Comparison of sprinkler,trickle and furrow irrigation efficiencies for onion production

In the Mesilla Valley of southern New Mexico, furrow irrigation is the primary source of water for growing onions. As the demand for water increases, there will be increasing competition for this limited resource. Water management will become an essential practice used by farmers. Irrigation efficiency (IE) is an important factor into improving water management but so is economic return. Therefore, our objectives were to determine the irrigation efficiency, irrigation water use efficiency (IWUE) and water use efficiency (WUE), under sprinkler, furrow, and drip irrigated onions for different yield potential levels and to determine the IE associated with the amount of water application for a sprinkler and drip irrigation systems that had the highest economic return.Maximum IE (100%) and economic return were obtained with a sprinkler system at New Mexico State University’s Agriculture Science Center at Farmington, NM. This IE compared with the 54–80% obtained with the sprinkler irrigation used by the farmers. The IEs obtained for onion fields irrigated with subsurface drip irrigation methods ranged from 45 to 77%. The 45% represents the nonstressed treatments, in which an extra amount of irrigation above the evapotranspiration (Et) requirement was applied to keep the base of the onion plates wet. The irrigation water that was not used for Et went to deep drainage water. The return on the investment cost to install a drip system operated at a IE of 45 was 29%. Operating the drip system at a IE of 79% resulted in a yield similar to surface irrigated onions and consequently, it was not economical to install a drip system. The IEs at the furrow-irrigated onion fields ranged from 79 to 82%. However, the IEs at the furrow-irrigated onion fields were high because farmers have limited water resources. Consequently, they used the concept of deficit irrigation to irrigate their onion crops, resulting in lower yields. The maximum IWUE (0.084 t ha⁻¹ mm⁻¹ of water applied) was obtained using the sprinkler system, in which water applied to the field was limited to the amount needed to replace the onions’ Et requirements. The maximum IWUE values for onions using the subsurface drip was 0.059 and 0.046 t ha⁻¹ mm⁻¹ of water applied for furrow-irrigated onions. The lower IWUE values obtained under subsurface drip and furrow irrigation systems compared with sprinkler irrigation was due to excessive irrigation under subsurface drip and higher evaporation rates from fields using furrow irrigation. The maximum WUE for onions was 0.009 t ha⁻¹ mm⁻¹ of Et. In addition, WUE values are reduced by allowing the onions to suffer from water stress.     

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.     

‘More crop per drop’: how to make it acceptable for farmers?

In countries facing water scarcity, governmental water agencies try to transfer this constraint to farmers, e.g. by encouraging them to shift from traditional to localized irrigation methods to save water. However, water shortage is often much less a problem for farmers than soil limitations, their objective being mostly to maximize their income per cultivated area (US$ per hectare rather than per cubic meter of water). This discrepancy can only be solved if governments find ways to ‘transfer’ water scarcity, e.g. through economic incentives such as water pricing and/or subsidies. The aim of this study was to address the question of how to match the interest of both water managers and farmers. We aimed particularly at evaluating whether shifting to drip irrigation is a relevant way to save water and increase farmer's income.Our analysis was based on the interactive impacts among economic, environmental, technical and methodological parameters on the net productivity of two crops. We focused on the case study of Turkey considering two crops with contrasted gross productivity, tomato and cotton, characterized by partial vegetation cover during a large part of crop cycle. A 3D crop energy balance model was applied showing that crop transpiration is increased by up to 10% when shifting from furrow to drip irrigation. These results were used to correct the maximal evapotranspiration (ET_m), estimated with the simple “crop coefficient” (K_c) method, and then used to enhance net productivity estimation both for furrow and drip irrigation.The results suggest that water managers and farmers share a common interest in adopting drip irrigation of tomato. Inversely, interests divergence may increase with low/medium value crops as cotton; the combination between water pricing and subsidies could be a way of agreement, but it would require subsidies for irrigation equipment of at least 40%, for low water tariffs, to 60%, for high water tariffs, to make the transfer from furrow to drip irrigation acceptable. This approach appeared generic enough to be applied for other economic, technical or environmental conditions, to modernize irrigation by harmonizing constraints faced by water managers and farmers.     

