地膜秸秆复合覆盖改善龟裂碱土水盐特性提高油葵产量
2018-08-10孙兆军陈小莉赵西宁高晓东吴普特
吕 雯,孙兆军,陈小莉,赵西宁,高晓东,吴普特
地膜秸秆复合覆盖改善龟裂碱土水盐特性提高油葵产量
吕 雯1,2,3,孙兆军2,3,陈小莉4,赵西宁1,高晓东1,吴普特1※
(1. 西北农林科技大学水土保持研究所,杨凌 712100; 2. 宁夏大学环境工程研究院,银川 750021;3.宁夏(中阿)旱区资源评价与环境调控重点实验室,银川 750021;4. 西北农林科技大学农学院,杨凌 712100)
为了提高盐碱地降水利用率,抑制化学(脱硫石膏)改良碱土过程中土壤盐分表聚及板结问题,该文以宁夏平罗县西大滩盐碱地试验站为例,设置了地膜秸秆复合覆盖(plastic and straw dual mulching,PSM)、地膜覆盖(plastic film mulching,PM)、秸秆覆盖(straw mulching,SM)和无覆盖常规种植(nomulching,CK)4个处理,探讨改良龟裂碱土过程中不同覆盖措施下旱地油葵的土壤水盐结构特征及其对产量的影响。结果表明,PSM处理有效提高了30~100 cm土层土壤贮水、持水能力,推迟油葵消耗相对深层60~100 cm土壤水分的时间;在30~90 cm 土层,其水分活跃性显著高于其他处理;比单一覆盖抑盐效果佳,土壤盐分缓冲性增强,盐分表聚程度显著降低;同时能显著降低土壤容重,提高土壤孔隙度。PSM处理提高了油葵苗期存活率和产量,其较PM、SM处理和CK分别增产35.45%,120.15%,87.80%(<0.05);PSM处理较PM、SM处理和CK的降水利用效率分别提高了14.71%、86.45%和59.05%(<0.05),其水分利用效率分别比SM和CK提高了10.80%和32.71%。综上,地膜秸秆复合覆盖(PSM)可增强土壤保墒抑盐能力,改善作物根区土壤水盐环境,提高天然降水的生产潜力;促进碱土改良初期的保苗增产,提高经济效益。
地膜;秸秆;土壤;复合覆盖;土壤水盐;产量;降水利用效率
0 引 言
盐碱荒地和盐碱化中低产田,是中国重要的后备耕地储备,开发潜力巨大。宁夏银北为龟裂碱土(白僵土)主要典型分布区[1],面积约2万hm2。近年来,国内外许多学者采用施用工业废弃物脱硫石膏(CaSO4·2H2O)的化学方法改良碱土方面取得了一定成果和良好的环保效益[2-8]。而碱土较之盐土改良周期长、难度大,在水资源紧缺与降水时空分布不均情况下,施入脱硫石膏的改良初期,部分残留的盐分[5]、碱分极易造成盐害及土壤的泥泞、板结。干旱缺水、土壤易板结和改良初期盐分表聚依然是制约化学改良中龟裂碱土农业生产发展的关键因素。
采用地膜、秸秆等地面覆盖是减少土壤水分蒸发,增加土壤的有效贮水量,提高降水利用效率及减少土壤盐分表聚的重要[9-18]手段。在实际生产推广采用单一地膜、秸秆覆盖方式种植时,也存在着一些问题,如碱土膜下土壤易泥泞、板结[19],造成缺株断行、抑制植株生长[19-20],后期水分的耗竭[21]及秸秆覆盖后出苗率降低等现象[22-24]。为了实现地膜与秸秆覆盖的优势互补,国内外针对地膜秸秆复合覆盖的研究已涉及土壤温度、水分、盐分及作物生长等多个方面。有研究表明,地膜秸秆复合覆盖可调节土壤温度,提高生育期土壤水分含量、土壤水分稳定性、用水效率及作物产量[24-29];地膜结合秸秆深埋能有效地控盐、抑盐[30-31];也有研究表明[32],在种植茶园时采用复合覆盖后造成了减产和水分利用效率的降低。综上前人研究焦点主要集中在单一覆盖或健康土壤中采用地膜秸秆复合覆盖及地膜结合秸秆深埋的土壤水热及作物方面的影响及变化的研究,对盐碱土采用地膜秸秆复合覆盖方式种植油葵方面的研究相对薄弱;而化学改良中的干旱、盐害和碱分板结同时出现时,土壤水盐动态及作物的响应研究涉及相对较少。油葵()是在新开垦的盐碱原土及低产田中普遍种植的一种耐旱、耐瘠薄及盐碱的盐碱地的先锋作物。随着引黄配给的减少和改良碱土储备耕地需求增加,复合覆盖对碱化土壤改良中田间尺度土壤的新的水盐动态分布、物理性质和对油葵生长及产量的影响亟待深入研究。鉴于以上研究现状,选取新开垦龟裂碱土农田为研究对象,通过对比4种不同覆盖方式下土壤剖面水盐分布及随降雨和时间的变化特点,拟对地膜秸秆复合覆盖对土壤水分、盐分、容重、孔隙度及作物生长发育及产量形成等方面进行系统的分析,探索脱硫石膏改良龟裂碱土荒地及碱化低产田初期,提高耕地土壤保水抑盐能力和降水利用效率的方法与途径,为该地区盐碱地原土改良种植油葵的可持续发展提供科学依据和技术支撑。
1 材料与方法
1.1 试验区概况
