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Northwest A&F University (2018)

Formation of Soil Crust and Its Effects of Different Spatial Distributions of Physical Soil Crusts on Runoff and Erosion

路培;

Titre : Formation of Soil Crust and Its Effects of Different Spatial Distributions of Physical Soil Crusts on Runoff and Erosion

Auteur : 路培;

Grade : Doctoral Dissertation 2018

Université : Northwest A&F University

Résumé partiel
Physical crust is a surface phenomena that generally exist in arid and semiarid region,which is a low porosity layer in surface produced by rainfall or irrigation.Soil crust increase runoff rates as a result of soil infiltration reduction,and their formation may also increase the soil strength compared to uncrusted soils,therefore it has an important influence on the erosion process.Soil crust is often accompanied by micro topography(surface roughness)in agricultural and their(structural crust and depositional crust)spatial distribution is affected by roughness,thus different erosion phenomenon occurs in these treatments.Therefore,under the simulated rainfall condition,we should refer to the actual situation of the slope land surface,we analyzed the strength characteristics of soil crust,the effect of crust strength on infiltration and soil erosion,Effects of different spatial distributions of soil crusts on soil erosion and the effect on soil erosion from soil crust and soil surface roughness.The main conclusions were as follows :(1)The soil physical and chemical properties of rainfall intensity were the important factors that affected the formation of soil crust,the greater the rainfall intensity was,the higher the crust strength was.The lowest the soil crust strength(11.6812.80 kPa)was formed under the 30mm h-1 rainfall,the soil crust strength formed under the 90 mm h-1rainfall was 15.0218.40 kpa,the 120 mm h-1 was the highest intensity(19.5920.62 kPa)formed under rainfall.Under the same rainfall condition,the order of crust strength in different types is:Heilu soil>Huangshan soil>Huangmian soil>red soil>Lou soil>(black soil,Lou soil+30 t/ha biological carbon,Lou soil+7.5 t/ha biological carbon),black soil and Biocharcoal soil with the smallest crust strength,and the Heilu soil with the highest.The greater content of the soil aggregate(>0.25 mm),clay and organic matter,the smaller strength of the crust,while the correlation between the exchangeable Na+and the soil crust strength was positive.The degree of soil crust was positively related to rainfall intensity,but negatively correlated with micro aggregates and clay content,and the correlation between rainfall and crust formation was the strongest.(2)The size distribution of the soil porosity is the main factor affecting the infiltration,soil crust can effectively reduce water infiltration,and with the crust strength increases,the larger effect of reducing infiltration,the reduction effect of soil crust on infiltration is8.8%60.3%.For the same type of soil,the infiltration rate decrease with the increase of crust strength,compared with noncrust soil,the reduction effect of lou soil with high strength crust,moderate strength crust,low strength crust is 37.4%,32.1%and 10.9%less than it’s for the black soil(20.6%,17.2%and 8.8%),which has a close relationship with the structure characteristics of the soil itself,the reason for the difference is the structure characteristics of the soil itself.Fractal dimension of soil particles can effectively characterize the structure characteristic

Mots clés : soil crust; tillage measures; spatial distribution; slope; runoff and sediment;

Présentation (CNKI)

Page publiée le 15 avril 2019