Effects of soil moisture on cotton root length density and yield under drip irrigation with plastic mulch in Aksu Oasis farmland

Effects of soil moisture on cotton root length density (total root length per unit soil volume) and yield under drip irrigation with plastic mulch were studied through field experiments. The results indicate that spatial distributions of root length density of cotton under various water treatments were basically similar. Horizontally, both root length densities of cotton in wide and narrow rows were similar, and higher than that between mulches. Vertically, root length density of cotton decreased with increasing soil depth. The distribution of root length density is different under different irrigation treatments. In conditions of over-irrigation, the root length density of cotton between mulches would increase. However, it would decrease in both the wide rows and narrow rows. The mean root length density of cotton increased with increasing irrigation water. Water stress caused the root length density to increase in lower soil layers. There is a significant correlation between root length density and yields of cotton at the flower-boll and wadding stages. The regression between irrigation amount and yield of cotton can be expressed as y = -0.0026x2+18.015x-24845 (R2 = 0.959). It showed that the irrigation volume of 3,464.4 m3/hm2 led to op-timal root length density. The yield of cotton was 6,360 .8 kg/hm2 under that amount of irrigation.

Cotton's Water Demand and Water-Saving Benefits under Drip Irrigation with Plastic Film Mulch

The primary purpose of this research was to give suitable irrigation program according to the growth period and water requirement.A cotton field experiment with mulched drip irrigation was conducted at the National Field Observation and Research Station for Oasis Farmland Ecosystem in Aksu of Xinjiang in 2008.Water balance method was adopted to study the water requirement and water consumption law of cotton under mulched drip irrigation in Tarim Irrigated Area.Statistical analysis of experimental data of irrigation indicates that the relationship between yield of cotton and irrigation presents a quadratic parabola.We fit the model of cotton water production on the basis of field experimental data of cotton.And the analysis on water saving benefit of cotton under mulched drip irrigation was done.Results indicate that water requirements for the irrigated cotton are 543 mm in Tarim Irrigated Area.The water requirements of seedling stage is 252 mm,budding stage is 186 mm,bolling stage is 316 mm and wadding stage is 139 mm.the irrigation amount determines the spatial distribution of soil moisture and water consumption during cotton life cycle.However,water consumption at different growth stages was inconsistent with irrigation.Quantitatively,the water consumed by cotton decreases upon the increase of irrigation amount.From the perspective of water saving,the maximal water use efficiency can reach 3 091 m3/ha.But the highest cotton yield needs 3464 m3/ha irrigation water.In summary,compared to the conventional drip irrigation,a number of benefits in water saving and yield increase were observed when using plastic mulch.At the same amount of irrigation,the cotton yield with plastic mulch was 30.2% higher than conventional approaches,and the efficiency of water utilization increased by30.2%.While at the same yield level,29.3% water was saved by using plastic mulch,and the efficiency increased by 41.5%.

Localized salt accumulation: the main reason for cotton root length decrease during advanced growth stages under drip irrigation with mulch film in a saline soil

High salinity in soil can prevent root growth of most plants. To investigate soil salinity dynamics under drip irrigation with mulch film （DI） and its effects on cotton root length, we conducted field experiments in saline soil based on a monolith method using flooding irrigation with mulch film （FI） as a control at the Korla Experimental Station of the Xinjiang Academy of Agricultural Sciences, China in 2009 and 2010. The results showed that the total root length decreased 120 days after sowing （DAS） under DI, and was mainly centered in the 0-30 cm soil layer and at distances of 30-70 cm from the drip-lines. There was almost complete overlap in the area of root length decline and salt accumulation. In the soil depth of 0-30 cm and at distances of 30-70 cm from the drip-lines at 110 to 160 DAS in 2009 and 171 DAS in 2010, the electrical conductivity （EC） in all soil samples was at least 3 mS/cm and in some cases exceeded 5 mS/cm under DI treatment. However, EC barely exceeded 3 mS/cm and no reduction in root length was observed under FI treatment. Correlation analysis of soil EC and root length density indicated that the root length declined when the soil EC exceeded 2.8 mS/cm. The main reason for the decrease of root length in cotton under DI was localized accumulation of salinity.

