本文關(guān)鍵詞： 黃土塬區(qū) 蘋果園 染色示蹤 活塞流 根系　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】：黃土塬區(qū)地處中國西北部,是黃土高原蘋果的主產(chǎn)區(qū)。但該區(qū)水資源極缺,80%以上果園是旱作農(nóng)業(yè)區(qū)。在高齡果園土壤深層存在嚴(yán)重的干燥化現(xiàn)象,深度甚至可深達10m以下,嚴(yán)重制約了果樹生長和生產(chǎn),由此迫切需要探明黃土塬區(qū)蘋果園降雨入滲機制。較多研究揭示在自然森林和人工林地中優(yōu)先流是降雨補給深層土壤的機制、樹干徑流及根系導(dǎo)流可以水分入滲通量及土壤中的大孔隙進而加強優(yōu)先流,但在土壤均勻、受人類影響(機械翻耕等)的黃土塬區(qū)果林地研究較少。選取長武黃土塬區(qū)20年樹齡蘋果園,使用4 g·L-1的亮藍溶液(Brilliant Blue FCF)作為染色劑,分別采用噴灑(6個重復(fù))、傾倒(3個重復(fù))和樹干徑流模擬(6個重復(fù))三種方式進行染色示蹤試驗,其中,噴灑方式代表雨量為50 mm的正常降雨入滲,傾倒方式代表雨量為50 mm的極端性暴雨入滲,樹干徑流模擬代表樹干徑流方式(18 L樹干徑流量)的雨水入滲。研究取得主要結(jié)論如下:(1)在噴灑方式下染色平均深度為0.28 m,深度較淺,均勻入滲比平均值超過0.65,中位數(shù)超過0.7,說明水分入滲過程中均勻部分所占比重較大,由此表明活塞流是黃土塬區(qū)蘋果園降雨入滲的主要機制。這可能主要是由塬區(qū)果園的土壤物理性質(zhì)、淀積粘化作用和機械耕作及壓實造成的。(2)傾倒方式下染色平均深度為0.53 m,最大深度為0.59 m,深度較淺,表明在極端暴雨、激活大孔隙等優(yōu)先路徑的條件下雨水也很難短時間內(nèi)補給深層土壤水。(3)噴灑條件下水分入滲比傾倒條件下水分入滲更均勻(p0.05),表明極端性暴雨會增大水分入滲的不均勻性,增大優(yōu)先流入滲的比重。(4)當(dāng)果樹根系良好時,樹干徑流模擬方式下的水分側(cè)滲影響較小,水分以近乎一維的方式入滲,染色最大深度為0.46 m,深度也較淺,表明在黃土塬區(qū)蘋果園雨水較難通過樹干徑流的方式沿著根系補給深層土壤水。(5)通過死根系與活根系染色比較分析,發(fā)現(xiàn)活根系(≥2 mm)不具有良好的導(dǎo)流作用,而腐爛根系(≥2 mm)形成的入滲通道則具有良好的導(dǎo)流作用;本研究中并未發(fā)現(xiàn)黃土豐富的大孔隙結(jié)構(gòu)及果樹細根系(2 mm)由于季節(jié)性死亡在土壤中留下的孔隙。(6)通過對蘋果樹次生根系數(shù)目、埋藏深度及根系與水平地面夾角進行統(tǒng)計分析,發(fā)現(xiàn)在土壤表層果樹根系以水平根系為主,由于活塞流是黃土塬區(qū)蘋果園降雨入滲的主要機制,從而使得果樹根系可以最大程度利用降雨入滲土壤中的水分,同時推斷當(dāng)表層根系腐爛時會更可能發(fā)生橫向優(yōu)先流,從而阻礙雨水對深層土壤水的補給。因此,在黃土塬區(qū)蘋果園,活塞流是深層土壤水降雨補給的主要機制,大孔隙和腐爛垂直根系等通道也可能作為雨水補給深層土壤水的途徑。通過農(nóng)田-果園輪作和間伐可能是維持果園可持續(xù)生產(chǎn)的必要手段。研究結(jié)果對揭示蘋果園土壤水補給機制、干層形成原因、以及氣候變化下更頻繁的極端性降雨對土壤水補給機制的影響具有重要意義。
[Abstract]:Loess Plateau is located in Northwest China, Loess Plateau apple producing areas. But the lack of water resources in this region, more than 80% orchards in dry farming areas. There is a dry phenomenon in old orchard soil deep, deep depth even below 10m, seriously restrict the growth and production of fruit trees, which is an urgent need to explore apple orchard in Loess Plateau rainfall infiltration mechanism. Many studies revealed that in the natural forest and plantation is the preferential flow mechanism of rainfall recharge deep soil, stemflow and root can guide water infiltration and soil macropore flux in the further strengthening of preferential flow in soil, but even the human impact (mechanical tillage etc.) of the Loess Plateau and fruit forest research. From Changwu loess tableland area 20 years old apple orchard, using 4 g - L-1 (Brilliant Blue FCF) blue solution as a coloring agent, the use of spraying (6 replicates), dumping (3 Repeat) and trunk runoff (6 replicates) three kinds of dyeing tracer test, the spray pattern represents the normal rainfall of 50 mm infiltration, dumping on behalf of rainfall of 50 mm extreme rainfall runoff simulation, trunk trunk represent runoff (18 L stemflow). The rain infiltration. The major conclusions are as follows: (1) in the spray dyeing under the average depth is 0.28 m, the depth is shallow, uniform infiltration than the average of more than 0.65, more than 0.7 of the median, indicating water infiltration process for uniform part of a larger proportion, so that the piston flow is the main mechanism of rainfall in Loess apple the garden tableland infiltration. This is probably mainly by soil physical properties of Tableland orchard, deposition clayization and mechanical tillage and compaction caused. (2) the dumping under staining with an average depth of 0.53 m, the maximum depth is 0.59 m, the shallower depth show In extreme storm, big pore preferred path activation conditions of rain water in a short time is difficult to recharge deep soil water. (3) spraying conditions of water infiltration conditions of water infiltration than dumping more uniform (P0.05), shows that the extreme rainfall will increase the uniformity of water infiltration, increase the inflow of priority the proportion of infiltration. (4) when the root is good, little effect infiltration of water side trunk runoff simulation under water, almost one-dimensional infiltration method, the maximum depth of staining was 0.46 m, depth is shallow, that in the apple orchard in Loess Plateau rain is difficult to pass through the stem flow along the root deep soil water supply. (5) through the analysis and comparison of dead root and living root were found living roots (over 2 mm) does not have good effect and diversion, root rot (over 2 mm) the formation of infiltration channel has a good guide for the study did not find yellow; Soil rich large pore structure and fine root fruit trees (2 mm) due to seasonal death left in the soil pore. (6) the apple tree root system and root number, buried depth angle and horizontal ground for statistical analysis, found mainly in the soil surface level root tree roots, because the piston flow is the main mechanism of rainfall infiltration in Loess Tableland orchard, which makes the tree roots can maximize the utilization of rainfall infiltration water in the soil, and inferred when the surface of root rot will more likely to hinder the occurrence of the preferential flow horizontal, rainwater on deep soil water supply. Therefore, in the apple orchard in Loess Plateau Area, piston flow is the main mechanism of the deep soil water recharge, large pore and vertical root decay pathways may also be used as a water supply channel and deep soil water. The farmland and orchard rotation may be to maintain the fruit thinning The results of this study are important for revealing the mechanism of soil water supply, the causes of dry layer formation and the impact of more frequent extreme rainfall on soil water recharge mechanism under climate change.

【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】：2017
【分類號】：S152.7;S661.1

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