Low-pressure Sprinkler Research Articles

INNOVATIVE TECHNOLOGIES IN SPRINKLER IRRIGATION: AN OVERVIEW

The overuse of water in conventional irrigation at the farm level is a global issue that can be addressed by improving irrigation techniques. Sprinkler irrigation can reduce water losses by carefully planning the crop, soil, landscape, and weather conditions, as well as installing the proper sprinkler hardware. The application efficiency of sprinkler systems may be enhanced when these systems are coupled with automation for precise irrigation. Sprinkler irrigation has advanced significantly, but new ideas and current practices are driving further progress. These novel ideas include low-pressure sprinklers, smart controllers, fertigation, water-pesticide integrated sprinkler systems, and variable-rate irrigation. The objective of this work is to highlight the introduction of innovative technologies to optimize sprinkler irrigation systems. Suggestions for the future development of sprinkler irrigation technology are offered to ensure its long-term viability.

ЗАСТОСУВАННЯ СУЧАСНИХ РОБОЧИХ ОРГАНІВ ДОЩУВАЛЬНИХ МАШИН ЯК ЗАСІБ ПОКРАЩЕННЯ ЯКОСТІ ДОЩУ ТА МІНІМІЗАЦІЇ ЙОГО ВПЛИВУ НА ФІЗИЧНІ ВЛАСТИВОСТІ ТА СТРУКТУРУ ҐРУНТУ

The article presents the results of research on the impact of qualitative and structural characteristics of artificial rain created by sprinklers and ways and means of minimizing its negative impact on the soil by using modern low-pressure sprinklers. The purpose of the research is to study the design features of different types of sprinklers, and the practice and effectiveness of their use in the conditions of irrigated agriculture in Ukraine. Methods and materials. The study of structural and technological features of the working bodies of sprinklers, the practice of their application, and the determination of the main indicators of the quality of the generated rain were carried out in the economic conditions of their operation during the tests. When assessing the quality of work, the intensity of rain, the average diameter of the drops created, the coefficient of effective watering along the sprinkler belt of the tested machines, the specific power of rain, and the comparison of these indicators when using different types of sprinklers were determined according to the standardized methods of the relevant regulatory documents: SOU 74.3-37-152, DSTU ISO 11545. Results. Modern sprinklers are equipped with highly efficient sprinklers with a large capture area and low energy impact on the soil, taking into account all components of the impact of the quality and structure of artificial rain. At low-pressure values, such sprinklers provide a low intensity of rain due to a large spray area, good uniformity, and optimal droplet sizes. The use of these working bodies provided a solution to the problem of minimizing the negative impact of irrigation on the ecology of the environment. The high efficiency of the use of modern sprinklers was confirmed by tests of machines equipped with similar working bodies, according to the results of which a decrease in the intensity of rain and its energy impact on the soil was noted due to the low-working pressure, large coverage area, a nominal spectrum of droplet size and speed of their fall. Conclusions. The use of low-pressure sprinklers makes it possible to reduce the energetic impact of rain on the soil, which ensures the preservation of its structure and reduction of erosion processes, ensures high uniformity of irrigation at low pressure in the irrigation network, reduces moisture loss from the influence of air temperature and wind, and irrigation costs due to the reduction of pressure in irrigation network. Keywords. sprinklers, intensity of rain, size of drops, sprinklers, uniformity of watering, water erosion of the soil, pressure.

Using 2DVD technology to explore droplet characteristic variations of sprinkler irrigation as affected by a maize canopy