Modeling the effects of plastic film mulching on irrigated maize yield and water use efficiency in sub-humid Northeast China

In sub-humid Northeast China,plastic film mulching(PFM)is increasingly used with drip irrigation system in maize(Zea mays L.)to cope with seasonal droughts and low temperatures during seedling stage.Although there were several studies showing the benefits of PFM on maize production in the region,quantification of the effects of PFM in sub-humid Northeast China are still lacking.Hybrid-Maize model has a special version that can not only simulate the effects of PFM on reduction of soil evaporation and rise of topsoil temperature,but also simulate the effects of PFM on crop development and other physiological processes.This paper reports how to verify the Hybrid-Maize model against observations and then applying the model to quantify effects of PFM on grain yield and water use efficiency(WUE)under irrigated scenarios.The Hybrid-Maize model was added the heating effects of PFM on rising surface-soil temperature and promoting subsequent crop development by establishing equations between surface-soil temperature and air temperature before V6 stage.A 3-year field experiment including maize growth and yield data measured at a drip-irrigated field in Heilongjiang Province was used to serve the model calibration.The simulated results indicated that the Hybrid-Maize model performed well in simulation of seasonal soil water storage and in-season aboveground dry matter in three years,but overestimated the leaf area index(LAI)for both treatments and underestimated the final aboveground dry matter at maturity for mulched treatments.Although the Hybrid-Maize model overestimated the grain yield and WUE,it did still reflect the effects of PFM on increasing grain yield and WUE during the three growing seasons.The average simulated grain yield and WUE for mulched treatments were 8%and 13%greater compared to non-mulched treatments using 30 years weather data,which were in agreement with observations that average grain yield and WUE was 11%and 14%increased by PFM,respectively.For evapotranspiration(ET),the average simulated ET for mulched treatments was 22 mm less than non-mulched treatments mainly due to less soil evaporation.For simulated irrigation requirements,at most 69 mm of irrigation water could be saved by PFM.In conclusion,PFM with drip irrigation could improve irrigated maize production in sub-humid Northeast China.

两种覆盖方式下灌水定额对土壤温度变化、棉花产量及水分利用效率的影响

【目的】探究不同覆盖方式和灌水定额对棉花生产的影响。【方法】于2017―2019年在新疆阿拉尔市开展大田试验,其中,2017―2018年膜下滴灌试验以新陆中46号为供试材料,设置24 mm(M1)、30 mm(M2)和36 mm(M3)3个灌水定额;2018―2019年无膜滴灌试验以中棉619为供试材料,设置36 mm(W1)、45 mm(W2)和54 mm(W3)3个灌水定额;分析不同处理对10 cm、20 cm、40 cm土层土壤温度和土壤含水量、籽棉产量以及灌溉水利用效率的影响。【结果】2种模式下棉田10 cm、20 cm和40 cm土层土壤含水量和籽棉产量均随灌水定额的增大呈增加趋势。M2、M3处理的籽棉产量分别较M1处理显著增加8.82%~11.47%和14.24%~18.96%;W2、W3处理的籽棉产量分别较W1处理显著增加15.18%~22.61%和32.53%~46.29%。土壤温度和灌溉水利用效率均随灌水定额的增大呈降低趋势。M2、M3处理的灌溉水利用效率分别较M1处理显著降低10.82%~12.94%和20.70%~23.84%;W2、W3处理的灌溉水利用效率分别较W1处理降低1.91%~7.85%和2.47%~11.65%。2018年灌水定额相同时,M3处理的土壤含水量、0~40 cm土层土壤温度、籽棉产量和灌溉水利用效率均高于W1处理。基于逼近理想解排序法(technique for order preference by similarity to ideal solution, TOPSIS)的综合评价表明,膜下滴灌处理配套30 mm灌水定额,无膜滴灌处理配套54 mm灌水定额可取得较好的效果。【结论】提高灌水定额可以在一定程度上弥补无膜种植模式引起的籽棉产量降低,但会降低灌溉水利用效率。研究结果可为无膜滴灌植棉技术在当地的推广提供参考。

新疆灌区农业节水发展现状与对策建议

水是新疆可持续发展的生命线,也是新疆农业发展的瓶颈。农业是新疆用水大户,占经济社会总用水量的90%以上,南疆农业用水占比更高。新疆节水潜力重点在农业,农业节水是新疆经济社会可持续发展的根本出路。为提高新疆农业水资源利用效率,促进农业高质量发展,本文梳理回顾了新疆灌区农业节水发展历程,分析了农业节水发展现状及存在问题,结合新时期国家对新疆农业发展的新定位、新要求,提出了大力发展适水型现代农业、加大高效节水工程建设、持续推进降盐节水、加强数字化灌区建设、加强农业节水宣传培训、健全农业节水服务体系等对策建议,以期为新疆现代农业可持续发展和保障国家粮棉油安全提供有力支撑。

