Assessing sprinkler systems performance with a novel experimental benchmark

Sprinkler systems are one of the most popular methods of irrigation worldwide. One of their key parameters is the so-called level of uniformity, i.e. every portion of the soil should be irrigated with the same amount of water. Assessing the level of uniformity is crucial for optimal design of sprinkler systems. In this manuscript, a novel experimental benchmark is presented in order to test irrigation sprinklers, assess their performance, and define their acceptable working conditions. Different sprinklers have been tested, their water application depth curves have been determined, and their performance has been evaluated using a combination of metrics. Results show that the majority of sprinklers are characterized by very good performance in terms of operating pressures in the range 2.0-3.0 bar and tend to decrease their efficiency for operating pressures outside of that range.

Effects of Plate Structure and Nozzle Diameter on Hydraulic Performance of Fixed Spray Plate Sprinklers at Low Working Pressures

HighlightsThe hydraulic performance of fixed spray plate sprinklers (FSPS) was evaluated at low working pressures.The effects of geometric structure on the hydraulic performance of FSPS were studied.A model was developed for estimating the application depth and uniformity of FSPS under a linear-move system.The recommended values of the most effective sprinkler combination spacing for FSPS are given.Abstract. Reducing the working pressure of sprinklers can effectively reduce the energy consumption of sprinkler irrigation systems. Fixed spray plate sprinklers (FSPS) have a simple structure, and their working pressure has potential to be reduced to 40 kPa. To evaluate the hydraulic performance of FSPS at low pressure, an experiment was conducted to investigate the effects of working pressure, plate structure, and nozzle diameter on sprinkler flow rate, wetted radius, and water application distribution. Two plates (FSPSB and FSPSY) and five nozzles were used in the tests. The cumulative water application depth and irrigation uniformity coefficient were calculated under a linear-move system. The results show that sprinklers with larger nozzle diameters and higher working pressures produce greater coefficients of discharge. The wetted radius gradually increases with the increase in working pressure and nozzle diameter. Two empirical equations for estimating the wetted radius of the two plates are proposed. The FSPSB has a concave trajectory structure that produces a longer wetted radius than the FSPSY, which has a flat trajectory structure. Along the wetted radius, the water application rate increases and then decreases, with a peak value at a certain distance. For the FSPSB, the peak rate of water application decreases with increasing working pressure. However, the FSPSY shows the opposite trend, with the maximum peak value occurring at the highest working pressure of 250 kPa. The water distribution for a single FSPSB sprinkler is discrete due to the greater water dispersal caused by the deeper grooves in the plate. In contrast, a single FSPSY sprinkler provides a more uniform water distribution. The irrigation uniformity of the FSPSY is higher than that of the FSPSB. The recommended values for the most effective sprinkler combination spacings for FSPSB and FSPSY are given in this article. The results may be useful for selecting appropriate sprinklers in hydraulic design procedures. Keywords: Cumulative spray water depth, Irrigation uniformity, Sprinkler irrigation, Water distribution, Working condition.

Response of the common bean to liquid fertilizer and Rhizobium tropici inoculation

The common bean production system is majorly based on the use of granular fertilizers to provide nutrients for the crop. Studies on the use of liquid fertilization at an appropriated depth and, seed inoculation with Rhizobium tropici can provide significant increases in the grain yield of the common bean. The objective of this study was to determine the growth and productivity of common bean as affected by N-P formulations, application depths and the inoculation with R. tropici. Field experiments were carried out in 2015 and 2016 cropping years using a complete block design, in a 2x2x2 factorial arrangement, with four replicates. The treatments involved the combination of N-P formulation (granular and liquid), two application depths of the N-P formulation (6 and 12 cm) and with or without rhizobia inoculant. The plant density (PD), number of pods (NP), number of grains (NG), mass of 100 grains (M100) and grain yield (GY) were determined. The granular and liquid N-P formulations provided similar results for PD, NP, NG, and GY of common bean. Similarly, the application depth of the N-P formulations did not affect GY. Inoculation of the seed with R. tropici stimulated NP and NG, increasing GY. Growth and productivity parameters were equally affected by the type of formulation and application depth; however, GY was greater with rhizobial inoculant. Thus, the liquid N-P formulation, applied at 6 cm depth, associated with rhizobial inoculant can improve the crop management providing better control of application uniformity, minimal soil mobilization, less fuel consumption, and increased grain yield.

