Rapid field evaluation of drip and microspray distribution uniformity

The Cal Poly ITRC irrigation evaluation programs have been widely used to assess the global distribution uniformity (DU) of drip and microsprayer irrigation systems. The field procedures and formulas used in the program are presented in this paper. The system DU is estimated by mathematically combining the component DU values. DU components include pressure differences, other causes (such as manufacturing variation, plugging, and wear), unequal drainage, and unequal application rates. Results are presented from evaluations by several entities, including Cal Poly ITRC. Cal Poly evaluations of 329 fields provided an average DU_lq of 0.85 for drip and 0.80 for microspray. Approximately 45% of the non-uniformity was due to pressure differences, 52% was due to other causes, 1% due to unequal drainage, and 2% due to unequal application rates. The data show that with good design and management, it is possible to have high system DU values for at least a 20-year system life.     

滚移式喷灌机压力对喷灌均匀性影响

为解决喷灌机械的喷灌均匀性差、移动不方便等问题,研制一种操控简单、适应性强的大型滚移式喷灌机,对其水量分布均匀系数和喷灌强度进行试验.试验采用单因素多重比较设计方法,选取距进水端距离分别为40,150,260 m处为测试处,喷灌压力分别为0.20,0.25,0.30,0.35,0.40 MPa,并运用Design-expert软件进行分析,研究各喷灌压力在各测试处对水量分布均匀系数和喷灌强度的影响.结果表明,各测试处的压力对水量分布均匀系数的影响均为显著性差异,且随喷灌压力上升,水量分布均匀系数升高.对喷灌强度的影响呈正相关性,但喷灌压力高于0.30 MPa时影响不显著.喷灌压力在0.40 MPa时,水量分布均匀系数平均可达88.75%,喷灌强度为12.3 mm/h,各处的水量分布均匀系数和喷灌强度能够保持均匀一致,并能够稳定作业,达到最优状态,完全满足大型滚移式喷灌机的性能要求.该项研究对于促进滚移式喷灌机推广和应用具有重要意义,为其深入研究提供了参考依据.     

Modeling crop yield as affected by uniformity of sprinkler irrigation system

The effect of sprinkler irrigation uniformity on crop yield is an important consideration for the design of sprinkler irrigation system. A model that relates yield response to evapotranspiration deficits at special growth stages to evaluate the impacts of uniformity on crop yield was developed from a crop water production function. The simulation results of the model showed that crop yield increased with increasing uniformity. Optimum irrigation amount and uniformity for the maximum net return were determined with the model. The optimum irrigation amount depends on irrigation uniformity and on economic factors, decreasing with the uniformity but increasing with the ratio of product price to water cost. The optimum uniformity increased with an increase of irrigation amount expressed by a ratio between gross and required irrigation amount, but approximated 90% when the ratio exceeded 0.85. Field experiments conducted to study the relationship between spatial distribution of soil moisture and sprinkler application uniformity demonstrated that the water in the soil was more uniformly distributed than that measured for the application at the soil surface.     

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.     

温室番茄对微小流量滴灌埋深与灌水量的响应

试验采用番茄品种为“中研998”,于2017年3-7月在中国农业大学通州实验站春秋大棚中进行.试验共6个处理,3个灌水梯度(以田持的85%,75%,65%计)与2个痕量带埋深梯度(15,30 cm).研究结果表明:埋深与灌水下限对番茄植株株高茎粗的影响规律性不强;深埋处理更有利于植株茎干物质积累,浅埋更有利于叶干物质积累,说明浅埋处理植株蒸腾量更大;埋深与灌水下限对根干重的影响规律性不强;深埋更有利于提高果实产量、氮素表观利用率与肥料偏生产力,浅埋更有利于提高水分利用效率;灌水下限越低,果实产量、水分利用效率、氮素表观利用率与肥料偏生产力越高.因此根据本试验研究的各项指标综合得出埋深为30 cm、灌水下限为65%田持时最适宜此种试验条件下温室番茄的生长.     

