Impact of drip and level-basin irrigation on growth and yield of winter wheat in the North China Plain

A field experiment was conducted for 3 consecutive years (2007–2009) to study the effects of two different irrigation methods, that is, level-basin irrigation (BI) and drip irrigation (DI), and different treatment levels on crop growth, yield, and WUE of winter wheat (Triticum aestivum L.) in the North China Plain (NCP). The results indicate that irrigation methods and treatment levels had significant effects on crop growth and yield of winter wheat. Irrigation amounts significantly influenced plant heights, LAI, and winter wheat grain yields (P < 0.05 level) for both irrigation methods. Further, the DI method significantly improved yield and WUE compared with the BI method (P < 0.05 level) under conditions of deficit irrigation. Without irrigation system investment consideration, crop water productivity was highest when DI was used and irrigations were scheduled when soil water was depleted to 60 and 50 % of field capacity.     

Simulation of point source wetting pattern of subsurface drip irrigation

Laboratory experiments and calculations were carried out to analyze the effect of subsurface drip irrigation (SDI) design features on soil wetting patterns for a point source. Experimental and simulated soil wetting patterns, using the SWMS-2D (simulating water movement and solute transport in two-dimensional) Galerkin finite element model, were investigated to maximize the efficiency of water saving. The analysis addressed the influence of water pressure head, back pressure and emitter diameter on wetting patterns. Predictions of water content distributions in the soils made with SWMS-2D were found to be in good agreement with the observed data. Results showed that this model provides confidence that model predictions are not too sensitive to back-pressure effects.     

种植密度对滴灌马铃薯生长、产量的影响

为了了解耕培土滴灌条件下种植密度对马铃薯生长、产量以及水分利用效率的影响.试验共设密度分别为7.28×10⁴ 株/hm²(RS25),6.67×10⁴ 株/hm²(RS35),5.55×10⁴ 株/hm²(CK)3个处理.结果表明:随着种植密度的增加,株高、茎粗、干物质积累量以及商品薯率均有降低的趋势;产量、水分利用效率随种植密度的增加表现出先增大后减少,其中RS35处理产量和水分利用效率均表现最高,分别达到47 325 kg/hm²和12.05 kg/m³;在马铃薯品质方面,种植密度对马铃薯粗蛋白含量的影响不具有统计学意义;淀粉和维生素C随着密度的大幅增加而降低,其中RS25处理的淀粉较CK降低了5.57%,RS25处理的维生素C较CK降低了7.96%,同时RS35与CK处理不具有统计学意义.综上所述,种植密度为6.67×10⁴ 株/hm²的RS35处理马铃薯高产优质,且水分利用效率最高,为黑龙江地区滴灌马铃薯较为适宜的种植密度.     

滴灌水温对土壤入渗和土壤温度的影响

为了解水温对滴灌土壤入渗特征和土壤温度的影响,研制一套恒温试验装置,可使水温变化控制在±0.5 ℃范围内,选择5,20,35 ℃作为试验水温,进行不同水温室内滴灌入渗试验,分析各水温下土壤水分入渗和土壤温度变化特征.结果表明:在相同时段内,随滴灌水温升高,水平和垂直湿润锋运移距离增大,垂直湿润锋运移速率增大.分别建立水平、垂直湿润锋运移距离与入渗时间和滴灌水温的关系模型,决定系数R²均大于0.99.湿润土体平均含水量与入渗时间关系不大,但随入渗水温的升高而减小.土壤水分扩散率与水温成正比;水温升高,饱和导水率随之增大,二者呈指数函数关系;土壤吸持水分的能力随温度的升高而降低.不同灌溉水温改变了土体中的温度分布,随着距滴头距离的增加,由水温引起的土壤温度的变化量逐渐减小.结论可为指导大田和温室滴灌技术提供理论依据.     

滴灌土壤湿润体迁移计算的人工神经网络模型

基于非饱和土壤水分运动理论和单点源滴灌中土壤水分迁移特征,应用HYDRUS-2D/3D模型对33种土壤质地(分属11类土质类型,美国制土壤质地分类系统)、不同滴灌流量(1,2,3 L/h)下的湿润体运动过程进行了数值模拟,然后根据不同土壤质地和滴灌流量下湿润体动态变化的HYDRUS模拟结果,以滴灌量和土壤饱和导水率与滴灌流量的比值作为输入变量,构建了描述滴灌湿润体在不同土质和滴灌流量下迁移变化的人工神经网络模型.该模型输入变量少、易于操作,且将模型计算结果与实测情况对比表明,计算的入渗过程与实测的入渗过程基本一致,相关系数的平方(R²)均在0.82以上,因此该模型对不同土质中湿润体运移规律的预测效果较好.     

