旱区微咸水膜下滴灌水—土—棉花系统溶质时空变化规律及其应用

发布时间：2017-12-31 06:05

本文关键词：旱区微咸水膜下滴灌水—土—棉花系统溶质时空变化规律及其应用　出处：《中国地质大学》2016年博士论文　论文类型：学位论文

【摘要】：微咸水膜下滴灌有利于作物增产,但利用不当则会造成土壤盐渍化和产量降低。为探讨干旱区膜下滴灌条件下微咸水的合理利用方式,本文以包气带土壤水流、溶质运移理论为基础,综合采用野外大田监测试验、盆栽控制性试验、室内分析测试和数值模拟等方法,研究典型植棉生态系统内溶质(指微量养分铜、铁、锰,宏量养分钙、钾,盐害离子钠等阳离子)时空变化规律及其对作物生长、耐盐性提高的积极作用,揭示典型植棉生态系统内溶质动态、均衡模式,建立根系吸收溶质作用下土壤水流、溶质运移二维数值模型,提出综合考虑土壤水-盐(钠)-养分的协同调控模式。结果表明：(1)受灌溉输入、植物截留、溶质迁移等因素影响,不同溶质在土壤剖面的分布变化规律差异显著：2012～2013年,土壤剖面有效态钙、钾未表现出明显的表聚性,铜、铁、锰最高值由20-30cm上移至O-10cm,具强烈的表聚性,而全咸水处理下钠由不表聚变为显著表聚。(2)在土壤盐害钠离子增加,微量元素减少的情况下,采用蕾期至花铃前期淡水灌溉、其余生育期微咸水灌溉的方式,钠离子未发生表聚,2013年棉花总根长密度高于全咸水处理约24%,地上部干物质、单位面积铃数和籽棉产量较全咸水处理高出13%-24%。(3)均衡期(蕾期至吐絮期整个灌水过程)内,系统上边界处由施肥带入的溶质量几乎为0,下边界处溶质随水运移的净输出量不到溶质储量变化的1%；灌溉水输入溶质是造成土壤中Ca2+、Na+储量变化的主要原因；棉花吸收作用是引起有效态Ca2+、K+储量降低的主要原因；溶质沉淀是造成土壤中Cu、Mn、Fe、Ca2+储量减少的主要原因。棉株还田后,土壤中有效态Cu、Fe、Mn在年际间呈负增长,Ca2+、K+、Na+呈正增长。(4)经盆栽试验验证及参数优化后的分室模型,能够准确刻画溶质在系统内的流动过程,溶质流动速率可作为棉田溶质运移模拟研究的参数。(5)加入根系吸收溶质项的非饱和带二维土壤水流、溶质运移模型,能够有效反映均衡期内土壤水流、溶质运移的结果。(6)利用校验认可的水流、溶质运移模型,综合考虑非生育期内棉株还田、春灌、增施底肥等影响因素,预测长期微咸水膜下滴灌条件下,棉田溶质时空分布与变化：连续耕作10年内,土壤溶液中Cu和Fe浓度逐年降低,Mn和Ca2+浓度基本不变,Na+和K+浓度逐年增加。建议采用咸淡水轮灌、降低棉花还田率、增施底肥等方式的田间土壤水、盐和养分协同调控模式为：蕾期至花铃前期采用淡水灌溉(淡水灌溉量占总灌量的20%)、其余生育期用微咸水灌溉；年均增施Cu、Fe、Mn、K底肥(按养分元素计)30、52、90和862kg/hm2;每年生育期结束后,移除棉花秸秆。以上成果可用于指导干旱地区合理利用微咸水,实现棉花优质稳产。
[Abstract]:Brackish water drip irrigation is conducive to crop production, but improper use will cause the decrease of soil salinization and yield. To explore the arid area under drip irrigation with brackish water utilization, the vadose zone soil water flow, solute transport theory, using the wild field monitoring test, pot experiment the indoor test, analysis and numerical simulation methods of typical cotton ecosystem (referring to solute micronutrient copper, iron, manganese, macro nutrient calcium, potassium salt, sodium ions and other cations) and its temporal variation on crop growth, improve the positive role of salt tolerant cotton, reveal typical ecosystem solute the dynamic equilibrium model, establish the root absorption of solute under soil water flow, solute transport in two-dimensional numerical model, put forward a comprehensive consideration of soil water and salt (sodium) - co regulation model of nutrients. The results showed that: (1) by irrigation pipeline The interception, the influence factors of solute migration, solute distribution differences in different soil profiles significantly: from 2012 to 2013, the soil available potassium calcium profiles, no obvious surface accumulation of copper, iron, manganese, the highest value by 20-30cm up to O-10cm, with a strong aggregation table, and the whole salt water treatment by sodium fusion was not accumulation. (2) and sodium ions in soil salt increased, trace elements decreased in the case of the bud stage to flowering stage of freshwater irrigation, the growth period of brackish water irrigation, sodium ion without surface accumulation, total root length density is higher than that of cotton in 2013 the salt water treatment of about 24%, the aboveground dry matter per unit area, boll number and seed yield than the whole water treatment of high 13%-24%. (3) balance period (bud stage to boll opening stage of the irrigation process), dissolved quality boundary system by fertilization into nearly 0, under the boundary of the solute with water The net output is not to change the solute migration reserves 1%; irrigation water is caused by soil solute input Ca2+, the main reason of Na+ reserves change; cotton absorption is caused by available Ca2+, mainly due to reduced K+ reserves; solute precipitation is caused by soil Cu, Mn, Fe, Ca2 + reserves reduce main reason the cotton field. Also, the soil available Cu, Fe, Mn showed negative growth in annual Ca2+, K+, Na+ positive growth. (4) the compartment model of pot experiment verification and optimized parameters, the flow process can describe the solute within the system, can be used as parameters of solute transport in cotton field simulation Study on the solute flow rate. (5) the absorption of solute in unsaturated soil water flow into two-dimensional root, solute transport model, which can effectively reflect the soil water balance period, solute transport results. (6) the use of check approved water flow, solute transport model, comprehensive test Consider the non growth period of cotton straw, spring irrigation, increasing factors of basal fertilizer and other factors, long term prediction of brackish water drip irrigation under mulch, solute spatiotemporal distribution and change of cotton field: continuous cropping for 10 years, every year to reduce the Cu and Fe concentration in soil solution, Mn and Ca2+ were unchanged, Na+ and K+ concentration increased year by year. Recommend the use of brackish water irrigation, reduce cotton returning rate, increasing soil water such as basal fertilizer, salt and nutrient synergistic regulation pattern: bud stage to flowering stage by freshwater irrigation (freshwater irrigation accounted for 20% of the total amount of irrigation), the growth stage with brackish water irrigation; the average annual growth rate of Cu, Fe Mn, K, base fertilizer (by nutrient meter) 30,52,90 and 862kg/hm2; growth period at the end of each year, remove the cotton straw. The above results can be used to guide the rational use of brackish water in arid regions, to achieve high-quality cotton production.

【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S562;S275.6

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