Solid-set Sprinkler Irrigation Research Articles

The Influence of Sprinkler and Drip Irrigation on the Incidence and Severity of Bacterial Disease in Onions Grown in Northeast California

Overhead sprinkler irrigation and its effect on leaf wetness are often referenced as a key factor for bacterial disease spread in onions grown in arid climates. A study was conducted in 2021 and 2022 in Tulelake, California, to compare the incidence and severity of bacterial disease under sprinkler and drip irrigation. The experiment was a split-plot randomized complete block design with drip and solid-set sprinkler irrigation as the main plot treatments and inoculation and no inoculation with plant-pathogenic bacteria as the split-plot treatments. The entire study area was irrigated with solid-set sprinklers from planting until the five-leaf stage to facilitate uniform onion germination and chemigation of herbicides for weed control. After the five-leaf stage, irrigation treatments were imposed for the remainder of the growing season. Total irrigation water amount and irrigation frequency were similar for both irrigation methods. Foliar disease severity and the incidence of bulb rot were 170 and 186% higher, respectively, for solid-set sprinkler compared with drip irrigation. Leaf wetness within the plant canopy during onion bulbing was on average 36% higher in the solid-set sprinkler compared with drip irrigation treatment, whereas relative humidity and temperature were similar between irrigation methods. Drip irrigation maintained lower soil water tension and increased average bulb size by 9% compared with solid-set sprinkler irrigation. This study confirms historical observations that overhead irrigation can extend leaf wetness and increase bacterial disease in onions in arid production areas and highlights the potential benefits of the adoption of drip irrigation.

AquaCrop Model Validation for Simulating Biomass and Water Productivity Under Climate Change for Potatoes

Effective crop development modelling is essential for crop management, water resource planning, assessing climate change's influence on agricultural production, and yield prediction. Validation and simulation of the measured data indicated that AquaCrop software is an effective and reliable program for designing pressurized irrigation systems to increase water application efficiency, system performance and the future prediction. The AquaCrop model was evaluated through a solid-set sprinkler and surface drip irrigation systems at 100%, 80%, and 60% of evapotranspiration (ETo) for the potato crop. The AquaCrop model has shown better performance to simulate potato growth and predicting crop variables under various water systems. The surface drip-irrigation system's at 80% of ETo (48.00, 8.05 ton ha-1) Yield had a substantial impact on the yield of potato and water productivity (WP), matching the yield of potatoes that was irrigated with solid-set sprinklers at 100% of ETo (37.39, 7.19 ton ha-1), with 20% water savings. Attributes of potatoes (canopy cover, biomass, potato crop factor (Kc), and water productivity) were affected by increasing water deficit. The simulated of AquaCrop model was a little higher than observed at 80% of ETo treatment, but still has a similar deviation, and it was slightly lower than seen for 60% of ETo treatment at the mid-season. The AquaCrop model predicted the yield of potatoes and biomass correctly when irrigation is adequate. The results indicated that there may be some changes in AquaCrop model simulation operations over future years based on the climate and irrigation method.

Analysis of Irrigation Performance of a Solid-Set Sprinkler Irrigation System at Different Experimental Conditions

The complexity of assessing the irrigation performance of a solid-set sprinkler irrigation system implies analyzing factors of the sprinkler features, the spacing among sprinklers, the evaluation heights, the meteorological variables and the crop. In this research, a number of solid-set experiments with impact sprinklers were evaluated with different operating conditions and a number of models of irrigation uniformity (CUC) and losses due to drift and wind (WDEL) were assessed at different catch-can heights. Statistical analysis and predictive models were performed for each variable analyzed. The results showed that ND 5035 and SEN 4023 impact sprinklers that presented the lowest variability in water distributions patterns based on the standard deviations of the irrigation depth collected in the catch can (0.85 mm/h). These sprinklers had demonstrated the best CUC values (mean of 86%) with low WDEL averages (lower than 9%). Regarding the CUC analysis, there was a statistically significant difference in measuring the irrigation uniformity from 1 to 2 m catch-can height based on the analysis of 396 solid-set experiments of different research works. Future research could be focused on more experimental conditions analyzing the effects of the irrigation on the crop agronomic development and its yield.

