咸淡水组合灌溉模式下盐碱土水盐分布及改良效果的试验研究

发布时间：2018-03-19 19:22

本文选题：微咸水　切入点：灌溉模式　出处：《山东理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：以取自山东省东营市的重度盐碱土为研究对象,进行了室内垂直一维积水入渗试验,研究微咸水矿化度、不同咸淡水组合次序和组合比例条件下,土壤剖面含水率分布规律,并分析一维代数模型在土壤剖面含水率模拟中的适用性;分析不同灌溉模式下的土壤剖面全盐量及钠钙镁离子垂直分布特征;采用达标脱盐率、达标脱盐深度、SAR、ESP等指标评价改良效果。主要研究结果如下:(1)微咸水参与灌溉有利于提高灌溉结束后的土壤剖面含水率,且不同的灌水模式对土壤剖面上含水率的影响不尽相同。直接灌溉条件下,矿化度为4 g·L-1的微咸水灌溉结束后的土壤剖面含水率最大,相较于淡水直接灌溉,在10-45 cm土层深度范围内,各个土层含水率平均提高4%;组合灌溉条件下,先咸后淡组合次序下的土壤剖面含水率大于先淡后咸,且均匀程度更高,而淡水比例决定了灌溉结束后土壤剖面含水率与淡水直接灌溉的相似程度,淡水比例越大,则相似程度越高。(2)不同灌溉条件下的一维代数模型的土壤剖面含水率模拟精度存在一定差异。在微咸水直接灌溉条件下,4 g·L-1微咸水一维代数模型模拟结果精度最低,均方根误差(RMSE)和符合度指数(D)分别为:2.29%和0.90;咸淡水组合灌溉条件下,先淡后咸模拟精度优于先咸后淡,且不同矿化度微咸水的一维代数模型模拟精度受组合比例影响显著;但所有实验条件下的模拟结果均方根误差(RMSE)均小于2.80%,符合度指数(D)均大于0.90,说明一维代数模型对描述微咸水灌溉条件下重度盐碱土剖面含水率具有较好的适用性。(3)相较于直接灌溉,先咸后淡组合次序有利于淋洗中上层土壤中的盐分,而先淡后咸组合次序有利于淋洗下层土壤中的盐分,淡水比例越大,则全盐量达到淡水直接灌溉条件的土层深度越大;当矿化度低于3 g·L-1时,先咸后淡组合次序使得土壤中钠离子淋洗程度超过淡水直接灌溉,且淡水比例越大,达到该结果的土层深度越大,其中,在0-40 cm土层深度范围内,2 g·L-1微咸水先咸后淡组合灌溉相较于直接灌溉的钠离子淋洗量平均提高15%以上;先灌淡水加速淋洗深层土壤钙离子,后灌淡水则加速淋洗上层土壤钙离子,淡水比例越大,钙离子淋洗效果较优的土层深度范围越大,随着淡水比例的增加,先咸后淡组合次序下的钙离子淋洗效果达到淡水直接灌溉效果的土层深度分别提升至15 cm、25 cm和35 cm;而微咸水直接灌溉对镁离子的淋洗程度超过淡水,且先咸后淡有利于淋洗深层土壤中的镁离子,而先淡后咸有利于淋洗中上层土壤中的镁离子,微咸水比例越大,镁离子淋洗程度更优的土层深度越大。(4)相较于微咸水直接灌溉,咸淡水组合灌溉不仅有利于增加达标脱盐深度,还有利于提高达标脱盐深度范围内的平均脱盐率,同时改善该范围内的脱盐均匀性;当土层深度超过40 cm时,直接灌溉和组合灌溉条件下的全盐量、SAR和ESP都会出现峰值,使得土壤质量恶化。当矿化度超过4 g·L-1时,在5-15 cm土层深度范围内,直接灌溉使得土壤质量出现恶化,但先咸后淡组合灌溉有利于改善这一问题,且淡水比例越大,改善效果越明显。
[Abstract]:From Shandong city of Dongying Province in the heavy saline soil as the research object, the indoor vertical one-dimensional infiltration experiments, study of brackish water salinity, brackish water and different combination order mix conditions, soil water content distribution, and analysis of one dimensional algebraic models in simulation of soil water content; the analysis of vertical distribution of calcium and magnesium salt in soil profile under different irrigation patterns and characteristics of the desalting rate of sodium; desalting, depth, SAR, ESP and other indicators of improvement effect evaluation. The main results are as follows: (1) the brackish water in irrigation is conducive to improve the soil moisture profile after the end of the irrigation rate and irrigation mode the different effects on soil moisture content is not the same. The direct irrigation condition, degree of mineralization of soil moisture profile of brackish water irrigation 4 g L-1 after the end of the maximum rate, compared with fresh water Direct irrigation at 10-45 cm soil depth range, the soil moisture content increased 4%; condition of combined irrigation, soil moisture profile first light after the combination of the salty rate is greater than after the first light salty, and more uniform, while the proportion of fresh water determines the soil water content similarity and freshwater irrigation directly after irrigation, water ratio increases, the degree of similarity is high. (2) there are some differences in soil profile moisture simulation accuracy model under different irrigation conditions in brackish water. One dimensional algebraic direct irrigation condition, 4 g - L-1 of brackish water one dimensional algebraic model simulation results the lowest precision, the root