Supplemental irrigation of wheat with saline water

In arid and semi-arid regions, both rainfall and surface irrigation water supplies are unreliable and inadequate to meet crop water requirement. Groundwater in these regions is mainly marginally saline (2-6 dS/m) to saline (>6 dS/m) and could be exploited to meet crop water requirement if no adverse effects on crops and land resource occur. The fear of adverse effects has often restricted the exploitation of naturally occurring saline water. The results reveal that substituting a part or all except pre-sowing irrigation with saline water having an electrical conductivity (EC_iw) of 8 dS/m is possible for cultivation of wheat. Similarly, saline water with EC_iw ranging between 8 and 12 dS/m could be used to supplement at least two irrigations to obtain 90% or more of the optimum yield. In low rainfall years, the use of such waters for all irrigations, except pre-sowing, produced more yield than skipping irrigations. Apparently, even at this level of osmotic salt stress, matric stress is more harmful. Thus, it would be interesting to use such waters for wheat production in monsoon climatic regions.     

Water conservation potential of smart irrigation controllers on St. Augustinegrass

A variety of technologies for reducing residential irrigation water use are available to homeowners. These “Smart Irrigation” technologies include evapotranspiration (ET)-based controllers and soil moisture sensor (SMS) controllers. The purpose of this research was to evaluate the effectiveness of these technologies, along with rain sensors, based on irrigation applied and turfgrass quality measurements on St. Augustinegrass (Stenotaphrum secundatum (Walter) Kuntze). Testing was performed on two types of SMS controllers (LawnLogic LL1004 and Acclima Digital TDT RS500) at three soil moisture threshold settings. Mini-Clik rain sensors (RS) comprised six treatments at two rainfall thresholds (3 mm and 6 mm) and three different irrigation frequencies (1, 2, and 7 d/wk). Two ET controllers were also tested, the Toro Intelli-Sense controller and the Rain Bird ET Manager. A time-based treatment with 2 days of irrigation per week without any type of sensor (WOS) to bypass irrigation was established as a comparison. All irrigation controller programming represented settings that might be used in residential/commercial landscapes. Even though three of the four testing periods were relatively dry, all of the technologies tested managed to reduce water application compared to the WOS treatment, with most treatments also producing acceptable turf quality. Reductions in irrigation applied were as follows: 7–30% for RS-based treatments, 0–74% for SMS-based treatments, and 25–62% for ET-based treatments. The SMS treatments at low threshold settings resulted in high water savings, but reduced turf quality to unacceptable levels. The medium threshold setting (approximately field capacity) SMS-based treatment produced good turfgrass quality while reducing irrigation water use compared to WOS by 11–53%. ET controllers with comparable settings and good turf quality had −20% to 59% savings. Reducing the irrigation schedule (treatment DWRS) by 40% and using a rain sensor produced water savings between 36% and 53% similar to smart controllers. Proper installation and programming of each of the technologies was essential element to balancing water conservation and acceptable turf quality. Water savings with the SMS controllers could have been increased with a reduced time-based irrigation schedule. Efficiency settings of 100% (DWRS) and 95% (TORO) did not reduce turf quality below acceptable limits and resulted in substantial irrigation savings, indicating that efficiency values need not be low in well designed and maintained irrigation systems. For most conditions in Florida, the DWRS schedule (60% of schedule used for SMS treatments) can be used with either rain sensors or soil moisture sensors in bypass control mode as long as the irrigation system has good coverage and is in good repair.     

Supplemental irrigation effect on canola yield components under semiarid climatic conditions