试验地处宁夏平罗县西大滩前进农场,位于银川平原北部(106°24′E,38°50′N,海拔1 156 m),中温带干旱地区,干旱少雨,温差较大,年降水量为105~205 mm,主要集中在7月-9月,多年平均蒸发量为1 755.1 mm,地下水深埋1.5~2.0 m。土壤类型为碱化土壤中典型的龟裂碱土。土壤碱化度为20.0%~35.3%之间,pH值在8.7~10.2之间,全盐质量分数为2.5~4.8 g/kg,盐分类型主要有NaCl、Na2SO4、Na2CO3,土壤质地粘重(容重1.42~1.74 g/cm),透水性差;土壤有机质含量为5.87~7.43 g/kg;田间最大持水量22%~41%,而凋萎系数高达14%~18%,湿时吸水膨胀泥泞不易透水,干时收缩板结。
1.2 试验设计
供试作物为油葵,品种为KWS203。设置(plastic and straw dual mulching,PSM)、地膜覆盖(plastic film mulching,PM)、秸秆覆盖(straw mulching, SM)和无覆盖常规种植(no mulching, CK)4个处理,3次重复,区组随机排列。各小区长8 m、宽6 m,间隔2 m作为保护行,共 12个小区。前一年秋收后整地,根据土壤碱化度计算[33-34]脱硫石膏施用量为2.45×104kg/hm2,平均撒施并进行机械翻耕(深度30 cm),与土壤混合均匀后,采用4.5×103m3/hm2定额进行泡田淋洗。脱硫石膏主要成分是CaSO4·2H2O,颗粒细小松散均匀,粒径主要集中在30~60m,含有12%游离水。2013年11月施用脱硫石膏并进行泡田淋洗,2014年6月1日不同材料覆盖试验小区,2014年6月3日人工播种油葵,10月8日收获。
供试油葵品种为KW203,播种量7.50 kg/hm2,行距50 cm,株距25~30 m。生育期内雨养不灌溉,各处理田间施肥、除草等其他管理措施一致。播种前施入有机肥(牛粪)30×103 kg/hm2,尿素225 kg/hm2,过磷酸钙60 kg/hm2,硫酸钾60 kg/hm2。
表1 试验处理内容
1.3 测定项目及方法
土壤水分:采用土钻烘干法,测定土壤质量含水率。测定深度为0~100 cm土层,取样间隔为10 cm,取样时间分别在油葵播种前一天(6月2日)、苗期(6月26日)、拔节期(7月31日)、开花期(8月28日)、成熟期(10月9日),3次重复。
土壤盐分:采用电导率法,采样日期同上,测定深度为0~60 cm土层,取样间隔为20 cm;
土壤容重及孔隙度:容重测定采用环刀法,分别于6月1日(覆盖处理前)和10月9日(收获前)取土,深度为0~10、>10~20、>20~40、>40~60 cm共4层,测定各土层土壤体积质量并计算孔隙度;其中,土壤孔隙度计算公式为
土壤孔隙度=(1−容重/密度)×100% (1)
油葵出苗、生长状况及产量:于幼苗期调查油葵每天的出苗数,并统计出苗率及出苗天数,收获前统计存活率。油葵收获期,选取各小区连续2行,每行10株,共20株油葵,常规方法测定株高、茎粗,盘径、单盘粒质量及百粒质量;其中,出苗率和存活率的计算公式为
出苗率=(实际出苗数/种子数)×100% (2)
存活率=(实际存活数/出苗数)×100% (3)
耗水量采用水量平衡法计算,
ET =ΔW+++−(4)
作物水分利用效率计算公式为:
WUE=/ET (5)
作物降水利用效率计算公式为:
PUE=/(6)
式(4)~(6)中,ET为作物生育期内的蒸散量,mm;为生育期降水量,mm;为生育期灌溉量,mm;Δ为相邻2次取样0~100 cm土层蓄水量变化,mm;为时段内地下水的补给量,mm;为时段内地表径流量,mm;为作物产量,kg/hm2。由于试验区在全生育期内次降雨量较小,且本试验高埂种植,地势平坦,未进行灌溉,有效降水量少,不产生地面径流,可忽略径流和地下水补给影响,因此耗水量与降雨和蒸散有关。
1.4 数据处理
试验数据采用Surfer8.0、SPSS22.0和 Microsoft Excel 2007 软件进行处理,Duncan新复极差法进行差异显著性检验(=0.05)。
2 结果与分析
2.1 试验期降水特征
根据试验期当年实测气象资料与多年平均降水资料图1显示,研究区降水量时间变异性强,各月份间有较大差异。该区多年平均降水量为176.87 mm,试验当年降水量为184 mm为平水年。生长期内,油葵苗期(6月)降水增多,现蕾期至成熟期内(7月—10月)降水减少是当年的降雨显著特征。同时出现了1个干旱少雨强蒸发阶段为8月1日至8月25日无有效降雨。
图1 研究区2014年和1992-2012年月降水量
2.2 土壤水分的变化
2.2.1 土壤含水率的空间变化特征
