本文選題：層狀土壤 + 土壤水分運(yùn)動(dòng)　； 參考：《西北農(nóng)林科技大學(xué)》2015年碩士論文

【摘要】：為了了解不同類型層狀土柱水分運(yùn)動(dòng)規(guī)律及其對植物生長的影響,利用砂土和砂黃土2種土壤,設(shè)置3種不同厚度分層土柱(11.25、22.5、45 cm)和2種勻質(zhì)對照土柱,測定了土柱自初始飽和條件下的排水過程、蒸發(fā)過程及紫花苜蓿生長過程。利用2種勻質(zhì)土柱排水過程測定的結(jié)果對2種土壤水力參數(shù)進(jìn)行優(yōu)化,利用優(yōu)化后的參數(shù)通過Hydrus-1D模型對排水和蒸發(fā)階段進(jìn)行模擬分析,獲得了不同類型層狀土柱的水分運(yùn)動(dòng)規(guī)律。結(jié)果表明:(1)層狀土柱持水能力隨著分層厚度的減小而增加,當(dāng)分層厚度減小到一定程度時(shí)土柱持水能力不再隨著分層厚度的減小而增加,該臨界厚度取決于下層粗質(zhì)土壤對上層細(xì)質(zhì)土的吸力與上層細(xì)質(zhì)土壤進(jìn)氣吸力之間的相對大小。本試驗(yàn)所用2種土壤分層臨界厚度大約在5 cm左右;土柱失水主要來自下層較粗質(zhì)地土壤;(2)蒸發(fā)結(jié)果顯示表層覆蓋砂土可明顯抑制土柱蒸發(fā)。表層為砂土的各土柱累積蒸發(fā)量差異不顯著,平均為8 mm;而表層為砂黃土的土柱累積蒸發(fā)量可達(dá)110 mm;(3)勻質(zhì)土柱中紫花苜蓿根系密度隨深度的增加而降低;層狀土柱中紫花苜蓿根系主要分布在質(zhì)地較細(xì)的砂黃土中,總根系密度隨分層數(shù)量的增加而增加;在相同深度的層狀砂黃土中,根系密度也隨著分層數(shù)量的增加而增加。相對于分層厚度和土層深度,土壤有效持水量(AWHC)是影響細(xì)根密度(FRD)的最主要因素;(4)相同灌水條件下,土壤水分變化受土壤分層類型和紫花苜蓿根系分布的影響,土壤分層數(shù)量越多,紫花苜蓿根系密度越大,土壤水分變化越劇烈,累積蒸散量越大。紫花苜蓿生物量隨著土壤分層數(shù)量的增加而增加,不同分層類型土柱苜蓿光合速率在不同時(shí)期差異不同,取決于根系到達(dá)土層的水分含量。
[Abstract]:In order to understand the water movement law of different types of layered soil columns and their effects on plant growth, three kinds of layered soil columns with different thickness (11.25 ~ 22.5 ~ 45 cm) and two kinds of homogeneous control soil columns were set up by using two kinds of soils, sandy soil and sandy loess. The drainage process, evaporation process and alfalfa growth process of soil column since initial saturation were measured. Two kinds of soil hydraulic parameters were optimized by using the results of the drainage process of two homogeneous soil columns, and the drainage and evaporation stages were simulated and analyzed by Hydrus-1D model. The water movement laws of different types of layered soil columns were obtained. The results show that: (1) the water holding capacity of layered soil columns increases with the decrease of delamination thickness, and when the delamination thickness decreases to a certain extent, the water holding capacity of soil columns does not increase with the decrease of delamination thickness. The critical thickness depends on the relative magnitude between the suction force of the lower coarse soil to the upper fine soil and the inlet suction of the upper fine soil. The critical thickness of soil stratification is about 5 cm, and the water loss of soil column mainly comes from coarse soil of lower layer. (2) the evaporation results show that soil column evaporation can be inhibited obviously by surface covered sandy soil. There was no significant difference in accumulative evaporation of each soil column with sandy soil on the surface, with an average of 8 mm, while that of soil column with sandy loess on the surface was 110 mm. (3) the root density of alfalfa decreased with the increase of depth in the homogeneous soil column. In layered soil column, alfalfa root system mainly distributes in fine sand loess, the total root density increases with the increase of stratified number, while in layered sand loess of the same depth, root density also increases with the increase of stratified number. AWHC was the most important factor affecting fine root density (FRD). (4) under the same irrigation condition, soil moisture change was affected by soil stratification type and alfalfa root distribution. The more the number of soil layers, the greater the root density of alfalfa, the more severe the change of soil moisture, and the greater the cumulative evapotranspiration of alfalfa. The biomass of alfalfa increased with the increase of soil stratification, and the photosynthetic rate of alfalfa with different soil layers was different in different periods, depending on the water content of root system to the soil layer.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S152.7;S541.9

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 薛崧,汪沛洪,許大全,李立人;水分脅迫對冬小麥CO_2同化作用的影響[J];植物生理學(xué)報(bào);1992年01期

，

本文編號：2107651