With the availability of irrigation water, supplemental irrigation in winter-grown crops, such as lentil, wheat, and barley, has been intensely practiced to prevent crop yield losses due to the incidence of intermittent drought stress. In the crop growing seasons of 2006-2007 and 2008-2009, a study was conducted to determine the effect of supplemental irrigations on Canola (Brassica napus L. cv. Elvis F1) under the semiarid climatic conditions of the Harran plain, Sanliurfa, Turkey. A sprinkler irrigation system was used to irrigate the study plots. The irrigation treatments included 0.0, 0.25, 0.50, 0.75, and 1.0 (full irrigation) of Class-A pan evaporation amounts. The full irrigation treatment during both years consisted of 250 and 225 mm, respectively. In turn, crop water use values during the same years and treatments were 462 and 449 mm. In general, plant height and 1000 seed weight ranged from 140 to 165 cm and from 2.5 to 3.3 g, respectively, and these variables significantly differed among irrigation treatments (p < 0.05). Crop yield and above ground biomass measurements were affected by irrigation treatments and varied from 1094 to 3943 kg ha⁻¹ and from 6746 to 18,311 kg ha⁻¹, respectively (p < 0.05). Similarly, harvest index values were affected (p < 0.05) and ranged from 0.16 to 0.23 on average. The water use efficiency obtained in the different treatments indicated a strong positive relationship between crop yield and irrigation. Overall, our results indicate that supplemental irrigation substantially increased canola yield; however, for an optimum yield, full irrigation is suggested.     

Supplemental irrigation — a safeguard technique for successful cultivation of Monsoon rice (Transplanted Aman) in Bangladesh

The study was conducted in Monsoon (Transplanted Aman) at BRRI farm, Joydebpur, from 1978–1987, to determine the impact and viability of supplemental irrigation. The results of 8 years of experimentation indicate that the impact of supplemental irrigation mainly depends on rainfall distribution patterns and the last precipitation of the season. Generally, the late transplanted crops suffer from moisture stress when the last rainfall ceases by the first week of October. Under this situation, one timely supplemental irrigation of 60 mm could produce about 58% more yield, and the consequent benefit cost ratio of supplemental irrigation would be 5.3 to 14.5, which is highly profitable. The study reveals that if the last rainfall continues up to the third week of October, the supplemental irrigation is still profitable. When sufficient rainfall occurs in November, there is no need for supplemental irrigation, even in late transplanting, and continuous standing water is not required for rice cultivation provided the rain water can be managed properly.Abbreviations BADC Bangladesh Agriculture Development Corporation - B/C Ratio Benefit Cost Ratio - BRRI Bangladesh Rice Research Institute - HYV High Yielding Variety     

Supplemental saline drip irrigation applied at different growth stages of two bell pepper cultivars grown with or without mulch in non-saline soil

The effect of supplemental saline (2.5 dS m⁻¹) drip irrigation and black polyethylene mulch on two cultivars of bell peppers (Capsicum annuum L.) was investigated under field conditions using a randomized complete block design with split-split plot restriction. The research included six irrigation treatments (main plots): (i) non-saline irrigation control applied throughout growth (None), (ii) saline irrigation from transplanting until formation of the first fruit set (S1S2), (iii) saline irrigation from transplanting until appearance of the first flower and from first harvest to final harvest (S1S4), (iv) saline irrigation from appearance of the first flower to first harvest (S2S3), (v) saline irrigation from fruit set to final harvest (S3S4), and (vi) saline irrigation throughout growth (All); two mulch treatments (subplots): (i) black mulch and (ii) bare soil; and two bell pepper cultivars (sub-subplots): (i) Early Sunsation and (ii) Red Knight. Production of fully ripened fruits was higher in mulched plants regardless of saline irrigation treatments. In humid areas with non-saline soil, supplemental saline drip irrigation could be used with black polyethylene mulch to save water while maintaining fruit production.     

卷盘式喷灌机在农作物灌溉中的应用

卷盘式喷灌机在农作物灌溉中有对地形适应性强、易于管理、省工省时、喷洒质量高、使用寿命长、投资适宜等优点，但单喷枪喷洒时耗能较高，受风影响较大。     

Performance assessment of irrigation water management of heterogeneous irrigation schemes: 2. A case study