Effect of a growing maize canopy on solid-set sprinkler irrigation: kinetic energy dissipation and water partitioning

The energy of sprinkler irrigation drops splashing on the soil surface or the crop canopy depends on their size and velocity. The kinetic energy of sprinkler irrigation drops is a major factor degrading the soil surface. The effect of a growing maize canopy on sprinkler drop energy dissipation and water partitioning was analyzed. A field experiment was performed on a solid-set sprinkler irrigated plot cropped with maize. Measurements were performed at different locations and heights into the sprinkler layout. Tests were performed at five maize heights. At each maize height, drop population characteristics and pluviometry were measured above and below the maize canopy. Drop population was measured with an optical disdrometer. Catch-can devices were used to measure pluviometry. Solid-set sprinkler irrigation distributes water quite homogeneously, but drop characteristics largely differ between layout locations. The effect of the crop on drop characteristics intensified as the canopy height increased. The canopy cover reduced drop diameter more than it reduced drop velocity. As the canopy grew, its capacity to intercept and derive irrigation water to stemflow increased. The largest part of energy dissipation by the maize canopy took place in the top 1.5 m. A fully developed maize canopy reduced the drop kinetic energy reaching the soil to 13.6% of that reaching bare soil. As a management practice, in sensitive soils or in sprinkler systems applying water with high specific kinetic power, irrigation of bare soils should be avoided.

Effect of Water Regimes and Polyvinyl Alcohol on Faba Bean Yield, Chemical Composition and Water Use Efficiency

Quantifying local crop response to irrigation is important for establishing proper irrigation management approaches.To apply that, a field experiment was carried out to evaluate the effect of three available soil moisture depletion(ASMD) levels, 25 %, 50 %, and 75% applied using solid set sprinkler irrigation system in combination with four concentrations (0.00%, 0.05%, 0.1% and 0.2 %)of poly vinyl alcohol soil conditioner. The combined effect of water regimes and different concentrations of soil conditioner was studied on faba bean (Vicia faba cvGiza 843), The experiment was carried out in the semiarid climate of northeast Farm of El-Ismailia Agricultural Research Station, El-Ismailia Governorate Egypt during two successive seasons(2012/2013 and 2013/2014).Evapotranspiration (ETa), yield productivity of faba bean, water use efficiency and macronutrients uptake were also evaluated. Results showed that the actual seasonal crop evapotranspiration (ETa) for ASMD treatments varied between (1605.36 –2482.45m3 fed-1.) in the first season (2012/2013) and (1439.26 – 2457.01m3 fed-1.) in the second season (2013/2014). There are three options to calculate seasonal ETc for faba bean crop in Ismailia condition. So, it can be use FAO-24RD, PMd or Droogers and Allen (2002)methods. Moreover,obtained data reveal that application of polyvinyl alcohol(PVA)synthetic soil conditioners (with high concentration), decreased available soil moisture depletion (ASMD) in sandy soil and caused a significant increase in faba bean yield, water use efficiency (WUE) and improved the macronutrient uptake by faba bean yield. Finally, the results clearly showed that the significant effect of PVA at (0.1or 0.2 %) concentration was most observed at 50% ASMD.

Comparing evapotranspiration and yield performance of maize under sprinkler, superficial and subsurface drip irrigation in a semi-arid environment

In arid and semiarid environments, with shortage of water resources, maize production is competing for available water. This study analyzed the effect of different irrigation systems on maize yield, crop evapotranspiration and its components, i.e., canopy transpiration (T) and soil evaporation (E). A 2-year field experiment was conducted at the ITAP Research facilities located in Albacete (southeast Spain). Four treatments were assessed: surface drip irrigation with a spacing between drip lines of 1.5 m (SDI_1.5) and 0.75 m (SDI_0.75); subsurface drip irrigation (SubDI); solid set sprinkler irrigation (Sprink). In all treatments, irrigation was applied to refill the estimated potential water demand. Crop evapotranspiration (ETc) and E/T partitioning were estimated using a Simplified Two-Source Energy Balance (STSEB) approach. Although there was an important difference in the irrigation water applied between treatments, ranging from 743 and 722 for Sprink system to 534 and 495 for SubDI system in 2014 and 2015, respectively, yield was unaffected by the irrigation regime, resulting in an increase in the irrigation water productivity (IWP) by an average of 25% when irrigation was applied by the subsurface system. Maize ETc was affected by the irrigation system, with the SubDI achieving in 2015 a 39% reduction of seasonal ETc in comparison with the Sprink system. Similar reductions were obtained for separated E and T components with soil evaporation accounting in general for 15–20% of the total ETc. It is concluded that subsurface irrigation is a water savings strategy for irrigation of maize reducing the consumptive water use and increasing IWP. The final convenience for the widespread adoption of subsurface irrigation will depend on water availability and prices.