从土壤含水率变化来看(图2),油葵对不同处理土壤水分的利用表现出一定的阶段性,不同覆盖方式水分消耗的土层深度有所不同。苗期PSM处理在30~100 cm的土层平均土壤含水率为28.25%,分别比PM和SM高出6.18%、2.85%,而其20~30 cm土层土壤含水率显著低于PSM、CK(<0.05),与SM差异不显著;3种覆盖PM、PSM、SM处理0~10 cm的土壤含水率均显著高于(<0.05)CK处理。现蕾期,有效降水(>5 mm)。大幅减少,PSM处理在60~100 cm土层土壤含水率分别比PM 、SM和CK高出12.95%、18.03%、7.04%;PSM处理的30~50 cm、SM处理的40~70 cm、PM处理的60~90 cm土层含水率与各处理苗期相比较显著消耗降低(<0.05)。8月1日至8月25日期间25 d无有效降雨,气温高蒸发量大,油葵正值开花期,营养与生殖生长并进,作物蒸发蒸腾需水量高,PSM、SM处理水分主要消耗在30~50 cm土层,分别比现蕾期显著降低了45.28%、36.27%;PM处理水分主要消耗在80~100 cm土层,降低了20.65%;CK处理水分主要消耗在80~100 cm土层降低了43.15%。在乳熟期,PSM处理水分主要消耗在60~100 cm土层比开花期有显著降低(<0.05),PM在40~50 cm土层土壤水分降了低19.99%。
注:PSM、PM、SM和CK分别为地膜秸秆复合覆盖、地膜覆盖、秸秆覆盖和常规无覆盖耕作4种处理,下同。
2.2.2 土壤水分垂直变异特征
土壤水分的变异系数CV表明了各土层土壤水分运动的活跃程度。土壤水分变异系数受降雨、作物蒸腾和覆盖处理不同的影响,呈现出波动性变化。如图3所示,0~20 cm土层,覆盖处理PM、PSM、SM均显著低于CK的变异系数(<0.05),变异系数由小到大依次为PM 图3 土壤含水率变异系数 播种至现蕾期(图4),PSM处理0~60 cm土体脱盐0.97 g/kg,SM处理脱盐0.37 g/kg,PM和CK处理分别积盐1.28,0.45 g/kg;现蕾期至乳熟期间,PSM处理积盐量为0.51 g/kg,显著低于PM(0.65 g/kg)、SM(1.32 g/kg)处理(<0.05),在整个生育期内,PSM处理40~60 cm土层保持相对较低土壤含盐量。说明PSM处理在0~60 cm耕层土壤比其他2种覆盖抑制盐分效果好。在现蕾至乳熟期间,在20~40cm、40~60cm土层PSM处理含盐量分别为1.33和1.41 g/kg,分别比PM的土壤含盐量4.07和4.87 g/kg,低了2.74和3.47 g/kg;乳熟期,PSM各层土壤含盐量均显著低于PM处理(<0.05)。PSM与SM处理相比较,PSM处理在开花期的0~20、40~60 cm和乳熟期的20~60 cm土层抑盐效果显著优于SM处理(<0.05)。SM处理由于后期秸秆腐解,表层土壤逐步暴露于空气中,表层积盐严重。PSM处理的土壤盐分表聚程度显著低于其他3个处理。3种覆盖处理0~20 cm土层的盐分表聚现象均出现生育期后半程,其中PSM、SM处理出现于现蕾期-开花期,PM处理发生在开花期-乳熟期。无覆盖CK处理于播种期-苗期发生盐分的表聚,正值幼苗期盐分敏感时段,必然造成一定程度的死苗及减产。由于作物根系的向下生长,越后期出现盐分的表聚,对作物生长负面影响越小一些。进一步说明了PSM处理可以增强土壤盐分缓冲性。 图4 油葵生育期内土壤含盐量动态变化 图5为不同覆盖对土壤容重和孔隙度的影响,经过一个生长期,在其自身重力作用及其他因素的影响下,成熟期土壤容重比处理前均有不同程度增加。>10~20 cm土层,PSM处理土层容重比PM、SM和CK处理分别低7.19%、4.05%和9.55%。PSM处理0~40 cm土层容重与处理前差异不显著。PM处理在0~40 cm以上土层的土壤容重比处理前显著增加(<0.05),在0~10 cm土层,其土壤容重达1.55 g/cm3,比PSM、SM和CK分别高出13.14%、9.93%和6.16%。40 cm以下各处理土层的土壤均未受到耕作机具扰动,处理间差异不显著。 0~40 cm土层,各处理收获期土壤孔隙度较处理前均有不同程度降低,随土层的加深而减小。其中PSM成熟期孔隙度与处理前差异不显著,PM处理与处理前孔隙度有显著降低(<0.05);PSM处理土层孔隙度均值比PM提高了8.85%(<0.05)>10~20 cm土层,PSM处理土层孔隙度均值比SM和CK处理提高了4.46%和12.01%(<0.05)。表明PSM处理较PM、SM和CK处理能使耕层土壤孔隙状况得到改善,促成良好土壤结构的形成。 注:同一土壤深度的不同小写字母表示处理间在5%水平上差异显著,下同。 