高频滴灌抑盐机理研究
发布时间：2018-08-07 17:06
【摘要】：土壤盐分运移过程包括“盐随水走”的入渗分布过程和盐随土壤水分蒸发的返盐运动过程。总体的抑盐效果应该取决于土壤水分压盐的深度和速度,以及蒸发返盐的速度。因此,当利用高频滴灌抑盐时,其灌水频率应该依据地表蒸发强度而定。本文以土壤水动力学和土壤溶质运移的基本原理为基础,通过室内土槽试验来研究高频滴灌抑盐机理。试验滴头设计流量为1L/h,各处理的滴水总量均为10 L。试验控制因素滴灌频率设4个处理,分别标注为IF1、IF2、IF3和IF4;相应的单次滴水量分别为2 L、3.33 L、5 L和10 L;滴水间隔分别为1 d、2 d、3 d和4 d。分析单次滴水量和滴水间隔天数对土壤盐分运移的影响以及导致的脱盐效率,探明高频滴灌的抑盐机理。蒸发强度设置4个处理,分别标注为EI1、EI2、EI3和EI4,讨论蒸发对土壤盐分的返盐作用。得到以下结果:(1)高频滴灌时,滴水可使土壤盐分即刻向下层运移即盐分向下运移速度快,而蒸发不会使土壤盐分即刻向上层运移即此时盐分向上运移速度较慢;只有滴水间隔天数较大时(大于2 d),盐分才会沿土层垂直方向上、下波动。(2)在没有地下水补充和地表蒸发不强烈的情况下,高频滴灌的抑盐作用主要取决于单次滴水量,在总滴水量相同的情况下,单次滴水量越大,土壤盐分淋洗的越深,抑盐效果越好。(3)在没有地下水补充和地表蒸发不强烈的情况下,滴水间隔天数所造成的蒸发返盐量有限,只是土壤下层积盐深度变浅,而土壤上层仍处在脱盐状态;高频滴灌抑盐,不绝对取决于蒸发历时,而是取决于水盐的耦合的状况。(4)在没有地下水补充的情况下,蒸发强度的增加所造成的蒸发返盐量有限。蒸发强度对于0~20cm土层的脱盐影响明显。增大蒸发强度时,蒸发不会使土壤盐分立即随水分向上层运移;只有滴水间隔天数较大时(大于2 d),盐分才会沿土层垂直方向上、下波动。(5)土壤下层的积盐层是动态的,滴水入渗时土壤上层脱盐速度快,而下层则逐步积盐。稳定蒸发深度内的上层土壤始终处于脱盐状态,而下层积盐区含盐率大,但是此处的含水率少,已超出稳定蒸发深度,土壤导水率小,盐分主要以弥散形式向上运移,返盐运移速度慢,所以盐分上升高度很有限。(6)高频滴灌抑盐主要是抑制底部的盐分。在高频滴灌时上层水分含量高处于稳定蒸发阶段,对流运移作用大是返盐主力,但是高频滴灌时上层含盐量少,处于脱盐状态,虽然可以返盐但是返上去的量不多;而下层虽然含盐量高是积盐层,但是下层含水率小、导水率也小,水分运移速度慢,盐分主要以对流弥散运移为主,底部盐分受蒸发作用而波动,但是返盐量小。因此,土壤的水盐耦合同步性决定了高频滴灌的抑盐效果。
[Abstract]:The process of soil salt migration includes the infiltration and distribution of salt with water and the movement of salt with evaporation of soil water. The overall effect of salt suppression should depend on the depth and speed of salt pressure in soil water and the rate of salt returning from evaporation. Therefore, when high frequency drip irrigation is used to suppress salt, the irrigation frequency should be determined by the surface evaporation intensity. Based on the basic principles of soil hydrodynamics and soil solute transport, this paper studies the salt suppression mechanism of high frequency drip irrigation by laboratory soil trough test. The designed flow rate of the emitter is 1 L / h, and the total amount of drip water treated is 10 L / h. Four treatments were used to control the frequency of drip irrigation, which were labeled IF1, IF2, IF3 and IF4, respectively, the corresponding single drip water volume was 2 L, 3.33 L, 5 L and 10 L, and the interval of drip water was 1 d ~ 2 d ~ 3 d and 4 d, respectively. The effects of single drip amount and interval days on soil salt migration and desalination efficiency were analyzed. The salt inhibition mechanism of high frequency drip irrigation was proved. The evaporation intensity was divided into 4 treatments, marked as EI1, EI2EI3 and EI4, respectively. The effect of evaporation on soil salt recovery was discussed. The results are as follows: (1) when high frequency drip irrigation, drip water can make the downward layer of soil salt move quickly, but evaporation will not make the soil salt immediately move to the upper layer, that is, the speed of upward movement of soil salt is relatively slow; Only when the interval of drip water is longer (more than 2 d), salt) will it fluctuate along the vertical direction of soil layer. (2) when there is no groundwater recharge and surface evaporation is not strong, the inhibition effect of high frequency drip irrigation mainly depends on the amount of single drip. In the case of the same amount of total drip water, the greater the amount of single drip, the deeper the soil salt leaching, the better the salt inhibition effect. (3) when there is no groundwater replenishment and surface evaporation is not strong, the amount of evaporative salt return caused by the days of drip interval is limited. It is only that the depth of salt deposits in the lower layer of the soil is shallower, while the upper layer of the soil is still in a desalination state; the high frequency drip irrigation for salt suppression does not depend absolutely on the evaporation duration, but on the coupling of water and salt. (4) in the absence of groundwater recharge, The increase in evaporation intensity results in a limited amount of evaporation back salt. Evaporation intensity has a significant effect on the desalination of 0~20cm soil. When the evaporation intensity is increased, the soil salt will not move to the upper layer immediately with the water content; only when the interval of drip water is longer (> 2 d), salt) will it fluctuate along the vertical direction of the soil layer. (5) the salt layer of the lower layer of the soil is dynamic, and the salt layer of the lower layer of the soil is dynamic. The desalination rate of the upper layer of the soil is fast, while the lower layer of the soil is gradually accumulated salt. The upper soil in the stable evaporation depth is always in the desalination state, but the salt content in the lower stratified salt area is large, but the water content here is less, which has exceeded the steady evaporation depth, the soil water conductivity is small, and the salt mainly moves upward in the form of dispersion. Because of the slow movement of back salt, the rising height of salt is very limited. (6) High frequency drip irrigation mainly inhibits the salt content at the bottom. In the high frequency drip irrigation, the high water content in the upper layer is in the stable evaporation stage, and the convection migration is the main force of salt return, but in the high frequency drip irrigation, the upper layer has less salt content and is in the desalting state. Although the lower layer with high salt content is a accumulative salt layer, the water content in the lower layer is small, the water conductivity is also small, the speed of water migration is slow, the salt content is mainly convection and dispersion migration, the bottom salt is fluctuated by evaporation, but the amount of back salt is small. Therefore, the salt suppression effect of high frequency drip irrigation is determined by soil water and salt coupling synchronism.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S275.6;S156.4