不同矿化度水源膜下滴灌对棉花土壤盐分分布及生长的影响

利用微咸水膜下灌溉是缓解干旱区农业灌溉资源短缺的有效途径之一,分析不同矿化度水源膜下滴灌对土壤盐分分布及作物生长的影响对于确定灌溉水源矿化度阈值具有重要意义。开展4 a不同梯度矿化度水源膜下滴灌棉花测坑试验,设置6个处理矿化度分别为1 g/L(CK)、2 g/L(A)、3 g/L(B)、4 g/L(C)、5 g/L(D)和6 g/L(E),分析不同梯度矿化度水源膜下滴灌土壤盐分累积及棉花生长特征,确定微咸水膜下滴灌棉花灌溉矿化度阈值。结果表明:2019-2022年,0~100 cm平均土壤电导率以每年0.920 dS/m、0.995 dS/m、1.196 dS/m和1.188 dS/m的速率呈线性增长的趋势。随着灌溉年限增加,不同梯度微咸水膜下滴灌下土壤电导率呈现增加趋势。5 g/L和6 g/L处理土壤盐分累积最大,分别为38.70%和39.19%;灌水12 h后,宽行表层20~40 cm土壤盐分累积最为明显,土壤电导率为0.30~2.1 dS/m;窄行土壤盐分在40~60 cm土层处出现累积,土壤电导率为1.26~1.93 dS/m。矿化度为3 g/L水源膜下滴灌棉花土壤盐分累积量较小,对棉花叶片光合作用指数影响最小,生长指标和产量达到最大,微咸水膜下滴灌棉花适宜的灌溉水源阈值为3 g/L。

滴灌水盐氮调控对棉田水肥盐运移及棉花产量的影响

为明析覆膜滴灌条件下水盐氮调控对土壤水盐养分运移变化、棉花生长指标及产量的影响,通过两年三因素全组合大田试验,设置灌水量三水平(W1:2700 m^(3)·hm^(-2)、W2:3600 m^(3)·hm^(-2)和W3:4500 m^(3)·hm^(-2))、含盐量三水平(S1:3 dS·m^(-1)、S2:6 dS·m^(-1)和S3:9 dS·m^(-1))、施氮量三水平(F1:105 kg·hm^(-2)、F2:210 kg·hm^(-2)和F3:315 kg·hm^(-2)),研究了不同水盐氮组合对土壤水分、盐分、氮素分布及植株生长、产量的影响。结果表明:土壤水分主要聚集在30~40 cm土层,不同土层深度的含水率基本呈先增大后减小的变化趋势;蕾期和花铃期的S3F3W1和S2F3W1比S1F3W1的0~40 cm土层平均含水率增大1.3%~21.8%;同一灌溉量下S1F3组合的平均含水率比S1F2和S1F1增大1.39%~13.83%。土壤盐分生育期内呈现先减少后增加的变化趋势;S1土壤盐分随施氮量的增大而先增大后减小,S2、S3土壤盐分随施氮量的增加而减少。W2、W3处理中,氮素在40~60 cm土层中缓慢积聚;S1处理的氮素含量明显高于S2、S3。土壤水分、盐分、氮素含量交互影响,在适宜的土壤水分、氮素条件下,较低的土壤含盐量,能使植株更好地利用养分,利于植株的生长进而促进产量的形成。为获得较高的经济效益,低、中盐土壤推荐灌溉量为3600 m^(3)·hm^(-2),施氮量为210 kg·hm^(-2);高盐土壤推荐灌溉量为4500 m^(3)·hm^(-2),施氮量为315 kg·hm^(-2)。研究为探索干旱区多年膜下滴灌棉花农田生态系统水盐养分运移机制及水肥高效利用提供科学的理论依据。