2.5.1 油葵生长及产量特征值 PSM处理产量比PM、SM处理和CK分别提高了35.45%,120.15%,87.80%(<0.05);PM处理产量比SM、CK分别提高了62.53%,38.65%(<0.05),SM处理产量低于CK17.22%(<0.05)。产量最高的PSM处理具有最高的株高株高、茎粗、单盘粒质量、百粒质量,而产量最小的SM处理在株高、单盘粒质量、茎粗显著低于CK。PSM、PM株高、茎粗、单盘粒质量、百粒质量均显著高于SM、CK(<0.05),这是PSM、PM产量构成方面增产的主要原因。由于试验为碱化土壤,油葵出苗率及成株率对产量影响较大。出苗天数的大小顺序为PSM 表2 不同覆盖处理油葵生育期特性与产量构成因素 2.5.2 耗水量与水分利用效率 PSM处理的耗水量较PM、SM处理和CK均显著提高,分别增加56.45、87.39和51.26 mm(<0.05),耗水强度的大小顺序与总耗水量趋势一致,PSM处理的耗水强度较PM、SM处理和CK均显著提高,分别增加 47.67%、99.27%和41.92%(<0.05)。 表3 不同处理对油葵水分及降水利用效率的影响 由WUE的分析结果可知,PSM处理的水分利用效率显著高于SM、CK(<0.05),分别比SM、CK提高了10.80%、32.71%,与PM处理差异不显著;从PUE的数据来看,PSM处理的降水利用效率显著高于PM、SM和CK(<0.05),SM与CK处理差异不显著;PSM处理的降水利用效率分别比处理PM、SM和CK提高了14.71%、86.45%和59.05%。PSM处理降水利用效率比相对于单一地膜或秸秆覆盖及传统无覆盖之中模式中得到了显著的提升,在水分利用效率的提高中起到了重要的作用。 在无灌水条件下,土壤水分主要受降雨、地表覆盖和作物耗水等因素影响。与单一覆盖和无覆盖方式相比较,地膜秸秆复合覆盖消耗的土壤水分深度的下移相对最慢,说明了其上表层抑制蒸发显著,中下层能较好贮存降水水分,在作物生长中后期调用60~90 cm土层水分来满足土壤蒸发和作物的高蒸腾需要,可与作物的需水期形成较好的同步。各覆盖消耗的土壤水的深度也有所不同,地膜秸秆复合覆盖处理于作物生育后期消耗60~100 cm土壤水分,地膜处理在作物生育前期即开始消耗该层土壤水分,这也是单一地膜覆盖会造成作物早衰的原因之一,复合覆盖可以有效减少此现象发生。成熟期,地膜秸秆复合覆盖处理在1 m土体平均土壤含水率显著小于无覆盖处理,可能由于作物地上部分比其他处理蒸腾大和根系量增加[31]及纵深分布范围加大造成的深层储水量消耗增加。这与覆膜措施存在消耗土层深层储水的已有研究结果是一致的[27,32]。另一方面,此种复合覆盖在降水充足时期通过膜侧汇集雨水[24-25]的特殊入渗方式,有利于地表浅层水分向深层运移和补充油葵的各生长阶段消耗;其浅表层(0~20 cm)土壤水分的变异系数规律与已有田飞等[28,31-32]指出的覆盖处理土壤水分稳定性增强的研究趋势相符合;在深层(>30~90 cm)土壤水分稳定性与前人研究有一定差异,复合覆盖此深度的土壤水分活跃性显著高于其他处理(<0.05)。在收获后降水较少情况下,建议有灌水条件的改良碱土利用冬灌来及时补充复合覆盖土壤水分的消耗,避免第二年土壤出现干层。 不同覆盖方式的影响着油葵生育期内土壤容重及孔隙的变化过程,对土壤水分及对降水的贮存量的有直接影响。地膜秸秆复合覆盖具有相对较低土壤容重和较高土壤孔隙度,从而增加了降水贮存量及土壤重力水的入渗,调节了耕层土壤有效水库容,减少了土壤毛管水无效蒸发,为后期作物高产创造了有利的水分条件。单一地膜覆盖在成熟期0~40 cm土壤容重显著大于他2种覆盖,这与已有的研究结果一致[27,35]。同时,地膜秸秆复合覆盖处理良好的土壤结构促进了残留的土壤碱分和脱硫石膏充分发生反应,并及时向下淋洗置换出的有害盐分,维持根区相对低盐适宜生长区,优化作物根区土壤水盐环境。 油葵的苗期至现蕾期为水盐敏感时期[19],降水易引发表土的板结及盐害,直接影响到作物出苗、成活及前期的营养生长。复合覆盖膜孔处因有秸秆,能保持较好土壤结构,增强了入渗和淋洗作用,有效减轻碱性土壤泥泞、板结及盐害。单一地膜处理的表层土壤一直处在较高水分状态,>20~60 cm土层脱盐效果不佳,造成作物中、后期受到盐害。在整个生育期内,地膜秸秆复合覆盖处理>40~60 cm土层保持在4种处理中最低土壤含盐量,其保持的良好耕层土壤结构,有利于利用降水充分向下淋洗耕层改良过程置换出的盐分或稳定盐分含量提高作物的耐盐适应性[36-37],从而大大降低了在淋洗量不足情况下,化学改良碱性土壤发生次生盐害的几率;同时,地膜秸秆复合覆盖处理增强了土壤盐分缓冲性强,减少和推迟了盐分的表聚,降低了表层盐分对作物的毒害性。