暗管控制排水条件下土壤硝态氮运移转化规律的试验研究

为研究控制排水措施对土壤硝态氮运移和转化的影响,通过测坑试验分析了不同控制排水位下土壤不同深度硝态氮的含量和分布。结果表明:①控制与非控制排水条件下土壤剖面硝态氮分布规律相似,硝态氮含量集中在0～40 cm土层,深层土壤中硝态氮浓度很小在1 mg/kg左右,不会污染地下水;②排水结束后至降雨前,表层至40 cm土壤剖面硝态氮浓度变化率和各田硝态氮含量的增大率与控制排水出口的高度成负相关,降雨至排水结束后,表层硝态氮的浓度均减小,表层以下硝态氮浓度变化与地下水埋深有关,地下水位以上硝态氮浓度一般增大,地下水位以下硝态氮浓度一般减小。结论为控制排水措施减小了深层土壤硝态氮含量,且大大减少了土壤中硝态氮的含量,且控制排水能有效减少硝态氮的流失量。     

麦田在降雨入渗和排水条件下化肥流失的试验研究

在南方渍害田地区,通常是稻麦连作区,为研究这些地区在排水条件下的氮肥流失规律,在上海青浦农田水利试验站进行了田间试验。试验表明,在小麦生长期,地下水埋深较小时、氮素在土壤中,在地下水位以下土壤剖面上的硝态氮含量很小,排水农田中氮自排水暗管流失量仅占总损失量中较小部分。     

基于机械收割要求的稻麦轮作农田暗管排水布局模拟

南方稻麦轮作区现有明沟排水系统影响农业机械作业效率,不利于农业现代化发展;建设暗管排水系统可提高土地利用率和农业生产效率。以江苏省扬州市江都区昭关灌区为例,用农田排水模型-DRAINMOD分析了稻麦轮作农田暗管排水系统布置方案。模拟结果表明:作物收获期机械作业天数受暗管埋深和埋设间距的影响,随着埋深的减小和间距的增大,机械作业天数逐渐减小;在相同保证率和目标水位埋深要求下,水稻收获期的机械作业天数相对小麦收获期更易受降雨的影响。在水稻收获期,当暗管埋深为80～100 cm,满足大型机械90%、95%作业保证率的最大暗管间距分别为:26.0～32.0 m、14.0～21.0 m;满足小型机械90%、95%作业保证率的最大暗管间距分别为:26.5～33.5 m、18.0～23.0 m。研究成果可为类似地区基于机械收割要求的农田暗管排水系统设计提供理论参考。     

麦田在降雨入渗和排水条件下化肥流失的试验研究

在南方渍害田地区,通常是稻麦连作区,为研究这些地区在排水条件下的氮肥流失规律,在上海青浦农田水利试验站进行了田间试验。试验表明,在小麦生长期,地下水埋深较小时,氮素在土壤中,在地下水位以下土壤剖面上的硝态氮含量很小,排水农田中氮自排水暗管流失量仅占总损失量中较小部分。表明地下水中氮素大部分以Ｎ２Ｏ 和Ｎ２ 形态散失。这些试验结果将为排水条件下氮素运移转化模拟计算提供依据     

控制平原湖区棉田暗管排水水位对氮素流失影响分析

选取控制水位为地下0、30、50、80、100 cm的5块棉花地,测定分析生育期内土壤和排水中氮素含量,探讨不同的地下水控制水位对土壤氮储量和径流中氮素排放量的影响。结果表明,5块棉花地雨后地下水水位与控制水位显著线性相关,单位面积土壤中氨态氮储量随控制水位的降低而减少,暗管径流中氨态氮排放量与暗管排水量有明显的线性正相关关系,硝态氮的排放量有随控制水位降低而增加的趋势。     

棉田暗管控制排水和氮素流失研究

在湖北荆州丫角排灌试验站进行暗管控制排水和自由排水对照试验,结果发现,暗管排水累积排水量随时间呈线性变化;暗管排水氮素累积流失量随时间呈二次曲线变化.控制水位为30 cm的田块氮素累积流失量随时间而增加,而其他控制排水及自由排水田块氮素累积流失量随时间而减少.控制排水可以减少累积排水量和氮素累积流失量,且随控制水位增加...     