Deficit irrigation and nitrogen effects on seed cotton yield, water productivity and yield response factor in shallow soils of semi-arid environment

A field experiment was conducted for 2 years to investigate the effects of deficit irrigation, nitrogen and plant growth minerals on seed cotton yield, water productivity and yield response factor. The treatment comprises six levels of deficit irrigation (Etc 1.0, 0.9, 0.8, 0.7, 0.6 and 0.5) and four levels of nitrogen (80, 120, 160 and 200 kg N ha⁻¹). These were treatments superimposed with and without plant growth mineral spray. Furrow irrigation treatments were also kept. Cotton variety Ankur-651 Bt was grown during 2006 and 2007 cotton season. Drip irrigation at 1.0 Etc saved 26.9% water and produced 43.1% higher seed cotton yield over conventional furrow irrigation (1.0 Etc). Imposing irrigation deficit of 0.8 Etc caused significant reduction in seed cotton yield to the tune of 9.3% of the maximum yield. Further increase in deficit irrigation from 0.7 Etc to 0.5 Etc significantly decreased seed cotton yield over its subsequent higher irrigation level. Decline in the yield under deficit irrigation was associated with reduction in number of bolls plant⁻¹ and boll weight. Nitrogen at 200 kg ha⁻¹ significantly increased mean seed cotton yield by 36.3% over 80 kg N ha⁻¹. Seed cotton yield tended to increase linearly up to 200 kg N ha⁻¹ with drip Etc 0.8 to drip Etc 1.0. With drip Etc 0.6-0.5, N up to 160 kg ha⁻¹ provided the highest yield, thereafter it had declined. Foliar spray of plant growth mineral (PGM) brought about significant improvement in seed cotton yield by 14.1% over control. The water productivity ranged from 0.331 to 0.491 kg m⁻³ at different irrigation and N levels. On pooled basis, crop yield response factor of 0.87 was calculated at 20% irrigation deficit.     

Comparison of drip and sprinkler irrigation strategies on sunflower seed and oil yield and quality under Mediterranean climatic conditions

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 (ky_seed) 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 (ky_oil) 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.     

Yield and water use efficiency of wheat and cotton under alternate furrow and check-basin irrigation with canal and tube well water in Punjab, India

A 4-year field experiment was conducted in a semi-arid area to evaluate the response of each furrow and alternate furrow irrigation in wheat-cotton system using irrigation waters of different qualities in a calcareous soil. Irrigation was applied to each and alternate furrow of bed-planted wheat followed by ridge-planted cotton for comparison with standard check-basin method of irrigation to both the crops. These methods of irrigation were evaluated under three water qualities namely good quality canal water (CW), poor quality tube well water (TW) and pre-sowing irrigation to each crop with CW and all subsequent irrigations with TW (CWpsi + TW). The pooled results over 4 years revealed that wheat grain yield was not affected significantly with quality of irrigation water, but significant yield reduction was observed in alternate bed irrigation under canal water and tube well water irrigations. In cotton, poor quality tube well water significantly reduced the seed cotton yield in all the three methods of planting. The pre-sowing irrigation with canal water and all subsequent irrigations with tube well water improved the seed cotton yield when compared with tube well water alone. However, this yield increase was significant only in alternate furrow irrigation, and the yield obtained was on a par with yield under alternate furrow in CW. When compared to check-basin irrigation, each furrow and alternate furrow irrigation resulted in a saving of 30 and 49% of irrigation water in bed-planted wheat, whereas the corresponding savings in ridge-planted cotton were 20 and 42%, respectively. Reduced use of irrigation water under alternate furrow, without any significant reduction in yield, resulted in 28.1, 23.9 and 43.2% higher water use efficiency in wheat under CW, TW and CWpsi + TW, respectively. The corresponding increase under cotton was 8.2, 2.1 and 19.5%. The implementation of alternate furrow irrigation improved the water use efficiency without any loss in yield, thus reduced use of irrigation water especially under poor quality irrigation water with pre-sowing irrigation with canal water reduced the deteriorating effects on yield and soil under these calcareous soils.     

地下滴灌对棉花生理性状及产量影响的研究

根据新疆生产建设兵团农五师90团在棉花上应用地下滴灌的实践，以膜下滴灌棉花为对照，研究分析了地下滴灌对新疆棉花生理性状及产量的影响，认为地下滴灌条件下的棉花生育期有所提前、株高较低、铃数较多、叶面积系数较大、根冠比较大、根系发达并有两个根系层，生物学产量和经济产量均比较高。     

不同灌溉方式对日光温室青椒生长及产量的影响

为了确定日光温室内青椒的最适合灌溉技术,在日光温室内分别对青椒进行了滴灌、小管出流和沟灌3种灌溉方式的试验研究,分析了不同灌溉方式对日光温室青椒生长发育的影响。试验结果表明:不同灌溉方式对青椒株高、茎粗均无明显影响;相同阶段所测叶绿素含量,滴灌>小管出流>沟灌,且叶片叶绿素的含量和光合速率呈正相关;用显著性水平α=0.1对各处理产量进行方差分析表明,不同处理对产量有显著影响,青椒产量以滴灌最高,小管出流次之,沟灌最低;通过不同处理比较发现,沟灌、滴灌、小管出流水分生产率分别为16.17、35.13、31.59 kg/m3。故日光温室栽培青椒比较适合采用滴灌方式。     

