不同覆盖方式对砂壤土水盐运移规律影响研究

发布时间：2018-06-25 16:20

本文选题：覆盖方式 + 砂壤土　；参考：《兰州理工大学》2017年硕士论文

【摘要】：西北地区降雨稀少,蒸发强烈,土壤水分易通过大气蒸发而损失,水分难以保持。而土壤表面采用覆盖处理可避免土壤直接与空气接触,减小因蒸腾作用造成的水分损失,改变表层土壤的结构和理化性质,进而影响到土壤水分入渗、蒸发和盐分运移的过程。本研究拟通过室内外模拟实验,设覆砂(S)、覆膜+覆砂(MS)、覆砂+覆秸秆(SJ)、覆膜+覆秸秆(MJ)和无覆盖(CK)这5种方式,对不同覆盖方式下砂壤土水盐运移规律展开对比研究。主要内容有:(1)通过室内土柱模拟实验,对比研究了不同覆盖方式对砂壤土水分入渗规律的影响。结果表明:土壤表面采用覆盖处理会影响湿润锋推进距离与累积入渗量,抑制土壤水分的入渗能力,对水分入渗具有一定阻渗作用,其表现为覆膜+覆砂最强,覆膜+覆秸秆次之,其次为覆砂+覆秸秆,覆砂最弱。同时,土壤水分入渗形成湿润锋的推进距离与时间符合幂函数关系,相关系数介于0.9930~0.9991;土壤水分累积入渗量与时间符合Kostiakov入渗公式,相关系数介于0.9916~0.9980;湿润锋推进距离与累积入渗量符合线性关系,相关系数介于0.9991~0.9999。(2)通过室外蒸发模拟实验,对比研究了不同覆盖方式对砂壤土水分蒸发规律的影响。结果表明:土壤表面采用覆盖处理的蒸发变化趋势和CK的基本一致,只是覆盖处理的蒸发变化趋势较平缓,CK处理的蒸发变化趋势起伏较大。同时,覆盖处理的累积蒸发量均小于小于CK的,S、MS、SJ、MJ和CK处理的累积蒸发量分别为450.6g、375.1g、712.2g、473.3g和1823.6g,与CK相比,覆盖处理的累积蒸发量分别减小了75.30%、79.40%、60.90%、74.00%,表明土壤表面采用覆盖处理会对土壤水分的蒸发产生抑制作用。土壤水分累积蒸发量与时间符合对数关系,相关系数介于0.9243~0.9800。(3)通过在5块面积均为1m2的正方形小区域内进行的室外模拟实验和室内土柱模拟实验,对比研究了不同覆盖方式对砂壤土水盐运移规律的影响。结果表明:土壤表面采用不同覆盖处理均具有明显的蓄水保墒效果,其保水效果为MSSJSMJ。同时,土壤表面采用的覆盖处理也能有效抑制土壤盐分向表层积聚,并对土壤盐分的垂向运移范围产生影响。有覆盖处理的土壤盐分的运移主要在0~20cm范围内发生,无覆盖处理的土壤盐分的运移主要在0~35cm范围内发生。这对改良盐渍化土壤和防治土壤的次生盐渍化有着重要的意义。(4)通过室内外模拟实验,对比分析了土壤表面采用不同覆盖处理对土壤水分入渗、蒸发和盐分运移规律的影响,以及考虑到实验区气候特征和该地区砂石资源容易获取的特点,认为砂石覆盖方式是更适合西北地区的覆盖方式。
[Abstract]:In Northwest China, rainfall is rare, evaporation is strong, soil moisture is easily lost through atmospheric evaporation, water is difficult to maintain. Soil surface mulching can avoid the direct contact between soil and air, reduce the water loss caused by transpiration, change the structure and physical and chemical properties of surface soil, and then affect the process of soil water infiltration, evaporation and salt migration. Through the indoor and outdoor simulation experiments, this paper presents a comparative study on the water and salt migration of sandy loam under different mulching modes, including sand covering (S), mulching sand (MS), mulching straw (SJ), mulching straw (MJ) and no mulching (CK). The main contents are as follows: (1) the effects of different mulching methods on the infiltration law of sandy loam soil were studied by laboratory soil column simulation experiment. The results showed that mulching treatment on soil surface affected the advance distance and cumulative infiltration amount of soil moisture front, inhibited the infiltration ability of soil water, and had a certain effect on water infiltration, which was the strongest in mulching sand. The second was mulching straw, followed by sand mulching straw, sand is the weakest. At the same time, the advancing distance and time of forming wetting front of soil moisture infiltration accord with power function, the correlation coefficient is between 0.9930 and 0.9991, and the cumulative infiltration amount and time of soil water infiltration accord with Kostiakov infiltration formula. The correlation coefficient is between 0.9916 and 0.9980, and the relation between the advancing distance of wetting front and the cumulative infiltration is linear, and the correlation coefficient is between 0.9991 and 0.999. (2) the effects of different mulching methods on the water evaporation law of sandy loam soil are compared through outdoor evaporation simulation experiments. The results showed that the evaporation change trend of soil surface treated by mulching treatment was basically consistent with that of CK, but the trend of evaporation change of mulching treatment was larger than that of CK treatment. At the same time, the accumulative evaporation of the mulching treatment was less than that of the control, the accumulative evaporation of the treatments were 450.6 g / g ~ 375.1g / g ~ 712.2g / g ~ 473.3g and 1823.6g / g, respectively. The cumulative evaporation of mulching treatment decreased 75.30% 79.400.90% and 74.00% respectively, which indicated that soil surface mulching treatment could inhibit soil water evaporation. The cumulative evaporation of soil moisture was in logarithmic relation with the correlation coefficient between 0.9243 and 0.98000.3.The results of outdoor simulation and indoor soil-column simulation were carried out in five small square areas with 1m2 area. The effects of different mulching methods on water and salt migration in sandy loam were studied. The results showed that the soil surface with different mulching treatments had obvious effect of water storage and moisture conservation, and its water retention effect was MSSJSMJ. At the same time, the mulching treatment of soil surface can also effectively inhibit the accumulation of soil salt to the surface, and have an effect on the vertical migration range of soil salt. The salt migration of soil with mulch treatment occurred mainly in 0~20cm range, and that of soil salt with no mulching treatment mainly occurred in 0~35cm range. It is of great significance to improve the salinized soil and control the secondary salinization of soil. (4) through indoor and outdoor simulation experiments, the effects of different mulching treatments on soil water infiltration, evaporation and salt migration are compared and analyzed. Taking into account the climatic characteristics of the experimental area and the easy to obtain the sand and stone resources in this area, it is considered that the sand and stone cover is more suitable for the northwest region.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152.7

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