Calibration and validation of SALTMED model under dry and wet year conditions using chickpea field data from Southern Portugal

The SALTMED model is one of the few available generic models that can be used to simulate crop growth with an integrated approach that accounts for water, crop, soil, and field management. It is a physically based model using the well-known water and solute transport, evapotranspiration, and water uptake equations. In this paper, the model simulated chickpea growth under different irrigation regimes and a Mediterranean climate. Five different chickpea varieties were studied under irrigation regimes ranging from rainfed to 100 % crop water requirements, in a dry and a wet year. The calibration of the model using one of the chickpea varieties was sufficient for simulating the other varieties, not requiring a specific calibration for each individual chickpea variety. The results of calibration and validation of the SALTMED model showed that the model can simulate very accurately soil moisture content, grain yield, and total dry biomass of different chickpea varieties, in both wet and dry years. This new version of the SALTMED model (v. 3.02.09) has more features and possibilities than the previous versions, providing academics and professionals with a very good tool to manage water, soil, and crops.     

Influence of irrigation on leaf water relations and dry matter production in coconut palms

Summary The effect of different frequencies of irrigation on the leaf water relations and dry matter production of the West Coast Tall coconut palms (Cocos nucifera L.) was studied during two growing seasons. Irrigation was applied in amounts of 60 mm at a ratio of irrigation water to cumulative pan evaporation (I/E) of 1.0, 0.75, 0.50 and 0.0. Measurements were made of stomatal resistance, leaf water potential and epicuticular wax content, and vegetative and reproductive dry matter production. Irrigation treatments resulted in a four-to five-fold increase in the soil water deficit at I/E ratios of 0.5 and 0.0 as compared to 1.0. Coconut palms experienced severe moisture stress at an irrigation level of 0.50, resulting in a greater stomatal resistance (111%) and epicuticular wax content (32%) and reduced transpiration rate (10%), leaf water potential (68%), and reproductive dry matter production (22%), compared with well watered palms. Based on the relationship between the soil water deficit and the stomatal resistance, the critical soil water deficit for irrigation scheduling was deduced to be 110 mm. However vegetative dry matter production was reduced at much lower soil water deficits than this value.     

温室滴灌条件下水分亏缺对番茄生长及生理特性的影响

为确定温室滴灌条件下番茄高产高效的适宜土壤水分控制指标,采用小区试验方法,在温室滴灌条件下研究了不同时期水分亏缺对番茄生长发育及生理特性的影响。研究结果表明,任何生育阶段发生水分亏缺均会降低番茄叶片光合速率及气孔的开度,进而影响干物质的累积和运转,但不同时期水分亏缺的影响形式及程度有所不同;苗期水分亏缺会抑制番茄的正常生长发育,但水分过高会使植株徒长,不利于光合产物向产量的运移;开花坐果期水分亏缺不仅抑制了番茄的生长发育,而且降低了干物质的累积,并最终影响到产量的形成;成熟采摘期水分亏缺会加速番茄植株的老化,降低最终干物质量,对番茄产量的形成影响最为明显。在不影响番茄植株正常生长发育及生理需水情况下,适度水分亏缺(T1处理)可实现高产与高效用水的统一。     

Effect of mulching on soil and plant water status, and the growth and yield of wheat (Triticum aestivum L.) in a semi-arid environment

Mulching is one of the important agronomic practices in conserving the soil moisture and modifying the soil physical environment. Wheat, the second most important cereal crop in India, is sensitive to soil moisture stress. Field experiments were conducted during winter seasons of 2004-2005 and 2005-2006 in a sandy loam soil to evaluate the soil and plant water status in wheat under synthetic (transparent and black polyethylene) and organic (rice husk) mulches with limited irrigation and compared with adequate irrigation with no mulch (conventional practices by the farmers). Though all the mulch treatments improved the soil moisture status, rice husk was found to be superior in maintaining optimum soil moisture condition for crop use. The residual soil moisture was also minimum, indicating effective utilization of moisture by the crop under RH. The plant water status, as evaluated by relative water content and leaf water potential were favourable under RH. Specific leaf weight, root length density and dry biomass were also greater in this treatment. Optimum soil and canopy thermal environment of wheat with limited fluctuations were observed under RH, even during dry periods. This produced comparable yield with less water use, enhancing the water use efficiency. Therefore, it may be concluded that under limited irrigation condition, RH mulching will be beneficial for wheat as it is able to maintain better soil and plant water status, leading to higher grain yield and enhanced water use efficiency.     

