黄土丘陵区干化土壤水分修复能力试验研究

发布时间：2018-07-05 12:38

本文选题：黄土高原 + 土壤水分　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：黄土丘陵地区人工林地普遍存在土壤干化现象,并且随着林木年龄的增加,干化现象出现逐年加重的趋势。为了探索半干旱区典型覆盖措施下土壤水分的恢复能力,本文以修复林地干化土壤水分和防控林地土壤永久性干层为目标,采用野外大型土柱和大田覆盖的方法,通过定位监测和实地取样调查相结合的方法监测了土壤水分在生育期和非生育期内的变化规律,阐释了山地林地土壤典型覆盖下的自然修复能力,获得以下结果:1)在枣树生育期观测野外大型土柱试验证明,受降雨的影响,干化土壤水分逐月呈现递增趋势,但不同覆盖措施下土壤水分的增加有所区别,到9月份时,薄膜覆盖㧐碎树枝覆盖㧐裸地㧐生草覆盖(早熟禾)。生草覆盖与裸地相比,裸地的含水率高于生草覆盖的,说明裸地在当地较生草覆盖有利于土壤水分的恢复。三种无植物生长的典型覆盖处理下土壤储水增量随着时间的变化呈直线上升的关系,有植物种植的处理中(早熟禾),土壤储水增量与时间呈非线性关系。不同覆盖下土壤水分垂直变化不同,随着土层深度的增加,变异系数逐渐减小,生草覆盖(早熟禾)和裸地在200 cm以下,基本达到稳定,碎树枝覆盖在240 cm以下达到稳定,薄膜盖在340 cm以下达到稳定。2)大田试验观测得出的几种典型覆盖措施其对土壤影响规律与土柱试验得出的规律一致,即仍然表现出地膜覆盖碎树枝覆盖裸地生草覆盖的顺序。但由于大田试验有枣树生长耗水的原因,表现出几种覆盖措施下的土壤含水量均低于土柱试验结果,经过雨季后的土壤水分修复深度也较小,裸地和生草覆盖对土壤水分的修复深度达150 cm左右,碎树枝覆盖对土壤水分的修复深度达200 cm,薄膜覆盖对土壤水分的修复深度最大,超过260 cm。3)通过大型土柱试验在非生育期内土壤水分的观测,发现冬季是一年中土壤水分损失的最关键时期,裸地在0-230 cm范围土壤水分由16.88%减少到10.42%;生草覆盖在0-220 cm范围土壤水分由14.67%减少到11.35%;碎树枝覆盖在0-150cm范围土壤水分由18.77%减少到14.61%;薄膜覆盖0-300 cm范围土壤水分由20.51%减少到18.02%;土壤水分损失的深度分别为230 cm、220 cm、150 cm和300 cm。但是裸地和生草覆盖下的土壤水分几乎没有下渗运移,碎树枝覆盖和薄膜覆盖在上部土壤水分降低同时还有明显的下渗现象,碎树枝覆盖土壤水分下渗约300 cm,薄膜覆盖土壤水分下渗约450 cm。生草覆盖、裸地、碎树枝覆盖和薄膜覆盖处理下损失的土壤水分总和依次为68.42 mm、51.53 mm、47.88 mm和3.29 mm。薄膜覆盖下土壤水分损失几乎为零,其次为碎树枝覆盖、裸地和生草覆盖。综上所述,试验所涉及的几种典型覆盖措施对土壤水分有不同的影响,其中薄膜覆盖具有较强的增加林地土壤水分的作用,也就是说具有较好的土壤水分修复能力。同时,我们修复林地土壤干化土壤需要重视非生育期(冬季)的保墒覆盖措施,因为冬季是林地土壤水分损失最为严重的时期,这点在我们生产实践中还缺乏足够的重视。
[Abstract]:In the loess hilly area, the soil dryness exists generally in the artificial forestland, and with the increase of the tree age, the drying phenomenon is increasing year by year. In order to explore the restoration ability of soil moisture under the typical cover measures of the semi-arid area, this paper aims at restoring the soil moisture of the forestland and preventing and controlling the permanent soil dry layer of the woodland soil. The method of large soil column and field mulching in the field was used to monitor the change of soil moisture during the growth period and non fertility period by combining the method of location monitoring and field sampling. The natural restoration ability of the soil under typical mulching of the mountain forest soil was explained. The following results were obtained: 1) the large soil column test was observed in the field of date tree growth. It was proved that the dry soil moisture showed an increasing trend month by month under the influence of rainfall, but the increase of soil moisture under different coverage measures was different. By September, the film covered? Covered branches covered? Bare land? Grasses covered (Kentucky bluegrass). The water content of bare land was higher than that of raw grass. Soil water storage is beneficial to the restoration of soil moisture. The soil water storage increment of three types of plant growth without plant growth is a linear rise with time, and there is a nonlinear relationship between the increment of soil water storage and time. The vertical change of soil moisture under different coverage is different with the depth of soil layer. The coefficient of variation decreases gradually. Grass mulching (POA grasses) and bare land are below 200 cm, basically stable, the broken branches cover less than 240 cm, and the film cover is under 340 cm to reach the stable.2). The soil water content under several covering measures is lower than the result of soil column test. The soil moisture restoration depth after the rainy season is smaller, and the soil moisture restoration is deep in bare land and grass cover. At about 150 cm, the restoration depth of soil moisture by broken branches is 200 cm, and the maximum restoration depth of soil moisture by film mulching is more than 260 cm.3. It is found that winter is the most critical period of soil moisture loss in one year through the observation of soil moisture in the non fertility period by large soil column test. The soil moisture in bare land is 0-230 cm range. Reduced from 16.88% to 10.42%; soil moisture was reduced from 14.67% to 11.35% in the range of 0-220 cm, and soil moisture in the 0-150cm range decreased from 18.77% to 14.61%, and the soil moisture in the cover 0-300 cm range was reduced from 20.51% to 18.02%, and the depth of soil moisture loss was 230, 220 cm, 150 cm and 300 cm., respectively. Soil moisture under ground and grass covered soil has almost no infiltration, while the broken branches and thin film covered soil moisture decreased at the same time, and there were obvious infiltration. The broken branches covered soil moisture under 300 cm, and the film covered soil moisture about 450 cm. and covered with grass, bare land, shredded branches and film cover treatment. The loss of soil moisture in turn is 68.42 mm, 51.53 mm, 47.88 mm and 3.29 mm. thin film covered soil moisture loss almost zero, followed by broken branches covering, bare land and grass cover. In summary, several typical cover measures involved in the experiment have different effects on soil moisture, in which film mulching has a strong increase of forest land. The effect of soil moisture means a good ability to repair soil moisture. At the same time, we need to pay more attention to the soil moisture conservation measures in the non fertility period (winter), because winter is the most serious time of the loss of soil moisture in the woodland, which is still lack of enough attention in our production practice.
【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】：2015
【分类号】：S152.7

【引证文献】