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1.
《Agricultural Water Management》2005,76(1):8-23
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. 相似文献
2.
Soil water distribution, uniformity and water-use efficiency under alternate furrow irrigation in arid areas 总被引：9，自引：0，他引：9
Soil water distribution, irrigation water advance and uniformity, yield production and water-use efficiency (WUE) were tested
with a new irrigation method for irrigated maize in an arid area with seasonal rainfall of 77.5–88.0 mm for 2 years (1997
and 1998). Irrigation was applied through furrows in three ways: alternate furrow irrigation (AFI), fixed furrow irrigation
(FFI) and conventional furrow irrigation (CFI). AFI means that one of the two neighboring furrows was alternately irrigated
during consecutive watering. FFI means that irrigation was fixed to one of the two neighboring furrows. CFI was the conventional
method where every furrow was irrigated during each watering. Each irrigation method was further divided into three treatments
using different irrigation amounts: i.e. 45, 30, and 22.5 mm water for each watering. Results showed that the soil water contents
in the two neighboring furrows of AFI remained different until the next irrigation with a higher water content in the previously
irrigated furrow. Infiltration in CFI was deeper than that in AFI and FFI. The time of water advance did not differ between
AFI, FFI and CFI at all distances monitored, and water advanced at a similar rate in all the treatments. The Christiansen
uniformity coefficient of water content in the soil (CUs) was used to evaluate the uniformity of irrigated water distribution and showed no decrease in AFI and FFI, although irrigation
water use was smaller than in CFI. Root development was significantly enhanced by AFI treatment. Primary root numbers, total
root dry weight and root density were all higher in AFI than in the FFI and CFI treatments. Less irrigation significantly
reduced the total root dry weight and plant height in both the FFI and CFI treatments but this was less substantial with AFI
treatments. The most surprising result was that AFI maintained high grain yield with up to a 50% reduction in irrigation amount,
while the FFI and CFI treatments all showed a substantial decrease of yield with reduced irrigation. As a result, WUE for
irrigated water was substantially increased. We conclude that AFI is an effective water-saving irrigation method in arid areas
where maize production relies heavily on repeated irrigation.
Received: 16 October 1999 相似文献
3.
This study compares the effects of different irrigation regimes on seed yield and oil yield quality and water productivity of sprinkler and drip irrigated sunflower (Helianthus annus L.) on silty-clay-loam soils in 2006 and 2007 in the Mediterranean region of Turkey. In sprinkler irrigation a line-source system was used in order to create gradually varying irrigation levels. Irrigation regimes consisted of full irrigation (I1) and three deficit irrigation treatments (I2, I3 and I4), and rain-fed treatment (I5). In the drip system, irrigation regimes included full irrigation (FI-100), three deficit irrigation treatments (DI-25, DI-50, DI-75), partial root zone drying (PRD-50) and rain-fed treatment (RF). Irrigations were scheduled at weekly intervals both in sprinkler and drip irrigation, based on soil water depletion within a 0.90 m root zone in FI-100 and I1 plots. Irrigation treatments influenced significantly (P < 0.01) sunflower seed and oil yields, and oil quality both with sprinkler and drip systems. Seed yields decreased with increasing water stress levels under drip and sprinkler irrigation in both experimental years. Seed yield response to irrigation varied considerably due to differences in soil water contents and spring rainfall distribution in the experimental years. Although PRD-50 received about 36% less irrigation water as compared to FI-100, sunflower yield was reduced by an average of 15%. PRD-50 produced greater seed and oil yields than DI-50 in the drip irrigation system. Yield reduction was mainly due to less number of seeds per head and lower seed mass. Soil water deficits significantly reduced crop evapotranspiration (ET), which mainly depends on irrigation amounts. Significant linear relationships (R2 = 0.96) between ET and oil yield (Y) were obtained in each season. The seed yield response factors (kyseed) were 1.24 and 0.86 for the sprinkler and 1.19 and 1.06 for the drip system in 2006 and 2007, respectively. The oil yield response factor (kyoil) for sunflower was found to be 1.08 and 1.49 for both growing seasons for the sprinkler and 1.36 and 1.25 for the drip systems, respectively. Oil content decreased with decreasing irrigation amount. Consistently greater values of oil content were obtained from the full irrigation treatment plots. The saturated (palmitic and stearic acid) and unsaturated (oleic and linoleic acid) fatty acid contents were significantly affected by water stress. Water stress caused an increase in oleic acid with a decrease in linoleic acid contents. The palmitic and stearic acid concentrations decreased under drought conditions. Water productivity (WP) values were significantly affected by irrigation amounts and ranged from 0.40 to 0.71 kg m−3 in 2006, and from 0.69 to 0.91 kg m−3 in 2007. The PRD-50 treatment resulted in the greatest WP (1.0 kg m−3) and irrigation water productivity (IWP) (1.4 kg m−3) in both growing seasons. The results revealed that under water scarcity situation, PRD-50 in drip and I2 in sprinkler system provide acceptable irrigation strategies to increase sunflower yield and quality. 相似文献
4.