Canopy cover influences the water distribution and droplet characteristics of sprinkler irrigation, creating uncertainty in the design optimization of sprinkler irrigation systems. To evaluate the effects of canopy cover on water distribution and droplet characteristics of sprinkler irrigation, the radial distribution of droplet diameters, velocities, impact angles, shear stresses, and kinetic energies were investigated by an indoor experiment using a two-dimensional video disdrometer (2DVD) with Nelson R33LP low-pressure sprinklers at three operating pressures (100, 200, and 300 kPa), three nozzle diameters (4.4, 4.8, and 5.2 mm), and two growing stages of the maize canopy. Additionally, the water application rates were measured by catch-can devices for each treatment. The results show that small droplets passing through the canopy converge into larger-diameter droplets and large droplets passing through the canopy break up into smaller-diameter droplets. The canopy cover significantly affected droplet kinetic energy and velocity and reduced shear stress by 2.48–96.09 %, which could minimize the risk of soil erosion. Meanwhile, an increase in the leaf area index (LAI) reduced the kinetic energy by 0.26–99.00 %. Canopy cover also had an obvious effect on the irrigation uniformity coefficients (CU). The CU without the canopy exhibited a significant linear correlation with the CU with the canopy. When the irrigation CU without the canopy was 62.00 %, the maize canopy at the jointing stage improved it by 16.62 %, and when the CU without the canopy was 88.47 %, the maize canopy cover at the jointing stage reduced it by 4.68 %. An increase in operating pressure improved the uniformity of the sprinkler by 0.57–151.58 % and reduced shear stress by 2.80–95.11 %. An increasing nozzle size increased the application rate and specific power. This study provides technical support for the design of sprinkler irrigation systems.

Evaluating soil water movement and soil water content uniformity under sprinkler irrigation with different soil texture and irrigation uniformity using numerical simulation

Water movement and its distribution uniformity in the soil are essential for the design of sprinkler irrigation systems. They are both crucial factors influencing nutrient migration and the productivity of crops. In this study, a new numerical simulation method was proposed to investigate the soil water movement in sprinkler irrigation under nonuniform infiltration boundary conditions using COMSOL software. Besides, two soil tank experiments were conducted to test the reliability of the simulation model. Finally, the model was applied to evaluate the effects of sprinkler irrigation uniformity, soil texture, and initial soil water content on soil wetting patterns and soil water content uniformity. The results showed that the COMSOL-2D predictions of the vertical wetting fronts were in good agreement with the experimental data. The soil texture and initial soil water content influenced the soil wetting pattern and the risks of surface runoff and deep percolation in sprinkler irrigation systems. When the water application rate was 11.35 mm h−1 with an irrigation duration of 10 h, it was easy to cause surface runoff in silty clay loam while deep percolation in loamy sand. Additionally, when the initial soil water content is high, it should be better to avoid irrigation or cut down the irrigation duration to prevent percolation. The water within the soil was more uniformly distributed than that applied through a sprinkler irrigation system. The uniformity coefficient of soil water content distribution (CUs) increased from 87.75 % to 95.56 %, as the uniformity coefficient of sprinkler irrigation (CU) increased from 40.74 % to 82.41 %. Although a higher initial soil water content brought a higher soil CUs value, it also led to a higher risk of percolation. The experimental and simulation results indicated that the COMSOL-2D model could be used to accurately simulate soil water movement in sprinkler irrigation and determine the suitable operation mode of low-pressure sprinklers.

A simulation tool to optimize the management of modernized infrastructures in collective and on-farm irrigation systems

Irrigated areas face new, pressing challenges due to escalating energy costs for pumping, increasing cost of seeds, fertilizers and agrochemicals, volatility of agricultural commodities, pressure of environmental regulations, water scarcity and mounting cost of irrigation infrastructure investments. At the same time, from the technical standpoint, farmers can chose from a wide array of irrigation design and operation alternatives for collective and on-farm systems, with variable effects on crop yield and profitability. These factors are often subjected to quick changes, complicating decision making. Simulation models have proven useful to support decision making in irrigation infrastructure, water / energy use, crop agronomy and soil management. In this research, new capacities of the Ador-Simulation software are reported, targeting comprehensive analyses of irrigation modernization. The model implements additional on-farm irrigation methods (low-pressure solid-set, center-pivot and drip irrigation); crop intensification (double cropping in the same season); and crop response to different on-farm irrigation management options (timing and frequency). Model performance was verified using a set of theoretical case studies. Finally, the model was applied to the optimization of irrigation design and management (water and energy) in the Bardenas XI project of northeastern Spain. Water application in center-pivot and drip irrigation were simulated using a normal distribution characterized by a user-defined Distribution Uniformity. In center-pivot, the application depth was randomized in every irrigation event, reproducing the random nature of wind disturbances. In drip irrigation, the application depth followed the same random distribution in all irrigation events, reproducing the deterministic effect of manufacturing and hydraulic variability. According to the literature, the effect of irrigation timing was treated differently for two key sprinkler irrigated crops: corn and alfalfa. Differences in water application and crop yield between on-farm methods resulted in different gross and net income. In the Bardenas XI project, irrigation performance indicators showed different patterns of inter-annual variability. Deep percolation was strongly affected by the amount of seasonal precipitation and by Distribution Uniformity. Indicators at the plot level were strongly determined by the on-farm irrigation method, the soil type, and the crop. In the conditions of Bardenas XI, the design option without pumping station was the most adequate. Natural pressure proved sufficient for a combination of low-pressure sprinkler irrigation, pivot and drip irrigation methods, distributed throughout the irrigated area. Escalating energy costs emphasize the need for careful assessment of pumping requirements at the design phase of irrigation projects.

