加氧灌溉对菠萝根区土壤呼吸和生理特性的影响

通过大田试验,研究了加氧灌溉对菠萝根区土壤呼吸作用、生理特性、生物量积累、果实产量、品质和水分利用效率的影响.采用Mazeei（空气注射器）给地下灌溉系统加入空气,设计了加氧和不加氧灌溉2种处理方式,7次重复.设计滴头埋深10 cm.研究表明,与对照相比,菠萝根区30 cm以内土壤水分质量分数和CO2质量分数没有明显差异,但是加氧灌溉使得土壤呼吸增加了100%;菠萝的果实鲜重、生物量鲜重、干物质重和收获指数明显增大,差异有统计学意义（p≤0.05）;加氧灌溉提高了菠萝的水分生产率,与对照相比增加了17.2%;同时,加氧灌溉明显改善了菠萝单果尺寸和重量,使得单果重量增加了17.3%,田间产量增加了4.3%,增加了果实的糖质量分数,减少了果实的透明物.研究结果为加氧灌溉技术的推广应用提供了理论依据.     

加气灌溉下气候因子和土壤参数对土壤呼吸的影响

为揭示温室内气候因子和加气灌溉下土壤温度、氧气含量和水分对土壤呼吸的影响,对比研究了加气灌溉和地下滴灌(对照)下,各因子与土壤呼吸速率的关系。结果表明:5 cm处土壤温度与土壤呼吸呈极显著正相关关系,加气灌溉和对照处理下相关系数分别为0.615和0.564,且两处理下5 cm处土壤温度分别解释了土壤呼吸变化的46.6%和32.4%。大气相对湿度和土壤氧气含量也影响着土壤呼吸的变化。加气灌溉和对照处理下,大气相对湿度解释了土壤呼吸速率变化的35.2%和23.7%。两处理下土壤氧气含量分别解释了20%左右的土壤呼吸变化。各因子交叉混合影响了76.8%(加气灌溉)和42.5%(对照)的土壤呼吸变化。由此可知,土壤温度是影响土壤呼吸变化的控制性因子,大气相对湿度和土壤氧气含量也是影响土壤呼吸变化的重要因子。各因子对土壤呼吸速率存在交叉影响,且加气灌溉下的拟合效果明显优于对照。加气灌溉下土壤含水率略有下降,土壤呼吸速率和土壤氧气含量与对照差异显著,分别提高了33.16%和16.61%。加气灌溉明显改善了根区土壤环境,土壤呼吸的其他限制因素减少,因此加气灌溉下土壤温度、大气相对湿度、土壤含水率和土壤氧气含量对土壤呼吸的交叉影响更明显,对土壤呼吸变化的拟合效果更优。     

循环曝气地下滴灌的温室番茄生长与品质

循环曝气滴灌可以大幅度提高灌溉水掺气比例,有效改善普通地下滴灌引起的黏质型土壤根区间歇性缺氧环境,提高作物生产力.以河南省中牟县黄河淤积黄黏土为供试土壤,以温室番茄为供试对象,研究循环曝气地下滴灌对番茄生理及品质的影响.结果表明,与普通地下滴灌(对照处理)相比,相同灌溉定额条件下曝气处理番茄果实前5次产量提高了29.15%;番茄的水分利用效率提高了20.72%.曝气处理气孔导度提高了30.51%,植物的生长活力得到增强.番茄果实维生素C含量提高了13.25%,可溶性固形物含量提高了8.62%,糖酸比提高了22.05%,而总酸含量和硬度分别下降了15.50%和11.19%.曝气处理最大根长增加了16.75%,根冠质量之比提高了25.81%.综合分析表明,曝气滴灌可显著促进黄黏土中番茄的生长,促进番茄果实成熟,有效提高作物产量,改善番茄品质.     