该处理中秸秆部分在腐解过程中,还可以改善土壤养分[38]和生物活性[14,39-40],促进作物的地上与地下部分生长,提高蒸发“无效水”向蒸腾“有效水”的转化,加快碱化土壤改良进程,形成良性的循环。 盐碱地低产田产量不稳定,与苗期保苗率低有关。地膜秸秆复合覆盖作物的存活率显著高于地膜覆盖、秸秆覆盖和无覆盖常规种植,为后期保产和增产打下了良好的基础。单一秸秆覆盖出苗率低而造成减产,可能由于其前期温度降低[22,26]影响了油葵的出苗率。降水利用效率(PUE)反映了旱地农业降水的生产潜力。在增加耗水量情况下,复合覆盖的种植模式相对于常规种植依然能显著提高产量和水分利用效率,尤其是降水利用效率显著高于地膜覆盖、秸秆覆盖和常规种植模式。这与前人的部分研究结果[41-42]中的覆盖栽培总体耗水量有所减少有一定差异,与前人研究得出的提高水分利用效率[24-25,43]趋势是一致的。究其原因可能由于在不同水分条件下,复合覆盖处理的抑蒸、保苗效果好,地上、地下部分生长的增加及物候期相对延长,因而复合覆盖油葵后期蒸腾作用的耗水量显著大于无覆盖处理。在龟裂碱土改良中,采用地膜秸秆复合覆盖方式旱作种植油葵能提高天然降水的生产潜力,促进节水生产,增加经济效益。 1)在降水量较多时期,地膜秸秆复合覆盖有效提高了30~100 cm土层土壤贮水、持水能力,相对单一覆盖延迟消耗深层土壤水分的时间,在30~90 cm的土壤水分活跃性显著高于其他处理。 2)地膜秸秆复合覆盖在碱土改良过程中比单一覆盖抑盐效果佳,其土壤盐分缓冲性强,盐分表聚推迟至作物生长后期,程度显著低于其他3个处理,减少单一覆盖和常规种植的土壤盐分对作物早起盐分敏感生长时段的毒害。 3)地膜秸秆复合覆盖能相对保持较低土壤容重和较高土壤孔隙度促进土壤结构的改良,有利于提高土壤有效水库容和加快淋洗进程。 4)地膜秸秆复合覆盖处理产量比地膜、秸秆处理和无覆盖种植分别提高了35.45%,120.15%,87.80%(<0.05),提高了苗期存活率;生育期的耗水量较地膜、秸秆处理和常规无覆盖种植分别增加 56.45、87.39 和 51.26 mm(<0.05);其降水利用效率分别比地膜、秸秆和无覆盖提高了14.71%、86.45%和59.05%;水分利用效率分别比秸秆、无覆盖提高了10.80%、32.71%。 综上所述,地膜秸秆复合覆盖种植方式可调节土壤有效水库容,增强土壤保墒抑盐能力,改善作物根区土壤水盐环境,提高天然降水的生产潜力;在碱土改良的初期促进保苗增产。同时,由于研究区降水变异性强,试验年限较短,得出的初步结论还有待于进一步结合田间蒸发蒸腾及作物多项指标做更深入的定点多年监测研究。 [1] 王遵亲,祝寿泉,俞仁培. 中国盐渍土[M]. 北京:科学出版社,1993. 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Acta Pedologica Sinica, 2013, 50(6): 1129-1137. (in Chinese with English abstract) Plastic film and straw combined mulchingimproving water and salt characteristics of Takyr Solonetzs and yield of oil sunflower Lü Wen1,2,3, Sun Zhaojun2,3, Chen Xiaoli4, Zhao Xining1, Gao Xiaodong1, Wu Pute1※ (1.,,712100,; 2.,,750021,; 3.()750021,; 4.,,712100,) Saline alkali wasteland and low-yield fields are important reserve of cultivated land in China. The chemical methods of industrial waste desulphurization gypsum (CaSO4·2H2O) have achieved certain results and good environmental protection benefits at the aspect of improving alkaline soil. Scarce water resource, soil hardening and salt concentration in early improvement are still the