Specific power or droplet shear stress: Which is the primary cause of soil erosion under low-pressure sprinklers?

Specific power and droplet shear stress are generally considered to be the most critical indicators of soil erosion in sprinkler irrigation, but there is controversy about which indicator has a greater impact. This creates uncertainty in the optimization design of low-pressure sprinkler irrigation systems. In this study, a commonly used low-pressure sprinkler, i.e., Nelson D3000, was used to carry out in soil box experiments, to study the effects of specific power and average droplet shear stress at the end of a spray jet on soil erosion during sprinkler irrigation under three nozzle diameters (3.97, 5.95, and 7.94 mm), two operating pressures (103 and 138 kPa), and two soil textures (loamy sand and silty loam). Overall, the larger specific power or average droplet shear stress resulted in higher initial and steady runoff rates and a shorter time until runoff occurs and stabilizes. Enlarging the specific power or average droplet shear stress could significantly increase the initial infiltration rate, sediment yield, and surface soil bulk density, but the infiltration depth prior to runoff and surface soil porosity decreased. Furthermore, the specific power was observed to have greater correlations than average droplet shear stress with the surface runoff rate, initial infiltration rate, and increase in the soil bulk density and decrease in the soil porosity after irrigation. However, it was weakly related to the infiltration depth prior to runoff and sediment yield, indicating that the specific power could more accurately reflect the soil erosion with respect to the shear stress. To minimize the risk of soil erosion, a small operating pressure (103 kPa) is recommended in the design of center pivot irrigation systems, especially for the overhang of the system with large nozzle diameters. This research can provide the technical support for soil erosion prevention under low-pressure sprinkler irrigation.

Experimental research on the jet-breaking characteristics and hydraulic performance of a novel automatic rotating sprinkler

Abstract To improve the performance of sprinklers that work under low pressure, a new type of automatic rotating sprinkler equipped with different water dispersion devices was designed and the jet diffusion angle and hydraulic performance of the new and original sprinklers were compared using experimental methods. The results indicate that, when the working pressure is below 200 kPa, the jet diffusion angle of the new sprinkler with the water dispersion device B is the largest. Although the pattern radius of the new sprinkler is slightly lower than that of the original, it is more effective in improving the combined coefficient of uniformity (CU) at lower working pressures. Specifically, when the working pressure was 100 kPa, the new sprinkler with the water dispersion device B, which has a square inner hole with a side length of 6.2 mm, improved the CU by 54.89% on average. Remarkably, the CU of the new sprinkler with water dispersion device B at a working pressure of 100 kPa was 6.65% higher than that of the original sprinkler at a working pressure of 200 kPa. The research results provide valuable insights into the design of sprinklers to improve the performance of low-pressure sprinkler irrigation systems.