Ensuring of irrigation machines application depth in uniformity’s distribution

A method of rain uniformity’s distribution was presented for different spraying devices, which were set on irrigation machines working in different mode of moving. A method for effective irrigation radius and width calculation was justified by using irrigation depth uniformity values from the area under water supply pipeline of the irrigation machine.

Effect of Biochar Application Depth on Crop Productivity Under Tropical Rainfed Conditions

Although inherently fertile, tropical soils rapidly degrade soon after cultivation. The period of time for which crops, mulch, compost, and manure provide nutrients and maintain mineral fertilizers in the soil is relatively short. Biochar, on the other hand, has the potential to maintain soil fertility and sequester carbon for hundreds or even thousands of years. This study determined the effect of biochar application depth on the productivity of NERICA-4 upland rice cultivar under tropical rainfed conditions. A fixed biochar–soil ratio of 1:20 (5% biochar) was applied in three depths—10 cm (TA), 20 cm (TB), and 30 cm (TC) with a non-biochar treatment (CK) as the control. The study showed that while crop productivity increased, root penetration depth decreased with increasing biochar application depth. Soil moisture was highest under TA (probably due to water logging in sunken-bed plots that formed after treatment) and lowest under TC (due to runoff over the raised-bed plots that formed too). Grain yield for the biochar treatments was 391.01–570.45 kg/ha (average of 480.21 kg/ha), with the potential to reach 576.47–780.57 kg/ha (average of 695.73 kg/ha) if contingent field conditions including pest damage and runoff can be prevented. By quantifying the effect of externalities on the field experiment, the study showed that biochar can enhance crop productivity. This was good for sustainable food production and for taking hungry Africa off the donor-driven food ration the nation barely survives on.

Modeling the Application Depth and Water Distribution Uniformity of a Linearly Moved Irrigation System

A model of a linearly moved irrigation system (LMIS) has been developed to calculate the water application depth and coefficient of uniformity (CU), and an experimental sample was used to verify the accuracy of the model. The performance testing of the LMIS equipped with 69-kPa and 138-kPa sprinkler heads was carried out in an indoor laboratory. The LMIS was towed by a winch with a 1.0 cycle/min pulsing frequency while operating at percent-timer settings of 30, 45, 60, 75, and 90%, corresponding to average moving speeds of 1.5, 2.3, 3.3, 4.0, and 4.7 m min−1, respectively. The application depth and CU obtained under various speed conditions were compared between the measured and model-simulated data. The model calculation accuracy was high for both operating pressures of 69 and 138 kPa. The measured application depths were much larger than the triangular-shaped predictions of the simulated application depth and were between the parabolic-shaped predictions and the elliptical-shaped predictions of the simulated application depth. The results also indicate that the operating pressure and moving speed were not significant factors that affected the resulting CU values. For the parabolic- and elliptical-shaped predictions, the deviations between the measured and model-simulated values were within 5%, except for several cases at moving speeds of 2.3 and 4.0 m min−1. The measured water distribution pattern of the individual sprinklers could be represented by both elliptical- and parabolic-shaped predictions, which are accurate and reliable for simulating the application performances of the LMIS. The most innovative aspect of the proposed model is that the water application depths and CU values of the irrigation system can be determined at any moving speed.

Ammonia volatilization and nitrogen runoff losses from moso bamboo forests after different fertilization practices

Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) is a major giant bamboo species. Unreasonable fertilization and nitrogen (N) loss is a serious problem. A field experiment was conducted to determine the effects of application methods (furrow and hole) and depths (0–20 and 20–40 cm) on ammonia (NH3) volatilization and N runoff losses from June to December, 2015. Ammonia volatilization was detected as a single peak curve after fertilization. Three weeks later, fluxes of all fertilization treatments were similar to those of the control and remained stable. After the experiment, the cumulative NH3 volatilization was 17.2–21.4 kg·ha−1. Approximately 90% of NH3 volatilization occurred within the first two weeks. The NH4+-N loss was higher than the NO3−-N loss, and the total runoff losses were relatively low. For the same application method, with the increase of application depth, the NH3 volatilization and N runoff losses reduced; for the same application depth, the NH3 volatilization and N runoff losses after furrow application were lower than those after hole application. Therefore, the deep and furrow application methods were effective in reducing N loss through NH3 volatilization and runoff. In the present study, furrow application at a 20–40 cm depth has been appropriate for field practice.