湿润速度与化学材料对土壤水力特性的影响及机理研究

发布时间：2018-03-03 23:03

本文选题：土壤　切入点：湿润速度　出处：《内蒙古农业大学》2016年博士论文　论文类型：学位论文

【摘要】：土壤结构不良是影响干旱半干旱地区农业发展的根本性问题,近年来研究化学调控材料改良措施的趋势蔚然成风。聚丙烯酰胺(Polyacrylamide,简称PAM)和高吸水性树脂(Super Absorbent Polymer,简称SAP)因其独特的分子结构和水解特性已经在土壤入渗和土壤水分运动等方面发挥了积极的作用,但是其影响机理仍然不是十分明确,导致两种改良材料在不同类型土壤中推广应用还存在一些阻碍。由于两种材料与土壤结合发挥自身作用并不是一蹴而就,需要一定的作用时间来完成,所以不同的水流湿润速度和测定阶段就导致了两种材料不同的作用效果,而这方面的研究却并不多见。为此,本文通过室内试验与少部分田间试验相结合的方法,研究了不同湿润速度和两种材料对土壤水力特性的影响,并且通过测定土壤物理参数等手段探索影响机理,旨在探讨湿润速度和化学材料对土壤水分运动的影响规律,为PAM和SAP在土壤结构改良方面的应用提供必要的数据支撑和理论指导,研究结果如下：(1)湿润速度显著影响土壤水力性质：湿润速度越大,同一吸力下的土壤质量含水率越大,对于ESP值较高的粉砂壤土和粉质壤土,湿润速度对土壤水分特征曲线的影响程度减弱；湿润速度显著影响土壤累计入渗量和入渗速率,湿润速度越快,土壤累计入渗量越少,入渗速率越低,四种土壤均呈现这样的变化规律,随着湿润速度的加快,累计入渗量降低幅度在10.32%～32.67%之间变化,入渗速率减小幅度在24.16%～31.37%之间变化；湿润速度越大,土壤饱和导水率越小,湿润速度由0mm/h增加至16.25mm/h时,土壤饱和导水率降低幅度在17.08%-31.51%之间。(2)湿润速度之所以对土壤水力性质产生影响是因为水流湿润过程的剪切力影响了土壤孔隙结构,湿润速度不同,剪切力的大小就不同,对土壤孔隙结构的影响程度亦不尽相同。湿润速度越大,土壤结构破坏越明显,孔隙度越低,导致了土壤质量含水率越大,土壤饱和导水率也越低。同时湿润速度的差异还改变了土壤孔隙分布状况的不同,尤其是土壤大孔隙含量的多少,通过试验表明湿润速度越大,土壤非毛管孔隙率和土壤导气率越小。(3)PAM能够增加土壤持水能力,增加土壤水平扩散速率：在影响土壤入渗性能方面,在不同阶段呈现不同的规律：在湿润阶段,施用PAM阻碍了土壤中的水流运动,土壤累计入渗量降低范围在11.19%-29.85%之间;而在连续流阶段,施用PAM却促进了水流运动,土壤稳定入渗率增加幅度在25.98%-88.57%范围内变化：PAM之所以在不同阶段对土壤入渗产生不同的影响,是由于PAM本身的水解特性有关,在湿润阶段,干粉PAM遇水后逐渐水解,分子链不断延展伸长堵塞了土壤孔隙,阻碍了水流运动,而到了连续流阶段.经过了干燥后再湿润的PAM已经完全水解.发挥了稳固土壤结构的作用：此外,PAM还使得土壤饱和导水率减小,减小幅度在8.25%-17.11%之间。(4)SAP同样能够增加土壤持水能力,增加土壤水平扩散速率;在影响土壤入渗性能方面,无论是湿润阶段还是连续流阶段均能起到促进水流入渗的作用。SAP处理使土壤累计入渗量增加11.19%-29.85%,稳定入渗率提高5.71%-25.00%;SAP之所以对土壤入渗产生积极的影响,是由于SAP吸水后体积迅速膨胀,改变了土壤结构,使得土壤孔隙含量特别是大孔隙含量增加,从而为土壤中水流的运动提供了通道。(5)PAM和SAP之所以对土壤水力特性产生影响,主要是因为PAM和SAP改变了土壤的结构。PAM和SAP都能提高土壤总孔隙率,对于不同类型的土壤,提高幅度在2.76%-16.18%之间变化,另外PAM和SAP对土壤孔隙分布也产生了影响,在不同的作用时间影响效果并不相同：在两种材料遇水湿润阶段,PAM增加9.38%-21.59%的毛管孔隙率,同时降低土壤非毛管孔隙率和导气率,降低幅度在7.24%-16.16%之间：而SAP却降低了土壤毛管孔隙率,降低幅度在11.16%-20.10%之间变化,同时增加了25.23%-63.48%的土壤非毛管孔隙率和土壤导气率。经过了干湿循环后,PAM与土壤充分结合,降低9.33%～33.29%的土壤毛管孔隙率,同时增加土壤非毛管孔隙率和土壤导气率,增加幅度均达到30%以上,在31.63%-37.45%之间,而SAP处理的土壤毛管孔隙率较对照有所增加,增加幅度在5.74%-20.21%之间变化,同时也提高了土壤非毛管孔隙率和土壤导气率,提高幅度在10.02%-15.41%之间。此外PAM和SAP还能够增加土壤团聚体含量,特别是PAM能够显著增加团聚体的水稳定性。PAM和SAP均改变了土壤的微观结构,PAM使土壤结构更加密实,颗粒表面的层次感减弱,而SAP使土壤颗粒的层次更加分明。(6)统计结果表明,施用PAM和SAP均能达到优化土壤结构和水力特性参数的目的,且四种类型土壤均在PAM施用量为45kg/hm2时各项指标达到最优。在生产实践中,PAM和SAP均起到了增加作物整个生育期土壤亚表层和根层的土壤含水率,同时增加了作物产量,施用PAM的小麦增产率达到19.11%,而施用SAP的胡萝卜增产率为16.78%。说明PAM和SAP起到了提高水分利用效率和增加产量的作用。
[Abstract]:The soil structure is the fundamental problem of adverse effects of agricultural development in arid and semiarid area, studies on chemical control of material improvement measures in recent years become the trend. Polyacrylamide (Polyacrylamide, referred to as PAM) and superabsorbent resin (Super Absorbent Polymer, referred to as SAP) because of its unique molecular structure and hydrolysis characteristics has been in terms of soil infiltration and the soil water movement has played a positive role, but its influence mechanism is still not very clear, resulting in two kinds of improved materials applied in different soil types. There are still some obstacles due to the two kinds of materials combined with soil to play their role is not easy, need a period of time to complete, so the water