Site Selection of Different Irrigation Systems Using an Analytical Hierarchy Process Integrated with GIS in a Semi-Arid Region

Site selection of different irrigation systems can lead to higher water productivity in drought conditions. The present study intends to evaluate suitable regions along the Izeh plain (Iran) for different pressurized and gravitational irrigation systems using Analytical Hierarchy Process (AHP) based on Geographic Information System (GIS). To that end, a variety of inputs such as climate, topography, skilled labor and system costs, etc. were identified and classified into two main categories of socio-economic and environmental criteria. Each criterion was subdivided into several criteria to make the site selection more specific. A matrix of the pair-wise comparison was, in turn, used to compare these criteria and sub-criteria, and to evaluate them based on their relative importance based on the region’s suitability for different irrigation system alternatives. Geographical layers were then obtained for each sub-criterion to select the most suitable sites for different irrigation systems in the study area. Pressurized irrigation systems including wheel move irrigation system, drip irrigation system and solid-set sprinkler irrigation system, together with gravitational irrigation systems consisting of surface irrigation system, and low-pressure irrigation system were considered as irrigation system alternatives during the site selection process in this study. The result map of site selection for different alternatives showed that surface irrigation, drip irrigation and low pressure systems were the best irrigation system alternatives for the region studied.

Influence of irrigation time and frequency on greenhouse gas emissions in a solid-set sprinkler-irrigated maize under Mediterranean conditions

Irrigation management may influence soil greenhouse gas emissions (GHG). Solid-set sprinkler irrigation systems allow to modify the irrigation time and frequency. The objective of this study was to quantify the effect of two irrigation times (daytime, D; nighttime, N) and two irrigation frequencies (low, L; high, H) on soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions in a solid-set sprinkler-irrigated maize (Zea mays L.) field located in NE Spain during 2015 and 2016 growing seasons and the fallow period between growing seasons. Compared with D irrigation, N irrigation increased soil water content (0–5 cm) in both growing seasons. Irrigation management did not affect CH4 emissions and the soil acted as a sink of CH4. Cumulative CO2 emissions were affected by the measurement period (growing season vs fallow) with the greatest values in 2015 growing season, being 81 and 32% higher over the fallow period and over the 2016 growing season, respectively, due to the effect of the preceding crop, alfalfa, and a better soil moisture conditions for the microorganism activity. Similarly, cumulative N2O emissions showed the highest values in 2015, reporting values 90 and 51% greater than the fallow period and the 2016 growing season, respectively. Moreover, N irrigation increased cumulative N2O emissions by 29% compared with D irrigation, but irrigation frequency did not affect cumulative N2O emissions. Irrigation time did not affect cumulative N2O emissions scaled per grain yield or per N uptake because N irrigation increased maize yield by 11% compared with D irrigation. Due to the lack of differences in the scaled N2O emissions, N irrigation should be consider as an appropriate strategy to optimize grain yield without compromising soil GHG emissions per unit of grain yield in Mediterranean agroecosystems.

Effects of irrigation uniformity on yield response and production economics of maize in a semiarid zone