Cotton root and shoot responses to subsurface drip irrigation and partial wetting of the upper soil profile

The ability of cotton roots to grow downwards through a partially-wetted soil (Calcic Haploxeralf) profile toward a water source located beneath them was investigated. Plants were grown in 60-cm-high soil columms (diameter 10 cm), the bottom 15 cm of which was kept wet by frequent drip irrigation, while the upper 45 cm was wetted three times per week up to 20, 40, 60, 80 or 100% of pot capacity. Pot capacity was defined as the water content which gave uniform distribution within the pot and was at a soil matric potential ( _m ) of –0.01 MPa. Plants were harvested 42 and 70 days after emergence (DAE). Root length density was reduced by decreased soil moisture content. At 42 DAE, density was reduced in the soil profile down to 36 cm. The density in the middle segment of the cylinder (24–36 cm) increased at the second harvest, from 0.1 to 0.35 cm · cm^–3 at 40% and from 0.2 to 0.5 cm · cm^–1 at 60% of pot capacity, respectively. A significant rise in root length density was found at all moisture contents above 20% in the two deepest soil segments. It was most marked at 40% where the rise was from 0.2 to 0.8 cm · cm^–3, due to the development of secondary roots at the wetted bottom of the column. When only 20% of pot capacity was maintained in the top 45 cm of the profile, almost no roots reached the wetted soil volume, and root length density was very low. Hydrotropism, namely root growth through dry soil layers toward a wet soil layer was thus not apparent. Root dry weight per unit length decreased with increasing depth in the column at all moisture levels. However, the only significant decrease was, found between the top and the second soil segments and was due to thicker primary roots in the top segment. There was no clear relationship between length and dry weight of roots. Total plant dry weight and transpiration were reduced significantly only at 20% of pot capacity. Dry matter production by roots was less severely inhibited than that by shoots, under decreased moisture content in the soil profile. Leaf water potential decreased when the soil moisture content of the top 45 cm of the profile was reduced below 60% of pot capacity. It was concluded that even at soil moisture content equivalent to a _m of 0.1 MPa, the rate of root growth was sufficient to reach a wetted soil layer at the bottom of the soil column, where the plant roots then proliferated. This implies that as long as the soil above the subsurface dripper is not very dry there is no real need for early surface irrigation.     

灌溉时段及水温对膜下滴灌棉花生长及产量的影响

为探究不同灌溉时段及水温对膜下滴灌棉花生理特性及产量的影响,设置4个灌溉水温梯度分别为15.00(正常灌溉水温),20.00,25.00,30.00℃,2个灌溉时段分别为日间、夜间(分别记为DW,NW)进行完全组合设计,共计8个处理.结果表明,增温灌溉提前了棉花生育进程,促进了棉花株高、茎粗、叶面积增长,有利于棉花光合作用的进行,且在夜间进行增温灌溉效果更显著.增温灌溉使棉花产量显著提高2.95%～14.13%,夜间灌溉较日间灌溉棉花产量平均提高3.34%.基于回归分析确定提高棉花产量的最佳灌溉时段为夜间,最佳灌溉水温为26.38℃,对应的产量为7 482.96 kg/hm².该研究可为北疆膜下滴灌棉花实施增温灌溉技术提供理论依据和技术参考.     

