【作者】 吕桂军；

【导师】 康绍忠； 张富仓；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2006， 硕士

【摘要】 土壤盐碱化问题是一个世界性问题。专家预测,二十一世纪土壤盐渍化还将继续发展,并会成为全世界关注的重要问题之一。我国的盐渍土面积分布甚广,约为l.0x108ha。土壤盐渍化主要是由水资源短缺引起,所以,土壤盐渍化地区大多又是水资源缺乏的地区。目前,由于我国水资源的短缺和土地资源的日益减少和退化,实行节水灌溉,提高土壤生产能力,改良和利用盐渍化土壤已成为提高农业生产、合理利用水资源和土地资源的一个重要问题。研究不同灌水方式下的土壤水盐运动,对于完善盐渍土壤节水灌溉的理论和机制、指导传统地面灌溉向节水型地面灌溉转变、改善生态环境、维持生态平衡、缓解水资源危机和高效利用盐渍化土地等都具有重要意义。本文针对不同灌水方式,通过室内外试验相结合的方法,在作物生长情况下,对土壤水、盐、热耦合迁移规律及作物生长的影响做了初步研究。取得了以下主要研究成果:1.盐渍土壤中饱和非饱和入渗条件下,土壤水渗透流速对土壤排盐效果有显著影响,入渗水量越大,土壤水流速越慢,排盐、压盐效果越好;渗透水量和与之对应的单位水量排盐率之间呈极显著幂函数关系。不同入渗水头的土壤水入渗过程中,土壤任一深度处的电导率与土壤水流经该处的时间之间呈显著幂函数关系。2.温室小区中作物常规灌溉、交替灌溉和固定灌溉的试验结果表明:节水灌溉的水量有限,不可能把盐分从土壤根系层中彻底排出或压入更深的土层。它所起到的主要作用一是限制水分渗透到含盐量较高的土壤下层。这样就限制了土壤水分蒸发导致的下层土壤盐分的回升;二是通过适宜的灌水处理去在时间和空间上调节水分和盐分在土壤中分布的形态。这样不但可以在土壤根系层中形成一个“局部肥沃区”,使作物根系在这个局部肥沃区内吸收土壤水分和养分,而且还可以达到利用作物生理机制进行节水抗盐、促进作物生长的目的;三是不仅减少了棵间土壤蒸发占农田总蒸散量的比例,使田间土壤水的利用效率得以显著提高,而且可以较好地改善作物根区土壤的通透性,提高根区土壤温度,促进根系生长发育和对水分养分的吸收。常规灌溉由于灌水量大,灌溉水较多地渗入了含盐量较大的土壤下层,在土壤水分蒸发的土壤毛管吸力作用下,又把土壤下层的盐分较多的带入上层,给玉米生长造成了较大的危害,所以玉米产量比交替灌溉和固定灌溉的都低。3.盆栽试验结果表明:对整个生长期而言,玉米长势有如下特点:常规灌溉>交替灌溉>固定灌溉;而在玉米生长的某一时段内,固定灌溉和交替灌溉的相同灌水水平之间进行比较,均有固定灌溉的玉米长势要优于交替灌溉的玉米长势的情况。这说明玉米更多还原

【Abstract】 Soil salinization is a world problem. Experts predict that soil salinization problem will still exist, even worsen in the 21st century, and it will become one of the most important problems in the whole world. The salinized soil distributes vastly in our country; with the area approaching l.0×108ha. Soil salinization is mainly caused by water shortage. Therefore, soil salinization exists mainly in the regions lacking of water resources. At present, owing to water shortage and degradation of land resources, implementing water-saving irrigation, increasing soil throughput, improving and reusing salinized soil have played important parts in increasing agriculture production and making good use of water resources and land resources. The study of water and salt movement under different irrigation methods, will be of great importance in many aspects, including consummating salinized soil water-saving irrigation theories and mechanism, guiding traditional ground irrigation towards water-saving ground irrigation, ameliorating ecological environment, maintaining ecological balance, relieving water crisis and utilizing salinized soil with high efficiency.By combining laboratory tests with field tests under different irrigation methods and planting crop, these characteristics of coupled movement of soil water, salt and heat transfer and corresponding effects on crop growth were studied systematically. The main results are as follows:1. Under saturated and unsaturated soil in salinized soil, water amount of infiltration and flow velocity have obvious effect on desalinization. There are very prominent power function relationship between infiltration water amount and its desalinization ratio of unit water amount. In course of infiltration under different water presses, very prominent power function relationships between soil electrical conductivity of any soil depth and the infiltration time were founded.2. Test results of normal irrigation, alternate irrigation and fixed irrigation in plot of greenhouse show that salinity can’t be expelled from soil or infiltrated into deeper soil layer because of limited water amount of water-saving irriation. The main functions of water-saving irrigation are: 1) to limit water infiltration into soil deeper layer with high salt content, then更多还原