平移式喷灌机行走速度及喷灌均匀度试验研究

为研究低压喷灌下喷灌机行走速度合理取值以及喷灌均匀度对土壤含水率均匀度的影响,以自行研制的轻小型平移式喷灌机为研究对象,通过室内单喷头试验和田间喷灌试验,探究了特定灌水定额下喷灌机的工作压力与行走速度关系,并对其水量分布、喷灌均匀度以及土壤含水率均匀度随时间变化进行了分析.结果表明：通过确定灌水定额能够计算出平移式喷灌机的行走速度和工作压力：当灌水定额分别为10,15,20 mm时,40~120 kPa喷灌压力下喷灌机行走速度最小为17.27 m/h,最大为58.65 m/h;增大喷灌压力能小范围提高均匀度,40 kPa工作压力均匀度为0.696,60~120 kPa喷灌压力下均匀度变化范围为0.731~0.788,喷灌水在土壤中的二次分布均匀度明显高于地表喷灌均匀度,40 kPa喷灌压力下喷后6 h土壤含水率均匀度达到0.906,24 h后达到0.953,可相应降低喷灌均匀度设计值以降低运行成本,节约能耗.     

Spatial root distribution of mature apple trees under drip irrigation system

The study was undertaken in order to quantify the effect of 12-year irrigation by drip emitters placed on one side of the tree trunk on the rooting pattern of Gloster apple trees (Malus domestica Borkh) grafted on M26 rootstock under the conditions of south-west Poland. The orchard was established in 1994 and since 1995 was drip irrigated under three treatments: V0 - without irrigation (control), V1 - intensive irrigation, and V2 - economical irrigation. In March 2007, after 12 years of irrigation, a profile trench observation method was used to map the number and the location of root distribution in clay loam (Luvisol) soil.The root system architecture was largely affected by irrigation. In case of the trees irrigated intensively (V1), the study showed asymmetry in the distribution of roots of diameter <1 mm and 1-3 mm. In V1, shallow root system, concentrated in the wetted zone developed on the irrigated side of the tree, where on the side of the tree trunk opposite the emitter trees developed significantly larger numbers of roots, which penetrated deeper soil layers. There were no statistically significant differences in the number of roots between both sides of the tree trunk under the treatment with economical irrigation (V2). Moreover, spatial roots distribution over the entire soil profile was found to be the most uniform compared to the other experimental treatments (V0 and V1). Finally, the study examined the relationship between root system and yield. Obtained results showed that in the 3-year period less frequent water application (V2) resulted in the highest yield.     

圆形喷灌机施肥灌溉均匀性及蒸发漂移损失

为了评估圆形喷灌机施肥灌溉均匀性和蒸发漂移损失量,通过测试圆形喷灌机入机压力为0.15 MPa时,与喷灌机连接的计量隔膜泵吸肥流量与工作比例间的关系.分析了计量隔膜泵吸肥性能,并通过田间试验测试圆形喷灌机水力性能,评估了不同肥料类型和肥液浓度的施肥灌溉均匀系数及蒸发漂移损失量.结果表明:计量隔膜泵吸肥流量实测值和理论值的标准均方根误差为8.9%,且流量控制精度在工作比例为60%~100%时(相对误差|RE|≤5.6%)远高于工作比例为20%~40%时(|RE|≥13.3%).圆形喷灌机行走速度百分数为100%时,径向肥液水深与施肥量的修正赫尔曼-海因均匀系数基本相等,其变化分别为80%~85%和78%~86%,均小于径向肥液浓度的均匀系数96%~99%.不同肥料类型和肥液浓度处理间灌水、肥液浓度均匀系数差异不具有统计学意义.当风速小于2 m/s时,利用圆形喷灌机进行施肥灌溉产生的蒸发漂移损失量占灌水量的比例为1.5%~10.1%.     

膜下滴灌水氮耦合效应对玉米干物质与产量的影响

通过大田试验研究膜下滴灌水氮耦合效应对玉米干物质与产量的影响,设置3个水分水平,按土壤含水率占田间持水率百分比的上下限不同设低、中、高水:低水 W1(拔节前60%~80%,拔节后55%~80%)、中水W2(拔节前65%~85%,拔节后60%~85%)、高水W3(拔节前75%~95%,拔节后70%~95%).施氮梯度按224,270,330 kg/hm²设低、中、高氮3个施氮水平.寻求适宜于科尔沁左翼中旗的玉米膜下滴灌适宜水氮用量,为玉米膜下滴灌达到高产、高效目标提供理论依据.研究结果表明:生育期中等施氮水平270 kg/hm²与高灌溉水平组合下可获得较高的全株干物质总量,但收获指数低于中水中氮的组合,中水中氮耦合用量下可获得较高的收获指数,能较好地调节光合产物在籽粒与营养器官间的分配;在当地典型地域及气候条件下,玉米采用膜下滴灌种植方式,增加水和氮的投入均能增产,并对产量有报酬递减效应,单因素施用水平的变动引起产量的改变是水分作用大于施氮作用.     