低压管喷及其节水高产机理研究

通过在中国农科院商丘试区实施低压管喷 ,结合麦棉套种作物需水特点、农田小气候相互关系进行了农业高效用水研究与实践 ,揭示出低压管喷麦田较连续畦灌节水 4 5%～ 4 7%,棉田较连续沟灌节水 4 3 %,小麦和棉花水分生产效率达 1 .88～ 1 .95kg/ m3和 0 .3 2 kg/ m3较高水平的节水高产机理     

不同灌水方式下基于水面蒸发量的夏玉米灌溉试验研究

为了探索依据水面蒸发量确定灌溉定额的可行性,在防雨棚下测坑中进行了夏玉米灌溉试验。结果表明,从总耗水量看,畦灌略高于沟灌,而沟灌又略高于滴灌,但差别不是很大。畦灌条件下植株发育快,滴灌次之,沟灌最慢。畦灌和滴灌下产量均以中等灌溉定额处理最高,而沟灌下产量以最大灌溉定额处理最高。总体上,滴灌条件下水分利用效率高于其他2种灌溉方式。干旱条件下,畦灌下以E601蒸发皿蒸发量(PE)作为夏玉米灌溉定额,每次灌水60mm;滴灌下以2/3PE作为灌溉定额为宜,灌水定额为20mm。     

A comparison of drip and furrow irrigated cotton on a cracking clay soil

Summary To determine if drip irrigation increases fertilizer requirements and/or the efficiency of utilization compared to furrow irrigation, growth and nitrogen uptake were measured in a four-year experiment comparing surface (SD) and buried (BD) methods of drip irrigation with furrow irrigation (F) of cotton. The soil was a slowly-permeable cracking grey clay (vertisol) at Narrabri, N.S.W Drip-irrigated treatments were maintained at a deficit of 45 mm below the fully-irrigated soil water content, while F was irrigated when the deficit reached about 90 mm. Nitrogen (N) fertilizer was applied weekly with drip irrigation to BD and SD over the first half of the season, and as a conventional single application to F before sowing. Leaf area index (LAI), dry matter and N uptake were influenced more by season than by method of irrigation. LAI during boll filling averaged 2.4 and was 10% greater in BD than in SD and F. Final dry matter averaged 988 g m^–2 and was 10% greater in BD and SD than in F. The efficiency of conversion of solar radiation into dry matter averaged 0.55 g MJ^–1; lint yield as a fraction of dry matter averaged 0.18; neither parameter was consistently influenced by the method of irrigation. Total N uptake ranged from 97 to 170 kg ha^–1 and was influenced by irrigation method in one season only, when it was less in F than in SD and BD. N was often taken up later under drip irrigation than under F: there was up to 40% less N taken up by SD than F in the early flowering stage. The delay was associated with later application of N to BD and SD compared with F, and the application of N to the surface of alternate furrows of SD. Plant factors such as root ageing and competition between roots and bolls, were also implicated. We conclude that all of the N should be applied to drip-irrigated cotton on these soils by mid flowering, and that some of the N should be applied in the soil before sowing.     

Managing subsurface drip irrigation in the presence of shallow ground water

A 3-year project compared the operation of a subsurface drip irrigation (SDI) and a furrow irrigation system in the presence of shallow saline ground water. We evaluated five types of drip irrigation tubing installed at a depth of 0.4 m with lateral spacings of 1.6 and 2 m on 2.4 ha plots of both cotton and tomato. Approximately 40% of the cotton water requirement and 10% of the tomato water requirement were obtained from shallow (<2 m) saline (5 dS/m) ground water. Yields of the drip-irrigated cotton improved during the 3-year study, while that of the furrow-irrigated cotton remained constant. Tomato yields were greater under drip than under furrow in both the years in which tomatoes were grown. Salt accumulation in the soil profile was managed through rainfall and pre-plant irrigation. Both drip tape and hard hose drip tubing are suitable for use in our subsurface drip system. Maximum shallow ground water use for cotton was obtained when the crop was irrigated only after a leaf water potential (LWP) of −1.4 MPa was reached. Drip irrigation was controlled automatically with a maximum application frequency of twice daily. Furrow irrigation was controlled by the calendar.     