改善土壤理化性质和作物出苗率的最佳生物质炭施用量

确定改善土壤理化性质和作物出苗率的最佳生物质炭施用量,可为田间管理提供依据。以新疆盐碱土为研究对象,在生物质炭施用量分别为0、10、50及100t·hm^(-2)条件下,开展了膜下滴灌田间小区试验,对比了生物质炭施用量对土壤容重、温度、有机碳等理化性质和作物出苗率的影响,并进一步分析了作物出苗率与土壤理化性质的关系。结果表明,生物质炭施用量增加显著降低了0~30 cm土层的容重,棉花和甜菜的土壤容重分别降低0~0.32和0.04~0.25 g·cm^(-3)。与不施用处理比较,100 t·hm^(-2)的生物质炭施用量显著增加了棉花和甜菜不同生育期的5 cm深度地温,但10和50 t·hm^(-2)的施用量只显著增加了棉花蕾期和铃期的5 cm深度地温。施用生物质炭增加了棉花和甜菜的土壤有机碳含量,不区分年份和生育期增幅相应为0.98~13.2和0.66~12.1g·kg^(-1);苗期和收获期(不区分年份和作物)增幅分别为1.20~7.43和0.66~13.2 g·kg^(-1),苗期各施用量下有机碳均显著增加,收获期部分施用量下有机碳显著增加。出苗率大致随容重增加而增加,随土壤温度增加先增加后减小,最适宜作物出苗的温度为22~26℃;出苗率随土壤有机碳增加先增加后减小,但高生物质炭施用量导致的土壤有机碳增加过高抑制了作物出苗。当生物质炭施用量为10t·hm^(-2)时,棉花和甜菜的出苗率大于0.7,高于其他3种生物质炭处理,因此推荐10 t·hm^(-2)作为最优生物质炭施用量。

汾河灌区玉米膜下滴灌水肥一体化技术试验与应用

在汾河灌区以传统的地面灌溉不覆膜种植玉米为对照,进行了玉米覆膜条件下滴灌水肥一体化技术应用试验。试验对比了两种模式下玉米生长动态、耗水量和耗水规律,以及灌溉、施肥、产量和经济效益等。结果表明:膜下滴灌玉米与不覆膜地面灌溉玉米耗水规律基本一致,但日均耗水量低于不覆膜玉米,且具有明显的节水、减肥、增效、增产和增收作用。提出确定膜下滴灌灌溉定额方法、玉米膜下滴灌水肥一体化灌溉制度和施肥制度,可为汾河灌区及我省其它条件相近地区农业生产提供借鉴和参考。

不同灌水量和施氮量对膜下滴灌甘薯生长的影响

针对山东地区甘薯灌水和施肥不合理,产量和水分利用效率较低等问题。于2020年和2021年在山东省日照市中国农业大学特色马铃薯优质高产试验示范基地,选用“普薯32号”进行了2 a膜下滴灌甘薯田间试验。试验考虑了灌水量与施氮量2个试验因素,设置3个灌水量水平(不灌水,P0;滴灌湿润比为30%,P1;滴灌湿润比为60%,P2)和3个施氮水平(氮肥90 kg/hm^(2),N1;氮肥180 kg/hm^(2),N2;氮肥270 kg/hm^(2),N3),共9个处理。试验测量了不同水氮处理条件下的甘薯田间土壤水分、甘薯生理生长、产量及构成因素和水分利用效率。研究结果表明:不同灌水量和施氮量影响土壤含水量、贮水量、水分分布和甘薯生长。N2处理的甘薯生长旺盛,会促进0~50 cm土层的土壤水分消耗,从而降低土壤贮水量。2021年N2处理的土壤贮水量较N1与N3处理分别降低17.8%与17.7%。2021年P2处理的平均甘薯蔓长较P0、P1提高29.3%、14.8%。相同灌水条件下,甘薯的单株结薯数和产量随施氮量增加而先增加后减少:2020年,N2P2处理的甘薯产量较N1P2、N3P2分别增加19.9%与3%;2021年,N2P2处理的甘薯产量较N1P2、N3P2分别增加18.7%与24.5%。相同施氮量条件下,甘薯产量随灌水量增加而增加,2021年,N2P2处理的甘薯产量较N2P0、N2P1分别增加14.4%与24.2%。总体上,N2P2可以促进甘薯生长,提高甘薯产量和水分利用效率,适宜山东地区膜下滴灌甘薯种植。