Optimized irrigation scheduling to better match applied water to crop requirements can reduce the consumptive use of water and energy, improve water use efficiency, and increase gross profit margin. However, the distribution uniformity of applied irrigation can modify the way reduced water applications influence field-averaged performance, especially for crops sensitive to water stress as maize, in which the most sensitive stages are those related with reproduction and grain formation. We evaluated the effect of irrigation uniformity on the yield and profitability of maize (Zea Mays L.) in Albacete, Spain in two adjacent sectors equipped with a solid set sprinkler irrigation system of a field managed according to FAO-56 methodology throughout the growing season to maximize grain yield without water stress (Sector S1) or irrigation scheduling determined by an experienced producer (Sector S2). Irrigation uniformity was evaluated using catch cans in both fields and grain yield was harvested within zones exhibiting 75% (Z1), 100% (Z2), and 125% (Z3) of area-averaged volume applications throughout the year. The average coefficient of uniformity (CU) in both sectors (S1 and S2) was 83.5%, and the net amount of applied irrigation water totaled 709 mm in S1 and 832 mm in S2. Average grain yield in sector S2 approached the maximum expected yield of 18.4 Mg ha−1 and exhibited no significant differences in yield among zones. In contrast, sector S1 exhibited significant yield differences (p < 0.05) among zones with a measured yield in Z3 of 18.5 Mg ha−1 and a yield reduction of 1.6 Mg ha−1 and 4.0 Mg ha−1 in Z2 and Z1, respectively. Consequently, the area-averaged yield in S1 was 8% less than in S2. This last treatment was positively influenced by a higher amount of irrigation water supplied to the crop (17%), which decreased the effect of low CU (83.5%). The grain yields simulated by MOPECO for each monitoring zone within the sectors exhibited similar magnitude and trends. Because of these yield differences and the relatively low cost of irrigation water, area averaged gross margin in S1 was 18% less compared with S2. Simulations with MOPECO over a range of CU’s demonstrated that improved irrigation uniformity increased area-averaged yields and gross margin when following S1 instead of S2 strategy. The main innovations of this work were to quantify the effect of irrigation uniformity on the gross margin of a maize crop, and to highlight that in arid and semiarid areas with water scarce conditions, it is a better strategy to improve the irrigation uniformity than supply a higher amount of irrigation water to mask the lack of uniformity.

Low-pressure sprinkler irrigation in maize: Differences in water distribution above and below the crop canopy

Reducing the working pressure at the sprinkler nozzles is one of the alternatives to reduce energy requirements in solid-set sprinkler irrigation systems. Previous studies reported ≈10% lower seasonal Christiansen uniformity coefficient (CUC) for low-pressure treatments than for standard treatments, but no differences in maize yield. This research analyses the effect of maize canopy water partitioning on irrigation performance indexes (CUC and wind drift and evaporation losses, WDEL). Three irrigation treatments were considered, based on the working pressure: 1) A standard brass impact sprinkler operating at a pressure of 300 kPa (CIS300); 2) A standard brass impact sprinkler operating at a pressure of 200 kPa (CIS200); and 3) A modified plastic impact sprinkler (with a deflecting plate attached to the drive arm) operating at a pressure of 200 kPa (DPIS200). Irrigation performance was measured using a catch-can network located above the maize canopy (CUCac, WDELac) along the whole crop season and using stemflow and throughfall devices below the maize canopy (CUCbc, WDELbc) in eight irrigation events. Maize growth, yield and its components were measured. Under low-wind and fully developed canopy conditions (a frequent situation for maize irrigation), CUCbc resulted higher than CUCac for the low-pressure treatments, while the opposite was observed for the standard pressure treatment. Maize canopy partitioning reduces the differences in irrigation performance indexes between pressure treatments, explaining why there are no differences in grain yield between them. Caution should be used when measuring sprinkler irrigation performance above tall canopies, since the elevation of the catch-cans and the crop canopy partitioning affect performance estimations.

Change in Soil Organic Carbon after Five Years of Continuous Winter Wheat or Switchgrass

Core Ideas Soil carbon sequestration under switchgrass depends on precipitation in semiarid regions. Changes in soil C were limited to the surface soil (15 cm) under switchgrass. Switchgrass and continuous winter wheat had similar biomass and soil carbon. Perennial grasses have been promoted to supply cellulose for ethanol production but possible consequences on soil organic carbon (SOC) should be assessed before adoption in a given region. Specific objectives were to (i) compare aboveground biomass C production and depth distribution of SOC content of continuous winter wheat (Triticum aestivum L.) and switchgrass (Panicum virgatum L.), (ii) determine the contribution of switchgrass to SOC, and (iii) characterize soil C inventories under each crop across a wide range of precipitation regimes. A 6‐yr (2008–2013) field study with winter wheat and switchgrass ‘Blackwell’ was conducted in northeastern Oregon. Solid set sprinkler irrigation was used to create a productivity gradient of low, medium, and high precipitation levels. The contribution of switchgrass to SOC was identified with δ13C measurements. Winter wheat had significantly higher 5‐yr‐average aboveground biomass C production than switchgrass across precipitation levels and winter wheat under high precipitation produced significantly higher aboveground biomass C than medium and low precipitation. After 5‐yr of cropping, SOC accrual in the 0‐ to 15‐cm depth was significantly higher under winter wheat than switchgrass in each precipitation regime. Results of δ13C indicated switchgrass contributed 7.9, 8.5, and 12.9% to profile SOC at low, medium, and high precipitation levels. Soil organic carbon in dry cropland is resistant to a shift in crop species. Switchgrass does not increase SOC more than continuous winter wheat in dry cropland of the semiarid Pacific Northwest.