不同节水灌溉技术的节水机理试验研究

根据甘肃省特殊自然地理条件，对于喷灌、滴灌、渗灌及波涌灌几种方式下，小麦和玉米两种作物的灌溉节水机理进行了对比试验研究，分析了不同节水灌溉方式下这两种作物的节水性和生育动态。试验结果表明，在降雨、灌溉水量和前期土壤特性一定的情况下，在喷灌、滴灌、渗灌及波涌灌几种节水灌溉技术中，渗灌的节水性最好，依次为滴灌、喷灌、波涌灌。小麦和玉米在渗灌条件下产量比滴灌、喷灌和波涌灌都高，小麦渗灌产量比滴灌增加7．6％，比喷灌增加13．1％，比波涌灌增加22．4％。玉米渗灌产量比滴灌增加1．3％．比喷道增加6．3％。     

Effects of irrigation method on chile pepper yield and Phytophthora root rot incidence

A field experiment was conducted in 1995 and 1996 to examine the effects of different irrigation methods on yields and Phytophthora root rot disease of chile plants (Capsicum annum New Mexico `6–4'). Three irrigation methods, daily drip, 3-day drip, and alternate row furrow irrigation, were applied to plots infested with P. capsici and uninfested plots. For both years, the drip irrigation (either daily or 3-day) created higher marketable green chile yields than the alternate row furrow irrigation (p < 0.05), and the yields between the daily and 3-day drip irrigation were statistically similar. The effect of irrigation on marketable combined yields was similar to that on green chile yields. In 1995, root rot disease incidence in the infested plots was significantly higher under alternate row furrow irrigation than for daily and 3-day drip irrigation. There was no disease development in the uninfested plots regardless of the irrigation method. The disease decreased green chile yield by 55% (p < 0.1), and combined yield (green + red chile) by 36% (p < 0.1) in 1995 compared to that in uninfested plots in alternate row furrow irrigation. In 1996, however, no disease occurred in any treatment. The results suggested that drip irrigation increases chile yield through providing either favorable soil moisture conditions or unfavorable conditions for Phytophthora propagation.     

Irrigation with brackish water under desert conditions I. Problems and solutions in production of onions (Allium cepa L.)

To identify the problems and suggest solutions for onion production under brackish water irrigation in a desert environment, a series of trials with brackish water (electrical conductivity, EC_i = 4.4 dS/m) and fresh water (EC_i = 1.2 dS/m) was conducted, using both sprinkler and drip irrigation systems.Under sprinkler irrigation with brackish water the mean electrical conductivity of the saturated soil extract ($\text{EC}$_e) was about 6.0 dS/m and the yield reduction was 60%. With drip irrigation, the $\text{EC}$_e under the drippers was about 5.0 dS/m and the yield reduction was 30%. Sprinkler irrigation affected yield through a reduction in both bulb size and bulb number per unit area. Drip irrigation affected the bulb number only. In the latter system seedling death occurred during the first 40 days following field emergence. Yield reduction was completely prevented by germinating and establishing the field with freshwater irrigation before transferring to brackish water irrigation, 45 days after sowing.With the sprinkler system, onion yield with brackish water irrigation could be increased by either increasing the sowing density or by alternating between brackish and fresh water irrigation.     

滴灌和常规沟灌马铃薯产量和经济价值比较（摘选）

土地和水资源是一个国家进行农业发展的基础投入,马铃薯滴灌栽培可以解决水资源和耕地短缺问题。该研究评估了不同滴灌频率相比于常规沟灌对作物生长、产量和水分利用效率的变化。试验结果表明,隔天滴灌要比每3、4和5 d进行滴灌增效更为显著。通过采用隔天滴灌单位供水面积上最高水分利用效率（56.24 kg（hm2·mm））和2.23的最高成本效益比（B∶C）,之后每3 d进行1次滴管的B∶C为2.25,而传统沟灌水分利用效率为14.16 kg（hm2·mm）、B∶C比值是1.91。该研究结果表明,对于像马铃薯这种高水分敏感作物来说,滴灌作为一种经济的用水方式在水分管理中起着重要作用。因此,采用节水的滴灌系统有利于增加马铃薯栽培面积。      

Comparison of different irrigation methods based on the parametric evaluation approach in Dosalegh plain: Iran