mean square error (RMSE) and conformity index (D) were 2.29% and 0.90; the combination of salt and fresh water irrigation condition, after the first light salty salty light after the simulation precision better than the first, and the model of different salinity of brackish water by the combination of one-dimensional algebraic simulation accuracy ratio influence Significant; but the result of the simulation of all the experimental conditions of the root mean square error (RMSE) were less than 2.80%, with index (D) were greater than 0.90, indicating one dimensional algebraic model for describing the brackish water irrigation under the condition of severe saline alkali soil profile moisture has good applicability. (3) compared to the direct irrigation, first salty light combination is conducive to salt leaching in the upper layer, and after the first light salty combination is conducive to leaching in the lower soil salinity, water depth, and the greater the proportion of the total salt content reached fresh water irrigation more directly; when the salinity is lower than 3 G - L-1, the first light after the combination of salt the order of the sodium ion leaching degree in soil than fresh water irrigation and water directly, and the greater the proportion of soil depth reached the result is bigger, which, at 0-40 cm soil depth range, compared with the direct combination of sodium light Irrigation irrigation 2 G - L-1 first salty brackish water Ion leaching amount increased by more than 15% on average; the first irrigation water to accelerate the leaching of deep soil calcium, after irrigation water accelerated the leaching of upper soil calcium, fresh water and the greater the proportion of calcium ion leaching optimum soil depth is larger, with the increase of the proportion of fresh water, the depth of soil calcium leaching effect after the combination of light salty in order to directly under freshwater irrigation effects were increased to 15 cm, 25 cm and 35 cm; and the brackish water irrigation directly leaching degree of Mg ions than fresh water, and the first light after salt is conducive to magnesium ion in deep soil leaching, and after the first light salty to the upper soil magnesium ion leaching in brackish water, the greater the proportion of soil depth, the magnesium ion leaching degree better more. (4) compared to brackish water irrigation directly, brackish water irrigation combination will not only help to increase the desalting depth, and to improve the desalting depth The average desalination rate range, and improve the uniformity of the desalting range; when the soil depth is more than 40 cm, the total salt content directly combined irrigation and irrigation condition, SAR and ESP will peak, so the soil quality deterioration. When the salinity is more than 4 g, L-1, cm in 5-15 the depth range of direct irrigation makes the soil quality deterioration, but the first salty light after combination irrigation is conducive to the improvement of the problem, and the greater the proportion of fresh water, improve the effect is more obvious.

【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S156.4

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