The non-uniformity of soils, weather, fields, cropping pattern and canal systems in most surface irrigation schemes makes irrigation water management complex, but optimum performance is important particularly in irrigation schemes with limited water supply. This paper focuses on the performance of irrigation water management during the area and water allocation with a case study of an irrigation scheme in the semi-arid region of India. Often the irrigation managers or authorities of these heterogeneous irrigation schemes also need to deal with different allocation rules. The allocation plans and the corresponding water delivery schedules during the allocation process were estimated with the help of a simulation–optimisation model for different allocation rules based on cropping distributions (free and fixed), water distributions (free and fixed-area proportionate), irrigation depth (full, fixed depth and variable depth irrigation) and irrigation interval (from 14 to 35 days). The performance measures of productivity (in terms of net benefits and area irrigated), equity (in water distribution), adequacy and excess were assessed for these different allocation plans and schedules. These were further compared with the performance measures of the existing rule (fixed depth irrigation at a fixed interval). The analysis revealed that these performance measures are in some cases complimentary and in other cases conflicting with each other. Therefore, it would be appropriate for the irrigation managers to understand fully the nature of the variation in performance measures for different allocation rules prior to deciding the allocation plans for the irrigation scheme.     

自流灌区节水灌溉及其对策

随着全球化水资源危机的出现,灌区发展中存在的问题明显暴露出来。一方面,灌区工程老化失修严重,灌水技术落后,管理粗放;另一方面,水资源不足,灌区引水量逐年下降,制约 了灌溉效益的发挥和灌区的发展。     

Performance assessment of irrigation water management of heterogeneous irrigation schemes: 1. A framework for evaluation

Studies of the performance assessment of irrigation schemes have gained momentum since the late 1980s due to the common perspective that the resources (land and water) in irrigation schemes are not being managed appropriately. In this paper irrigation water management is considered as one of the activities of the irrigation scheme. Three phases of irrigation water management namely planning, operation and evaluation are identified. A framework for the performance assessment of irrigation water management in heterogeneous irrigation schemes is proposed in this paper, based on earlier studies made in this direction. The paper presents two types of allocative measures (productivity and equity) and five types of scheduling measures (adequacy, reliability, flexibility, sustainability and efficiency), together with the methodologies for estimating these for the scheme as a whole during different phases of irrigation water management.     

Examining traditional irrigation methods,irrigation scheduling and alternate furrows irrigation on vertisols in northern Ethiopia

In northern Ethiopia, where traditional (farmers) irrigation management on Vertisols is widely practiced, sustainable food security has always been a challenge. The reasons for this are multi-dimensional, but of utmost importance is, low-tech irrigation water management. The main objective of the present study is, therefore, to examine technologies of irrigation water management that might enable farmers to increase water productivity (WP) on vertisols.A comparative study has been undertaken between the traditional irrigation management (every furrow-traditional scheduling) and alternative water management options on maize plots in northern Ethiopia. The options include alternate furrows-scientific scheduling and every furrow-scientific scheduling. A field experiment was undertaken over two irrigation seasons (1998/1999 and 1999/2000). Results were compared on the basis of yield, WP and economic productivity concepts.Yield-based comparison has shown that every furrow-scientific scheduling generates the highest yield levels followed by alternate furrows-scientific scheduling. The yield increase (by every furrow-scientific scheduling) over the traditional management was found to be 54%.WP-based comparison has shown that alternate furrows-scientific scheduling generates the highest WP values followed by every furrow-scientific scheduling. The increase (by alternate furrow irrigation, scientific scheduling) over the traditional irrigation management was 58%.Economic productivity-based comparison has shown that the highest economic return was obtained from every furrow-scientific scheduling followed by alternate furrows-scientific scheduling. The increase in income (by every furrow-scientific scheduling) over the traditional irrigation management was 54%.The overall observation is that depending on the availability of water and labour resources, one can decide to use either of the alternate management options to obtain economically reasonable yield. In northern Ethiopia, where water is limiting (and not labour), every furrow-scientific scheduling can be an option.     