key factors that restrict the development of agricultural production in chapped alkali soil by using waste desulfurization gypsum from power plant. In order to improve rainfall utilization efficiency, and restrain the problems of salt aggregation on soil surface and soil compaction in the process of chemical improvement of alkaline soil, a field experiment was conducted, which included 3 soil surface mulching methods: combined mulching of plastic film and straw (the straw was firstly used, then covered with mulching film, and later seeding was conducted artificially; the aperture was 4 cm, and the straw mulch was restored at the orifice after sowing), plastic film mulching (white transparent polyethylene film, width of 2 m, thickness of 0.02 mm), and straw mulching (spring wheat straw, length of 8-12 cm, coverage amount of 0.6 kg/m2). The experiment included 4 treatments: plastic film and straw combined mulching (PSM), plastic film mulching (PM), straw mulching (SM) and conventional tillage (CK), which were designed to explore the dynamic structure characteristics of soil water salt and its effect on yield of oil sunflower () at Pingluo saline-soil Experimental Station in Ningxia. The soil moisture contents at the depth of 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 cm were measured; soil salt contents and soil bulk densities of different soil depth profiles (10, 20, 30, 40, 50, 60 cm) were measured for different treatments. And the results showed that: The PSM treatment effectively improved the water storage and water holding capacity of 30-100 cm soil layer. It delayed the time of oil sunflower consuming the moisture in 60-100 cm soil depth. The water activity in the 30-90 cm soil layer under PSM treatment was higher than that of other single coverage models. Salt accumulation on soil surface was delayed to the later stage of crop growth, and its level was significantly lower than the other 3 treatments, reducing the toxicity of soil salinity in