不同毛沟布置方式下农田次降雨氮素流失特性分析

为了研究田间工程对农田氮素随径流流失的影响,该文通过设置不同排水毛沟布置方式下农田对比试验,观测研究了农田出口的降雨径流特征以及氮素流失特征,结果表明：与毛沟布置多的处理相比,毛沟布置少的处理径流对雨强变化敏感度相对较小,其径流峰值滞后,且高峰径流量持续时间长,但总氮输出负荷减少7.44%;2个处理之间铵态氮和硝态氮的流失量均差异显著;在径流初始及峰值阶段铵态氮占总氮的比例显著高于径流消减阶段,硝态氮的比例全过程变化不大;硝态氮、铵态氮、总氮的输出负荷与径流量呈线性正相关。研究表明：汇水面积小,毛沟布置多的处理减少农田涝渍效果明显,而汇水面积大,毛沟布置少的处理能有效降低总氮的输出负荷。     

农田暗管-明沟组合排水系统布设参数计算与设计软件编程

暗管排水是高地下水埋深地区农田排水的主要方式之一。【目的】确定农田暗管-明沟组合排水系统的布设参数。【方法】根据农田排水理论,建立了农田暗管-明沟组合排水系统布设参数计算模型及其C#语言编程。【结果】在题设条件下,考虑地下水蒸发影响时的吸水管间距比不考虑其影响可增大2.9%~17.3%;吸水管间距由15 m增大到25 m时,地下水埋深降深减小24.7%~27.5%;当吸水管埋深由1.5 m增加到2.0 m时,地下水埋深降深可增大34.8%。计算结果与相关算例的最大相对差异小于1.2%,运行速度快,在5 s内可以完成计算过程,适用于不同土壤质地、地下水埋深、地下水蒸发条件和作物种植条件。【结论】设计的软件减轻了农田水利工程基层设计人员的工作量,可以进一步推广。     

旱地控制排水条件下氮素运移试验

为探讨在旱地采取控制排水措施、控制不同深度时土壤中氮元素的迁移转化规律,在旱地进行了控制排水试验,对土壤的硝态氮及铵态氮进行了追踪测定。试验表明,不同控制深度时,土壤剖面硝态氮浓度在80cm深度以内随着深度的增大而增大,且在80cm深处时已趋近于0,而土壤剖面铵态氮浓度并没有随着深度增大而呈现一定的趋势;控制排水水位高,对应田块中土壤剖面各层硝态氮及铵态氮浓度均较高,控制排水在旱地能起到保肥及减少施肥的作用。     

旱地控制排水条件下氮素运移试验研究

为探讨在旱地采取控制排水措施、控制不同深度时土壤中氮元素的迁移转化规律,在旱地进行了控制排水试验,对土壤的硝态氮及铵态氮进行了追踪测定.试验表明,不同控制深度时,土壤剖面硝态氮质量分数在80 cm深度以内随着深度的增大而增大,且在80 cm深处时已趋近于0,而土壤剖面铵态氮浓度并没有随着深度增大而呈现一定的趋势;控制排水水位高,对应田块中土壤剖面各层硝态氮及铵态氮质量分数均较高,控制排水在旱地能起到保肥及减少施肥的作用.     

Efficiency of controlled drainage and subirrigation in reducing nitrogen losses from agricultural fields

In northeast Italy, a regimen of controlled drainage in winter and subirrigation in summer was tested as a strategy for continuous water table management with the benefits of optimizing water use and reducing unnecessary drainage and nitrogen losses from agricultural fields.To study the feasibility and performance of water table management, an experimental facility was set up in 1996 to reproduce a hypothetical 6-ha agricultural basin with different land drainage systems existing in the region. Four treatments were compared: open ditches with free drainage and no irrigation (O), open ditches with controlled drainage and subirrigation (O-CI), subsurface corrugated drains with free drainage and no irrigation (S), subsurface corrugated drains with controlled drainage and subirrigation (S-CI). As typically in the region free drainage ditches were spaced 30 m apart, and subsurface corrugated drains were spaced 8 m apart.Data were collected from 1997 to 2003 on water table depth, drained volume, nitrate-nitrogen concentration in the drainage water, and nitrate-nitrogen concentration in the groundwater at various depths up to 3 m.Subsurface corrugated drains with free drainage (S) gave the highest measured drainage volume of the four regimes, discharging, on average, more than 50% of annual rainfall, the second-highest concentration of nitrate-nitrogen in the drainage water, and the highest nitrate-nitrogen losses at 236 k ha⁻¹.Open ditches with free drainage (O) showed 18% drainage return of rainfall, relatively low concentration of nitrate-nitrogen in the drainage water, the highest nitrate-nitrogen concentration in the shallow groundwater, and 51 kg ha⁻¹ nitrate-nitrogen losses.Both treatments with controlled drainage and subirrigation (O-CI and S-CI) showed annual rainfall drainage of approximately 10%. O-CI showed the lowest nitrate-nitrogen concentration in the drainage water, and the lowest nitrogen losses (15 kg ha⁻¹). S-CI showed the highest nitrate-nitrogen concentration in the drainage water, and 70 kg ha⁻¹ nitrate-nitrogen losses. Reduced drained volumes resulted from the combined effects of reduced peak flow and reduced number of days with drainage.A linear relationship between daily cumulative nitrate-nitrogen losses and daily cumulative drainage volumes was found, with slopes of 0.16, 0.12, 0.07, and 0.04 kg ha⁻¹ of nitrate-nitrogen lost per mm of drained water in S-CI, S, O, and O-CI respectively.These data suggest that controlled drainage and subirrigation can be applied at farm scale in northeast Italy, with advantages for water conservation.     