Optimizing irrigation scheduling for winter wheat in the North China Plain

In the North China Plain (NCP), more than 70% of irrigation water resources are used for winter wheat (Triticum aestivum L.). A crucial target of groundwater conservation and sustainable crop production is to develop water-saving agriculture, particularly for winter wheat. The purpose of this study was to optimize irrigation scheduling for high wheat yield and water use efficiency (WUE). Field experiments were conducted for three growing seasons at the Wuqiao Experiment Station of China Agriculture University. Eleven, four and six irrigation treatments, consisting of frequency of irrigation (zero to four times) and timing (at raising, jointing, booting, flowering and milking stage), were employed for 1994/95, 1995/96 and 1996/97 seasons, respectively. Available water content (AWC), rain events, soil water use (SWU), evapotranspiration (ET) and grain yield were recorded, and water use efficiency (WUE) and irrigation water use efficiency (IWUE) were calculated.The results showed that after a 75-mm pre-sowing irrigation, soil water content and AWC in the root zone of a 2-m soil profile during sowing were 31.1% (or 90.7% of field capacity) and 16.1%, respectively. Rainfall events were variable and showed a limited impact on AWC. The AWC decreased significantly with the growth of wheat. At the jointing stage no water deficits occurred for all treatments, at the flowering stage water deficits were found only in the rain-fed treatment, and at harvest all treatments had moderate to severe soil water deficits. The SWU in the 2-m soil profile was negatively related to the irrigation water volume, i.e. applying 75 mm irrigation reduced SWU by 28.2 mm. Regression analyses showed that relationships between ET and grain yield or WUE could be described by quadratic functions. Grain yield and WUE reached their maximum values of 7423 kg/ha and 1.645 kg/m³ at the ET rate of 509 and 382 mm, respectively. IWUE was negatively correlated with irrigated water volume. From the above results, three irrigation schedules: (1) pre-sowing irrigation only, (2) pre-sowing irrigation + irrigation at jointing or booting stage, and (3) pre-sowing irrigation + irrigations at jointing and flowering stages were identified and recommended for practical winter wheat production in the NCP.     

Effects of drip irrigation with saline water on waxy maize (Zea mays L. var. ceratina Kulesh) in North China Plain

In order to study the effects of drip irrigation with saline water on waxy maize, three years of field experiments were carried out in 2007-2009 in North China Plain. Five treatments with average salinity of irrigation water, 1.7, 4.0, 6.3, 8.6, and 10.9 dS/m were designed. Results indicated that the irrigation water with salinity <10.9 dS/m did not affect the emergence of waxy maize. As salinity of irrigation water increased, seedling biomass decreased, and the plant height, fresh and dry weight of waxy maize in the thinning time decreased by 2% for every 1 dS/m increase in salinity of irrigated water. The decreasing rate of the fresh ear yield for every 1 dS/m increase in salinity of irrigation water was about 0.4-3.3%. Irrigation water use efficiency (IWUE) increased with the increase in salinity of irrigation water when salinity was <10.9 dS/m. Precipitation during the growing period significantly lightened the negative impacts of irrigation-water salinity on the growth and yield. Soil salinity in depth of 0-120 cm increased in the beginning of irrigation with saline water, while it was relatively stable in the subsequent year when salinity of irrigation water was not higher than 4.0 dS/m and the soil matric potential (SMP) at 0.2 m directly underneath the drip emitter was controlled above −20 kPa.     

Effect of drip irrigation frequency on radish (Raphanus sativus L.) growth and water use

Irrigation frequency is one of the most important factors in drip irrigation scheduling, and a proper irrigation frequency can establish moderate moist and oxygen conditions in the root zone throughout the crop period. Field experiments on the effects of irrigation frequency on radish growth and water use were carried out in 2001 and 2002. The experiment included six irrigation frequencies: once every day, once every 2 days, once every 3 days, once every 4 days, once every 6 days and once every 8 days. There was no significant difference among the six treatments on radish development and yield, but significant differences in radish roots distribution and market quality were found. Radishes irrigated once every 3 days had well-developed roots throughout the crop period, the lowest cracking rate and the least number of radishes of Grade 3. The observation results of lysimeter in 2002 showed that radish evapotranspiration decreased as irrigation frequency decreased, and the general changing tendency of 2-day ET of high irrigation frequency was related to that of 2-day evaporation. It is recommended that radish irrigation frequency should be once every 3 days and the irrigation amount should be estimated according to the evaporation of 20 cm diameter pan in the North China Plain.     