Estimations of permissible irrigation rates from soil properties in high frequency irrigation

The effect of irrigation dynamics and soil physical properties on the permissible rate of application was analyzed using the analytic solution of Richard’s equation for periodic flux type boundary conditions typical to high frequency irrigation. Dynamics of irrigation regime was defined by its instantaneous application rate, R ₀, its frequency, and the duty cycle which is the ratio of irrigation duration and irrigation interval (period). Soil properties were saturation, hydraulic conductivity, diffusivity, and Gardner’s soil type coefficient. Fourier Transform was used to derive a closed form analytical expression for the maximal permissible value of R ₀, which would not result in water logging and saturation at soil surface. The analytical expression ties the three irrigation parameters with the above three soil parameters together. Prevention of aeration stress by restricting the moisture content at the soil surface, to become less than the minimal air pore volume (drainable porosity), was also used as an upper constraint of moisture at the surface soil. The effect of irrigation frequency and duty cycle on the permissible R ₀ values was analyzed and computed regarding three soil types: coarse sand, sand, and sandy loam. Under short duration periods of water application resulting from either small values of duty cycle or short irrigation periods (high frequency), or both, the soil surface would not become saturated even for very high R ₀ values. The maximal application depth V _max, depends on both the duty cycle and the frequency. For a given soil, V _max remains essentially constant per irrigation periods of 1 h or less, typical to pulsed irrigation and independent of the duty cycle. For periods longer than 1 day for coarse soils, V _max increases with the duty cycle while for sandy loam soils, the increase in V _max becomes insignificant for duty cycles larger than 0.3. The computed values of maximal R ₀ and V _max based on the water logging concept are much higher than the ones used in irrigation design and should be considered as upper permissible limits only. The permissible values of R ₀ and V _max are much lower if the aeration stress concept is adopted and found in the range used in practice. This analysis may be useful for the design of precision irrigation for high frequency microdrip, high frequency trickle irrigation, as well as for trunk diameter measurement (TDM) irrigation methods.     

温室番茄滴灌灌水指标试验研究

研究了日光温室中番茄的需水量、需水规律、产量与耗水量的关系。对日光温室番茄进行了滴灌灌水制度的研究。根据番茄不同生育期的生理特性及其需水特性确定其相应适宜的土壤含水率范围（占田间持水量的百分比）为：苗期45％～55％，开花坐果期55～75％，坐果期65-85％。不同生育期的灌水定额为：苗期10～15mm，开花坐果期15-25mm，结果期20-30mm。     

Empirical functions for dependent furrow irrigation variables.

A complete set of dependent furrow irrigation variables has been identified, for which empirical functions, of general applicability, have been developed. A one-dimensional sensitivity analysis technique coupled with dimensional analysis was employed to reduce the number of independent irrigation variables to a manageable size. Simulation experiments were carried out to generate the data used in developing the pertinent functional relationships. Regression analysis was used to ascertain the specific form of the equations. The predictive quality of the functions has been assessed by comparing their output with those of a zero-inertia model, and was found to be satisfactory. Received: 22 May 1996     

Response of green bean (P. vulgaris L.) to subsurface drip irrigation and partial rootzone-drying irrigation

Effects on water use, green bean yield, irrigation water-use efficiency (IWUE), water-use efficiency (WUE), plant dry weight and crop water relationship were investigated for two-drip irrigation techniques and four irrigation water levels in the Mediterranean region of Turkey. The treatments were conventional (SDI) and alternating subsurface drip irrigation (SPRD). At each irrigation event, half of the volume of water applied to the SDI was applied to one side of the crop, representing the partial rootzone-drying treatment. All treatments received 295 mm of irrigation during crop establishment, prior to beginning the different irrigation regimes. Differing irrigation amounts corresponded to four crop-pan coefficients (Kcp₁ = 0.6, Kcp₂ = 0.8, Kcp₃ = 1.0 and Kcp₄ = 1.2), appropriate to pan data. Total water applied to the SDI and SPRD treatments ranged from 366 to 437 mm and from 331 to 366 mm, respectively, depending on Kcp values, with water uptake varying from 396 to 470 mm and 364 to 409 mm, respectively. While differences of green bean yield and dry plant weights were not significantly affected by the SDI and SPRD irrigation techniques, the overall irrigation water saving was found to be 16% for the SPRD irrigation treatment compared with the SDI treatment. SPRD irrigation techniques increased IWUE, WUE, and slopes of yield water relationships. Increase in slopes of the yield–irrigation water and yield–water-use function of SPRD according to the equivalent slopes of the SDI were 215.8 and 151.4%, respectively. SPRD increased the green bean yield response factor (ky) with value of 128.4% according to the equivalent slopes of the SDI. In conclusion, irrigation scheduling based on a 0.8 crop-pan coefficient is recommended for conventional SDI, with 1.0 being more appropriate for partial rootzone-drying practice.     