加氧灌溉对菠萝根区土壤呼吸和生理特性的影响 总被引：5，自引：0，他引：5
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. 相似文献
5.
Abolfazl Faraji Nasser Latifi Amir Hossain Shirani Rad 《Agricultural Water Management》2009,96(1):132-140
The effects of high temperature stress and supplemental irrigation on seed yield and water use efficiency (WUE) of canola (Brassica napus L.) were studied in a field experiment conducted for 2 years. The experiment was a randomized complete block design arranged in split plot, conducted at Agricultural Research Station of Gonbad, Iran. It was arranged in two conditions, i.e. supplemental irrigation and rainfed. Two cultivars of canola (Hyola401 and RGS003) as subplots were grown at five sowing dates as main plots. The sowing dates were 9 November, 6 December, 5 January, 4 February and 6 March in 2005-2006 and 6 November, 6 December, 5 January, 4 February and 6 March in 2006-2007, to have a wide range of environmental conditions around flowering and seed filling periods, and to coincide reproductive stages of the crop with high temperature stress. Seed yield was improved due to field management practices, such as supplemental irrigation and optimum sowing date. Supplemental irrigation was an efficient practice to mitigate water stress, and to increase aboveground dry matter and seed yield. There was a strongly negative relationship between seed yield and air temperature during reproductive stages. Delay in sowing led to more rapid developmental of canola, decreased aboveground dry matter, leaf area index (LAI), harvest index (HI), WUE, and seed yield. Achieving a high aboveground dry matter was an essential prerequisite for high reproductive growth and a high seed yield. Greater seed yield and WUE at first sowing date were associated with greater LAI and aboveground dry matter, and lower temperatures during reproductive stages. The results support the view that WUE can be used as an indirect selection criterion for seed yield in genotypic selection. 相似文献
6.
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. 相似文献
7.
Jordi Marsal G. Lopez J. del Campo M. Mata A. Arbones J. Girona 《Irrigation Science》2010,28(2):181-189
We examined, over the postharvest seasons of 2005–2007, regulated deficit irrigation (RDI) for its potential of saving water
and maintaining fruit yield and quality in ‘Summit’ sweet cherry. The postharvest irrigation treatments were: full irrigation
(Control), receiving 80% of water in Control (RDI-80%), and receiving 50% of water in Control (RDI-50%). Midday stem water
potential (Ψstem) was used for assessing plant water status. In 2006, trees produced a large crop and commercial fruit thinning had to be
applied, whereas 2007 was a low crop year. The RDI treatment, first applied in 2005, reduced fruit set in 2006 and also reduced
root winter starch concentration. In 2006, fruit set was lower in RDI-50% than in Control. But fruit thinning had still to
be done with the final yield being the same among treatments. In 2007, RDI-50% produced more fruit and higher yields than
Control. Relationship between postharvest Ψstem and crop load in the following season varied according to the year. They were negatively correlated in 2006 and positively
correlated in 2007. Fruit firmness did not vary with irrigation treatments in any of the years. Fruit soluble solid concentration
(SSC) and fruit relative dry matter (RDM) for RDI-50% was the highest in 2006 when RDI-50% trees had the lowest fruit set.