Effects of deficit irrigation scheduling on yields and soil water balance of irrigated maize

This paper presents the findings of the effect of some selected deficit irrigation scheduling practices on irrigated maize crop in a sub-catchment in south western part of Tanzania. Field experiments, in which maize (TMV1-ST) variety was planted under total irrigation, were conducted during the dry seasons of 2004 and 2005. Surface irrigation method was used and the crop was planted in basins. The seasonal water applied ranged from 400 to 750 mm. Soil moisture content from both cropped and bare soils, leaf area index, dry matter, and grain yields were measured. The dry matter yield ranged between 6,966 and 12,672 kg/ha, and grain yields obtained were between 1,625 and 4,349 kg/ha. The results showed that deficit irrigation at any crop growth stage of the maize crop led to decrease in dry matter and grain yields, seasonal evapotranspiration and deep percolation. Deficit irrigation in any one growth stage of the maize crop only seems to affect grain production and no significant effect on biomass production, but deficit irrigation that spanned across two or more growth stages affect both biomass and grain production drastically. Crop water use efficiency (WUE) and Irrigation water use efficiency (IWUE) were strongly influenced by the number of growth stages in which deficit irrigations were applied and how critical the growth stages were to moisture stress rather than the amount of irrigation water applied. While maximum WUE was obtained under full irrigation, maximum IWUE was obtained in the deficit irrigation treatment at vegetative growth stage, which suggest that IWUE may be improved upon by practicing deficit irrigation at the vegetative growth stage of the maize crop.     

苗期土壤水分控制对线辣椒生长和水分利用效率的影响

以我国北方普遍种植的经济作物线辣椒为研究对象,根据线辣椒的生理生长特点,通过盆栽试验,研究了苗期不同土壤水分下限对线辣椒长势、产量和WUE的影响。结果表明,在试验条件下,土壤水分下限控制在田间持水率(θF)的45%～60%时,线辣椒生长状况良好,50%θF时线辣椒的生物量、根冠比最大;各处理按线辣椒单株产量大小排序为:处理4>处理3>处理2>处理1>处理5>处理6;各处理按线辣椒全生育期WUE大小排序为:处理3>处理4>处理2>处理1>处理5>处理6。产量最高时的苗期土壤含水率为50%θF,WUE最高的苗期土壤含水率为55%θF,从而得出线辣椒获得较高产量所对应的苗期土壤水分下限为(50%～55%)θF。     

膜下滴灌调亏对加工番茄产量和水分利用效率的影响

通过加工番茄不同生育期膜下滴灌水分调亏试验,研究了水分调亏对土壤水分、株高、干物质积累、经济产量及水分利用效率和灌溉水利用效率的影响。结果表明,在苗期占田间持水率55%的水分调亏滴灌,可以在降低灌溉水量、耗水量和移栽前后土壤水分的同时,显著(p<0.05)增加番茄单株果数、单株果质量、产量、灌溉水利用效率和水分利用效率,而花期和盛果期分别施以上述水分调亏则结果相反,其中以花期表现最为显著(p<0.05),其次为盛果期。全生育期不进行水分调亏和仅在采收期施以水分调亏,虽产量显著(p<0.05)增加,但水分利用效率和灌溉水利用效率却显著(p<0.05)降低。     

Impact of sustained deficit irrigation on spearmint (<Emphasis Type="Italic">Mentha spicata</Emphasis> L.) biomass production,oil yield,and oil quality

Crop response to deficit irrigation is an important consideration for establishing irrigation management strategies when water supplies are limited. This study evaluated the response of native spearmint to water deficits applied using overhead sprinklers in eastern Washington, US. Five levels of irrigation were applied ranging from full irrigation (100%) to 5% of weekly averaged full crop water needs. Soil water monitoring with soil water balance was used to estimate soil water deficits for irrigation scheduling and soil water use. Mint oil yields, oil components, dry matter production, and the water-use efficiency of the spearmint were assessed. There was significant reduction in fresh mint hay (harvested biomass) yield with increasing water deficit. However, spearmint oil yields remained generally uniform across irrigation treatments at the first cutting but decreased at the driest plots during the second harvest due to a loss of plant stand. The wet harvest index and water-use efficiency improved significantly for both harvests with increasing water deficit. Hay yield, oil yield, wet harvest index, and water-use efficiency are pooled across sides and replicate blocks to provide trends with changes in maximum evapotranspiration. The three major monoterpenes show changes suggesting less mature oil yields. The study demonstrates the feasibility of sustaining native spearmint yields under managed deficit irrigations for deficits not lower than 0.5 ETc.     