Effects of drip irrigation frequency on soil wetting pattern and potato growth in North China Plain

The effect of irrigation frequency on soil water distribution, potato root distribution, potato tuber yield and water use efficiency was studied in 2001 and 2002 field experiments. Treatments consisted of six different drip irrigation frequencies: N1 (once every day), N2 (once every 2 days), N3 (once every 3 days), N4 (once every 4 days), N6 (once every 6 days) and N8 (once every 8 days), with total drip irrigation water equal for the different frequencies. The results indicated that drip irrigation frequency did affect soil water distribution, depending on potato growing stage, soil depth and distance from the emitter. Under treatment N1, soil matric potential (ψ_m) Variations at depths of 70 and 90 cm showed a larger wetted soil range than was initially expected. Potato root growth was also affected by drip irrigation frequency to some extent: the higher the frequency, the higher was the root length density (RLD) in 0–60 cm soil layer and the lower was the root length density (RWD) in 0–10 cm soil layer. On the other hand, potato roots were not limited in wetted soil volume even when the crop was irrigated at the highest frequency. High frequency irrigation enhanced potato tuber growth and water use efficiency (WUE). Reducing irrigation frequency from N1 to N8 resulted in significant yield reductions by 33.4 and 29.1% in 2001 and 2002, respectively. For total ET, little difference was found among the different irrigation frequency treatments.     

加氧灌溉对烟草生长影响规律的研究

加氧灌溉能很好地解决常规灌溉中“水氧矛盾”的问题,从而实现低水肥,高吸收,高产量,高品质的目标。通的对烟草进行机械加氧灌溉、化学加氧灌溉及常规对照三个处理进行试验研究,通过检测并分析烟草根系和农艺性状的相关指标,得出相对于常规对照处理,两种加氧灌溉处理均显著促进根系生长,增大叶面积,提高烟叶产量。机械加氧灌溉比化学加氧灌溉更有利于根系的扎深,化学加氧灌溉比机械加氧灌溉更有利于营养物质向地面植株的分配。     

不同增氧滴灌方式对蔬菜生长生理指标的影响

为了研究不同增氧方式对盆栽小白菜生长生理指标的影响,以小白菜为供试作物,采用盆栽地下滴灌的方式,以普通地下滴灌作为对照(CK),设置循环曝气(MAI)、双氧水(H₂O₂)、纯氧扩散器曝气(OC)及射流振荡器曝气(FO)4个增氧灌溉处理.结果表明,增氧地下滴灌显著提高了土壤呼吸速率,处理MAI,OC和FO较对照处理分别增大了65.87%,66.79%和111.62%.增氧地下滴灌促进了小白菜的根系生长、光合作用、蒸腾速率和气孔导度,进而提高了小白菜的物质量积累和产量.与对照相比,处理MAI的地下部鲜质量增大了42.03%,地下部干质量增大了79.85%;处理MAI,H₂O₂,OC和FO的光合速率分别增大了868.62%,794.14%,778.67%和650.19%;处理MAI,H₂O₂和OC的气孔导度较CK增大了157.14%,128.57%和85.71%,蒸腾速率增大了55.61%,32.38%和19.58%;处理MAI和H₂O₂的产量分别增大了56.36%和38.72%.综上,增氧地下滴灌可增强小白菜根区的土壤呼吸作用,改善光合作用、蒸腾速率和气孔导度,提高了产量及水分利用效率.其中,循环曝气处理的改善效果最为显著.     

Effect of different drip irrigation regimes on sugar beet (Beta vulgaris L.) yield, quality and water use efficiency in Middle Anatolian, Turkey