In 2007, SSC and RDM for RDI-50% were the lowest with the trees having the highest fruit set and crop load at harvest. This
study indicates that RDI-50% firstly applied in an “off” year, after crop has been harvested, can maintain fruit yield at
similar levels to fully irrigated trees while saving water by 45%. Correction of biennial bearing and partial saving of thinning
costs are additional advantages of this treatment. 相似文献
8.
在作物生长的不同时期分别对各处理进行了35 mm限量单次滴灌,测定了土壤水分、籽粒产量及产量构成要素千粒重、穗粒重、株高等,并计算了水分利用效率和土壤水势。结果表明,小麦灌浆期限量单次滴灌对套作冬小麦增产效果最好,水分利用效率亦是如此。套作小麦灌水处理大多数产量构成要素及其它经济性状表现出明显差异。回归分析发现,WUE与籽粒产量间的关系可用幂函数来描述:WUE=-12.262+0.276Ye1/2(R2=0.912**,p<0.05)。土壤水势是降雨量和补灌量的函数。灌水后的第2个测定生育期所有套作小麦2个土层土壤水势均高于未灌水处理,且30~60 cm土层土壤水势比0~30 cm土层下降更为剧烈。 相似文献
9.
A field study was conducted at North Platte, Nebraska in 2007–2009, imposing eight irrigation treatments, ranging from dryland to fully irrigated. Four of the eight treatments allowed for various degrees of water stress only after tasseling and silking. In 2007, corn yield ranged from 8.9 Mg ha?1 with a season total of 41 mm of irrigation water to 11.5 Mg ha?1 for the fully irrigated treatment (264 mm of irrigation water). The treatment with the greatest reduction in irrigation water after tasseling and silking (158 mm) had a mean yield of 10.9 Mg ha?1, only 0.6 Mg ha?1 less than the fully irrigated treatment. In 2009, yields ranged from 12.6 to 13.5 Mg ha?1. There were no significant yield differences between the irrigation treatments for several possible reasons: more in-season precipitation and cooler weather required less irrigation water; much of the irrigation water was applied after the most water-stress sensitive stages of tasseling and silking; and lower atmospheric demand allowed for soil water contents well below 50 % management allowed depletion (MAD) not to cause any yield losses. 相似文献
10.
咸水灌溉对棉花耗水特性和水分利用效率的影响 总被引：4，自引：0，他引：4
采用田间对比试验,连续3 a研究了1、3、5、7 g/L 4个矿化度咸水(记作S1、S2、S3、S4)灌溉对棉田土壤水盐、土壤蒸发、棉花阶段耗水量、籽棉产量和水分利用效率的影响。结果表明,棉花生育期内根系层土壤含水率和电导率有随灌溉水矿化度的增加而增大的趋势,土壤电导率增加尤为明显;年际间,各处理土壤含水率和电导率差异非常大,经过连续3 a灌溉,根系层土壤电导率均未逐年增加。S3和S4处理的平均土壤蒸发强度大于S1处理,S2与S1处理间的差异很小;7 g/L以下咸水灌溉对棉花耗水过程产生了一定影响,但对总耗水量影响并不明显。3 a的平均籽棉产量和水分利用效率由大到小顺序均为:S2、S1、S3、S4,S2比S1处理增产2.43%,水分利用效率增加1.15%,S3和S4比S1处理减产1.67%和8.88%,水分利用效率降低0.25%和7.31%,其中,S2和S3与S1处理间差异不显著,S4处理产量和水分利用效率降低显著。 相似文献
11.
Field studies were done in 2003 and 2006 to evaluate the performance of water pillow (WP) irrigation as an alternative to furrow irrigation (FI) for soybean growth in semi-arid climatic conditions. There were four irrigation treatments: two of which (FI and WP1.0) were full irrigation, in that the water deficit in the soil profile (0.9 m) was brought to field capacity in 10-day intervals. The other two treatments (WP0.75 and WP0.50) were deficit irrigation treatments, and received 75% and 50% of WP1.0 irrigation amount. The highest seed yield was achieved with the WP1.0 treatment. Irrigation water use efficiency (IWUE) and water use efficiency (WUE) were influenced significantly by the irrigation methods and levels (P ≤ 0.05). The highest values of WUE and IWUE were obtained by the WP0.75 and WP0.50 treatment, respectively, in both study years. However, the smallest irrigation amount resulted in lower total yield for the WP0.50 treatment, and is not recommended. In conclusion, the WP0.75 treatment is recommended for soybean production in order to attain higher values of IWUE and WUE, and to conserve water and maximize yield with the same volume of water. 相似文献
12.
