【作者】 张春晖；

【导师】 吴普特；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2017， 硕士

【摘要】 小麦/玉米套作作为我国西北干旱半干旱地区的主要种植模式之一,种植面积广,但其耗水量大、棵间土壤蒸发量(E)占作物蒸散量(ETc)比例高的特点严重制约了其规模化应用。针对小麦/玉米套作复合群体耗水量大,E/ETc相对较高的特点,本研究以冬小麦/春玉米套作复合群体为研究对象,设置不同的灌水处理并以相应单作模式作为对照,系统研究冬小麦/春玉米套作群体土壤水分时空变化动态、套作群体与单作群体棵间土壤蒸发的比较、套作群体蒸发蒸腾的分配及作物系数等。主要研究结论如下:(1)套作群体生长初期的预留行可以增加后种作物的前期土壤含水量,而前种作物收获后,土地休耕可以补给作物生育期内土壤水分的过度消耗,并为后期的耕作创造良好的水分条件。此外,套作群体生长过程中,增加了对侧向表层土壤水分的利用,有效减小了深层土壤水分的消耗。主要表现为:套作群体生长过程中,前期小麦生长占优势则小麦行土壤含水量逐渐降低而玉米行土壤含水量则相对增加;后期玉米生长阶段也表现出相同的变化趋势,而全生育期土壤含水量的波动范围在10%-24%之间。同时,土壤含水量垂直剖面变化表现为:0-40 cm土层的土壤含水量随土层深度的增加而增大且变化幅度较大,40-50 cm土层的土壤含水量略有降低,50-160 cm土层的土壤含水量则是先增加后减小。(2)套作群体可以降低后种作物生育前期的棵间土壤蒸发量,但由于预留行及作物收获后裸地的存在增加了整个生育期的土壤蒸发量;同时,表层土壤含水量直接影响棵间土壤蒸发的逐日变化,而大气温度和太阳辐射则共同决定着棵间土壤蒸发的日变化。具体表现为:套作群体不同灌水处理全生育期的日均蒸发量分别为0.58mm/d和0.47 mm/d,高于单作小麦的日均蒸发量而低于单作玉米的日均蒸发量。棵间土壤蒸发的增加均发生在灌水或降雨之后,而土壤蒸发日变化的峰值均出现在中午12:00—14:00之间。对于影响棵间土壤蒸发的因素分析,棵间土壤蒸发量与土壤含水量呈明显的脉冲波动变化;同时,套作群体的叶面积指数(LAI)表现出“双峰型”的变化趋势,E/ETc随LAI的增大而减小,与LAI成呈负幂次函数关系。(3)套作群体因两种作物生育期并不重合,其耗水规律也不同于单作。尽管套作群体全生育期耗水量大,相对蒸发强度高,但作物非共生阶段耗水量及单月耗水量最大值均低于相应单作且全生育期平均耗水量的波动幅度相对较小,对土壤水分环境表现出更强的适应能力。具体表现为:套作群体全生育期灌水处理的ETc和E/ETc分别为510.14 mm和34.68%,不灌水处理的ETc和E/ETc分别448.02 mm和32.47%均高于单作,而套作群体各生长阶段Kc的变化趋势呈现“双峰型”且数值小于单作群体,其第一个峰值出现在小麦后期+玉米发育期为1.08,第二个峰值出现在玉米生长中期为1.21。更多还原

【Abstract】 Wheat/Maize Intercropping as a main cropping pattern is widely promoted in arid and semi-arid region of northwest China,but the high water consumption and high ratio of evaporation and evapotranspiration(E/ETc)restrict its large-scale application.This study was focused on winter wheat/spring maize Intercropping system,set different irrigations and corresponding monoculture treatments,there were three research directions in this study: Dynamic of soil moisture in winter wheat/spring maize Intercropping system,The compare of soil evaporation between winter wheat/spring maize Intercropping and corresponding monoculture,The separation of evapotranspiration and crop coefficient calculation of winter wheat/spring maize Intercropping.The main results were listed as follows:(1)Soil moisture content was difference in winter wheat/spring maize intercropping under three points with the development of crop growth.With the growth of wheat,soil moisture content of wheat lines were gradually reduce.And maize lines had the same change trend.Vertical soil moisture distribution was shown as: 0-40 cm soil moisture content increased with the increase of soil depth,40-50 cm slightly reduced,50-160 cm soil moisture content increase first and then decrease.(2)The soil evaporation of intercropping pattern at relatively high levels in each processing stage,and the movement of soil evaporation in monoculture is greater than intercropping pattern.The change of soil evaporation was obviously influenced by irrigation and rainfall,and the increase of soil evaporation had occurred after irrigation or rainfall.The peak of daily variation of soil evaporation in different points from 12:00 to 14:00,and it was obviously effected by solar radiation and surface coverage.It was a pulse wave change between soil evaporation and soil moisture content.Leaf area index(LAI)of intercropping pattern showed the tendency of the "two peaks",E/ETc was decreased with the increase of LAI and there was a negative exponential function relation between E/ETc and LAI.(3)The ETc and E/ETc in intercropping pattern were greater than monoculture,the Kc of intercropping pattern showed the tendency of the "two peaks" and the value were less than monoculture.The first peak appeared in the late of wheat + the development of maize,and the second peak appeared in the middle of spring maize.The order of cumulant of ETc in the whole growth period under different treatments were: WMI > WMN > SMI > SMN > SWI > SWN,the cumulant of E had the same order with ETc,but the order of cumulant of E/ETc was different,which was WMI > WMN > SMI > SMN > SWN > SWI.更多还原