宁夏引黄灌区滴灌条件下春小麦干物质转移与灌浆特征

为优化春小麦滴灌灌溉制度,提高水分利用效率,对宁夏引黄灌区滴灌条件下灌水对春小麦千粒质量、干物质转移和灌浆特征的影响展开研究。在总灌水量一致的条件下,分别设置增大三叶期、分蘖期和拔节期灌水量(W1)、增大分蘖期、拔节期和抽穗期灌水量(W2)、增大拔节期、抽穗期和灌浆期灌水量(W3)、各生育期灌水量平均分配(W4)和对照(CK)5个水量分配处理,研究春小麦千粒质量、各营养器官干物质转移量及籽粒灌浆特性。W3籽粒千粒质量最大,花后37 d其千粒质量为53.96 g,较CK大2.64%。W2的干物质转移总量、同化物转移总量和干物质转移对籽粒的贡献率均为最大,分别为0.67 g/株、2.992 g/株和22.165%。不同水量分配下小麦籽粒灌浆速率满足Logistic模型,经过水量优化分配,W2最大灌浆速率出现时间提前0.366 d,虽然最大灌浆速率有所降低,但是通过增加快增期时间(增加0.15 d)和活跃灌浆期时间(增加2.35 d),可以显著提高籽粒干物质积累量,收获时穗粒质量较CK提高32.1%,该处理籽粒产量也达到最大,较CK提高6.88%。因此可以通过优化灌水量分配,增加小麦千粒质量,提高各器官对籽粒的干物质转移量及灌浆速率,进而达到高产高效的目的。     

过滤后黄河水对滴灌系统的影响

为探明黄河水经孔径为0.05 mm(300目)过滤器过滤后进行滴灌的可能性,模拟大田滴灌研究了黄河水滴灌条件下4种滴灌带(Nf0.72,Nf1.60,Nf2.20,Dy1.38)不同位置流量变化规律,滴灌系统平均相对流量Q_r与流量变异系数C_v、系统均匀度C_u变化规律及相关关系.结果表明:黄河水对滴头的堵塞早期呈快速发育状态,不同类型引黄滴灌系统平均相对流量随灌水次数的增加呈平缓下降—快速下降—平缓下降的规律,均在相对流量75%附近快速下降;滴头流量变异系数在系统运行初期线性增大,之后平缓变化,且与系统平均相对流量具有很好的线性关系(p<0.001);当系统平均相对流量Q_r大于75%时,滴灌系统克里斯琴森均匀度系数C_u与Ln Q_r呈线性关系(R²=0.790 9),因此,引黄滴灌系统可通过系统平均相对流量Q_r来判断系统均匀度C_u,以方便及时快速了解系统堵塞状况,以便对其运行管理进行决策.     

温室番茄循环曝气地下滴灌土壤水分动态及耗水特性

为探求循环曝气地下滴灌对温室番茄土壤水分及耗水特性的影响规律,采用正交试验,研究了不同滴灌带埋深、曝气水平及灌水量对温室番茄土壤含水率、耗水量、产量及水分利用效率的影响.整个生育期内番茄耗水量呈先增大后减小的趋势,曝气处理番茄耗水量显著高于不曝气处理.相比于不曝气处理,曝气滴灌处理番茄产量提高10%.15 cm滴灌带埋深、溶氧值30 mg/L以及K_P为0.75灌水量处理的番茄产量和水分利用效率达到最大值,分别为64 951.3 kg/hm²和23.26 kg/(hm²·mm).结果表明,曝气处理对番茄产量、水分利用效率的影响具有统计学意义(P<0.05).曝气对于土壤含水率有一定影响,且曝气处理有助于番茄对水分的吸收.滴灌带埋深和灌水量交互作用对番茄产量的影响具有统计学意义(P<0.05),滴灌带埋深和曝气量交互作用对番茄产量的影响具有统计学意义(P<0.01),灌水量与滴灌带埋深、灌水量与曝气水平交互作用分别对番茄水分利用效率的影响具有统计学意义(P<0.01).     