分根区交替灌溉下水分亏缺对夏玉米生长和水分利用效率的影响

为探讨玉米节水灌溉方式的理论依据,通过桶栽试验研究了分根区交替灌溉(APRI)方式下,不同生育期水分亏缺对夏玉米生长、干物质累积质量、籽粒产量、总耗水量和水分利用效率(WUE)的影响.结果表明:常规灌溉(CI)方式下,苗期和全生育期水分亏缺的株高、叶面积和总耗水量均显著低于充分灌溉,但苗期水分亏缺可以提高WUE.相同的灌水方式和亏缺时期,中度亏缺的根干物质质量、地上和总干物质质量以及籽粒产量均显著高于重度亏缺;相同的灌水方式和灌水水平,苗期水分亏缺的株高、叶面积、根干物质质量、地上和总干物质质量以及总耗水量均显著的低于灌浆期,但籽粒产量和WUE均显著高于灌浆期;相同的灌水水平和亏缺时期,APRI的根干物质质量和总耗水量均显著低于CI的,但APRI的籽粒产量和水分利用效率均显著高于CI的.本研究结果表明,APRI在苗期进行中度亏缺有利于营养生长的调控,并达到节水高产,提高WUE的目的.     

Dry matter,harvest index,grain yield and water use efficiency as affected by water supply in winter wheat

Food production and water use are closely linked processes and, as competition for water intensifies, water must be used more efficiently in food production worldwide. A field experiment with wither wheat (Triticum Aestivum L.), involving six irrigation treatments (from rain-fed to 5 irrigation applications), was maintained in the North China Plain (NCP) for 6 years. The results revealed that dry matter production, grain yield and water use efficiency (WUE) were each curvilinearly related to evapotranspiration (ET). Maximum dry matter at maturity was achieved by irrigating to 94% and maximum grain yield to 84% of seasonal full ET. A positive relationship was found between harvest index (HI) and dry matter mobilization efficiency (DMME) during grain filling. Moderate water deficit during grain filling increased mobilization of assimilate stored in vegetative tissues to grains, resulting in greater grain yield and WUE. Generally, high WUE corresponded with low ET, being highest at about half potential ET. At this location in NCP, highest WUE and grain yield was obtained at seasonal water consumption in the range 250–420 mm. For that, with average seasonal rainfall of 132 mm, irrigation requirements was in the range of 120–300 mm and due to the deep root system of winter wheat and high water-holding capacity of the soil profile, soil moisture depletion of 100–150 mm constituted the greater part of the ET under limited water supply. The results reveal that WUE was maximized when around 35% ET was obtained from soil moisture depletion. For that, seasonal irrigation was around 60–140 mm in an average season.     

不同滴灌灌溉制度对绿洲棉田土壤水热分布及产量的影响

【目的】探究不同滴灌灌溉制度对绿洲棉田土壤水热分布状况及对产量的影响。【方法】于2017年在策勒地区开展田间试验,设置了2种灌水模式:基于计算机模型的预报灌溉与基于土壤墒情的灌溉,每种灌水模式设置2种灌溉梯度:充分灌溉(100%)和非充分灌溉(75%的充分灌溉)。【结果】预报灌溉的土壤含水率和贮水量在花蕾与花铃期显著高于墒情灌溉;不同灌溉制度各剖面的土壤温度变化趋势一致,整个生育期的表层土壤平均温度表现为墒情亏缺最高,预报充分最低。作物产量在一定范围内随灌溉量的增加而增加,预报充分的产量较预报亏缺,墒情充分,墒情亏缺分别提高13.7%、12.1%、47.6%。水分利用效率表现为预报亏缺最高,且产量与预报充分的产量无显著差异。【结论】在策勒绿洲地区,预报亏缺灌溉可达到节水增产的目的。     