[Abstract]:The process of soil salt migration includes the infiltration and distribution of salt with water and the movement of salt with evaporation of soil water. The overall effect of salt suppression should depend on the depth and speed of salt pressure in soil water and the rate of salt returning from evaporation. Therefore, when high frequency drip irrigation is used to suppress salt, the irrigation frequency should be determined by the surface evaporation intensity. Based on the basic principles of soil hydrodynamics and soil solute transport, this paper studies the salt suppression mechanism of high frequency drip irrigation by laboratory soil trough test. The designed flow rate of the emitter is 1 L / h, and the total amount of drip water treated is 10 L / h. Four treatments were used to control the frequency of drip irrigation, which were labeled IF1, IF2, IF3 and IF4, respectively, the corresponding single drip water volume was 2 L, 3.33 L, 5 L and 10 L, and the interval of drip water was 1 d ~ 2 d ~ 3 d and 4 d, respectively. The effects of single drip amount and interval days on soil salt migration and desalination efficiency were analyzed. The salt inhibition mechanism of high frequency drip irrigation was proved. The evaporation intensity was divided into 4 treatments, marked as EI1, EI2EI3 and EI4, respectively. The effect of evaporation on soil salt recovery was discussed. The results are as follows: (1) when high frequency drip irrigation, drip water can make the downward layer of soil salt move quickly, but evaporation will not make the soil salt immediately move to the upper layer, that is, the speed of upward movement of soil salt is relatively slow; Only when the interval of drip water is longer (more than 2 d), salt) will it fluctuate along the vertical direction of soil layer. (2) when there is no groundwater recharge and surface evaporation is not strong, the inhibition effect of high frequency drip irrigation mainly depends on the amount of single drip. In the case of the same amount of total drip water, the greater the amount of single drip, the deeper the soil salt leaching, the better the salt inhibition effect. (3) when there is no groundwater replenishment and surface evaporation is not strong, the amount of evaporative salt return caused by the days of drip interval is limited. It is only that the depth of salt deposits in the lower layer of the soil is shallower, while the upper layer of the soil is still in a desalination state; the high frequency drip irrigation for salt suppression does not depend absolutely on the evaporation duration, but on the coupling of water and salt. (4) in the absence of groundwater recharge, The increase in evaporation intensity results in a limited amount of evaporation back salt. Evaporation intensity has a significant effect on the desalination of 0~20cm soil. When the evaporation intensity is increased, the soil salt will not move to the upper layer immediately with the water content; only when the interval of drip water is longer (> 2 d), salt) will it fluctuate along the vertical direction of the soil layer. (5) the salt layer of the lower layer of the soil is dynamic, and the salt layer of the lower layer of the soil is dynamic. The desalination rate of the upper layer of the soil is fast, while the lower layer of the soil is gradually accumulated salt. The upper soil in the stable evaporation depth is always in the desalination state, but the salt content in the lower stratified salt area is large, but the water content here is less, which has exceeded the steady evaporation depth, the soil water conductivity is small, and the salt mainly moves upward in the form of dispersion. Because of the slow movement of back salt, the rising height of salt is very limited. (6) High frequency drip irrigation mainly inhibits the salt content at the bottom. In the high frequency drip irrigation, the high water content in the upper layer is in the stable evaporation stage, and the convection migration is the main force of salt return, but in the high frequency drip irrigation, the upper layer has less salt content and is in the desalting state. Although the lower layer with high salt content is a accumulative salt layer, the water content in the lower layer is small, the water conductivity is also small, the speed of water migration is slow, the salt content is mainly convection and dispersion migration, the bottom salt is fluctuated by evaporation, but the amount of back salt is small. Therefore, the salt suppression effect of high frequency drip irrigation is determined by soil water and salt coupling synchronism.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S275.6;S156.4
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相关期刊论文 前10条
1 张磊;曾胜和;马军勇;梁飞;王国栋;;灌水频率对膜下滴灌水稻土壤水盐分布及产量的影响[J];西北农业学报;2014年03期
2 王峰;孙景生;刘祖贵;宁慧峰;强小Z，
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