wetting rate of different and the measurement period leads to the effect of two kinds of different materials, and the research of this aspect is rare. Therefore, this article through The indoor test method and some field test combination, the effects of different wetting rate and two kinds of materials on soil hydraulic properties, and through the determination of soil physical parameters and other means to explore the influence mechanism, aims to explore the wetting velocity and chemical material influence the dynamic of soil moisture, provide theoretical support and guidance necessary data the application of PAM and SAP in the improvement of soil structure, the research results are as follows: (1) wetting rate had significant effect on soil hydraulic properties: wetting velocity increasing, the content of soil water quality under the same suction rate is high, for the high ESP value of silty loam and silty loam, wetting rate influence on soil moisture the characteristic curves of the decline; wetting rate significantly affected soil cumulative infiltration and infiltration rate, wetting faster, less accumulated into the soil infiltration, the infiltration rate is low, four kinds of soil Show the same variation, with the wetting speed, the cumulative infiltration decreased greatly varied from 10.32% to 32.67%, the infiltration rate decrease changes from 24.16% to 31.37%; the greater the wetting rate, soil saturated hydraulic conductivity decreases, wetting rate increased from 0mm/h to 16.25mm/h, soil saturated hydraulic conductivity to reduce the rate of 17.08%-31.51%. (2) the wetting rate influence on soil hydraulic properties because of shear flow wetting process affected the soil pore structure, wet shear stress at different speeds, the size is different, the influence degree of the soil pore structure is different. The greater the wetting rate, the destruction of soil structure obviously, the lower the porosity, lead to soil moisture increases, soil saturated hydraulic conductivity is low. At the same time, the wetting rate also changed the soil pore distribution is different, especially How much is the soil macropore content, the experiments show that the wetting velocity increasing, the capillary porosity and soil air permeability of soil. The smaller (3) PAM could increase soil water holding capacity, increase the level of diffusion rate in soil: effects of soil infiltration properties, showing different rules in different stages: in the humid the application of PAM stage, hinder water movement in the soil, soil cumulative infiltration decreased in the range of 11.19%-29.85%; while in the continuous phase, the application of PAM can promote the movement of water flow and soil stable infiltration rate increases in the range of 25.98%-88.57% PAM in different stages of change: the reason for soil infiltration effect is due to the hydrolysis of PAM its own characteristics, in the wet, dry PAM water gradually after hydrolysis, molecular chain has been extended blocked soil pore, hinder water movement, and to the continuous phase. After