Comparing theoretical irrigation requirement and actual irrigation for citrus in Florida

Florida ranks first in citrus production, with nearly 68% of all U.S. citrus growing in the season 2005-2006. Most of the citrus groves are located from central to south Florida, and agricultural irrigation permitting is regulated by three of Florida's five water management districts. Most of the permitting for citrus production in Highlands, Polk and Hillsborough counties is conducted by the Southwest Florida Water Management District (SWFWMD), and quantities are based on the District's AGMOD computer program. In 2003, the SWFWMD implemented new permit criteria so that permitted amounts were more representative of actual water use. This paper compares grower reported citrus irrigation water use in Highlands, Polk and Hillsborough counties from 1994 through 2005 with permitted and theoretical irrigation requirements calculated by a daily water balance. Two different sets of crop coefficients (K_c's) developed for citrus in Florida were compared in the daily soil water balance calculation of theoretical irrigation requirements. The percentage of irrigated area considered in this study ranged from 40 to 60% to simulate a range of grower practices. Meteorological data from two weather stations and additional rainfall information from 50 locations within the three counties was used in the water balance. Missing and error values in the meteorological historical record data were filled with weather generators. The multiannual average water consumption (including cold protection water use) from growers ranged from 243 (Hillsborough) to 406 mm (Highlands) and the multiannual average permitted irrigation requirement (without cold protection) ranged from 295 to 557 mm. The simulated gross irrigation requirements under different scenarios of location-K_c-wetted area were variable but mostly lower than the limits established by the district, except for some scenarios in Polk County, whose maximum simulated irrigation value reached 578 mm year⁻¹. In general, permitted limits recommended by the SWFWMD seem to be reasonable for the actual water use by growers in these counties.     

浅谈农作物灌溉用水计算在灌溉制度建立中的应用

本文通过建立灌水模数,结合当地实际情况,介绍了灌溉用水进行计算和科学分析方法,为类似灌溉制度的建立提供借鉴.     

Timeliness of irrigation

Despite considerable discussion of the importance of timeliness as a key dimension of irrigation performance, few studies have assessed how well irrigation systems deliver timely water supplies, nor the magnitude of the effect on agricultural production. This paper lays out indicators of timeliness of irrigation supply which distinguish between deliveries which meet crop needs, and surplus water supplies which cannot be used by crops. These indicators are then applied to empirical data from the Sone Irrigation System of Bihar, India. Using these indicators in an analysis of the contribution of irrigation to rice production shows that incorporating measures of timeliness explains much more of the variability in agricultural production than do simple measures of total water applications over a season. Results of production functions show that if water deliveries cannot be matched with crop requirements, they have a negative, rather than a positive, impact on yields. Water scarcity has the greatest adverse impact in production in the middle of the season, while surpluses are most damaging at the beginning and end of the season. Temporal redistribution from surplus periods to times of water scarcity therefore offers considerable scope to increase productivity without increasing water use.An earlier version of portions of this paper was presented at the IFPRI/ICAR Workshop on Agricultural Growth in India: A Review of Research Findings, 1–6 May 1994 in New Delhi.     

