本文關(guān)鍵詞： 季節(jié)性凍融 凍融循環(huán) 廣義土壤結(jié)構(gòu)指數(shù) 土壤三相結(jié)構(gòu)距離 土壤可蝕性　出處：《西北農(nóng)林科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：黃河中游地區(qū),屬于溫帶中緯度地區(qū),該區(qū)凍土層解凍時期產(chǎn)生的土壤流失量占全年土壤流失量的50%以上,是研究季節(jié)性凍融條件下土壤可蝕性變化的典型區(qū)域,然而該區(qū)域關(guān)于凍融作用對土壤可蝕性的研究相對較為薄弱。本研究以季節(jié)性凍融區(qū)典型風(fēng)沙土、褐土、黑壚土、黃綿土為例,通過室內(nèi)模擬凍融試驗,測定土壤理化性質(zhì)的變化,研究凍融作用對土壤可蝕性的影響,并運用EPIC模型估算土壤可蝕性K值,分析凍融作用對土壤可蝕性因子K值的定量影響,構(gòu)建凍融作用前后土壤可蝕性K值的關(guān)系式,探討土壤可蝕性對凍融作用的響應(yīng)機制,為凍融作用下坡耕地土壤侵蝕的機理研究奠定基礎(chǔ),并以期為季節(jié)性凍融區(qū)土壤侵蝕防治提供理論依據(jù)和科學(xué)指導(dǎo)。所得主要結(jié)論如下:(1)季節(jié)性凍融作用顯著影響土壤理化性質(zhì),影響程度與凍融循環(huán)次數(shù)、土壤初始含水率和土層深度有關(guān)。風(fēng)沙土、褐土、黑壚土、黃綿土的含水率、土壤孔隙度、土壤容重、粘粒含量、砂粒含量、微團聚體含量、土壤團聚度、分散率、土壤硬度和土壤抗剪強度、有機質(zhì)含量等變化在前9次凍融循環(huán)過程中,各次凍融循環(huán)之間均有顯著差異(P0.05),而9次循環(huán)后變化幅度減小,每次凍融循環(huán)之間差異性不顯著(P0.05);凍融循環(huán)過程中高含水率土壤的理化性質(zhì)變化較低含水率土壤更為明顯,表明高含水率土壤對凍融作用的響應(yīng)更為劇烈;凍融作用對表層土壤(0~5 cm)的破壞最嚴(yán)重,表層土壤的理化性質(zhì)變化與深層土壤相比均有顯著性差異(P0.05),。(2)季節(jié)性凍融作用顯著增加了土壤可蝕性K值,土壤可蝕性K值的變化程度主要受凍融循環(huán)次數(shù)及土壤類型影響。凍融循環(huán)過程中土壤可蝕性K值呈現(xiàn)整體增加趨勢,風(fēng)沙土、褐土、黃綿土可蝕性K值與凍融循環(huán)次數(shù)(1~15次)呈現(xiàn)對數(shù)函數(shù)關(guān)系。在1~5次凍融循環(huán)過程中風(fēng)沙土可蝕性K值變化幅度較大,風(fēng)沙土經(jīng)5次凍融后土壤可蝕性K值增加了0.0376[t ha h/(ha MJ mm)],與未凍融(0次)土壤相比增加了19.00%,15次凍融循環(huán)后風(fēng)沙土可蝕性K值增加了20.55%;0~9次凍融循環(huán)過程中,褐土、黃綿土可蝕性K值增加幅度較大,褐土、黃綿土可蝕性K值在9次循環(huán)后土壤可蝕性K值分別增加了:7.37%、9.45%,15次凍融循環(huán)后土壤可蝕性分別增加了:10.57%、11.79%;黑壚土可蝕性K值在凍融循環(huán)過程中的變化無明顯規(guī)律,但隨著凍融循環(huán)次數(shù)的增加,總體表現(xiàn)增加趨勢,黑壚土可蝕性K值在15次凍融循環(huán)后增加了2.77%;凍融后的土壤可蝕性K值約為未凍融土壤可蝕性K值的1.173倍,即:K_(凍融)=1.173K_(未凍融)。(3)季節(jié)性凍融作用一方面破壞土壤團聚體,降低土壤團聚度、土壤粘粒含量、土壤容重、廣義土壤結(jié)構(gòu)指數(shù)及土壤物理學(xué)特性,另一方面增加土壤有機質(zhì)含量、砂粒含量、粗粉粒含量、中值粒徑d50、土壤分散率,通過這兩方面作用,使得土壤可蝕性K值呈現(xiàn)不同程度的增加。凍融作用顯著降低土壤粘粒、增加土壤砂粒含量,降低大粒徑微團聚體含量而增加小粒徑微團聚體含量,導(dǎo)致土壤砂化,土壤團聚度降低,分散率增加;凍融循環(huán)顯著降低土壤容重、土壤硬度及土壤抗剪強度,增加土壤含水率、土壤孔隙度、有機質(zhì)含量,從而降低土壤抵抗外界營力破壞的能力;凍融循環(huán)后影響土壤可蝕性的首要主導(dǎo)因子為土壤團聚體含量,粘粒含量、砂粒含量、粉粒含量次之,然后依次是土壤有機質(zhì)含量、土壤容重及孔隙度等;影響季節(jié)性凍融區(qū)土壤可蝕性的因子可以概化為:土壤質(zhì)地、有機質(zhì)因子,土壤團聚作用因子及土壤三相結(jié)構(gòu)因子。
[Abstract]:In the middle reaches of the Yellow River, which belongs to the temperate latitudes, the area of permafrost thawing period, soil erosion amount accounted for more than 50% of the amount of soil loss, is the study of seasonal freezing and thawing conditions of typical area of soil erodibility changes, however, the area about freeze-thaw action research on soil erodibility is relatively weak in this paper, seasonal freeze-thaw area of typical aeolian sandy soil, cinnamon soil, loessial soil, loessial soil as an example, through the indoor simulated freeze-thaw test, determination of soil physical and chemical properties, can affect the corrosion resistance of soil freezing and thawing, and use EPIC model to estimate soil erodibility K value can be. The quantitative effects of erodibility factor K value analysis on soil freezing and thawing, construction of freezing and thawing soil before and after the relationship between erodibility K value of soil erodibility, the freeze thawing response mechanism, for freezing and thawing slope land soil erosion mechanism of The foundation, and in order to seasonal freezing and thawing soil erosion prevention and provide theoretical basis and scientific guidance. The main conclusions are as follows: (1) effects of seasonal freezing and thawing significantly affected the soil physicochemical properties, the influence degree and the number of freeze-thaw cycles, with initial soil water content and soil depth. Sandy soil, cinnamon soil. Loessial soil, soil water content, soil porosity, soil bulk density, clay content, sand content, soil micro aggregate content, degree of aggregation, dispersion rate, shear strength of soil hardness and soil organic matter content changes in the first 9 freeze-thaw cycles during the freeze-thaw cycles were between significant differences (P0.05), and after 9 cycles reduced the amplitude of variation, each freeze-thaw cycle not significant difference between them (P0.05); freezing thawing soil physical and chemical properties of high moisture cycle in low water content of soil is more obvious, showed high water content on soil freezing and thawing 浣滅敤鐨勫搷搴旀洿涓哄墽鐑，

本文編號：1461961