灌水模式及下限对滴灌棉花产量和品质的影响

为探索滴灌条件下棉花优质高效灌溉指标,在新疆石河子研究了地下滴灌(SSDI)和膜下滴灌(SDI)条件下不同灌水控制下限对棉花耗水量、品质以及水分利用率的影响.结果表明,相同滴灌模式,棉花蕾期耗水量随灌水控制下限的提高而增加,花铃期水分胁迫处理的棉花阶段耗水量普遍低于对照处理;蕾期适度水分胁迫(灌水控制下限为60% FC)花铃期充分供水(灌水控制下限为75% FC)处理(SDI-7和SSDI-7)有利于籽棉产量的提高,与对照处理相比,籽棉产量提高了14.48%(SDI-7)和11.60%(SSDI-7);水分处理对棉花衣分、棉纤维整齐度的影响不明显,蕾期和花铃期水分胁迫对棉纤维上半部平均长度的影响随水分胁迫程度的加重而加剧,蕾期适度水分胁迫(灌水控制下限为60% FC)有利于棉纤维断裂比强度的提高.相同水分处理,地下滴灌棉花产量和灌溉水利用率均高于膜下滴灌棉花.与对照处理相比,蕾期和花铃期灌水控制下限分别为60% FC和75% FC,灌水定额为30 mm处理在节约灌溉水的同时提高了籽棉产量并改善了棉纤维品质,可作为石河子垦区滴灌棉花适宜的灌水指标.     

滴灌施肥生育期比例分配对榆林市马铃薯生长和水分利用的影响

以当地主栽品种“紫花白”为研究材料,按前期(苗期+块茎形成期,ES)少、后期(块茎膨大期+淀粉积累期,LS)多的施肥比例,基于马铃薯苗期、块茎形成期、块茎膨大期、淀粉积累期占全生育期总施肥量的比例设置了8个处理(T1-T8),研究了同一滴灌施肥水平下,生育期内施肥比例分配对马铃薯的生长、产量和水分利用的影响.结果表明:马铃薯LAI和干物质值均表现为苗期和块茎形成期,ES_0.4~0.5处理大于ES_0.2~0.3,在块茎膨大期时,处理ES_0.2大于ES_0.3~0.5;淀粉积累期和成熟期,处理T7的LAI和干物质下降明显.而块茎形成期开始施肥的处理T1,T2在块茎膨大期、淀粉积累期和收获时都获得了较高的LAI和干物质.对于干物质转运而言,开花后块茎积累量表现为ES_0.2>ES_0.3~0.5,块茎干物质累积主要是在花后同化作用下建立的.产量变化规律为ES_0.2>ES_0.5(处理T7除外)>ES_0.4(处理T5除外)>ES_0.3(处理T2除外).各处理马铃薯单株商品薯质量变化规律与产量一致,而平均单薯质量、单个商品薯质量和单株结薯数间没有统一的变化规律.施肥处理水分利用和肥料偏生产力变化趋势与产量类似,各处理耗水量差异不具有统计学意义.综上,从产量和节水角度考虑,试验条件下滴灌施肥马铃薯生育期内比例分配最优方案为苗期和块茎形成期总施肥比例20%(苗期不施肥,形成期20%),块茎膨大期占施肥总量的55%和淀粉积累期占施肥总量25%.     

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.     

滴灌条件下揭膜时间对土壤酶活性及玉米吸氮量的影响

为了了解玉米滴灌水肥试验研究揭膜时间和施肥处理对土壤脲酶活性、天门冬酰胺酶活性及玉米吸氮量的影响,试验设置了3个揭膜时间处理和1个未覆膜处理,每个处理考虑施肥和不施肥情况,共8个处理.研究结果表明:苗期揭膜、抽穗期揭膜和全生育期覆膜均会提高土壤NH⁺₄-N含量和含水率,显著降低土壤脲酶活性,各揭膜处理差异不具有统计学意义;不同揭膜时间并不会显著影响土壤天门冬酰胺酶的活性;各揭膜处理可显著提高苗期玉米的吸氮量,但在施肥条件下全生育期覆膜处理却降低玉米吸氮;土壤水热和无机氮的含量与土壤脲酶差异具有统计学意义,而覆膜下土壤脲酶活性的降低与土壤NH⁺₄-N和含水率升高有关;土壤天门冬酰胺酶活性与土壤水热和无机氮含量差异不具有统计学意义;由试验可得东北地区玉米苗期或抽穗期揭膜可使土壤酶活性保持在适宜的活性水平,为玉米生长提供有利的土壤环境.     

极端干旱区降解膜对滴灌棉花土壤水热及产量的影响

为了探明降解膜在哈密盆地滴灌棉花种植的应用效果,选取降解膜M1,M2,M3,M4及普通塑料地膜PE(CK)开展对照试验,研究降解膜的降解性能及其对滴灌棉花土壤水热变化与产量的影响.结果表明:M2在覆膜80 d左右最早出现降解、180 d左右进入残存期,生育期末仍有小块地膜残片存在;而降解膜M1与M3于生育期末才进入崩解...     