【目的】提高华北地区紫花苜蓿水分利用效率,兼顾产量与品质。【方法】于2018年4―9月,在河北涿州中国农业大学教学实验场,以紫花苜蓿品种WL363HQ为试验材料,开展紫花苜蓿田间灌溉试验。试验设置3个灌水处理:W1处理,灌水下限45%FC(田间持水率),灌水上限90%FC;W2处理,灌水下限60%FC,灌水上限90%FC;W3处理,根据当地生产经验定额灌溉为39 mm,研究了不同灌水下限对紫花苜蓿生长、产量和品质的影响。【结果】建植第5年的紫花苜蓿,全生长季需水量511.9 mm。苜蓿细根根系主要分布在0~40 cm土层,0~20 cm土层根系密度最高。灌水对第1、第2茬及全年产量没有显著影响(P>0.05),对第3茬产量有显著影响(P<0.05)。第1、第2、第3茬内采用W1处理苜蓿水分利用效率最高。不同灌水处理对苜蓿粗蛋白量没有显著影响(P>0.05),减少灌水量能增加苜蓿相对饲喂价值。【结论】建议华北地区紫花苜蓿第1、第2、第3茬采用45%FC灌水下限,第4茬采用60%FC灌水下限。 相似文献
13.
Summary An eddy correlation system (ECS) was used to estimate evapotranspiration (E) in a daily drip irrigated cotton field. Cotton yield, water use, and their ratio (Water use efficiency; WUE) were compared in four irrigation treatments. Three treatments were irrigated at levels of 85, 100, and 115% of E, while the fourth was irrigated according to grower's usual practice. E data were used to verify a one dimensional numerical model which simulates, in real time, the different energy fluxes existing in the soil-plant-atmosphere system. The model requires input of vegetation parameters (leaf area index, photometric properties, shading factor, root density distribution), soil parameters texture, hydraulic and photo-metric properties, temporal micrometeorological data (solar radiation, wind speed, air temperature and humidity) measured above the field, and irrigation quantities. The verification study was carried out during a cotton growing season in Hula Valley, Northern Israel. Results show that E rates are strongly affected by the intensity and arrival time of the inland penetrating Mediterranean sea breeze. WUE in the treatment which was irrigated according to the ECS was highest. Accurate estimations were also made by the model. 相似文献
14.
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。 相似文献
15.
水分调控对麦茬棉产量和水分利用效率的影响 总被引：3，自引：0，他引：3
为研究麦后移栽棉对水分调控的响应,于2012年6月~2012年10月通过人工控水试验研究了水分供应对麦后移栽棉生长、产量和品质的影响。小区试验结果表明,蕾期轻度水分亏缺花铃期充分灌水处理(T2)的籽棉产量、成铃数以及单铃质量均为最大,但蕾期和花铃期轻度水分胁迫处理(T4)的产量与处理T2差异不显著,但水分利用效率和灌溉水利用效率分别提高了23.93%和34.01%;管栽试验结果表明,对照处理(T7)的单株成铃数的收获籽棉产量均最高,与对照处理相比,全生育期轻度水分胁迫处理(T8)减产3.98%,水分利用效率和灌溉水利用效率分别提高了9.70%和20.02%;桶栽试验结果表明,灌水定额为1.6倍ETp处理(T11)的籽棉产量和单株成铃数均最高,与处理T11相比,灌水定额为1.3ETp处理(T12)的籽棉产量仅降低了9.7%,而灌水定额为1.0 ETp处理(T13)的籽棉产量降低了30%。说明适宜的水分胁迫(灌水下限为60%~65%FC,灌水上限为80%~85%FC)有利于麦后移栽棉的高产和水分利用效率的提高。 相似文献
16.
