt movement in the study area.The main results are as follows:(1)In the range of 0～120 cm soil layer,the average soil moisture content increased with the increase of the buried depth and spacing of the subsurface pipes,and the expression was A3>A2>A1.The average soil moisture content decreased with the increase of the smashing ridge tillage depth,which was F1>F2>F3.During the growth period of cotton,soil moisture content showed:after spring irrigation>flowering boll stage>seedling stage>boll opening stage.The combination of smashing ridge tillage and subsurface pipe had extremely significant effects on soil moisture during the growth period of cotton(P<0.01).Under the combination of smashing ridge tillage and subsurface pipe,the F1A3treatment had the highest average soil water content in the 0～120 cm soil range.The average soil water content was 23.10%,18.80%,21.79%and 18.52%during the after spring irrigation stage,seedling stage,flowering and boll stage,and boll opening stage,respectively.(2)In the range of 0～120 cm soil layer,the soil desalination rate decreased with the increase of buried depth and spacing of subsurface pipes,which was A1>A2>A3.The soil desalination rate increased with the increase of smashing ridge tillage depth,which was F3>F2>F1.The soil salinity content showed during the growth period of cotton:seedling stage>after spring irrigation>flowering and boll stage>boll opening stage.The combination of smashing ridge tillage and subsurface pipe had extremely significant effects on soil desalination rate during the growth period of cotton(P<0.01).Under the combination of smashing ridge tillage and subsurface pipe,the F3A1 treatment had the highest soil desalination in the 0～120 cm soil range.The soil desalination was 41.68%,31.75%,44.67%and 49.32%during the after spring irrigation stage,seedling stage,flowering and boll stage,and boll opening stage,respectively.(3)The combinatorial of the smashing ridge tillage and the subsurface pipe drainage had significant effects(P<0.01)on boll weight,dry matter weight,and yield.The boll weight,dry matter weight and yield of F3A1 treatment all reached the highest value among all treatments,which were 4.89 g,98.24g/plant,and 5460.36 kg/hm~2,respectively.The economic benefit decreases with the increase of the buried depth and spacing of the subsurface pipe,and increases with the increase of the depth of the smashing ridge tillage.The economic benefit of F1A3 treatment is the lowest,which is 5662.01RMB/hm~2,and the economic benefit of F3A1 treatment is the highest,which is 19389.64 RMB/hm~2,and the difference of net income is 3.42 times.Conclusion:The technology of controlling soil water and salt movement by smashing ridge tillage and subsurface pipe drainage can achieve the effect of reducing salt,increasing yield and high efficiency.When the depth of the smashing ridge tillage is 60 cm,and the arrangement mode of the subsurface pipe is 0.6 m buried depth+12 m spacing,the soil desalination rate,cotton yield and economic benefit can reach the maximum value at the same time,and the soil desalination improvement effect and economic benefit are the best.It is the optimal combination mode of smashing ridge tillage and subsurface pipe drainage suitable for the Xinjiang region.