Water use efficiency of narrow row cotton

Summary A field experiment was conducted on the west side of the San Joaquin Valley in California to determine water use, crop growth, yield and water use efficiency of Acala (SJ-2) cotton (Gossypium hirsutum L.) grown in 0.5 m spaced rows on a Panoche clay loam soil (Typic Torriorthents). Evapotranspiration was determined by water balance techniques utilizing neutron soil moisture measurements. All neutron measurements were made within a 3 m soil profile in 0.20 m increments. The measured evapotranspiration was compared to climatic estimates of potential evapotranspiration, and to calculations using a one-dimensional soil water balance model that separately computed soil water evaporation and plant transpiration. Crop growth was determined by weekly destructive plant sampling. Leaf area was determined along with dry matter components of leaves, stems, fruiting parts (flowers and squares) and bolls. Final yield was determined by machine harvesting (brush stripper) 720 m² from each plot. Lint yields and fiber quality were determined by sample ginning and fiber analysis at the U.S. Cotton Research Station at Shafter, California. Three irrigation regimes were established that resulted in an evapotranspiration range from a high deficit condition to full irrigation at the calculated atmospheric demand.The measured evapotranspiration of narrow row cotton under a full irrigation regime was 778 mm, 594 mm under a limited irrigation regime and 441 mm under a regime with no post-plant irrigation. The evapotranspiration from these irrigation treatments was accurately simulated by a water balance model. that used inputs of potential evapotranspiration, leaf area index, soil water holding capacity and root development.The average lint yield from narrow row cotton with a full irrigation regime was 1583 kg/ha, the average lint yield from a limited irrigation regime was 1423 kg/ha and the average lint yield from a treatment with no postplant irrigation (fully recharged soil profile at planting) was 601 kg/ha. The full irrigation regime resulted in a dry matter production of approximately 16 t/ha while the limited irrigated regime produce 11 t/ha and the no-postplant irrigation regime produced 7 t/ha of dry matter. The fiber quality results indicated significant (0.05 level) differences only in 50% span length and micronaire, with the 2.5% span length, uniformity index, elongation and strength indicating no difference.Cotton lint yield was found to be directly related to total evapotranspiration although the relationship was slightly non-linear while dry matter yield was found to be linearly related to evapotranspiration. Both lint and dry matter yield were found to have a linear relationship to estimated transpiration from the water balance model calculations.Contribution from the Unived States Department of Agriculture, Agricultural Research Service, Western Region and the University of California     

调亏灌溉对河西绿洲灌区春小麦耗水特征的影响

对河西绿洲灌区调亏灌溉春小麦0~120 cm土层的耗水特征、产量指标体系与阶段耗水量和不同生育时期土壤水分的相关关系进行了分析研究。结果表明,在调亏灌溉条件下,不同水分调亏处理、不同产量水平下春小麦阶段耗水量和日耗水强度差异较小;春小麦耗水模系数全生育期变化趋势也较为一致,在播种—分蘖期和分蘖—拔节期最小,而拔节—孕穗期和抽穗—灌浆期最大;春小麦孕穗、抽穗期仍可进一步施以适时适度的较为严格的土壤水分调亏而不会降低小麦生产力,而降低成熟期的土壤含水量不仅不会降低小麦生产力,反而会提高其水分利用效率和供水效率。     

添加生物质炭对猪场废水灌溉土壤养分状况及铅有效性的影响

[目的]为养猪废水安全灌溉提供科学依据.[方法]试验选取新乡郊区农田0～20 cm表层土壤,采用PVC根箱法种植小麦,试验设置4种水平的生物质炭添加量0％、0.5％、2％、5％(W0、W0.5、W2、W5)和对照CK(无作物和生物质炭).测定了各处理根际和非根际土壤养分状况与含铅量,探讨了处理间土壤养分状况和铅迁移规律...     