Non-negligible factors in low-pressure sprinkler irrigation: droplet impact angle and shear stress

Non-negligible factors in low-pressure sprinkler irrigation: droplet impact angle and shear stress

Result of the influence for center pivot irrigation machine operations on rain intensity

The impact of two parameters - the pressure regulator X1 at the nozzle and the speed of the machine X2 for the amount of water flow through the sprinkler (Y, mm) experiment were determined by 8 mm diameter nozzles. The experiment was carried out in the laboratory of “Design of Irrigation and Equipment” used by “Sprinkler’s uniformity distribution measuring equipment” at the School of Engineering and Technology of MULS. In order to determine the rain intensity of low pressure sprinkler nozzle, mathematical statistical methods was used and it was found that the maximum amount of water supplied by the sprinkler nozzle is 1.727 mm/min with a maximum pressure of 30 PSI and a minimum speed is 1 m / min with a minimum flow rate of 0.313 mm/min. At a pressure regulator value of 20 PSI, the speed was a maximum of 3 m/min.

АВТОНОМНОЕ ЭНЕРГЕТИЧЕСКОЕ ОБЕСПЕЧЕНИЕ ДОЖДЕВАЛЬНОЙ ТЕХНИКИ ПОСРЕДСТВОМ ИСПОЛЬЗОВАНИЯ МИКРОГИДРОЭЛЕКТРОСТАНЦИИ

Purpose: to assess the potential for the functional implementation of a micro-hydropower station in the design of a sprinkler machine to meet the in-system needs for electrical energy. Materials and methods: the study was carried out on the basis of an example of calculating the installation of a micro-hydropower station by A. G. Chernykh and the formulas presented in the handbook on hydraulics. To construct the multiple regression equation, the inverse matrix solution method was used. The calculation of the economic efficiency of the micro-hydropower station was carried out using the method of technical and economic analysis of possible options for electrification by S. G. Obukhov. Results and discussion: based on the results of the verification energy calculations, the effective power on the hydraulic turbine shaft with average technical parameters of low-pressure sprinkler machines was 1.202–15.648 kW. At the same time, linking the operation of the micro-hydropower plant to the irrigation systems of the North Caucasus territory has the potential to get 2596.32–33799.68 kW of generated electricity per year at a cost of 1 kW·h of 0.6204 rubles. Conclusions: the introduction of a micro-hydropower station in the design of sprinkler equipment will provide the ability to generate electricity within the available hydraulic characteristics. With this in mind, for the operation of hydropower equipment, it is necessary to have or create an additional water pressure. The multiple regression equation obtained on the basis of verification calculations of the parameters of the energy block of a microhydroelectric power plant showed that an increase in the water pressure per 1 m Н2О leads to an increase in effective power by an average of 0.611 kW.

Water distributions of low-pressure sprinklers as affected by the maize canopy under a centre pivot irrigation system

Selection of a suitable low-pressure sprinkler can be an effective measure to reduce energy consumption, wind drift and evaporation losses. The crop canopy often redistributes the applied water during sprinkler irrigation. Therefore, we investigated the water distributions above and below the canopy as well as their differences in Heermann and Hein uniformity coefficient (CUH) under three commonly used sprinkler types (Nelson D3000, Nelson R3000, and Komet KPT) and two growth stages of summer maize (6-leaf stage and tasselling stage) to evaluate the effect of crop canopy on the water distribution of low-pressure sprinklers. The variations in the soil water content (SWC) and Heermann and Hein uniformity coefficient of soil water content (CUHS) were investigated further at 1 h before, 1 h after, and 24 h. Additionally, the effects of growth indices and sprinkler types on CUH and CUHS values were analysed. Both the water application depths and CUH values above the canopy were significantly higher than those below the canopy and the differences above and below the canopy increased significantly with the growth of maize. The CUHS after irrigation mainly depended on the initial SWC and CUHS values but was minimally correlated with the plant height, leaf area index, and sprinkler application uniformity. Although the CUH above the canopy (78.1%) of D3000 was significantly lower than R3000 and KPT sprinklers (both exceeding 90%), the CUHS of D3000 reached more than 93% after irrigation. This result indicated that the effect of sprinkler application uniformity was not important as predicted, and a good CUHS would be achieved after canopy interception and soil water redistribution irrespective of sprinkler types. This study provides an insight into the selection of best low-pressure sprinklers in centre pivot irrigation systems.