Agricultural production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant plant varieties or water management for arid and semi-arid areas under water shortage conditions. A field study was conducted to determine effects of seasonal deficit irrigation on plant root yield, quality and water use efficiency (WUE) of sugar beet for a 2-year period in the semi-arid region. Irrigations were applied when approximately 50–55% of the usable soil moisture was consumed in the effective rooting depth at the full irrigation (FI) treatment. In deficit irrigation treatments, irrigations were applied at the rates of 75, 50 and 25% of full irrigation treatment on the same day. Irrigation water was applied by a drip irrigation system. Increasing water deficits resulted in a relatively lower root and white sugar yields. The linear relationship between evapotranspiration and root yield was obtained. Similarly, WUE was the highest in DI25 irrigation conditions and the lowest in full irrigation conditions. According to the averaged values of 2 years, yield response factor (k _y ) was 0.93 for sugar beet. Sugar beet root quality parameters were influenced by drip irrigation levels in both years. The results revealed that irrigation of sugar beet with drip irrigation method at 75% level (DI25) had significant benefits in terms of saved irrigation water and large WUE, indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25% saving of irrigation water (DI25) caused 6.1% reduction in the net income.     

Subsurface drip irrigation of onions: Effects of drip tape emitter spacing on yield and quality

Improved irrigation water use efficiency is an important component of sustainable agricultural production. Efficient water delivery systems such as subsurface drip irrigation (SDI) can contribute immensely towards improving crop water use efficiency and conserving water. However, critical management considerations such as choice of SDI tube, emitter spacing and installation depth are necessary to attain improved irrigation efficiencies and production benefits. In this study, we evaluated the effects of subsurface drip tape emitter spacing (15, 20 and 30 cm) on yield and quality of sweet onions grown at two locations in South Texas—Weslaco and Los Ebanos. Season-long cumulative crop evapotranspiration (ETc) was 513 mm in Weslaco and 407 mm at Los Ebanos. Total crop water input (rain + irrigation) at Weslaco was roughly equal to ETc (92% ETc) whereas at Los Ebanos, water inputs exceeded ETc by about 35%. Onion yields ranged from 58.5 to 70.3 t ha⁻¹ but were not affected by drip tube emitter spacing. Onion pungency (pyruvic acid development) and soluble solids concentration were also not significantly influenced by treatments. Crop water use efficiency was slightly higher at Weslaco (13.7 kg/m³) than at Los Ebanos (11.7 kg/m³) partly because of differences in total water inputs resulting from differences in irrigation management. The absence of any significant effects of drip tape emitter spacing on onion yield may be due to the fact that irrigation was managed to provide roughly similar irrigation amounts and optimum soil moisture conditions in all treatments.     

Tomato yield, biomass accumulation, root distribution and irrigation water use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling

Florida is the largest producer of fresh-market tomatoes in the United States. Production areas are typically intensively managed with high inputs of fertilizer and irrigation. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on yield, irrigation water use efficiency (iWUE) and root distribution of tomato cultivated in a plastic mulched/drip irrigated production systems. Experimental treatments included three irrigation scheduling regimes and three N-rates (176, 220 and 230 kg ha⁻¹). Irrigation treatments included were: (1) SUR (surface drip irrigation) both irrigation and fertigation line placed right underneath the plastic mulch; (2) SDI (subsurface drip irrigation) where the irrigation line was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with irrigation and fertigation lines placed as in SUR and irrigation being applied once a day. Except for the “TIME” treatment all irrigation treatments were controlled by soil moisture sensor (SMS)-based irrigation set at 10% volumetric water content which was allotted five irrigation windows daily and bypassed events if the soil water content exceeded the established threshold. Average marketable fruit yields were 28, 56 and 79 Mg ha⁻¹ for years 1-3, respectively. The SUR treatment required 15-51% less irrigation water when compared to TIME treatments, while the reductions in irrigation water use for SDI were 7-29%. Tomato yield was 11-80% higher for the SUR and SDI treatments than TIME where as N-rate did not affect yield. Root concentration was greatest in the vicinity of the irrigation and fertigation drip lines for all irrigation treatments. At the beginning of reproductive phase about 70-75% of the total root length density (RLD) was concentrated in the 0-15 cm soil layer while 15-20% of the roots were found in the 15-30 cm layer. Corresponding RLD distribution values during the reproductive phase were 68% and 22%, respectively. Root distribution in the soil profile thus appears to be mainly driven by development stage, soil moisture and nutrient availability. It is concluded that use of SDI and SMS-based systems consistently increased tomato yields while greatly improving irrigation water use efficiency and thereby reduced both irrigation water use and potential N leaching.     