Yield and water use of eggplants (Solanum melongena L.) under full and deficit irrigation regimes

Field experiments were conducted in 2008 and 2009 to determine the effects of deficit irrigation on yield and water use of field grown eggplants. A total of 8 irrigation treatments (four each year), which received different amounts of irrigation water, were evaluated. In 2008, deficit irrigation was applied at full vegetative growth (WS-V), pre-flowering (WS-F) and fruit ripening (WS-R), while in 2009 deficit irrigation was applied during the whole growing season at 80 (WS-80), 60 (WS-60) and 40% (WS-40) of field capacity. Deficit-irrigated treatments were in both years compared to a well irrigated control. Regular readings of soil water content (SWC) in 2008 and 2009 showed that average soil water deficit (SWD) in the control was around 30% of total available water (TAW) while in deficit-irrigated treatments it varied between 50 and 75% of TAW. In 2008, deficit irrigation reduced fruit fresh yield by 35, 25 and 33% in WS-V, WS-F and WS-R treatments, respectively, when compared to the control (33.0 t ha⁻¹). However, the reduction in fresh yield in response to deficit irrigation was compensated by an increase in fruit mean weight. Results obtained in 2009 showed that fruit fresh yield in the control was 33.7 t ha⁻¹, while it was 12, 39 and 60% less in WS-80, WS-60 and WS-40 treatments, respectively. On the other hand, fruit dry matter content and water productivity were found to increase significantly in both years in deficit-irrigated treatments. Applying deficit irrigation for 2 weeks prior to flowering (WS-F) resulted in water saving of the same magnitude of the WS-80 treatment, with the least yield reduction, making more water available to irrigate other crops, and thereby considered optimal strategies for drip-irrigated eggplants in the semi-arid climate of the central Bekaa Valley of Lebanon.     

Scheduling irrigations by merging water-use and radar backscatter models

Penman-Monteith methods were merged with the water cloud radar model to simulate soil moisture, canopy moisture and radar backscatter for a field of potatoes (Solanum tuberosum) in the United Kingdom. The objective of this paper is to present the irrigation scheduling potential of the merged model. This study simulates water-use: radar backscatter simulation results are presented elsewhere and yield is not calculated by the merged model. Soil moisture deficit switches control the model, which in turn uses predetermined application rates defined by the user. The simulation results show that the most effective irrigation application during the 1999 simulation period would utilise 25 mm of water when a soil moisture deficit of 30 mm is reached. Significantly, this would have required less water application than that actually applied to the field.     

华北典型区冬小麦区域耗水模拟与灌溉制度优化

以经校验Aquacrop模型模拟了不同土壤条件下冬小麦水分与产量响应关系,结合北京大兴区土壤分布及其冬小麦实际种植情况,对模型模拟结果进行区域尺度拓展,以此为基础分析了研究区不同灌溉制度下冬小麦耗水量、产量及水分生产率的变化规律,并推荐了与华北地区水资源实际情况相适宜的冬小麦亏缺灌溉制度。结果表明:应用Aquacrop模型能较好模拟冬小麦生育期内土壤墒情和冠层覆盖度的动态变化过程及其生物量与产量情况,可利用经校验后的模型进行冬小麦水分与产量响应关系研究。灌溉定额在300 mm范围内,随着灌溉量增加,耗水量增大;在灌水次数相同条件下,灌溉日期不同,因蒸腾量变化导致耗水量差异显著。在相同处理下总体上降水多年份产量较高,而不同处理之间随着灌溉量增加产量增大;在灌水次数相同情况下,灌溉关键生育时段选择对冬小麦产量形成及水分生产率提高至关重要。以冬小麦增产提效为原则,在灌1水情况下重点保障拔节-抽穗阶段的需水;灌2水情况下重点保障返青-拔节、抽穗-乳熟阶段需水;灌3水情况下重点保障返青-拔节、拔节-抽穗、抽穗-乳熟阶段需水。针对华北水资源严重短缺实际,建议北京大兴区冬小麦采用灌2水的亏缺灌溉制度,较灌4水情况下的灌溉量与耗水量分别减少140、65 mm,能确保75%产量。可见,在与华北类似的资源性缺水区域,选择适宜亏缺灌溉制度,能大幅降低区域灌溉量与耗水量,在稳定区域冬小麦产量及涵养地下水源方面具有重要的现实意义。     

Agronomic response and water productivity of almond trees under contrasted deficit irrigation regimes