Effects of Pressure and Nozzle Size on the Spray Characteristics of Low-Pressure Rotating Sprinklers

Using low-pressure sprinklers in agricultural irrigation has become an alternative way of reducing water and energy stress. To determine the applicability of the low-pressure rotating sprinkler, an experiment was conducted to evaluate the effects of working pressure and nozzle size on sprinkler rotation speed, application rate, droplet size, droplet velocity, droplet trajectory angle, and kinetic energy distribution. The results showed that the mean droplet diameter increased exponentially along with the increase in distance from the sprinkler, and a logarithmic relation was derived between droplet diameter and droplet velocity. Due to the low breakup degree of the jet under the lowest working pressure of 100 kPa, the peak values of specific power and application rate were high, which reached 0.09 W m−2 and 11.35 mm h−1, and were 3.1–5.4 times and 2.5–3.1 times those of other working conditions. Meanwhile, the peak specific power of the biggest nozzle (diameter = 5.2 mm) was 2.4–2.8 times that of smaller nozzles. With an increase in working pressure, the sprinkler time per rotation decreased and the distributions of kinetic energy and water became more uniform. Thus, it is not recommended to equip the sprinkler with a large nozzle under low working pressure.

Effects of water application uniformity using a center pivot on winter wheat yield, water and nitrogen use efficiency in the North China Plain

In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain (NCP). The combined effects of water and nitrogen application uniformity on the grain yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) have become a research hotspot. In this study, a two-year field experiment was conducted during the winter wheat growing season in 2016–2018 to evaluate the water application uniformity of a center pivot with two low pressure sprinklers (the R3000 sprinklers were installed in the first span, the corresponding treatment was RS; the D3000 sprinklers were installed in the second span, the corresponding treatment was DS) and a P85A impact sprinkler as the end gun (the corresponding treatment was EG), and to analyze its effects on grain yield, WUE and NUE. The results showed that the water application uniformity coefficients of R3000, D3000 and P85A along the radial direction of the pivot (CUH) were 87.5, 79.5 and 65%, respectively. While the uniformity coefficients along the traveling direction of the pivot (CUC) were all higher than 85%. The effects of water application uniformity of the R3000 and D3000 sprinklers on grain yield were not significant (P>0.05); however, the average grain yield of EG was significantly lower (P<0.05) than those of RS and DS, by 9.4 and 11.1% during two growing seasons, respectively. The coefficients of variation (CV) of the grain yield had a negative correlation with the uniformity coefficient. The CV of WUE was more strongly affected by the water application uniformity, compared with the WUE value, among the three treatments. The NUE of RS was higher than those of DS and EG by about 6.1 and 4.8%, respectively, but there were no significant differences in NUE among the three treatments during the two growing seasons. Although the CUH of the D3000 sprinklers was lower than that of the R3000, it had only limited effects on the grain yield, WUE and NUE. However, the cost of D3000 sprinklers is lower than that of R3000 sprinklers. Therefore, the D3000 sprinklers are recommended for winter wheat irrigation and fertigation in the NCP.

Comparative Evaluation on Performance Characteristics of an Impact Sprinkler with Nozzle-Dispersion Devicesand Rotary Plate Sprinkler

Abstract. A set of nozzle and water dispersion devices were designed to obtain a desirable jet breakup and save water from an impact sprinkler (IS) at low pressure conditions. Comparative performance indicators were obtained for the commercial LP and IS sprinkler heads. Results show that under the same working conditions, the IS produced a large spray range and the water distribution in the middle of the spray range (R) was better than the LP. The best simulated uniformity from the IS was obtained for the combined spacing factor of 1.4*R and the combined uniformity was 4% larger than the LP. Considering the middle position of the spray range, the number and diameter of the droplets from the IS were larger than the droplets from the LP. However, in the end position of the spray range, the droplet diameters from the IS were quite smaller than the LP. Velocities from IS ranged between 0.2 and 6.4 m/s, while that from LP sprinkler were slightly higher ranging from 0.15 to 7.7 m/s at 150 kPa. Overall, introduction of the fixed dispersion device with a pointed tip profile combined with the 6 mm nozzle offered some advantages for the IS over the LP sprinkler at low-pressure conditions. Keywords: Dispersion device, Droplet distribution, Impact sprinkler, Low pressure sprinkler, Nozzle, Spray range, Uniformity.