河套灌区排水工程管理的数值模拟研究

利用SWAP(Soil-Water-Atmosphere-Plant)模型对河套灌区的永联试验区进行了排水工程管理的数值模拟研究,分析了排水沟的间距和深度对田间水均衡要素的影响。结果显示,现有排水沟深度下的排水沟间距调整对区域排水和潜水埋深的影响不明显,但当排水沟深度增加时,排水沟排水量和控制区域的潜水埋深发生显著变化。根据模拟结果,认为永联试验区的排水沟间距取500 m,深度取2.5 m较为适宜。     

Predicting effects of drainage water management in Iowa's subsurface drained landscapes

Long-term hydrologic simulations are presented predicting the effects of drainage water management on subsurface drainage, surface runoff and crop production in Iowa's subsurface drained landscapes. The deterministic hydrologic model, DRAINMOD was used to simulate Webster (fine-loamy, mixed, superactive, mesic) soil in a Continuous Corn rotation (WEBS_CC) with different drain depths from 0.75 to 1.20 m and drain spacing from 10 to 50 m in a combination of free and controlled drainage over a weather record of 60 (1945-2004) years. Shallow drainage is defined as drains installed at a drain depth of 0.75 m, and controlled drainage with a drain depth of 1.20 m restricts flow at the drain outlet to maintain a water table at 0.60 m below surface level during the winter (November-March) and summer (June-August) months. These drainage design and management modifications were evaluated against conventional drainage system installed at a drain depth of 1.20 m with free drainage at the drain outlet. The simulation results indicate the potential of a tradeoff between subsurface drainage and surface runoff as a pathway to remove excess water from the system. While a reduction of subsurface drainage may occur through the use of shallow and controlled drainage, these practices may increase surface runoff in Iowa's subsurface drained landscapes. The simulations also indicate that shallow and controlled drainage might increase the excess water stress on crop production, and thereby result in slightly lower relative yields. Field experiments are needed to examine the pathways of water movement, total water balance, and crop production under shallow and controlled drainage in Iowa's subsurface drained landscapes.     

滴灌条件下排水暗管间距对土壤盐分淋洗的影响

在滴灌淋洗条件下设计暗管排水试验,研究暗管不同埋设间距(15、20、25 m)对土壤剖面盐分分布及脱盐淋洗效果的影响。结果表明:滴灌淋洗期间,0~70 cm土层含盐量显著降低,与CK相比,试验地不同地段土壤平均含盐量减少10 g/kg以上。从暗管上方至相邻暗管中点位置处不同剖面土壤平均脱盐率逐渐减小,15、20、25 m间距小区在0~100 cm埋深土壤中点位置处最大脱盐率分别为84.01%、77.75%、73.98%,土壤整体脱盐率介于51.82%~60.43%之间。吸水管埋管间距越小,小区暗管排水阶段排水流量越大,排水矿化度、电导率也越大,但成本会略高。15 m间距相比20、25 m间距小区每公顷多投入的成本和平均脱盐率差值分别为8 430、12 570元和4.78%、8.61%;15 m间距暗管处理在水平距离暗管0、5、7.5 m处土壤脱盐率最大值分别为86.47%、85.15%、84.01%,且排水期间排水流量、矿化度、电导率最大,分别为2 m~3/h、189.15 g/L和35.9 mS/cm;土壤盐分淋洗效果优于20、25 m间距小区,淋洗相同盐分含量土壤所需灌水量也低于20、25 m间距;2次灌水后0~70 cm土层盐分整体已降至10 g/kg以下,作物生长条件大为改善,适宜作为指导新疆盐渍土改良滴管条件下暗管间距布设参数的依据。     