Assessing low-pressure solid-set sprinkler irrigation in maize

Water and energy are limited and expensive resources. Conserving water and energy is a requirement to ensure the viability of modern pressurized irrigation systems. The objective of this research was to analyze the possibilities of reducing the nozzle operating pressure of impact sprinklers from 300kPa (standard pressure) to 200kPa (low pressure) in solid-set irrigation systems without reducing the sprinkler spacing and maintaining crop yield. Three treatments resulting from combinations of sprinkler type, and working pressure were analyzed: 1) Conventional impact sprinkler operating at 300kPa (CIS300); 2) Conventional impact sprinkler operating at 200kPa (CIS200); and 3) Modified deflecting plate impact sprinkler operating at 200kPa (DPIS200). A randomized experimental design was applied to a maize crop during two seasons (2015 and 2016). Irrigation performance was measured by catch-can monitoring at one replicate of each treatment. Maize growth, yield and its components were measured. Differences between treatments in soil water, maize growth and yield variables were analyzed using ANOVA. Seasonal irrigation uniformity evaluated at the top of the canopy was larger for the standard pressure treatment (93%) than for the low pressure treatments (82% and 84% for DPIS200 and CIS200, respectively). The average wind drift and evaporation losses for the 2016 irrigation season were higher for the CIS300 treatment (17%) than for the low pressure treatments, DPIS200 (15%) and CIS200 (13%). Low pressure treatments did not reduce grain yield compared with the standard pressure treatment. Differences in irrigation performance and maize yield between the low pressure treatments, DPIS200 and CIS200, were not statistically significant. The reduction in energy use by reducing the operating pressure from 300kPa to 200kPa would allow to increase the net farming benefit of individual and collective systems. This is particularly true if low pressure irrigation is considered at the design phase of the irrigation system.

A simulation tool for advanced design and management of collective sprinkler-irrigated areas: a study case

More than one million hectares have undergone irrigation modernization in Spain during this century. Irrigation modernization to pressurized systems is currently facing challenges derived from increasing electricity prices and decreasing public subsidies. The economic viability of such projects is compromised, and the number of projects is decreasing. Pressurized collective networks are commonly designed and managed using hydraulic simulation tools and probabilistic hypotheses on hydrant use. In this paper, a simulation tool is presented that widens the scope of the analysis by combining hydraulics with agronomy, agrometeorology, solid-set sprinkler irrigation and economics. The CINTEGRAL software simulates the net benefit of the seasonal operation of a collective pressurized irrigation network. The software incorporates an optimization module for the electricity contract associated with the pumping station. CINTEGRAL runs on a time step of a half-hour, and simulates the irrigation season of a variety of crops. The software was applied to analyze the economic benefit of a Water User Association (WUA) under different design and management scenarios (on-demand, network sectoring and dividing the irrigated area in separate networks). In the studied WUA, the network sectoring scenario provided important energy savings (22%) but negatively affected yield by a similar economic magnitude. The division of the area in two independent networks was the most cost-effective scenario. Network topologies, cropping patterns, market prices, irrigation infrastructure, soil conditions and management rules determine the optimum WUA management options. CINTEGRAL is a comprehensive simulation tool designed to help designers and managers guarantee the economic viability of their projects.