Emitter discharge variability of subsurface drip irrigation in uniform soils: effect on water-application uniformity

Emitter discharge of subsurface drip irrigation (SDI) decreases as a result of the overpressure in the soil water at the discharge orifice. In this paper, the variation in dripper discharge in SDI laterals is studied. First, the emitter coefficient of flow variation CV _q was measured in laboratory experiments with drippers of 2 and 4 L/h that were laid both on the soil and beneath it. Additionally, the soil pressure coefficient of variation CV _hs was measured in buried emitters. Then, the irrigation uniformity was simulated in SDI and surface irrigation laterals under the same operating conditions and uniform soils; sandy and loamy. CV _q was similar for the compensating models of both the surface and subsurface emitters. However, CV _q decreased for the 2-L/h non-compensating model in the loamy soil. This shows a possible self-regulation of non-compensating emitter discharge in SDI, due to the interaction between effects of emitter discharge and soil pressure. This resulted in the irrigation uniformity of SDI non-compensating emitters to be greater than surface drip irrigation. The uniformity with pressure-compensating emitters would be similar in both cases, provided the overpressures in SDI are less than or equal to the compensation range lower limit.     

不同灌溉方式对番茄初花期生长及

以东圣一号番茄为试验材料，初步研究了无压灌、滴灌和沟灌三种灌水方式对作物根区土壤水分条件、番茄的形态指标、水分生理指标和光合生理指标的影响。结果表明，无压灌溉通过调节作物根区土壤水分，优化了根冠比，提高了壮苗指数。无压灌溉和滴灌相对沟灌，减小了气孔导度和蒸腾失水，而光合速率并未降低，水分利用效率分别提高了51%和17.2%。     

Analysis of AET and yield predictions under surface and buried drip irrigation systems using the Crop Model PILOTE and Hydrus-2D

Innovative irrigation solutions have to face water scarcity problems affecting the Mediterranean countries. Generally, surface (DI) or subsurface drip irrigation systems (SDI) have the ability to increase water productivity (WP). But the question about their possible utilisation for crops such as corn would merit to be analysed using an appropriate economic tool. The latter would be necessary based on the utilisation of a modelling approach to identify the optimal irrigation strategy associating a water amount with a crop yield (Yc). In this perspective, a possible utilisation of the operative 1D crop model PILOTE for simulating actual evapotranspiration (AET) and yield under a 2D soil water transfer process characterizing DI and SDI was analysed. In this study, limited to a loamy soil cultivated with corn, the pertinence of the root water uptake model used in the numerical code Hydrus-2D for AET estimations of actual evapotranspiration (AET) under water stress conditions is discussed throughout the Yc = F(AET) relationship established by PILOTE on the basis of validated simulations. The conclusions of this work are (i): with slight adaptations, PILOTE can provide reliable WP estimations associated to irrigation strategies under DI and SDI, (ii): the current Hydrus-2D version used in this study underestimates AET, compared with PILOTE, in a range varying from 7% under moderate water stress conditions to 14% under severe ones, (iii): A lateral spacing of 1.6 m for the irrigation of corn with a SDI system is an appropriate solution on a loamy soil under a Mediterranean climate.A local Yc = F(AET) relationship associated with a Hydrus-2D version taking into account the compensating root uptake process could result in an interesting tool to help identify the optimal irrigation system design under different soil conditions.     