CO_(2)水溶液对膜下滴灌玉米农艺性状及籽粒营养品质的影响

以MC670玉米为材料,在膜下滴灌条件下,通过CO_(2)溶水装置关键技术,研究玉米在不同生育时期滴施CO_(2)水溶液对其农艺性状、产量及籽粒营养品质的影响。结果表明:在玉米整个生育期内,与常规灌溉相比,滴施CO_(2)水溶液能够缩短玉米的生育进程,使生育期提前7 d,促进了玉米早熟;玉米的株高、茎粗、SPAD值都有所增加,对改善玉米植株生长有促进作用;产量、行粒数、穗长分别增长了21.94%、16.36%、8.26%,说明滴施CO_(2)水溶液具有显著的增产作用;玉米籽粒蛋白质、脂肪质量分数较常规灌溉分别增长了8.85%、27.78%,表明滴施CO_(2)水溶液有利于玉米籽粒蛋白质和脂肪的积累形成,可以提高玉米产量和改善玉米籽粒营养品质。

不同施肥量及施肥运筹对大麦产量及农艺性状的影响

为优化巴中地区大麦种植施肥措施,研究了不同施肥量对甘啤8号产量的影响。试验设置以基施225 kg/hm^(2)复合肥为对照(CK),处理分2类[基施+追施(A)与单纯基施(B)],每类处理又分4个水平。结果表明:大麦产量与株高、穗长、成穗率、结实率、穗粒数、穗数、单株茎蘖数呈极显著正相关关系,与千粒质量呈显著正相关关系;B_(1)、B_(2)、B_(3)、B_(4)处理下,大麦产量随基肥使用量的增加而增加,B_(4)处理下大麦产量最高,为4882.4 kg/hm^(2),较CK显著增产166.0%;当总施肥量在450、600 kg/hm^(2)时,产量表现为A1比B_(1)高、A_(2)比B_(2)高,超过600 kg/hm^(2)时则相反,即足量基肥有助于巴中地区大麦产量与效益提高。

新疆棉田膜下滴灌盐分运移规律

该文主要从不同生育阶段和滴灌年限、不同方向(垂直和水平)、不同土壤质地三个方面对膜下滴灌盐分的运移进行了分析比对,初步得出:随着生育期的推后,各土层含盐量都有不同程度的加大;垂直方向盐分的积累在0～60cm土层逐渐增加,60～100cm土层盐分积累受膜下滴灌影响较小;水平方向背行(露地部分)中央土层处盐分积累最多,滴头处盐分积累最少;对于不同土壤质地,壤土中的盐分分布较黏土中的呈更规律的变化;不同滴灌年限中滴灌年限越长,棉田中的盐分积累就越多。

干旱区膜下滴灌条件下洋葱水分生产函数与优化灌溉制度

为探索西北内陆旱区膜下滴灌条件下洋葱节水、高产和高效的灌溉制度,开展了2a田间试验,分析了洋葱的耗水规律及其影响因素,建立了洋葱的水分生产函数,并对洋葱的灌溉制度进行了优化。结果表明:膜下滴灌条件下洋葱的耗水量为170.1～395.7mm,产量随灌水量和耗水量的增加而增加,水分利用效率则随灌水量的增加而降低。苗期和成熟期亏水对洋葱产量和水分利用效率无显著影响。洋葱水分敏感指数在鳞茎膨大期最大,发叶期次之,苗期和成熟期较小。膜下滴灌条件下,西北旱区干旱年洋葱全生育期灌水量为375mm时,可获得较高的产量;其优化灌溉制度为苗期灌水30～40mm,发叶期灌水130～140mm,鳞茎膨大期灌水170～190mm,成熟期灌水25mm,灌水间隔可采用5d。该优化灌溉制度对西北内陆旱区洋葱的节水灌溉实践具有一定参考价值。

不同灌溉制度对棉田盐分分布与脱盐效果的影响

以直径20cm蒸发皿蒸发量为基础，采用双因素组合随机区组设计，研究了不同灌溉制度对膜下滴灌棉田土壤盐分分布与脱盐效果的影响。结果表明：增大灌水频率与灌水定额，有利于对棉花根区盐分在水平方向的淋洗，5d和8d灌水频率对水平方向含盐量有影响的土层深度分别为0～20cm和0～30cm；5d灌水频率的土壤盐分随深度的增加呈现先降后升趋势，8d灌水频率0～100cm深度内各土层含盐量相差不明显，中等灌水定额（T60）0—60cm土层含盐量小于高水（T80）和低水（T40）处理；与播前相比，棉花收获时0—20cm含盐量降低，但30—60cm土层含盐量增加，0～60cm土层含盐量总体表现增加，中等灌水定额（T60）处理含盐量变化幅度最小，脱盐率为0．44％。灌水处理对0～100cm深度土壤总含盐量无明显影响。此外，灌水量过高与过低均不利于提高棉花产量，与其他处理相比，高频（5d）中定额灌溉（T60）处理不但可以获得合理的盐分分布与脱盐效果，且籽棉产量最高，为9．18t／hm^2，是实现抑盐、控水、高产、高效的适宜棉花灌溉制度。