Application of Variable Pulsed Irrigation Algorithm (VPIA) for Runoff Losses Reduction: Case Study of Different Soil Types

The low-pressure sprinklers have been widely used to replace the high-pressure impact sprinklers in the lateral move sprinkler irrigation system due to its low operating cost and high efficiency. However, runoff losses under the low-pressure sprinkler irrigation machine can be significant. This study aims to evaluate the performance of the variable pulsed irrigation algorithm (VPIA) in reducing the runoff losses under low-pressure lateral move sprinkler irrigation machine for three different soil types. The VPIA uses the ON-OFF pulsing technique to reduce the runoff losses by controlling the number and width of the pulses considering the soil and the irrigation machine properties. Also, the VPIA aims to achieve a balance between four critical goals: reduce the runoff losses, deliver the highest possible irrigation depth, ensure a high level of water distribution uniformity in the direction movement, and with the lowest number of pulses. From a wide range of pulses numbers and widths tested applying a certain water depth to three soil types (Loamy Sand, Sandy Loam, Loam), the best solution that satisfies the algorithm goals was selected. A MATLAB code was written to simulate the soil infiltration rate, the sprinkler application rate, and to apply the proposed algorithm. The simulation results show a runoff reduction of at least 91.76% for Loamy sand, 90.7% for Sandy Loam, and 97.79% for Loam soils with a high level of distribution uniformity while delivering the highest possible irrigation depth using the lowest number of pulses.

Variable Pulsed Irrigation Algorithm (VPIA) to Reduce Runoff Losses under a Low-Pressure Lateral Move Irrigation Machine

Due to restrictions and limitations on agricultural water worldwide, one of the most effective ways to conserve water in this sector is to reduce the water losses and improve irrigation uniformity. Nowadays, the low-pressure sprinkler has been widely used to replace the high-pressure impact sprinklers in lateral move sprinkler irrigation systems due to its low operating cost and high efficiency. However, the hazard of surface runoff represents the biggest obstacle for low-pressure sprinkler systems. Most researchers have used the pulsing technique to apply variable-rate irrigation to match the crop water needs within a normal application rate that does not produce runoff. This research introduces a variable pulsed irrigation algorithm (VPIA) based on an ON–OFF pulsing technique to conserve irrigation water through (1) decreasing the runoff losses by considering the soil infiltration rate, surface storage capacity, and sprinkler wetting diameter; and (2) ensuring a high level of water distribution uniformity in the direction of machine movement. From a wide range of pulse numbers and widths tested applying a certain water depth to a sandy loam soil, the best solution that gives the lowest runoff and highest uniformity while delivering an acceptable water depth was selected. A MATLAB code was written to simulate the soil infiltration rate, the sprinkler application rate, and to apply the proposed algorithm. The simulation results showed a runoff reduction of at least 90.7% with a high level of distribution uniformity in the direction of movement while delivering the highest possible irrigation depth using the lowest number of pulses.

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.

Windrowing poultry litter after a broiler house has been sprinkled with water

In-house windrowing of poultry litter between broiler flocks has been promoted as a management practice to improve the litter condition upon chick placement. Before the onset of the current study, low-pressure sprinklers were used during the grow-out period in a broiler house. Different methods of windrowing were then utilized to determine the effect each had on litter composition. Covered, turned, and static 9 d windrow treatments, and one non-windrowed control were applied to a broiler house containing litter used over multiple flock grow-outs. The house was divided into 16 6 × 6 m plots with each treatment being applied to 4 blocks within the house. Litter from each plot was analyzed for particle size, moisture, N, NH3, P, K, pH, and temperature over a 20-day period, with d 20 representing 7 d after chick placement. All variables except particle size were statistically different. Of all the treatments, the covered treatment showed the greatest reduction in moisture over the 20-day period. Nitrogen content was lowest in the turned treatment. Ammonia decreased from d 9 to 20. Both the covered and static treatments were able to reach recommended temperatures in both the core and the periphery of the windrows. Conclusively, in-house windrowing after utilizing low-pressure sprinklers did not improve N retention, reduce NH3 volatilization, or decrease P or K in the litter compared to the control. However, the temperatures obtained in the periphery and core of the covered and static treatments show potential for eliminating pathogens present in the litter.