不同灌水量与灌水频率对加工番茄根系生长和产量的影响

为了了解不同灌水量和灌水频率对加工番茄根系生长和产量的影响,试验设置3个灌水定额和2个灌水频率.试验结果表明,加工番茄根系主要分布在(10,40］ cm土层(约占比63.20%~85.67%),随着土壤深度的增加,根系生长和干物质量逐渐减小;常规频率(F2)和低水(W3)有促使根系向深层土壤发育的趋势,高频灌溉(F1)和高水(W1)会促进根系在相对浅层的土壤范围内分布;相比常规频率,高频处理下土壤含水量波动较小,且保持在稳定的范围内.同时发现,土壤含水量、叶面积指数、干物质量和产量随着灌水定额和灌水频率的增大,均呈现出增加趋势;相同灌水频率下,高水和适水处理下加工番茄产量差异不具有统计学意义(P>0.05),但显著高于低水处理下加工番茄产量(P<0.05).综合考虑根系生长、产量和节约水资源,适用于西北地区加工番茄种植的较优灌溉制度为:75%ET₀的灌水定额,灌水频率苗期一周 1 次,开花坐果期至拉秧期一周3次.     

小麦不同生育期微喷带水量分布均匀性

试验以常用的机械打孔的Ф32微喷带为研究对象,通过调节微喷带的工作压力,研究2种长度微喷带(20,40 m)下春小麦不同生育期水量分布均匀系数的变化规律,通过对不同高度春小麦遮挡下水量分布均匀系数的分析,探究大田试验中微喷带的水量分布均匀性.试验结果表明:作物遮挡会降低微喷带的水量分布均匀性,改变水量空间分布特征,不同...     

留果数和源库距离对温室番茄干物质分配的影响

为探索源库比例和源库距离对温室番茄同化产物分配的影响规律,2016年1—12月在江苏大学Venlo型试验温室中进行试验,分为早春茬和秋冬茬,采用双杆整枝,设置了3个留果数水平(T1留3果;T2留2果;T3留1果)和2个不同源库距离(T4第1果枝留1果;T5第2果枝留1果),采用已建立的叶长与叶干质量、株高与茎干质量和果径与果干质量的数学公式来计算各器官的同化产物动态变化.结果表明:T1,T2和T3之间的同化产物产量差异不大,但均高于T4和T5,T4和T5之间差异不大.同化产物向果实的分配系数在处理后22 d T1显著大于T2和T3;处理T4同化产物向果实中分配系数在处理后16 d显著大于T5.不同处理间源库比例和源库距离均影响温室番茄同化产物分配,这为温室番茄的整枝管理提供了理论依据和技术支持.     

Yield,water use and root distribution of wheat as affected by pre-sowing and post-sowing irrigation

Irrigation water is a limited resource, and therefore irrigation practices must be rationalized for high water-use efficiency. Little is known about the influence of stored water in deep soils on the water needs and the post-sowing irrigation requirements of crops. A 3-year field experiment was conducted to determine the effects of combinations of light and heavy pre-sowing irrigations with two post-sowing irrigation regimes on yield, root growth, water use and water-use efficiency of wheat on a deep alluvial sandy loam soil. Post-sowing treatments consisted of (i) five 75-mm irrigations at five growth stages, and (ii) irrigations based on pan evaporation, i.e. at IW/PAN-E ratio of 0.75 (75 mm of irrigation water were provided as soon as the open-pan evaporation minus rainfall since previous irrigation was 100 mm).The latter regime required 175 mm less water than that with irrigation at growth stages. Profile water utilization was inversely related to post-sowing irrigation water. Where pre-sowing irrigation was light, post-sowing irrigations based on pan evaporation yielded significantly less than those based on growth stages. With heavy pre-sowing irrigation, irrigation based on the pan evaporation yielded as much as five irrigations at growth stages. The former decreased the mean water application by 153 mm and increased the water-use efficiency by 26%. Irrigation based on pan evaporation stimulated greater utilization of stored water by increasing the rooting density in deeper layers.It is indicated that for higher water-use efficiency and yield, wheat should be sown after a heavy pre-sowing irrigation, and post-sowing irrigation should be based on 0.75 pan evaporation.     