荒漠气候区膜下滴灌棉花需水量和灌溉制度的试验研究

20 0 0年 5～ 8月在新疆石河子 12 1团土壤改良实验站进行了棉花膜下滴灌需水量和灌溉制度的试验研究。结果表明 ,膜下滴灌条件下灌水量过多或过少均不利于高产 ,为了取得高产和较高的水分利用率 ,全生育期的耗水量应在 345～ 380mm之间。生育期适度缺水可以提高棉花的品质。在当地气候、土壤及栽培模式下 ,棉花膜下滴灌的灌溉制度为全生育期灌水 12～ 14次 ,灌水定额 2 5～ 30mm。

新疆棉花膜下滴灌技术的发展与完善

新疆棉花膜下滴灌技术发展经历了试验研究、示范推广和大面积应用三个阶段。"密、早、膜、矮、壮、高"栽培体系的建立等阶段性成果有力地保证了棉花膜下滴灌技术的应用推广;因地制宜、多种毛管田间布置模式的发展适应了棉花种植方式的多样性;对棉花膜下滴灌水分蒸散特征、干旱诊断技术的深入研究为制定灌溉制度和进行科学的水分管理提供了依据,保证了膜下滴灌技术的高效应用;施肥推荐系统和水分自动控制系统的应用增强了棉花膜下滴灌管理的目标性;各级职能部门的重视有力地推动了膜下滴灌技术的发展。当前棉花膜下滴灌技术需解决主要问题有:加快膜下滴灌技术普及与培训;加大对膜下滴灌技术推广的政策扶持力度,调整水价,努力实现经济效益、社会效益和生态效益的统一;继续深入研究棉花膜下滴灌灌溉制度和施肥技术,提高肥水利用效率;加强地下滴灌技术研究。

塑料大棚渗灌灌水下限对番茄生长和产量的影响

利用土壤水分张力计监测土壤水分吸力的变化 ,以灌水时 30cm土层的土壤水分吸力表示渗灌灌水下限 ,研究灌水下限为 10、16、2 5、4 0和 6 3kPa时对塑料大棚番茄生长和产量的影响 .结果表明 ,番茄株高、生物量分别随灌水下限的增大而减小 .番茄的产量和水分利用率与灌水下限间的关系曲线为抛物线 ,而茎粗 /株高比与灌水下限间的关系曲线为三次多项式曲线 .灌水下限不同 ,番茄的根 /冠比 (R/S)动态不同 ,番茄根系与株冠的生长状况不同 .灌水下限在 2 5～ 33kPa时 ,番茄植株生长健壮 ,根冠比例协调 ,产量大 ,水分利用率高 .此指标作为渗灌灌水下限 ,灌水时土壤水分的含量比常规灌水低 ,灌水次数少 ,有利于提高保护地番茄栽培的水分利用率和劳动生产率 .

干旱区大田膜下滴灌土壤盐分运移与调控

膜下滴灌节水技术在新疆已推广应用了160多万hm2且面积仍在持续增加。为研究干旱区大田膜下滴灌土壤盐分运移特征,该文通过在新疆巴州灌溉试验站进行的膜下滴灌试验,结果表明,在单次滴灌后,剖面土壤内的盐分产生了定向重分布,形成脱盐区、稳定区与积盐区,具有调控田间尺度土壤盐分的作用。脱盐区的面积要大于积盐区。在0～40cm的深度内,双管对表层盐分重分布的作用大于单管;在0～80cm深度,双管对剖面盐分重分布的作用弱于单管。在棉田的整个生育期内,剖面土壤的盐分则受灌水周期的影响,呈上下振荡、振幅缩小且总体脱盐的变化趋势,形成了一种对作物生长有利的局部环境。膜下滴灌不仅是一种滴灌和覆膜相结合的节水技术,而且通过对其控制性精准灌溉的灵活应用,可达到生育期控盐与非生育期排盐的结合,从而为在干旱区实现节水控盐的目标提供技术保障。