Fertigation Uniformity under Sprinkler Irrigation: Evaluation and Analysis

In modern farming systems, fertigation is widely practiced as a cost effective and convenient method for applying soluble fertilizers to crops. Along with efficiency and adequacy, uniformity is an important fertigation performance evaluation criterion. Fertigation uniformity is defined here as a composite parameter consisting of irrigation and fertilizer application uniformity indicators. The field and computational procedures for sprinkler irrigation uniformity evaluation have been the subject of various studies. The objective of the study reported in this paper, however, is the development of an analytical framework for the evaluation and analyses of test-plot scale fertilizer application uniformity under solid-set sprinkler irrigation systems. Irrigation uniformity indices are adapted for use in fertilizer application uniformity evaluation. Fertilizer application rate, given as a function of irrigation depth and fertilizer concentration, is identified as the appropriate variable to express fertilizer application uniformity indices. Pertinent mathematical properties of the uniformity indices along with their practical fertigation management implications are outlined. Carefully designed hypothetical fertigation scenarios were analyzed to examine the significance of the interactive effects, of the local spatial trends of depth and concentration data, on the test-plot scale uniformity of the resultant fertilizer application rate data. The results of the study show that the spatial overlap patterns between depth and concentration data sets are the main determinants of test-plot scale fertilizer application rate uniformity. The study also shows that often the uniformity levels of irrigation and fertilizer concentration data sets cannot be uniquely related to the uniformity of the resultant application rate data. However, some practically useful qualitative relationships between the uniformity of irrigation depth, solute concentration, and application rate data sets are defined. Application of the approach presented here in the evaluation and analysis of fertigation uniformity data sets, measured under sprinkler irrigated conditions, is highlighted.

Solid-set sprinklers irrigation of field boundaries: experiments and modeling

Numerous studies have analyzed the solid-set sprinkler irrigation system performance. However, the effect of field-boundaries irrigation has not been considered in the whole-field performance. The objectives of this study were (1) to characterize two different solutions to irrigate field boundaries (full-circle sprinkler equipped with a deflecting plate, DP, and partial-circle sprinklers, PC); (2) to calibrate and validate a ballistic model to adequately simulate these solutions; and (3) to analyze the two different designs (DP or PC) from a whole-field perspective. Two types of experiments were designed. The first was carried out with an isolated sprinkler under no windy conditions to estimate drop size distribution parameters. The second was performed in a solid-set sprinkler layout under windy conditions to calibrate and validate the ballistic model. The experimental design allows the comparison of both solutions under equal technical and meteorological conditions. Comparisons between designs (DP or PC) were established for a whole-field area in terms of irrigation performance and crop yield. From a technical point of view, PC sprinklers perform better than DP sprinklers. From an economical point of view, the shape and orientation of the plot and the legal requirements of the irrigation system design (minimum distance of the sprinkler line to the border) have an important effect on the optimal solution to irrigate field boundaries.

Sprinkler irrigation uniformity and crop water productivity of barley in arid region

An investigation has been organized To study the effect of the sprinkler irrigation system design on irrigation uniformity and its impact on barley crop yield and crop water productivity (CWP). The spring irrigation operating pressures (P) were 200 kPa (P1), 250 kPa (P2) and 300 kPa (P3). The sprinkler riser heights were 100 cm (H1), 125 cm (H2) and 150 cm (H3) from the ground. The results demonstrated that the maximum values of coefficient of uniformity (CU) and distribution uniformity (DU) (91.37 % and 0.85, respectively) were obtained at P3H3, while the minimum values (78.21 % and 0.71, respectively) were obtained at P1H1.Under P3H3 treatment, the highest values of 5.50 t ha-1 and 63.49 cm of grain yield (GY) and barely plant height (PH), respectively were recorded. The highest CWP value (0.75 kg m-3) was obtained when the P3H3 treatment was applied, while the lowest yield (0.36 kg m-3) was recorded under P1H1 treatment. According to the results of this experiment, under Sebha environmental conditions and similar regions, it is recommended to operate the solid set sprinkler irrigation system at P3H3 to obtain the highest CU and DU and consequently the highest GY, PH and CWP.