《Journal of Agricultural Engineering Research》1998,69(4):331-341
This study concerns the evaluation of the root zone water quality model (RZWQM) to simulate the seasonal water and nitrate movement in a level basin irrigated corn field under three different nitrogen (N) fertilizer treatments. The three N treatments, superimposed over a split basal dose applied before and at planting, were: a single broadcast application of 150 kg N/ha as urea (100% amidic form), a single fertigation application of the same N as UAN (50% amidic, 25% ammonium and 25% nitrate) with the first irrigation, and multiple UAN fertigations with three irrigations. Certain variety-specific maize crop parameters in the model were obtained by fitting these parameters to field data from the single fertigation treatment. The model was then evaluated on water and N results for the treatments. The model adequately simulated the water and nitrate transport for the season, with the seasonal averages of measured and predicted values differing by less than 5%. The most significant differences between measured and simulated water and nitrate occurred near the soil surface (15 cm depth), mostly during the days when the soil was extremely wet following irrigations. With the soil hydraulic properties estimated by simple means, the model tends to overestimate downward water fluxes and related nitrate transport through a compacted layer; however, it is found to be a useful tool to study the relative impacts of alter- nate nitrogen fertilizer and irrigation practices on root zone water quality. 相似文献
17.
18.
Field experiments were conducted at the Luancheng Agro-Ecosystem Experimental Station of the Chinese Academy of Sciences during the winter wheat growing seasons in 2006-2007 and 2007-2008. Experiments involving winter wheat with 1, 2, and 3 irrigation applications at jointing, heading, or milking were conducted, and the total irrigation water supplied was maintained at 120 mm. The results indicated that irrigation during the later part of the winter wheat growing season and increase in irrigation frequency decreased the available soil water; this result was mainly due to the changes in the vertical distribution of root length density. In ≤30-cm-deep soil profiles, 3 times irrigation at jointing, heading, and milking increased the root length density, while in >30-cm-deep soil profiles, 1 time irrigation at jointing resulted in the highest root length density. With regard to evapotranspiration (ET), there was no significant (LSD, P < 0.05) difference between the regimes wherein irrigation was applied only once at jointing; 2 times at jointing and heading; and 3 times at jointing, heading, and milking. Compared with 1 and 3 times irrigation during the winter wheat growing season, 2 times irrigation increased grain yield and 2 times irrigation at jointing and heading produced the highest water-use efficiency (WUE). Combining the results obtained regarding grain yield and WUE, it can be concluded that irrigation at the jointing and heading stages results in high grain yield and WUE, which will offer a sound measurement for developing deficit irrigation regimes in North China. 相似文献
19.
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. 相似文献
20.
Precision irrigation involves the accurate and precise application of water to meet the specific requirements of individual
plants or management units and minimize adverse environmental impact. Under precision irrigation applications, water and associated
solute movement will vary spatially within the root zone and excess water application will not necessarily result in deep
drainage and leaching of salt below the root zone. This paper estimates that 10% of the irrigated land area (producing as
much as 40% of the total annual revenue from irrigated land) could be adversely affected by root zone salinity resulting from
the adoption of precision irrigation within Australia. The cost of increases in root zone salinisation due to inappropriate
irrigation management in the Murray and Murrumbidgee irrigation areas was estimated at AUD 245 million (in 2000/01) or 13.5%
of the revenue from these cropping systems. A review of soil–water and solute movement under precision irrigation systems
highlights the gaps in current knowledge including the mismatch between the data required by complex, process-based soil–water
or solute simulation models and the data that is easily available from soil survey and routine soil analyses. Other major
knowledge gaps identified include: (a) effect of root distribution, surface evaporation and plant transpiration on soil wetted
patterns, (b) accuracy and adequacy of using simple mean values of root zone soil salinity levels to estimate the effect of
salt on the plant, (c) fate of solutes during a single irrigation and during multiple irrigation cycles, and (d) effect of
soil heterogeneity on the distribution of water and solutes in relation to placement of water. Opportunities for research
investment are identified across a broad range of areas including: (a) requirements for soil characterisation, (b) irrigation
management effects, (c) agronomic responses to variable water and salt distributions in the root zone, (d) potential to scale
or evaluate impacts at various scales, (e) requirements for simplified soil–water and solute modelling tools, and (f) the
need to build skills and capacity in soil–water and solute modelling. 相似文献