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Ningxia University (2022)

Study on Soil Evaporation Impedance and Evaporation Simulation under Mixed Sand Mulch of Sandy Field in Arid Regions of Central Ningxia

贾振江

Titre : Study on Soil Evaporation Impedance and Evaporation Simulation under Mixed Sand Mulch of Sandy Field in Arid Regions of Central Ningxia

Auteur : 贾振江

Grade : Master 2022

Université : Ningxia University

Résumé partiel
The arid regions of central Ningxia is arid with little rainfall,strong evaporation and fragile ecology.It is important to explore the soil evaporation characteristics and resistance mechanism,and realize the simulation of soil evaporation process under mixed gravel and soil mulch to effectively improve the ecological environment of the central arid regions and promote sustainable agricultural development Based on this,this study explores the soil evaporation impedance and evaporation estimation based on theoretical analysis and micro-lysimeters field experiment,taking loamy soil in Xiangshan area,Zhongwei,Ningxia province as an example and combining with the local unique gravel mulch pattern,and achieves the following innovative results.(1)The actual evaporation pattern and the changes of "Evapotranspiration capacity" and"Evapotranspiration impedance" in the sandy loam soil in the study area and the corresponding environmental factors were explained based on the field measurement data.The study found that with the extension of the experiment time,the relative evaporation intensity(REs)and the relative evaporation resistance(RErs)of the soil showed a pattern of change,meanwhile,the Logistic model could better reflect the actual relationship between them and the time,and there were two inflection points respectively,so that the soil evaporation process could be divided into three stages ;The meteorological factors(soil surface temperature,net radiation flux at the surface)and soil parameters(soil surface water content)were the key factors affecting soil evaporation intensity(Es),and the polynomial mathematical correction model of E,based on the key factors was constructed,with R2 reaching above 0.95 and the average accuracy A increasing to 76.47% ;while soil surface water content were only the main control factors affecting REs and RErs and the Logistic models of RES and RErs based on soil surface water content were finally constructed respectively,with R2 reaching 0.95.The average accuracy A was more than 70%,and the soil evaporation process was also divided into three stages by statistical second-order derivation.(2)To investigate the microscopic mechanism of soil evaporation,the intrinsic relationship between relative soil evaporation intensity and soil water surface tension in the second stage of soil evaporation and intermolecular forces in the third stage of soil evaporation was investigated based on theoretical analysis,respectively.The study showed that the water bend surface radius reached 20095 nm and the equilibrium relative humidity changed slowly,at the beginning of the non-saturated state.It finally droped to 77 nm until the pore water disappeared,and the equilibrium relative humidity decreased abruptly.The interfacial tension did not change significantly throughout the unsaturated evaporation process,and was basically stable at 71-72 mN·m-1.By the third stage of soil evaporation,the relative evaporation intensity was maintained at 0.07,and the water film thickness varied from 1.0 to 2.42 nm.

Mots clés : Gravel-soil mixing ;Evaporation resistance ;Evaporation estimation ;Arid regions of central Ningxia ;

Présentation (CNKI)

Page publiée le 20 octobre 2022