Declining water resources and limited clean water reservoirs call for more efficient water use for food production in the future. The objective of this research was to compare different irrigation methods based on a parametric evaluation system in an area of 60,000 ha in the Dosalegh plain of the Khuzestan province, in the southwest of Iran. After the soil properties were analyzed and evaluated, suitability maps were generated for surface, sprinkler and drip irrigation methods, using Remote Sensing (RS) techniques and Geographic Information System (GIS). The results demonstrated that by applying sprinkler and drip irrigation instead of surface irrigation method, the land suitability of 23,790 and 33,261 ha (39.89%) in the Dosalegh plain will improve, respectively. The comparison of the different types of irrigation techniques revealed that the drip and sprinkler irrigations methods were more effective and efficient than that of surface irrigation for improved land productivity. However, the main limiting factor in using either surface or/and sprinkler irrigation methods in this area were soil texture, salinity, and slope, and the main limiting factor in using drip irrigation methods were the calcium carbonate content, soil texture and salinity.     

Cotton yield and water use efficiency at various levels of water and N through drip irrigation under two methods of planting

The present investigation was undertaken to evaluate the effect of various levels of water and N application through drip irrigation on seed cotton yield and water use efficiency (WUE). In this experiment three levels of water (Epan 0.4, 0.3, and 0.2) and three levels of N (100, 75, and 50% of recommended N, 75 kg/ha) through drip were compared with check-basin method of irrigation under two methods of planting (normal sowing, NS; paired sowing, PS). The results revealed that when the same quantity of irrigation water and N was applied through drip irrigation system, it increased the seed cotton yield to 2144 from 1624 kg/ha (an increase of 32%) under check-basin method of irrigation. When the quantity of water through drip was reduced to 75%, the increase in seed cotton yield was 12%; however, when water was reduced to 50%, it resulted 2% lower yield than check-basin. The decrease in N through fertigation resulted in reduction in seed cotton yield at all the levels of water supply, but the magnitude of reduction was the highest at highest level of water supply. In paired sowing (PS), 20% higher seed cotton yield was obtained as compared with check-basin method under NS along with 50% saving of water. In paired sowing the sacrifice of 9% seed cotton yield as compared with NS resulted in saving of 50% water as well as the cost of laterals because there was one lateral for two paired rows. The WUE increased by 26% (22.1 from 17.6 kg/ha cm) in drip irrigation system when same quantity of water and N fertilizer was applied as compared with check-basin. WUE was not affected with quantity of water but decrease in rate of N caused a decrease in WUE at all the quantities of water applied. In general, WUE was higher in PS as compared with NS. The agronomic efficiency of nitrogen increased from 21.65 to 28.59 kg of seed cotton per kg of N applied when same quantity of water and N was applied through drip irrigation as compared with check-basin. However, decrease in quantity of water applied resulted in a decrease in agronomic efficiency of N but reverse was true for rates of N applied. When the same quantity of water and N was applied under both the methods of planting, PS produced 22% higher seed cotton yield and along with reduced cost owing to half the number of laterals required.     

不同灌溉方式下玉米节水增产效果试验研究

在降雨、灌溉水量和前期土壤特性一定的情况下,对玉米在喷灌、滴灌、渗灌3种灌溉方式下的土壤水分变化特性和玉米生育特性进行了试验研究,分析了各种灌溉方式下玉米的生长特性和玉米地土壤水分的变化规律。试验结果表明：渗灌的节水增产效果最好,产量比滴灌增加1．3％,水分生产率由2．64kg／m^3提高到2．68kg／m^3;比喷灌增加6．3％,水分生产率由2．52kg／m^3提高到2．68kg／m^3。     

A simulation study of comparison of the evaluation procedures for three irrigation methods

Standard evaluation procedures, based on field measurements and statistical, hydraulic models, have been developed for assessing irrigation systems performance. However, given the diverse nature of the irrigation methods, it is not possible to use a unique evaluation procedure. Ideally, variables would be measured at every point throughout the field under study, but that is clearly impractical. Instead, measurements are taken of selected samples, or irrigation models are used to predict field-wide distributions of the variables. In this paper, irrigation models for trickle, sprinkler and furrow irrigation are used to assess how well the irrigation performance indicators generated by standard procedures match those generated by whole-field simulations. Six performance indicators were used: distribution uniformity, uniformity coefficient of Christiansen, application efficiency, deep percolation ratio, tail water ratio and requirement efficiency. The analysis was applied to systems typical of cotton crops in Southern Spain. The results show that the procedure used to determine performance indicators in trickle irrigation provides good estimates of the whole field performance. The procedure used in sprinkler irrigation is also acceptable, but yields variable results. Finally, the standard procedure used for furrow irrigation produces biased, highly variable results and overestimates distribution uniformity.