黄土塬区苹果园降雨入渗机制研究

发布时间：2018-02-13 18:14

本文关键词： 黄土塬区苹果园染色示踪活塞流根系　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：黄土塬区地处中国西北部,是黄土高原苹果的主产区。但该区水资源极缺,80%以上果园是旱作农业区。在高龄果园土壤深层存在严重的干燥化现象,深度甚至可深达10m以下,严重制约了果树生长和生产,由此迫切需要探明黄土塬区苹果园降雨入渗机制。较多研究揭示在自然森林和人工林地中优先流是降雨补给深层土壤的机制、树干径流及根系导流可以水分入渗通量及土壤中的大孔隙进而加强优先流,但在土壤均匀、受人类影响(机械翻耕等)的黄土塬区果林地研究较少。选取长武黄土塬区20年树龄苹果园,使用4 g·L-1的亮蓝溶液(Brilliant Blue FCF)作为染色剂,分别采用喷洒(6个重复)、倾倒(3个重复)和树干径流模拟(6个重复)三种方式进行染色示踪试验,其中,喷洒方式代表雨量为50 mm的正常降雨入渗,倾倒方式代表雨量为50 mm的极端性暴雨入渗,树干径流模拟代表树干径流方式(18 L树干径流量)的雨水入渗。研究取得主要结论如下:(1)在喷洒方式下染色平均深度为0.28 m,深度较浅,均匀入渗比平均值超过0.65,中位数超过0.7,说明水分入渗过程中均匀部分所占比重较大,由此表明活塞流是黄土塬区苹果园降雨入渗的主要机制。这可能主要是由塬区果园的土壤物理性质、淀积粘化作用和机械耕作及压实造成的。(2)倾倒方式下染色平均深度为0.53 m,最大深度为0.59 m,深度较浅,表明在极端暴雨、激活大孔隙等优先路径的条件下雨水也很难短时间内补给深层土壤水。(3)喷洒条件下水分入渗比倾倒条件下水分入渗更均匀(p0.05),表明极端性暴雨会增大水分入渗的不均匀性,增大优先流入渗的比重。(4)当果树根系良好时,树干径流模拟方式下的水分侧渗影响较小,水分以近乎一维的方式入渗,染色最大深度为0.46 m,深度也较浅,表明在黄土塬区苹果园雨水较难通过树干径流的方式沿着根系补给深层土壤水。(5)通过死根系与活根系染色比较分析,发现活根系(≥2 mm)不具有良好的导流作用,而腐烂根系(≥2 mm)形成的入渗通道则具有良好的导流作用;本研究中并未发现黄土丰富的大孔隙结构及果树细根系(2 mm)由于季节性死亡在土壤中留下的孔隙。(6)通过对苹果树次生根系数目、埋藏深度及根系与水平地面夹角进行统计分析,发现在土壤表层果树根系以水平根系为主,由于活塞流是黄土塬区苹果园降雨入渗的主要机制,从而使得果树根系可以最大程度利用降雨入渗土壤中的水分,同时推断当表层根系腐烂时会更可能发生横向优先流,从而阻碍雨水对深层土壤水的补给。因此,在黄土塬区苹果园,活塞流是深层土壤水降雨补给的主要机制,大孔隙和腐烂垂直根系等通道也可能作为雨水补给深层土壤水的途径。通过农田-果园轮作和间伐可能是维持果园可持续生产的必要手段。研究结果对揭示苹果园土壤水补给机制、干层形成原因、以及气候变化下更频繁的极端性降雨对土壤水补给机制的影响具有重要意义。
[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.

【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152.7;S661.1

【参考文献】