基于分形理论的地下滴灌灌水器水力特性研究

为了研究滴头工作压力和土壤物理特性对地下滴灌灌水器流量的影响,采用分形理论分析各种级配土壤的分形特征;以土壤颗粒质量分形维数、灌水器工作压力、土壤容积密度、土壤初始含水率为试验因素,运用混合水平均匀设计方法进行试验。结果表明,粘粒含量大小是土壤分形维数的主要影响因素,土壤分形维数随着粘粒含量的增加而增大;PLASSIM公司地下滴灌灌水器流量随土壤分形维数的增大而减小,即土壤质地越细地下滴灌滴头流量就越小;通过试验所建立的包含有土壤分形维数因素的地下滴灌灌水器流量计算经验公式的普适性较高。     

Bell pepper response to surface and subsurface drip irrigation under different fertigation levels

A two-year field experiment was conducted in 2007 and 2008 to investigate different bell pepper responses to subsurface drip irrigation (SDI) and surface drip irrigation (DI) under four nitrogen levels: 0, 75, 150, and 300 kg/ha N (N₀, N₇₅, N₁₅₀, and N₃₀₀, respectively). Irrigation interval was set at 4 days. Bell pepper yield under SDI was significantly higher than that under DI by 4% in 2007 (13% in 2008). Water consumption under SDI was lower than that under DI by 6.7% in 2007 (7.3% in 2008). Meanwhile, root length density under SDI was obviously higher than that under DI by 11.8% in 2007 (12.5% in 2008). The percentage of root length below 10-cm soil depth under SDI was higher than that under DI by 7%, proving that SDI promotes crop root growth and enhances downward root development. Soil N residue under SDI was lesser than that under DI. Lastly, SDI with N application of 150 kg/ha is recommended as an optimal fertigation practice in improving bell pepper yield and water-use efficiency, as well as in NO₃ ⁻-N leaching.     

黄土高原重力式地下滴灌水分运动模型与分区参数研究

建立了重力式地下滴灌条件下的土壤水分运动模型,分析地下滴灌土壤水分入渗规律.对黄土高原不同分区的4种典型土壤、不同灌水技术要素条件下的地下滴灌土壤湿润体形态、滴孔处出流量及土壤土水势进行数值模拟得出:榆林紧砂土土壤导水率较大,向下渗漏过多,不适宜地下滴灌;安塞砂壤土、洛川中壤土、武功重壤土在相同灌水量下,供水压力与滴孔孔径对地下滴灌湿润体形态影响微弱,但对滴孔出流量有较大影响,因此在地下滴灌工程设计时,只需根据田块长度和渗水管损失设计孔径和供水压力,并采用较小供水压力,降低供水水池高度,减小工程量;对武功重壤土,孔径和供水压力较大时地下滴灌滴孔处土壤易饱和板结,宜采用较小的孔径和供水压力.     

Numerical simulations of water movement in a subsurface drip irrigation system under field and laboratory conditions using HYDRUS-2D

Due to the decreasing availability of water resources and the increasing competition for water between residential, industrial, and agricultural users, increasing irrigation efficiency, by methods like subsurface drip irrigation (SDI) systems, is a pressing concern for agricultural authorities. To properly manage SDI systems, and increase the efficiency of the water/fertilizer use while reducing water losses due to evaporation, the precise distribution of water around the emitters must be known. In this paper, the Windows-based computer software package HYDRUS-2D, which numerically simulates water, heat, and/or solute movement in two-dimensional, variably-saturated porous media, was used to evaluate the distribution of water around the emitter in a clay loam soil. The simulation results were compared with two sets of laboratory and field experiments involving SDI with emitters installed at different depths, and were evaluated using the root-mean-square-error (RMSE). The RMSE at different locations varied between 0.011 and 0.045 for volumetric water contents, and between 0.98 and 4.36 cm for wetting dimensions. Based on these values, it can be concluded that the correspondence between simulations and observations was very good.     