施肥量对温室滴灌番茄干物质累积、产量及水肥利用的影响

为研究日光温室秋冬茬番茄生育时期干物质生产动态规律,探索高产高效的科学施肥模式,以标准冲施肥(含N量16%,含P_2O_5量5%,含K_2O量19%)为施肥种类,施肥量以N素为基准分为4个肥料处理水平,即F1(高肥)、F2(中肥)、F3(低肥)、F4(不追肥),分析了不同施肥量对日光温室番茄干物质累积、产量和水肥利用的影响。结果表明,番茄产量和水分利用效率(WUE)与施肥量呈"抛物线"关系,当N施量为290.6 kg/hm2(F2)时达到最高值,分别为67 776.93 kg/hm2和49.27 kg/m3,说明适量施肥可提高产量及水分利用效率。但肥料生产效率(PFP)在施肥量为(N)41.4~539.9 kg/hm2范围内呈现负指数降低趋势。植株干物质累积量表现出F2处理F1处理F3处理F4处理。果实干物质累积进程符合logistic函数轨迹,中肥处理比高肥、低肥处理提前进入快速累积期,使快速累积期持续时间比其他处理长1~8 d。全株总干物质转移量对果实贡献率为1.97%~6.96%,说明果实干物质高达90%以上依靠株体自身光合作用填充。因此,番茄结果期加强水肥的供给是必要的。     

灌排方案对避雨番茄需水特性与产量的影响

为了实现南方地区番茄节水、优质、高效生产,在避雨栽培条件下,研究了不同灌排方式对番茄需水特性与产量的影响.研究结果表明:各亏缺灌溉处理土壤含水率随时间总体呈下降趋势,暗管埋深08 m的处理较埋深06 m处理,土壤含水量下降更快但不明显.番茄不同生育阶段的蒸发蒸腾量差别较大,表现为始花坐果期>果实成熟与采收期>苗期.随着番茄的生长,其日蒸发蒸腾量大体呈逐渐上升的趋势.在不同灌排模式和避雨措施条件下,苗期的日蒸发蒸腾量变化范围为107～271 mm／d,始花坐果期日蒸发蒸腾量变化范围为160～309 mm／d,果实成熟与采收期日蒸发蒸腾量变化范围为178～335 mm／d.在相同的排水措施,不同灌溉条件下,番茄果实产量随着灌水量的减少而减少,水分利用率和灌溉水利用率却随着灌水量的减少而增大.研究可为南方避雨栽培下番茄灌排方式的选择及其节水、优质、高产提供参考.     

Yield and quality of two tomato (Solanum lycopersicum L.) cultivars as influenced by drip and furrow irrigation using waters having high residual sodium carbonate

Performance of tomato when irrigated with sodic waters particularly under drip irrigation is not well known. A field experiment was conducted for 3 years to study the response of tomato crop to sodic water irrigation on a sandy loam soil. Irrigation waters having 0, 5 and 10 mmol_c L⁻¹ residual sodium carbonate (RSC) were applied through drip and furrow irrigation to two tomato cultivars, Edkawi (a salt tolerant cultivar) and Punjab Chhuhara (PC). High RSC of irrigation water significantly increased soil pH, ECe and exchangeable sodium percentage progressively; the increases were higher in furrow compared to drip irrigation. Effect of high RSC on increasing bulk density and decreasing infiltration rate of soil was also pronounced in furrow-irrigated plots. Higher soil moisture and lower salinity near the plant was maintained under drip irrigation than under furrow irrigation. Performance of the two cultivars was significantly different; pooled over 2002–03 and 2003–04 seasons, PC yielded 38.8 and 30.0 Mg ha⁻¹ and Edkawi yielded 31.8 and 22.9 Mg ha⁻¹ under drip and furrow irrigation, respectively. At RSC10, cultivar PC produced 38 and 46% higher fruit yield than cultivar Edkawi under drip and furrow irrigation, respectively. Reduction in fruit yield at higher RSC was due to lower fruit weight under drip irrigation and due to reduced fruit number as well as fruit weight under furrow irrigation. Decrease in fruit weight was more pronounced in cultivar Edkawi than in cultivar PC. Increase in RSC lowered quality of the fruits except the ascorbic acid content. High RSC under drip irrigation, in general, had lesser deteriorating effect on the fruit quality particularly for cultivar PC than under furrow irrigation. For obtaining high tomato yield and better-quality fruits using high RSC sodic waters, drip irrigation should be preferred over furrow irrigation. Better performance of local cultivar PC compared to Edkawi at medium and high RSC suggests that cultivars categorized as tolerant to salinity should be evaluated in the sodic environment particularly when irrigated with high RSC sodic waters.     

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.