Evaluation of humic substances fertigation through surface and subsurface drip irrigation systems on potato grown under Egyptian sandy soil conditions

The aim of this study was to evaluate the effect of humic substances application in sandy soil under surface and subsurface drip irrigation systems on potato tubers yield quantity, quality, nutrients concentration in tubers and soil fertility after harvesting. For this purpose, field experiment was carried out at the experimental farm of the Agricultural Research Station, National Research Center, El-Nubaria district, Egypt during the winter season of 2007/2008. The used experimental design was split plot design with three replicates, main treatments were presented irrigation systems, i.e. surface and subsurface drip irrigation, while subtreatments were presented rates of humic substances additives which were 0, 60 and 120 kg ha⁻¹. Results showed that increasing humic substances application rates up to 120 kg ha⁻¹ enhanced tubers yield quantity, starch content and total soluble solids. The increase of humic substances application rates was associated with the decrease of nutrients leaching, which was reflected on increasing macro- and micronutrients concentration in potato tubers, as well as increasing concentration of these nutrients in soil after tubers harvesting. Subsurface drip irrigation system was found to be more efficient than surface drip irrigation system on improving tubers yield quantity, quality parameters and nutrients concentration content, in addition to soil fertility after harvesting.     

Distribution and dynamics of soil water and salt under different drip irrigation regimes in northwest China

A 2-year experiment was carried out to investigate the effects of different drip irrigation regimes on distribution and dynamics of soil water and salt in north Xinjiang, China. Five treatments—F7 (0.24 dS m^?1 + Once every 7 days), B7 (4.68 dS m^?1 + Once every 7 days), S7 (7.42 dS m^?1 + Once every 7 days), F10 (0.24 dS m^?1 + Once every 10 days) and F3 (0.24 dS m^?1 + Once every 3 days)—were designed. For all treatments, additional 150-mm fresh water was applied on 10th November in 2009 (winter irrigation) to leach the accumulated salt. The results revealed that irrigation frequency and water quality had significant effects on the spatial distribution and change of soil water content, soil salt and the crop water consumption rate, but had a limited impact on the seasonal accumulative water consumption, and the cotton yield decreased with the decrease in irrigation frequency and water quality on the whole. During the cotton growing season, results showed that the salt mainly accumulated in the 0- to 60-cm soil layer, while the soil salt in 60- to 100-cm layer changed slightly, indicating that the drip irrigation could not leach the soil salt out of the root zone under the irrigation regimes. Therefore, salt leaching was necessary to maintain the soil water–salt balance and to prevent excessive salt accumulation in the root zone. After the 150-mm winter irrigation and subsequent thawing, soil salts were leached into the deeper layers (below 60 cm), and the soil salt content (SSC) (EC_1:5) in root zone in the next year was about 0.2 dS m^?1. Moreover, compared to 2009 season, the SSC within the root zone did not increase even the EC of the irrigation water was up to 7.42 dS m^?1. Additionally, it is important to note that the results were concluded based on the data of the 2-year experiment; further studies are need to optimize winter irrigation amount and assess the sustainability of saline water irrigation since long-term utilization of saline water may lead to soil degradation.     

Analysis of soil wetting and solute transport in subsurface trickle irrigation

The increased use of trickle or drip irrigation is seen as one way of helping to improve the sustainability of irrigation systems around the world. However, soil water and solute transport properties and soil profile characteristics are often not adequately incorporated in the design and management of trickle systems. In this paper, we describe results of a simulation study designed to highlight the impacts of soil properties on water and solute transport from buried trickle emitters. The analysis addresses the influence of soil hydraulic properties, soil layering, trickle discharge rate, irrigation frequency, and timing of nutrient application on wetting patterns and solute distribution. We show that (1) trickle irrigation can improve plant water availability in medium and low permeability fine-textured soils, providing that design and management are adapted to account for their soil hydraulic properties, (2) in highly permeable coarse-textured soils, water and nutrients move quickly downwards from the emitter, making it difficult to wet the near surface zone if emitters are buried too deep, and (3) changing the fertigation strategy for highly permeable coarse-textured soils to apply nutrients at the beginning of an irrigation cycle can maintain larger amounts of nutrient near to and above the emitter, thereby making them less susceptible to leaching losses. The results demonstrate the need to account for differences in soil hydraulic properties and solute transport when designing irrigation and fertigation management strategies. Failure to do this will result in inefficient systems and lost opportunities for reducing the negative environmental impacts of irrigation.Communicated by J. Annandale