全膜覆土穴播冬小麦农田土壤含水率与耗水量时空动态

Study on the special-temporal dynamics of winter wheat water use efficiency and evapotranspiration under bunch planting and plastic film mulching with soil on flat field during the whole growth season

2008-2010年度,通过田间试验,研究了全膜全生育期覆土穴播平作栽培技术（简称M）对冬小麦全生育期0～100 cm土层内土壤含水率和耗水量时空动态的影响,以期为提高全膜覆盖冬小麦土壤水分利用效率、优化地膜覆盖技术提供理论参考.设计M和露地（CK）、10粒/穴密度（相当于267.75 kg/hm2的播种量）、重复3次、随机区组排列的二因素试验.结果表明,M全生育期显著影响到30～40 cm和40～50 cm土层水分;M在抽穗和灌浆前期能够显著影响30～50 cm土层含水率,使供水峰值提前出现.M灌浆中、后期能够充分调动50～60 cm水分到0～30 cm土层,对60～70 cm产生显著的提升作用以补充上层水分的亏缺.M也有效拉升70～90 cm区域水分的向地表运动,作为重要的水源在生长关键期发挥有效补给作用.本试验结果同时表明,M的水分利用高效区域主要发生在0～90 cm;对90～100 cm含水率和耗水量动态变化的分析表明,M效应可以达到100 cm以下.露地栽培（CK）在相同时期、相同土层,水分补给现象不显著;在灌浆中、后期,对50～70 cm水分的利用率较高,造成阶段性的水分高消耗和含水率快速降低现象,无法及时获得补给;对水分的利用主要发生在0～70 cm土层.此外,M最大的效应之一就是在生育期内、0～40 cm土层内拥有的水分含量总体远高于CK.对各层相关分析表明,取样层次、取样阶段、覆膜与含水率存在显著关系;M条件下,水分呈连续体,在补给、平衡能力方面显著高于CK,从而保证了小麦的生长.该技术能够显著提升中、深层土壤水分,有效保蓄土壤水分,从而增强小麦抗旱能力;其对旱地冬小麦生产或可产生较大的影响,值得进一步深入研究.较之以往雨养旱区小麦覆膜技术有突破,即全生育期全地面平作覆膜、膜上覆土1～2 cm、一膜多年连用、免耕,解决了苗穴错位、前期低温有碍生长、后期高温逼熟问题,达到变无效降水为一部分或绝大部分有效、高效保墒、增温提墒、调动中深层水分的效果.

In order to make clear the dynamic character of soil moisture and evapotranspiration under bunch planting and plastic film mulching with soil on flat field （M） during the whole growth season,we did field experiments of studying different soil moisture and water use efficiency （WUE） of 0-100 cm depth from 2008 to 2010 year which were aiming to get the water consuming and supplying character.The experiments were de signed of M and CK （bare cultivation）,a randomized complete block with 3 replications,267.75 kg/ha seeds and 10 seeds per hole.The results shows that M is able to significantly affect soil moisture （SM） of 30-40 cm and 40-50 cm during whole growth and 30-50 cm at the stage of earing and grain filling comparing with CK.At the middle and end of grain filling,M could transfer SM from the layer of 50-60 cm to 0-30 cm and significantly move SM from 60 70 cm to upper layer.The SM in 70-90 cm had also been used as important water supplication in key growth stage.Under M condition,the SM in 0-90 cm could be used efficiently and is the most important water supply area.Analyzing the dynamic character of WUE and ET in 90-100 cm soil,we could infer that M can significantly affect SM below 100 cm soil.But the traditional cultivation （CK） couldn＇t get the effect whenever and wherever.CK could use SM in 50-70 cm efficiently at the middle and end stage of grain filling,which led to quick and much water shortness.The SM of 0-70 cm is the main supplier of CK at the stage of grain filling instead of SM in 0-90 cm as M.During the whole growth stage,the general SM of M in 0-40 cm was higher than CK.M could significantly improve soil moisture from the middle and deeper soil layer to the upper as important water supplier at the key growth stage.M could highly improve yield by high WUE and efficient ET,which could enhance drought tolerant ability of winter wheat in rain-fed areas and save much water.