重力式地下滴灌土壤水分运动规律的模拟研究

基于非饱和土壤水运动理论,建立了重力式地下滴灌条件下土壤水分运动数学模型,用Galerkin有限元法推导了重力式地下滴灌土壤水分运动有限元方程,并通过试验进行了验证,在此基础上模拟分析了中壤土条件下的滴灌管道埋深、出水孔孔径、供水压力对简易重力式地下滴灌土壤湿润特征和滴孔出水量的影响。结果表明所建模型可以分析地下滴灌土壤水分入渗规律,在中壤土条件下,不同供水压力、滴孔孔径虽对重力式地下滴灌的滴孔出流量有较大影响,但对土壤湿润特征影响微弱,地下滴灌管道埋深对土壤水分湿润特征影响较大,这些结论可为重力式地下滴灌合理的设计及运行提供理论依据。     

磷肥施入方式对土壤速效磷含量及玉米生长的影响

2016年和2017年分别进行了玉米盆栽和大田试验.盆栽试验中,磷肥施入方式设置磷肥基施和磷肥分3次随水施入2种,滴灌带埋深设置0,15,30 cm 3个水平.大田试验中增加了地表滴灌不施磷肥处理作为对照.结果表明磷肥以随水施入方式分次施入土壤时,能提高土壤剖面中速效磷含量,土壤剖面中速效磷呈随距滴头距离增加而减小的趋势.磷肥随水施入措施可以有效促进作物生长及产量形成,对玉米产量的影响在α=0.1水平上达到显著.滴灌带埋深为15 cm时,作物生长及产量优于地表滴灌处理.当滴灌带埋深为30 cm时,在一定程度上降低了施入磷肥对作物生长的促进作用.建议采用地下滴灌磷肥随水施入方式,但也应该避免使用过深的滴灌带埋深.     

Comparing soil moisture under trickle irrigation modeled as a point and line source

The validity of the assumption that an irrigation event from point sources can be approximated as an infinite line source is investigated in this article. This is accomplished by comparing soil water dynamics under line and point sources. Two existing mathematical models which simulate point and line drip irrigation were used. The models consider root water uptake, evaporation of soil water from the soil surface and incorporate hysteresis in the soil water characteristic curve. The comparison was made for two soil types (loamy sand and silt).The results showed that the treatment of a point source as a line source underestimates the water content values for both the soil types. This difference decreases when the depth of comparison increases. For soil depths greater than 30 cm and for time greater than irrigation duration the two models gave very close results. For the same emitter spacing and for the horizontal direction perpendicular to the drip line on the emitter spot, when the distance from the point and the line sources increases the difference of water content values increases. On the contrary, in the direction parallel to the drip line when the distance from the emitter increases (the distance from the line source remains the same) the difference of water content decreases. Lastly, differences are greater in the case of coarse grained soil than in fine grained soil.     

不同灌溉方式对冬小麦生长发育及水分利用效率的影响

为了确定山西省晋南地区冬小麦高产高效的节水灌溉模式,采用田间小区试验,研究了微喷灌(MSI)、滴灌(SDI)和传统漫灌(CK)3种灌溉方式对冬小麦不同生育期的土壤水分变化、生长性状、产量和水分利用效率的影响。其中SDI处理和MSI处理生育期灌水3次,分别为越冬期(12月9日)、拔节期(4月1日)、灌浆期(5月20日),每次灌水量为600 m~3/hm~2;CK按当地灌水习惯,于越冬期和拔节期灌水,每次灌水量为2 250 m~3/hm~2。结果表明,各处理越冬期0~100 cm土层土壤含水率没有明显差异,灌浆期0~80 cm土层土壤含水率表现为SDI处理MSI处理CK,MSI处理、SDI处理灌浆期灌水,可满足灌浆期对水分需求,促进籽粒灌浆;与CK相比,SDI处理与MSI处理可以明显增加单株分蘖数和总茎数、促进群体生长,显著增加冬小麦成穗数、穗粒数和千粒质量,因而显著提高了籽粒产量。与CK相比,MSI处理穗粒数、千粒质量分别提高16.54%、5.21%,SDI处理穗粒数、千粒质量分别提高9.10%、11.78%,MSI、SDI处理籽粒产量分别增加了2.79%、3.35%;同时,SDI处理与MSI处理冬小麦生育期的耗水总量分别减少43.88%和41.64%,水分利用效率分别提高了83.15%和77.09%。因此,在山西临汾盆地采用微喷与滴灌可以取得明显的节水高产效果。