陕西渭北农田土壤盐碱化动态及影响因素研究

发布时间：2018-03-11 10:40

本文选题：土壤盐碱化　切入点：动态变化　出处：《中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)》2017年硕士论文　论文类型：学位论文

【摘要】：渭北地区是陕西省的第二粮仓,但该地区土壤盐碱化问题较突出,土壤犁底层容重较大,内涝灾害和土壤次生盐渍化比较严重。目前,对渭北地区土壤盐碱化的研究主要围绕着卤泊滩展开,对渭北地区土壤盐碱化动态分布及成因研究较少,尤其是犁底层土壤紧实结构对该区土壤盐碱化的影响尚不清楚。因此,从区域尺度研究渭北地区农田土壤盐碱化问题、探究犁底层对土壤水盐运移的影响有重要的现实和科学意义。本研究以陕西渭北农田土壤为研究对象,通过10 km×10km网格布点法进行野外调查采样,明确了渭北农田土壤盐分类型、土壤盐分空间分布特征,揭示了土壤物理性质对剖面土壤盐分的影响;通过定位监测,分析了土壤盐碱化的年内动态变化及水、热、盐之间的关系;以交口抽渭灌区和洛惠灌区为典型区,分析了灌区土壤盐碱化年际动态变化;通过室内模拟试验,针对地下水浅埋区犁底层容重对水盐运移的影响进行了探讨。本研究的主要结论如下:(1)陕西渭北地区农田土壤阴离子以Cl-和SO42-为主,硫酸盐型土壤点位比约55.9%,阳离子以Na+为主,钠盐型土壤点位比约41.2%。土壤以非盐渍化和轻度盐渍化为主,约占76.2%,剖面土壤含盐量随土层深度的增加而增加,存在土壤盐渍化加剧的风险。(2)土壤电导率在高含盐量区呈现出夏季秋季春季冬季的趋势,在低含盐量区呈现出春季夏季秋季冬季的趋势。高含盐量区电导率受多种因素的综合影响,低含盐量区主要受温度和海拔的影响。温度对电导率的影响随着土层深度增加而减小,但水分对电导率的影响随着土层深度的增加而增加。一年之中,水分对电导率的影响大于温度,且土壤水分在15%~30%(相当于质量含水量11%~21%)范围内对电导率具有明显影响。(3)两大灌区近10年内土壤盐碱化面积呈上升趋势。灌区土壤盐碱化面积的动态变化受到排灌措施的影响,交口抽渭灌区的灌溉亩次是土壤盐碱化的主要影响因素,土壤盐碱化面积随着灌溉亩次的增加而增加。(4)土壤颗粒组成仅影响0-20 cm的含盐量,容重和团聚体对剖面含盐量的影响表现出明显的异位影响,且这种异位影响与含盐量水平有关。土壤含盐量1 g/kg时,40-60 cm土壤容重与20-40 cm含盐量是幂函数关系呈递增趋势;含盐量2 g/kg时,0-20 cm土壤容重与20-40 cm含盐量是一次函数关系呈递减趋势,其中当含盐量在2~4 g/kg时,20-40 cm土壤容重与0-20 cm含盐量是一次函数关系呈递增趋势。含盐量2 g/kg时,20-40 cm水稳性团聚体与0-20 cm含盐量之间呈显著负相关;含盐量2 g/kg时,水稳性团聚体与含盐量之间无显著相关性。(5)紧实犁底层可阻碍水盐自下而上迁移,抑制表土积盐。随着犁底层土壤容重的增加,各土层土壤电导率呈抛物线型变化。犁底层容重影响耕层土壤积盐的临界值为1.60 g/cm3。对于地下水浅埋区,当犁底层容重大于该临界值时,保留犁底层有利于防止地下水中盐分表聚。当犁底层容重小于该临界值时,可考虑适当打破犁底层,减小毛管作用,防止下层盐分表聚。
[Abstract]:Weibei area in Shaanxi province is the second granary, but the problem of soil salinization in this area is relatively outstanding, plow soil bulk density, soil salinization and waterlogging disaster is more serious. At present, the research on the saline alkali soil in Weibei area is mainly on the lubotan, the saline alkali soil in Weibei area of distribution and the causes of dynamic less, especially the influence of plough layer soil compaction on soil salinity in the area of structure is not clear. Therefore, the soil salinization problem research in regional scale north area, has important practical and scientific significance to explore effects of plow on soil water and salt transport. In this study, the soil of farmland in Shaanxi in the north as the research object, through field investigation and sampling by 10 km * 10km grid, clear in soil salinity North farmland types, distribution characteristics of soil salinity in space, reveals the soil physical properties on soil profile Effects of soil salinity; through location monitoring, analyzing the dynamic changes of soil salinization and water, the relationship between years of heat, salt; in Jiaokou irrigation area and irrigation area is a typical area of Luohui irrigation, analysis of soil salinization interannual dynamic change; through simulation test, the needle has carried on the discussion to the shallow groundwater buried area of plough layer density effects on water and salt transport. The main conclusions of this study are as follows: (1) Shaanxi Weibei area soil anion by Cl- and SO42-, the sulfate type soil point is about 55.9%, mainly in Na+ type sodium cation, soil point about 41.2%. in soil and mild salinity. About 76.2%, increase soil salt content decreased with soil depth increasing, there is a risk of soil salinization. (2) the soil conductivity in high salinity area showed a trend of spring summer autumn winter, in the low salinity zone Showing the spring summer autumn winter trend. High salinity zone conductivity is affected by many factors, the effect of low salinity region is mainly affected by temperature and altitude. The effect of temperature on the conductivity decreases with the increase of soil depth, but the effect of water conductivity increases with the increase of soil depth in a year. And the effect of water on conductivity is greater than the temperature, and soil moisture in 15%~30% (equivalent to the quality of water within the range of 11%~21%) has obvious effect on the electrical conductivity. (3) the two major irrigation areas in the past 10 years soil salinization area increased. The dynamic changes of irrigation area soil salinization area affected by irrigation and drainage measures, Jiaokou in pumping irrigation acres is the main influencing factors of soil salinization, soil salinization area increased with the increase of irrigation times. (4 acres) of soil particle composition affects only the amount of salt 0-20 cm, bulk density and The ectopic aggregates influence on the effect of salinity profiles, and the effects of ectopic and salinity levels. The soil salt content of 1 g/kg, 40-60 cm and 20-40 cm soil salt content is the power function relationship showed an increasing trend; the salt content of 2 g/kg, 0-20 cm soil volume weight with 20-40 cm salt is a function of the decreasing trend, when the salt content in 2~4 g/kg, 20-40 cm and 0-20 cm soil salt content is a function of the increasing trend. The salt content of 2 g/kg, 20-40 cm and 0-20 cm water stable aggregates containing salt a significant negative correlation; the salt content of 2 g/kg, there was no significant correlation between water stable aggregates and salinity. (5) compaction plow can hinder water and salt migration inhibition of salt accumulation in topsoil from top to bottom, with the increase of the plow. The soil bulk density, soil conductivity was a parabola. The bulk density of the plow Influence of the critical value of soil salt accumulation was 1.60 g/cm3. for shallow groundwater area when the plow density is higher than the critical value, retain the plough layer to prevent groundwater salt accumulation. When the plow density is less than the critical value, could be considered appropriate to break the plough layer, reduce capillary effect, prevent the lower salt poly.

【学位授予单位】：中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S156.4

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