太阳能暗管排水对银北灌区油葵土壤环境及产量影响

针对土壤盐渍化严重影响了宁夏银北灌区土壤环境和作物产量的问题,通过太阳能暗管排水区和非暗管排水区对比试验方法,着重研究了2017和2018两年太阳能暗管长时间持续排水对土壤环境和油葵产量的影响。结果表明:太阳能暗管排水可以有效改善土壤环境,使两年的地下水平均埋深分别增加4.5%和6.4%,地下水平均矿化度分别降低7.9%和9.0%,两年土壤平均脱盐率分别为4.7%和8.2%,对表层土壤的脱盐效果最为明显。同时提高了油葵产量和水分生产效率,两年油葵产量分别提高13.8%和21.6%,灌溉水分生产效率分别增加13.3%和21.8%,作物水分生产效率分别增加16.4%和22.9%。综合试验结果和经济成本考虑,油葵生育期灌水2次、播前灌水1次、冬灌1次,生育期5-9月持续排水,这是适宜惠农当地太阳能暗管排水条件下油葵的灌排制度。     

冬小麦生长条件下土壤水与地下水转化试验研究

基于不同地下水埋深土壤水与地下水转化田间试验,探讨冬小麦生长条件下不同地下水埋深对土壤水与地下水转化的影响机理。试验结果表明,地下水埋深为1.5 m,在冬小麦需水高峰期,地下水为冬小麦生长提供的水资源量占耗水量的30%以上;随着地下水埋深增大,地下水对冬小麦需水的动态调节作用减弱;当地下水埋深为3.5 m,地下水已基本失去对冬小麦需水的动态调节能力。     

Pipe drainage in the Eastern Padano-Veneta plain in north-east Italy

A survey has been carried out in three Regions of north-eastItaly, Emilia Romagna, Veneto and Friuli Venezia Giulia, withfour objectives: (a) to update the statistics on the use of pipedrainage; (b) to describe the farms that adopt this technique asa replacement of the traditional surface drainage methods;(c) to characterise the features of the drained soils and of thedrainage systems, and (d) to assess their performance. Withalmost 70.000 ha drained, the Regions present almost all of thepipe drained area in Italy. Pipe drainage first saw applicationsin the last seventies and became increasingly popular during theeighties. Most pipe drainage systems are installed in heavysoils, where the underground waterlogging is due to seasonalperched water table or to infiltrations from rivers or sea. Due tothe pedoclimatic variability of the area, slightly differentsolutions in terms of design variables and installation criteriaare found, but the following features are quite common: drainspacing 11–13 m slope 0.1–0.3%, depth 0.9–1 m. The pipe drains discharge in open collectors (single systems). Anincreasing interest for the use of the drainage systems forsubirrigation purposes has been observed, particularly inVeneto, requiring some adjustment in the drainage design. Theperformance of drainage in terms of control of water tabledepth and maintenance requirements are considered satisfactoryin almost all the cases. The most effective solutions forsuccessfully managing the subirrigation are also described.The introduction of pipe drains allows to enlarge fields (to morethan 10 has) and to save time for carrying out the operations forcrop cultivation. The crop yield in pipe drained fields is slightly higherto that obtained in the traditionally drained fields, withthe exception of winter wheat.     

无压地下灌溉新技术试验

对局部控水灌溉(无压地下灌溉)技术从理论上进行了分析，并给出了其土壤水分运动方程。在大田试验的基础上，研究分析了无压灌溉不同孔径孔口出水规律和根区局部湿润状况。试验结果表明：无压孔口出水规律与孔口孔径、地温和土壤含水量等因素有关；出水孔口孔径和初时土壤含水量对湿润锋推进速度影响较大，孔径和初时土壤含水量越大，湿润锋推进速越快；适宜的出水孔径沿管道长度方向出水均匀，5～35cm深度的土壤含水量变化无明显差异，能够满足作物需水和生理需水要求。     

应用DRAINMOD对测坑控制排水条件下地下水位的模拟分析

为研究控制排水措施对农田地下水位的影响,在湖北省荆州市四湖工程管理局丫角排灌试验站进行了测坑控制排水试验,并利用DRAINMOD模型对不同试验方案下地下水位进行数值模拟。模拟结果表明：在棉花生育期内,地下水位模拟结果和实测结果的一致性较好,该模型可有效地模拟预测水测坑控制排水条件下地下水位特性;控制排水措施能有效调控地下水位．