Assessment of irrigation and environmental quality at the hydrological basin level: II. Salt and nitrate loads in irrigation return flows

Irrigation return flows may induce salt and nitrate pollution of receiving water bodies. The objectives of this study were to perform a salt and nitrogen mass balance at the hydrological basin level and to quantify the salt and nitrate loads exported in the drainage waters of three basins located in a 15,500 ha irrigation district of the Ebro River Basin (Spain). The main salt and nitrogen inputs and outputs were measured or estimated in these basins along the 2001 hydrological year. Groundwater inflows in the three basins and groundwater outflow in one basin were significant components of the measured mass balances. Thus, the off-site impact ascribed solely to irrigation in these basins was estimated in the soil drainage water. Salt concentrations in soil drainage were low (TDS of around 400–700 mg/l, depending on basins) due to the low TDS of irrigation water and the low presence of salts in the geologic materials, and were inversely related to the drainage fractions (DF = 37–57%). However, due to these high DF, salt loads in soil drainage were relatively high (between 3.4 and 4.7 Mg/ha), although moderate compared to other areas with more saline geological materials. Nitrate concentrations and nitrogen loads in soil drainage were highest (77 mg NO₃⁻/l and 195 kg N/ha) in basin III, heavily fertilized (357 kg N/ha), with the highest percentage of corn and with shallow, low water retention flood-irrigated soils. In contrast, the lowest nitrate concentrations and nitrogen loads (21 mg NO₃⁻/l and 23 kg N/ha) were found in basin II, fertilized with 203 kg N/ha and preponderant in deep, alluvial valley soils, crops with low N requirements (alfalfa and pasture), the highest non-cropped area (26% of total) and with fertigation practices in the sprinkler-irrigated fields (36% of the irrigated area). Thus, 56% of the N applied by fertilization was lost in soil drainage in basin III, as compared to only 16% in basin II. In summary, a low irrigation efficiency coupled to an inadequate management of nitrogen fertilization are responsible for the low-salt, high-nitrate concentrations in soil and surface drainage outflows from the studied basins. In consequence, higher irrigation efficiencies, optimized nitrogen fertilization and the reuse for irrigation of the low-salt, high-nitrate drainage waters are key management strategies for a better control of the off-site pollution from the studied irrigation district.     

Landscape irrigation by evapotranspiration-based irrigation controllers under dry conditions in Southwest Florida

Due to high demand for aesthetically pleasing urban landscapes from continually increasing population in Florida, new methods must be explored for outdoor water conservation. Three brands of evapotranspiration (ET) controllers were selected based on positive water savings results in arid climates. ET controllers were evaluated on irrigation application compared to a time clock schedule intended to mimic homeowner irrigation schedules. Three ET controllers were tested: Toro Intelli-sense; ETwater Smart Controller 100; Weathermatic SL1600. Other time-based treatments were TIME, based on the historical net irrigation requirement and RTIME that was 60% of TIME. Each treatment was replicated four times for a total of twenty St. Augustinegrass plots which were irrigated through individual irrigation systems. Treatments were compared to each other and to a time-based schedule without rain sensor (TIME WORS) derived from TIME. The study period, August 2006 through November 2007, was dry compared to 30-year historical average rainfall. The ET controllers averaged 43% water savings compared to a time-based treatment without a rain sensor and were about twice as effective and reducing irrigation compared to a rain sensor alone. There were no differences in turfgrass quality across all treatments over the 15-month study. The controllers adjusted their irrigation schedules to the climatic demand effectively, with maximum savings of 60% during the winter 2006-2007 period and minimum savings of 9% during spring 2007 due to persistent dry conditions. RTIME had similar savings to the ET controllers compared to TIME WORS indicating that proper adjustment of time clocks could result in substantial irrigation savings. However, the ET controllers would offer consistent savings once programmed properly.     

喷灌和软管灌溉两用轻小机组特性

介绍了一种新型喷灌和软管灌溉两用轻小机组的结构和工作原理,该新型灌溉机组由绞盘车提供行走动力和压力水源,通过喷水车进行喷洒灌溉.机组可配置喷灌和软管灌溉两种不同的灌水系统,满足了不同作物在不同生育期对水分的要求;喷水车安装有高度调节装置,始终使灌水器处于最佳灌水高度;机组上采用低压折射式喷头和软管洒水带等低压灌水系统,使机组的工作压力降低了30%.通过对该机组水涡轮特性、运行特性、喷洒特性的分析,确定了该机组的技术参数.喷洒试验表明,新型灌溉机组可克服受风影响较大的弱点,减少灌溉水分的漂移损失,灌水均匀度可达90%.