early salt-sensitive growth period of crops compared with single coverage and conventional planting. The combined mulch promoted the improvement of soil structure with relatively low soil bulk density and higher soil porosity, which is beneficial to improve soil effective water storage capacity and accelerate the process of leaching. The PSM treatment improved survival rate and yield of oil sunflower in seedling stage. The precipitation use efficiency under the PSM treatment was increased by 14.71%, 86.45% and 59.05% respectively compared with the PM, SM and CK treatments, and the water use efficiency was increased by 10.80% and 32.71%, respectively, compared with the SM and CK treatments. Therefore, the plastic film and straw combined mulch can improve soil structure, which is beneficial to enhance soil effective water storage capacity and accelerate the process of leaching. plastic film; straw; soils; combined mulch; soil water and salt; yield; precipitation use efficiency 吕 雯,孙兆军,陈小莉,赵西宁,高晓东,吴普特. 地膜秸秆复合覆盖改善龟裂碱土水盐特性提高油葵产量[J]. 农业工程学报,2018,34(13):125-133.doi:10.11975/j.issn.1002-6819.2018.13.015 http://www.tcsae.org Lü Wen, Sun Zhaojun, Chen Xiaoli, Zhao Xining, Gao Xiaodong, Wu Pute. Plastic film and straw combined mulchingimproving water and salt characteristics of Takyr Solonetzs and yield of oil sunflower[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(13): 125-133. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2018.13.015 http://www.tcsae.org 2017-04-15 2018-05-23 国家自然科学基金(41571506、51579212),国家重点研发计划(2016YFC0400204),国家林业公益性行业科研重大专项(201504402),陕西省科技统筹创新工程项目(2015KTCL02-25、2016KTZDNY-01-03)。 吕 雯,助理研究员,主要从事水土资源高效利用研究。 Email:lvwen2011@hotmail.com 吴普特,研究员,主要从事水土保持与节水农业方面研究。Email:gjzwpt@vip.sina.com 10.11975/j.issn.1002-6819.2018.13.015 S156.4; S152.7 A 1002-6819(2018)-13-0125-092.3 土壤盐分的变化
2.4 土壤容重及孔隙度的变化
2.5 覆盖对油葵生长、产量和水分利用效率的影响
3 讨 论
3.1 地膜秸秆复合覆盖提高土壤保墒和深层储存降水能力
3.2 地膜秸秆复合覆盖有效降低土壤容重、提高土壤孔隙度
3.3 地膜秸秆复合覆盖抑制土壤积盐
3.4 地膜秸秆复合覆盖提高油葵出苗存活率、产量及降水利用率
4 结 论