drying after wet hydrolysis. PAM has completely played solid soil structure effect: in addition, PAM also makes the soil saturated hydraulic conductivity decreases, decreases in the range of 8.25%-17.11%. (4) SAP can also increase soil water holding capacity, increase the level of diffusion rate in soil; effect of soil infiltration. Whether it is wet or continuous phase can play a role in promoting.SAP water infiltration of soil cumulative infiltration increased 11.19%-29.85%, stable infiltration rate is increased by 5.71%-25.00%; SAP has positive impact on soil infiltration, is due to SAP water after the rapid expansion of the volume, change of soil structure, the soil pore content especially large pores increases, so as to provide a channel for soil water movement. (5) PAM and SAP's influence on soil hydraulic properties, mainly due to changes in PAM and SAP The structure of.PAM and SAP in soil can increase soil total porosity, for different types of soil, increase the amplitude changes between 2.76%-16.18%, PAM and SAP also have an effect on soil pore distribution, the effect in different time is not the same: in water wet in two kinds of materials, PAM increased capillary porosity 9.38%-21.59%, at the same time reduce the soil non capillary porosity and air permeability, decrease in the range of 7.24%-16.16%, while SAP decreased the soil capillary porosity, reduce the amplitude changes between 11.16%-20.10%, while increasing the capillary porosity and soil air permeability of 25.23%-63.48% soil. After non wetting drying cycles, and reduce soil PAM fully integrated. 9.33% ~ 33.29% of the soil capillary porosity, and increase the capillary porosity and soil air permeability of soil, increase rate reached more than 30%, in 31.63%-37.45% Between the SAP treatment compared with the control soil capillary porosity increased, the increase in the range of 5.74%-20.21%, but also improve the soil non capillary porosity and soil air permeability, improve the rate of 10.02%-15.41%. In addition PAM and SAP can also increase soil aggregate content, especially PAM can significantly increase the water stability of aggregates.PAM and SAP have changed the microstructure of soil, PAM makes the soil more compact structure, particle surface layering weakened, while SAP made soil particles clearer. (6) the statistical results showed that the application of PAM and SAP can optimize soil structure and hydraulic characteristic parameters, and four types of soil in the PAM application amount was 45kg/hm2 when the index reached the optimum. In practice, PAM and SAP were to increase the crop growth period of water soil sub surface and root layer rate, at the same time increased With the increase of crop yield, the yield of wheat increased by 19.11% when applying PAM, while the yield increasing rate of SAP was 16.78%., indicating that PAM and SAP played an important role in increasing water use efficiency and increasing yield.

【学位授予单位】：内蒙古农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S152.7

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