Effect on Hydraulic Performance of Low-Pressure Sprinkler by an Intermittent Water Dispersion Device

An intermittent water dispersion device disperses the water outflow from the nozzle of a sprinkler discontinuously. The shape, location, and number of the dispersion teeth have significant effects on the hydraulic performance of low-pressure sprinklers. In this study, the shortest spray distance (R) and affected area angle (I±) were chosen as indexes of the effect on the sprinkler‘s hydraulic performance caused by dispersion teeth, and a method to calculate R was established. An orthogonal experiment was carried out for sprinklers having the following parameters: tooth width (a), insertion depth of tooth into the water jet (h), and distance from the outlet nozzle to the tooth (c). The optimum sprinkler performance was obtained with a = 1.6 mm, h = -1 mm, and c = 4 mm (test 1) and with a = 1.6 mm, h = 0 mm, and c = 9 mm (test 4). Dynamic water distribution curves for different tooth parameters were obtained by rotationally adding the static radial water distribution curves using MATLAB. The results show that the calculated values agreed well with the experimental values. The lowest working pressure was 230 kPa for nine teeth in test 1 and 180 kPa for eleven teeth in test 1, which means that uniform low-pressure irrigation can be implemented by increasing the number of dispersion teeth to compensate for the decrease in uniformity that results from lowering the pressure.

Finite element method in estimation of lag time of rainfall recharge to Holocene groundwater aquifer in Hung Yen province

In the Red River delta, Holocene aquifer has main recharge from rainfall and irrigation. The recharge is much dependent upon the unsaturation-saturation condition of the semipermeable layer covering the aquifer. The paper presents the analysis of moisture transfer in this covering semipermeable layer to estimate the lag time of rainfall recharge to the Holocene aquifer in Hung Yen province in the Red River delta. A finite element modeling had been developed and applied for this purpose. The lag time results have been based on the condition that the degree of saturation of 90% or more is representative for saturation water movement, and therefore the rainfall is actually recharging the aquifer via saturated flow through the covering semipermeable layer. The lag time is 3 days for continuous wet condition from the rainfall if the thickness of the semipermeable layer is 2m, and 5.5 days if the thickness is 3m. For consecutive wet day and dry day condition the lag time is 4 days if the thickness is 2m and 13 days if the thickness is 3m. Therefore, the duration of rainfall for recharge estimation for the study area would be up to about two weeks.References Vu The Hai, 2005: Study on low flow rate and low pressure sprinkler watering for plants in Vietnam northern mountainous and hilly areas. Doctoral diserstesia thesis-Hanoi Water Resources University (in Vietnamese). Huyakorn Pinder, 1987: Computational method in subsurface flow. Academic Press. Nguyen Van Hoang, 2012-2015: Research study No. NCCB-ĐHUD.2012-G/04 "Compilation of FEM software for groundwater movement and solute-transport in groundwater - application to the central coastal area". Jacob Bear and Arnold Verruijt, 1987: Modeling groundwater flow and pollution, D. Reidel Publishing Company, Dordrecht, Holland. Jiunsheng Li and Hiroshi Kawano, 1997: Sprinkler Water Utilization Efficiency. Journal of International Rainwater Catchment Systems, Vol, 3, No, 1, July, 1997, pp. 41-51. Polubarinova-Kochina, 1977: Theory of Groundwater Movement. Higher education publishing house. Moscow (in Russian). Omer Nawaf Maaitah, 2012: Soil-Water Characteristic Curve Model-Silty Sand Soil. Jordan Journal of Civil Engineering, Volume 6, No. 1, 2012 Zienkiewics O.C. and Morgan K., 1983: Finite Elements and Approximation. John Willey &amp; Sons. Department of geology and mineral resources-MoNRE. 2013. Groundwater monitoring in Bac Boc Plain. Center for Geological Information and Archive-MoNRE. Hung Yen Statistic Office, 2014: Hung Yen statistical book year 2013. National Center for Meteorology and Hydrology-MoNRE, 2013: Meteorological and Hydrological monitoring data.