Wind Erosion Resistance By No-tillage And Water Saving Effect Of Wheat Field Regulated By Irrigation And N Fertilization At Oasis Irrigated Region In Hexi Corridor

Reducing the soil and water loss from farmland and meanwhile reasonable utilizing of soil and water resources is a severe challenge facing by present world,especially for arid and semi-arid region where ecological environment is fragile,wind erosion is obvious,and water shortage is severe.It is urgent to form the scientific conservation measures for soil and water to improve soil erosion resistance and water-saving potential.Tilling of farmland soil and managing of water and fertilizer may affect soil wind erosion,soil water storage and water productivity,whereas,the mechanisms of wind erosion resistance and water saving effect influenced by previous plastic film mulching with notillage and interaction of irrigation and N fertilization are not clear.Thus,at Hexi Oasis Irrigation Region in 2019-2020,the soil of previous plastic film mulching with no-tillage(NT)and conventional tillage(CT)were employed as the research object,the wind erosion was measured by wind tunnel simulation test,so as to clarify the relationship between wind erosion and key soil physi-chemical factors,and to reveal the mechanism of wind erosion resistance.Based on this,we implement a split-split plot experiment,where tillage as the main plot(i.e.,NT and CT),irrigation quota as the sub-plot(i.e.,high irrigation,the I2;and low irrigation,the I1),and N fertilizer rate as the sub-sub-plot(i.e.,high N rate,the N3;medium N rate,the N2;and low N rate,the N1).The soil water storage capacity,water consumption characteristics,yield performance and soil physichemical properties were determined,so as to explore the water-saving effect of wheat and the relevant mechanisms.The aim of this research was to provide theoretical basis and technical support for building a high-efficient soil and water conservation programs.The main conclusions obtained are as follows:(1)No-tillage can improve soil physi-chemical properties and improve soil resistance to wind erosion,thus reducing the amount of wind erosion at different wind speeds.Compared to CT,the main mechanism of improved wind erosion resistance by soil of NT is as follows: the soil non-erodible particle content,water stable aggregate content ≥0.25 mm,average weight diameter of water stable aggregate,soil bulk density,soil water content,and organic matter content were all improved,while the structure damage rate was significantly decreased.(2)The average soil water storage during the growth period of wheat was increased by no tillage,and the spatial distribution and consumption of soil water storage were changed by no tillage,lower irrigation and lower N fertilization.Compared to CT,the NT treatment improved soil water storage at 0-30 cm layer,which facilitate soil water storage been increased by 12.4% across entire growth period.This were mainly represented by the improvement before sowing(10.8%),45 d after wheat sowing(13.8%),60 d after wheat sowing(21.6%),75 d after wheat sowing(12.4%),and 120 d after wheat sowing(15.7%).For soil water storage consumption,it with NT was increased in the mid-period of wheat,which lead to the amplitude of increase of soil water storage with NT was decreased compared to CT.I1 treatment significantly reduced soil water storage at 90-120 cm layer,and increased soil water storage consumption compared with I2.N1 treatment significantly increased soil water storage at 60-90 cm and 90-120 cm layer compared to N3.The water storage consumption of N1 and N2 was decreased by 20.4%and 9.0% compared with N3.(3)Tillage method and N fertilizer rate had no significant effect on total water consumption,but lower irrigation reduced total water consumption compared with higher irrigation.Compared to CT,NT lowered the stage and total evaporation,but increased transpiration at middle growth period and the total transpiration across entire growth period.In terms of stage water consumption,it with early growth stage(28.8%)and late growth stage(13.5%)of NT was lowered compared to CT,but with middle growth stage increased by 33.5%.Thus,the total water consumption of NT and CT showed no significant difference.Compared with I2,I1 treatment decreased soil evaporation during early,middle,late and entire growth period.It also decreased transpiration during middle growth stage and entire growth period.Accordingly,I1 significantly reduced total water consumption.Compared to N3,N1 increased soil evaporation at late growth stage and during entire growth period,but decreased transpiration during middle growth stage,which reduced total transpiration.Therefore,N fertilizer rate had no significant effect on stage and total water consumption.(4)Grain yield of wheat with no-tillage combined with lower irrigation and medium N fertilization was equivalent to that with higher irrigation and higher N fertilization.Compared with CT,NT increased dry matter accumulation at early and middle growth stages of wheat,as well as N uptake in the middle and late growth stages,which significantly increased dry matter accumulation and N uptake,and laid a foundation for higher grain yield.The lower irrigation reduced N uptake but did not affect dry matter accumulation.There was no significant difference in dry matter accumulation and N uptake between medium and higher N fertilization.The interaction of tillage,water and N fertilizer rate significantly affected wheat grain yield.The grain yield decreased with the decreasing of irrigation quota and N fertilizer rate under CT treatment,while showed no significant decrease managed with I1 and N2 under NT treatment.(5)No-tillage combined with lower irrigation and medium N fertilizer rate could improve the yield scale and total dry matter accumulation scale water productivity of rotated wheat.Compared with CT,NT increased the yield scale and total dry matter accumulation scale water productivity,as it increased the water productivity based on dry matter accumulation at early and late growth stage of wheat.Compared with I2,I1 increased the yield scale and total dry matter accumulation scale water productivity,and significantly increased the water productivity based on dry matter accumulation at middle growth stage of wheat.Compared with N3,N1 decreased the grain yield scale and total dry matter accumulation scale water productivity,and the water productivity based on dry matter accumulation at late growth stage.No significant difference of water productivity between N2 and N3 was found.(6)No-tillage can optimize water saving effect by improving the soil physi-chemical properties.Compared with CT,NT increased microbial biomass carbon and nitrogen,organic matter content,the content of water-stable aggregate >0.25 mm,bulk density,and temperature in 0-30 cm soil layer.In addition,through direct and indirect effects of soil physi-chemical properties,NT increased the average soil water storage and water productivity,and reduced the total water consumption.Thus improved the comprehensive evaluation index of water saving effect.NTI1N2 and NTI1N3 had the highest comprehensive evaluation indexes,which were 0.91 and 0.93,respectively.As medium N application treatment could save 20% of N fertilizer,the present study recommended that NTI1N2 might be the best management scheme of water-saving production mode for spring wheat in the testing area.In conclusion,maize plastic film mulching with no-tillage improved resistance capability of soil to mitigate wind erosion.Meanwhile,by integrating irrigation and N fertilizer reduction at 20%,it could improve water-saving effect of subsequent wheat.This demonstrated that the integrated practice is an applicable and efficient soil-water conservation measure for arid and semi-arid areas.