旱地玉米栽培土壤水热运移特征与模型模拟

发布时间：2018-03-23 14:19

  本文选题：栽培模式　切入点：土壤水分　出处：《西北农林科技大学》2017年硕士论文

【摘要】：黄土高原雨养农业区水分缺乏是制约农业生产的关键因子。本研究通过在黄土高原长武塬(35?12'N,107?40'E)进行土壤水热野外连续观测小区试验,同时结合Hydrus-1D与Hydrus-2D模拟的方法,对比玉米传统栽培与垄作覆膜栽培模式下土壤水分和温度变化特征与差异,分析影响因素,阐明传统栽培模式玉米生产受水分胁迫的机制以及覆膜栽培下水热耦合运移过程特征,以期为解决该地区限制作物生产的土壤水分胁迫问题提供基础理论依据。研究结果表明:(1)垄作覆膜-垄和沟在30~60 cm土层土壤含水量分别显著高于平作不覆膜约49%和55%,而平作不覆膜在深层(100~160 cm)土壤土体储水量明显高于垄作覆膜约26%。垄沟覆膜-垄土壤表层10 cm处温度较垄沟覆膜-沟与平作不覆膜分别高2.01℃和1.91℃。两种栽培模式下,降雨事件对于土壤水分动态变化影响差异显著。平作不覆膜在玉米生长季初期由于干旱引起强烈的土壤蒸发以及作物耗水导致犁底层“自覆盖”现象产生,而垄作覆膜由于改善了土壤水分和温度条件,促使深层水分得到利用,从而避免“自覆盖”现象对玉米生长的不利影响,因而对于维持作物生长具有重要的意义。(2)Hydrus-1D可以很好的模拟玉米传统栽培模式下土壤水分变化趋势,校准期(2013年玉米生长期)和验证期(2014年玉米生长期)拟合程度分别为70.6%和77.0%。模拟与实测数据表明,土体储水量(SWS)在表层0~10 cm变化明显,受降雨入渗(P/In)、土壤蒸发(ES)和作物蒸腾(Tp)影响,根系吸水(RT)对60~100 cm土层SWS的影响最明显,深层土壤(100~160 cm)SWS相对稳定。而犁底层不同容重条件对土壤水分入渗的模拟表明,犁底层容重的越大,水分入渗滞后效应越明显,土体储水量越小。在玉米生长初期降雨稀少,犁底层由于蒸发作用以及根系吸水极易形成干层(出现“自覆盖”现象),因此玉米生长初期的干旱时期与犁底层分别是黄土高原玉米生长受水分胁迫的敏感时期与敏感土层。但种植时土体前期含水量也是犁底层是否形成干层的重要影响因素。(3)通过设置不同的边界条件,Hydrus-2D可较好的模拟覆膜栽培下土壤水热耦合运移过程特征。无降雨情况下,垄下表层土壤水分横向补充沟内;膜下温度比沟内表层温度高,并向沟内传输;当降雨量小时,土壤基本处于非饱和态,重力势作用较小,土壤水分仅由沟内表层入渗;强降雨事件下,土壤水分下渗明显,且60 cm土层以上沟内降雨横向补充垄下土壤。雨后由于蒸发作用,沟内水分向上迁移,同时,膜下浅层土壤水具有向沟内侧向迁移的驱动力。
[Abstract]:Water deficiency in rain-fed agricultural areas of the Loess Plateau is a key factor restricting agricultural production. 12? The field continuous observation plot experiment of soil water and heat was carried out, and the variation characteristics and differences of soil water and temperature under traditional maize cultivation and ridge mulching cultivation were compared with Hydrus-1D and Hydrus-2D simulation, and the influencing factors were analyzed. The mechanism of maize production under water stress and the characteristics of water-heat coupled transport in film mulching cultivation were expounded. The results showed that the soil water content of ridge mulching, ridge mulching and furrow mulching was significantly higher than that of non-mulching soil layer (about 49%), respectively. And 55m, and the water storage of soil mass was significantly higher than that of ridge mulching film mulching about 26cm. The temperature of the top layer of furrow film mulching and ridge mulching was 2.01 鈩，

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