We investigated the long-term effects of different deficit irrigation (DI) options on tree growth, shoot and leaf attributes, yield determinants and water productivity of almond trees (Prunus dulcis, cv. Marta) grown in a semiarid climate in SE Spain. Three partial root-zone drying (PRD) irrigation treatments encompassing a wide range of water restriction (30%, 50% and 70% of full crop requirements, ET_c) and a regulated deficit irrigation treatment (RDI, at 50% ET_c during kernel-filling) were compared over three consecutive growth seasons (2004–2006) to full irrigation (FI). The results showed that all deficit irrigation treatments have a negative impact on trunk growth parameters. The magnitude of the reduction in trunk growth rate was strongly correlated through a linear relationship with the annual volume of water applied (WA) per tree. Similarly, a significant relationship was found between WA and the increase in crown volume. In contrast, leaf-related attributes and some yield-related parameters (e.g., kernel fraction) were not significantly affected by the irrigation treatments. Except in PRD₇₀, individual kernel weight was significantly reduced in the deficit irrigated treatments. Kernel yield, expressed in percent of the maximum yield observed in the FI treatment, showed a linear decrease with decreasing WA and a slope of 0.43, which implies that a 1% decrease in water application would lead to a reduction of 0.43% in yield. Water productivity increased drastically with the reduction of water application, reaching 123% in the case of PRD₃₀. Overall, our results demonstrate the prevalence of direct and strong links between the intensity of the water restriction under PRD – i.e., the total water supply during the growing season – and the main parameters related to tree growth, yield and water productivity. Noteworthy, the treatments that received similar annual water volumes under contrasted deficit irrigation strategies (i.e., PRD₇₀ and RDI) presented a similar tree performance.     

干旱处理对土壤水分变化及大豆产量的影响

采用框栽方式,研究不同阶段干旱处理对土壤水分、大豆植株干物质积累及产量的影响。结果表明,土壤含水率随干旱历时的增加而递减,长时间干旱后稳定在20%～24%;对于短期干旱处理,灌溉量较大时,土壤含水率会迅速恢复到稳定值32%～34%,但是对于18d以上的干旱历时,较少的灌溉量并不能保证土壤含水率在1～2次灌溉后得到恢复,表明较少的灌溉量对土壤含水率的提升能力有限。各干旱处理结束时期,大豆植株干物质积累均随干旱历时增加呈下降趋势,长期干旱会使全株干物质积累下降13%～30%;苗期和花荚期的短期干旱处理产生激发补偿效应,不会使大豆减产,结荚鼓粒期对水分供应较为敏感,干旱导致大豆减产。     

Modeling the potential for closing quinoa yield gaps under varying water availability in the Bolivian Altiplano

In the Bolivian Altiplano, the yields of rainfed quinoa are relatively low and highly unstable. We use a validated crop water productivity model to examine the potential of closing quinoa yield gaps in this region. We simulate the expectable yields under rainfed cultivation and under different deficit irrigation (DI) strategies using the AquaCrop model for the Northern, Central and Southern Bolivian Altiplano. Simulated DI scenarios include a reference strategy avoiding stomatal closure during all sensitive growth stages and allowing drought stress during the tolerant growth stages (DI₀) and various restrictive deficit irrigation strategies (DI_i) representing cases when water resources are limited. We obtain a logistic crop water production function for quinoa by plotting the seasonal actual evapotranspiration versus total grain yield. Due to the large scatter, this function only indicatively provides expectable yields. From the scenario analysis, we derive yield probability curves for the 3 agro-climatic regions. DI, without restriction in irrigation water during the drought sensitive growth stages, is able to close the yield gaps in the Northern, Central and Southern Bolivian Altiplano, and would guarantee a high and stable level of water productivity (WP). The yields of quinoa under rainfed cultivation during dry years are only 1.1, 0.5 and 0.2 Mg ha⁻¹ in the Northern, Central and Southern Bolivian Altiplano, whereas under DI₀ they are 2.2, 1.6 and 1.5 Mg ha⁻¹, respectively. Under limited water availability for irrigation, these stable yield levels decrease, most drastically in the Southern Bolivian Altiplano. Below a minimum water availability of 600 m³ per ha and 700 m³ per ha in the Central and Southern Bolivian Altiplano, respectively, the application of DI for quinoa is not significantly effective and should be avoided to save valuable resources. The yield probability curves we derive can serve as input for stochastic economic analysis of DI of quinoa in the Bolivian Altiplano.