【作者】 雪静；

【导师】 王全九；

【作者基本信息】 西安理工大学 ， 农业水土工程， 2009， 硕士

【摘要】 合理的开发利用微咸水是缓解农业淡水资源短缺的重要途径。本文在查阅国内外有关微咸水地面灌溉研究成果的基础上,采取了理论分析与室内外试验相结合的方法,微咸水灌溉土壤水盐运移特征及苜蓿耐盐特性进行了研究,取得了如下结论。1.相同入渗水量,不同矿化度微咸水间歇入渗试验表明,相同入渗历时内,随着入渗水矿化度的增大,累积入渗量增加,土壤入渗深度逐渐增大；淡水间歇入渗有减渗效果,而微咸水间歇入渗发生增渗现象。停水阶段停水时间越长,微咸水间歇入渗比连续入渗湿润深度增大越显著,增加湿润深度效果随着矿化度的增大而增大。同一土层含水量随着矿化度的增大而减少,间歇入渗较连续入渗土壤含水量分布均匀,微咸水间歇入渗有利于盐分离子向下层土壤运移,表层浓度较低,湿润峰处盐分积累；2.相同灌水量,不同咸淡交替间歇入渗的试验表明,交替入渗次序对土壤入渗速率有很大的影响,第一阶段入渗水质对土壤入渗特性起决定性的作用,且第一阶段入渗微咸水,入渗速率则快；交替入渗次序对土壤水分分布的影响并不明显。交替次序淡咸淡和咸淡咸入渗后,土壤剖面上盐分浓度相对较低,尤其淡咸淡交替方式,表层盐分浓度较低,有利于盐分向深层土壤移动,在实际中,有利于作物吸水。有利于Na+向深层土壤运移及Na+的淋洗；淡咸淡交替方式最佳,更有利于Ca2+保存于表层土壤中。3.施钙条件下微咸水间歇入渗实验表明,入渗水中钙离子浓度的增大有利于微咸水中所带钠离子向下运移,钙离子阻碍表层土壤吸附微咸水中的钠离子,表层钠离子浓度降低,在实际中有利于作物生长。4.盆栽苜蓿耐盐试验表明,以出苗率达到80%为苜蓿苗期耐盐标准,在土壤初始含盐量为0.08%时,灌溉水质不能超过7g/L；在土壤初始含盐量0.3%时,灌溉水质不能超过3g/L；在土壤初始含盐量0.6%时,灌溉水质只能是淡水。在灌溉水质1g/L时,土壤初始含盐量不能超过0.6%；在灌溉水质3g/L时,土壤初始含盐量不能超过0.3%；在灌溉水质5g/L时,土壤初始含盐量不能超过0.3%。土壤含盐量和灌溉水质对苜蓿分枝数无明显的影响,分枝数只与苜蓿的生育期有关。5.田间灌溉矿化度等于或大于5g/L后,土壤出现轻度盐化；苜蓿产量随着灌水矿化度的增加而降低；苜蓿的株高随矿化度的增大先增大后减小；混灌时灌水矿化度尽量控制在5g/L范围以内,一是防止微咸水灌溉造成土壤盐化现象的发生,而是保证苜蓿一定的产量。6.田间咸淡轮灌实验表明,轮灌条件下土壤含盐量与苜蓿产量均介于淡水与咸水之间,采用咸淡咸轮流灌溉的方式有利于提高作物产量。7.田间石膏改良试验表明,施钙量越大,土壤盐分浓度越大,表层土壤钠离子含量越低,苜蓿产量越低,故选择低钙量70g/(2*3)m2适当,即能降低表层土壤钠离子含量的同时土壤盐分浓度不会太高,而且产量上相对有一定的保证。更多还原

【Abstract】 Reasonably development and utilization of saline water is an important approach of relieving the agricultural freshwater resource shortage. On the basis of using for reference of saline water sueface irrigation research findings both abroad and home, the paper adopt method of combining theoretical analysis and laboratory and field experiments, soil water and salt distribution characterisrics and alfafa growth characterisrics by saline water irrigation was studied, the impact on it made conclusions as below:1.Experiments in soils with the same irrigation quantity and different saline water intermittent infiltration showed that soil cumulative infiltration and soil depth of infiltration increase with increase of at the same infiltration time. Freshwater intermittent infiltration was infiltration reduction, but saline water intermittent infiltration was increased permeation,and the more long was water pause time at intermittent stage, the more prominent was enlargment of soil depth of infiltration saline water intermittent infiltration than continuous infiltration,and enlargement of increased permeation was increased with increase of salinity. Water content was decreased with increase of salinity at the same soil layer, and the distribution of soil water content on intermittent infiltration was uniformer than continuous infiltration. Saline water intermittent infiltration was beneficial to salt ions towards on subsoil movement. The surface concentration of salt ions was lower, but salt accumulation appeared on the soil profile.2.Experiments in soils with the same irrigation quantity and alternating intermittent infiltration with saline and fresh water showed that alternating infiltration sequence has great effect on infiltration rate. Infiltration water quality of the first stage played a decisive role on soil infiltration characteristics, and when saline water infiltration at the first stage, infiltration rate was faster. Alternating infiltration sequence had no significant effect on soil water distribution. After alternating infiltration sequence fresh-saline-fresh and saline-fresh-saline infiltrating, salt concentration in soil profile was lower, especially fresh-saline-fresh sequence, salt concentration in upper soil layer was the lowest, it was beneficial to salt ions towards on subsoil movement, and was beneficial to absorbing water of crop at actual. And even alternating sequence of resh- saline- fresh was beneficial to surface soil leaching sodium ions and storing calcium ions in surface soil.3.Experiments in soils with soil water and salt transport features of saline water intermittent infiltration and under calcium fertilizer application showed that the increase of calcium ions concentration in infiltrating water was beneficial to sodium ions of saline water moved towards to subsoil. Calcium ions hindered surface soil to absorb sodium ions of saline water, the decrease of sodium ions concentration in surface soil was beneficial to crops growth.4. Experiments in pot with alfafa salt tolerance showed that, seedling emergence rate reaching 80% was used as the seedling stage standard,when initial soil salt content was 0.08%, salinity water was less than 7g/L; When initial soil salt content was 0.3%, salinity water was less than 3g/L; When initial soil salt content was 0.6%, salinity water only was freshwater; But, when irrigation water quality was 1g/L, soil salt content was less than 0.6%;when irrigation water quality was 3g/L, soil salt content was less than 0.3%; when irrigation water quality was 5g/L, soil salt content was less than 0.3%. Initial soil salt content and irrigation water quality had on significant effect on alfafa branch number, alfafa branch number was related to growth period of alfafa.5. The field mixing irrigation experiments showed that the soil salinity occurred when the concentration was larger than or equal to 5g/L.The alfafa yield decreased with the increasing salinity of irrigation water. The alfafa plant height increased at first then decreased with the increasing salinity of irrigation water. So the suitable concentration of irrigation water was should be less than 5g/L, one was preventing saline water irrigation to the soil salinity,the other was ensured a certain alfafa yield.6. The field experiments with saline and fresh water alternating irrigation showed that soil salt content and wheat yield were between that with saline water or fresh water only. The saline and fresh water alternating irrigation may improve alfafa yield.7. The field experiments with gypsum improvement showed that the greater Ca application. the greater soil salt concentration, and the lower alfafa yield. So selection lower Ca application 70g/(2*3) m2 was better, both decreased soil calcium ions contents in surface soil and soil salt concentration was’t too high, and even ensured a certain alfafa yield.更多还原