Development and validation of a modified model to simulate the sprinkler water distribution

Water distribution uniformity is important for the design of a sprinkler irrigation system. The movement of enormous water droplets after leaving the sprinkler nozzle significantly affect the water distribution of an individual sprinkler. Based on modified mathematical models of droplet dynamics and evaporation, a method for simulating droplet motion was proposed, and a corresponding software was developed as well. Using the given radial water distribution data of an individual sprinkler, the software can predict the water distribution of an individual sprinkler or a solid-set sprinkler irrigation system under different sprinkler spacing combinations and various environmental parameters. The corresponding combined application rate (P¯), coefficient of uniformity (CU) and evaporation loss rate of an irrigation system could be calculated. The model was validated by indoor and field experiments. The side length of the grid elements constituting the square region was recommended as 0.5m and the number of spray directions was 180 in the simulation. The results of model validation showed that the simulated radial water distribution of an individual sprinkler agreed well with the measured values, with a confidence coefficient of 0.899. The average relative errors in P¯ and CU between the measured and simulated values were 3.46% and 2.46%, respectively. The developed software package was capable of predicting the water distribution of sprinkler irrigation systems with relatively high accuracy under the conditions investigated.

Design of Sprinkler Irrigation Subunit of Minimum Cost with Proper Operation. Application at Corn Crop in Spain

MATLAB™ software named PRESUD (Pressurized Subunit Design) was developed to identify the optimum solid set sprinkler irrigation subunit design with a criterion of minimizing the annual water application cost (CT). This CT is defined as the cost per cubic meter of water applied to the soil for crop use. In this study, only rectangular subunits are considered, using an iterative method for calculating the lateral and manifold pipelines. The results indicate that water cost (Cw), which includes the investment and operation costs for pumping water from the source to the subunit inlet, makes up 75 % of CT. Another important factor is energy cost, which comprises 14 % of CT. The remaining variables, such as sprinkler spacing and layout, or application rate (ARa), have a lower impact on CT. In cases of use groundwater, the proportion of energy cost in CW can reach 40 %; thus, energy is an important part of CT. Results shows that the criterion of limiting the maximum difference in pressure heads in the irrigation subunit (Δh < 20 %), widely used when designing a sprinkler irrigation subunit, does not always lead to a minimum CT, and the use of tools such as PRESUD can help obtain better solutions.

Effect of Low Pressure on Irrigation Uniformity of Solid Set Sprinkler Irrigation System

The irrigation requires an efficient and effective method of water application to realize maximum return and conserve water resources. The low pressure sprinkler irrigation system is the most commonly used due to: its low energy cost, but the irrigation uniformity of this system is not constantly good because it is affecting by the design factors such as: nozzle type, nozzle diameter, operating pressure and spacing layout. But the most important factors are the operating pressure and nozzle diameter. In this study the effect of low pressure on the irrigation uniformity of the solid set sprinkler irrigation system was studied. Different low operating pressures (62, 82, 102 and122 kPa) were selected and different nozzle diameters (4, 5 and 7 mm) were used. The solid set layout was square (12 m between the sprinklers along the line and 12 m among the line). The catch-cans test was used to determine the uniformity coefficients such as: Christiansen’s coefficient of uniformity (CU), coefficient of variation (CV), distribution uniformity of low quarter (DUlq) and distribution uniformity of low half (DUlh). The distribution characteristics such as: throw radius and rotation speed were monitored. A comparison was made between the results obtained from different combination of operating pressures and nozzle diameters. The results of this study showed that, CU, DUlq and DUlh were increased when the pressure increased for all the nozzles. The greater values of CU, DUlq and DUlh were found with the combination of 7 mm nozzle diameter and 122 kPa. The coefficient of variation was increased when the pressure decreased for all the nozzles. The throw radius and rotation speed were increased gradually when the pressure increased. The throw radius was not significantly affected by the nozzle diameter while the rotation speed was more affected by the nozzle diameter.

Field-Scale Sprinkler Irrigation System Hydraulic Model. II: Hydraulic Simulation

AbstractThis paper describes a mathematical model for the hydraulic characterization of a field-scale solid set sprinkler irrigation system with a double-line lateral layout configuration. Formulation of the basic hydraulic equations along the mainline and laterals is based on manifold hydraulics. Lateral hydraulics remains the same as that described in a previously published paper, for systems with single-line laterals. A description of the mainline hydraulics of systems with a double-line lateral layout configuration, which requires the formulation and iterative solution of a system of nonlinear equations, is presented here. The hydraulic characterization functionality of the model, described in a previously published paper, serves as an interface for coupling the numerical solutions of the lateral and mainline hydraulic equations. In addition, this paper presents a description of the simulation functionality of the sprinkler hydraulic model and a related numerical algorithm, which is based on one-dimen...