Drip Tape Research Articles

Perspective method for construction of drying and watering network for growing potatoes

In the Central region of the Russian Federation, precipitation is uneven both during the growing season of plants and during the calendar year. Therefore, to obtain sustainable yields and ensure the optimal water-air balance of the soil, agro-reclamation measures are required, including the organization of additional irrigation. During the winter period, a significant amount of snow accumulates, which during the melting period does not have time to soak into the soil, forming surface runoff. The construction of a drainage and water supply network will make it possible to accumulate excess moisture in reservoirs to moisten the soil during the rainless period. The joint use of the drainage network and the drip irrigation system is recommended. Using such a system will allow at the estimated time to supply or divert water to a specific area, removing excess moisture from the soil by drainage to storage tanks and then directing irrigation water to the drip irrigation system during the dry period. The calculation of the irrigation rate, taking into account the semi-elliptical shape of the humidification contour, showed that the required volume of water could be accumulated in special storage tanks. Drip tape laying can be carried out mechanized using a special stacker based on a ridge former.

Effect of different managements with drip irrigation (tape)

Conventional irrigation methods to new methods have been altered with respect to reduction of water resources and climate change. Considering the corn cultivation development, applying modern irrigation methods namely drip irrigation with the aim of improving the efficiency of water consumption as well as the zone under cultivation has been investigated. In this research, the performance of corn (SC 704) in various managements of drip irrigation (by strip method) both in single-row and double-row planting patterns was considered with a variety of densities. This test was carried out on random complete blocks in the form of a 3-repetitive Split Design in Isfahan-Iran during the years 2018–2019. Four irrigation levels containing: 80, 100 and 120% of full water requirement with drip irrigation (strip) and 100% of water requirement with normal drip irrigation were utilized. The results indicated that applying the aforementioned drip tapes and different surface treatments with soil and water monitoring, the water consumption of corn seasonal irrigation can be saved by 81, 71, 61, 52 and 36% compared to normal drip irrigation without soil, water and root monitoring, respectively. Seasonal yield (Kc), the yield response coefficient (Ky), and pan coefficient (Kp) for corn were 0.80, 0.76 and 0.97, respectively.

Analysis of Soil Moisture, Temperature, and Salinity in Cotton Field under Non-Mulched Drip Irrigation in South Xinjiang

The mulch film residues in cotton fields in south Xinjiang have caused serious harm to the soil environment and ecological security in the oasis areas. Non-mulched planting provides an alternative approach to this problem. In this experiment, irrigation was provided on the basis of the reference crop evapotranspiration (ET0). Two layouts of drip tapes (1T4R—one tape for four rows; 2T4R—two tapes for four rows) were applied to the non-mulched, drip-irrigated cotton fields in south Xinjiang, and their impacts on soil water–heat–salt dynamic changes and the water consumption and yield of cotton were compared and analyzed. The experiment shows that the 2T4R layout provided an excellent soil water–salt environment for cotton growth and yield formation. Soil temperature decreased by 0.8 °C and drip irrigation belt input increased by CNY1200·hm−2. However, a higher profit derived from the 2T4R layout could compensate for the increased expenditure. The results show that cotton cultivation using non-mulched drip irrigation instead of mulched drip irrigation can potentially alleviate soil environmental and ecological security problems caused by plastic mulch residues in oasis areas. Although cotton yield was reduced by about 15%, water and nitrogen strategies and other field management could be adjusted to compensate for the disadvantages.

Effects of ridge planting on crop seedlings under saline water drip irrigation

AbstractA field experiment was conducted in northwest China to study the effects of different irrigation water salinity levels on the emergence and growth of corn, sunflower, summer squash, and cowpea. Two tillage systems (flat and ridge planting) and five salinity levels (at 1.7, 4.0, 6.3, 8.6, and 10.9 dS/m) were tested. Compared with flat planting, the soil salinity within 30 cm horizontally from the drip tapes decreased by 15% in the ridge planting system. Ridge planting significantly improved the emergence and growth of crops, which was mainly manifested in higher emergence rates, reduced emergence time, and increased dry biomass, especially under high‐salinity conditions (electrical conductivity of irrigation water >4 dS/m). The electrolytic conductivity of the saturation extract threshold at which corn, sunflower, summer squash, and cowpea endured without reduced emergence rates was 5.8, 5.8, 4.8, and 4.0 dS/m, respectively. Above this threshold, the relative emergence rate decreased by 11%, 16%, 14%, and 20%, respectively. Our results indicate the agronomic benefits of ridge planting, and the soil environment was improved by ridge planting with saline water drip irrigation. In addition, we discuss the crop responses in terms of emergence rates and relative seedling dry biomass in relation to soil salinity. Suggestions for the secure and efficient use of saline water for irrigation in arid regions have been put forward.

The effect of water and nitrogen on drip tape irrigated silage maize grown under arid conditions: Experimental and simulations

Nutrients and nitrate move to the boundary of the wetted zone under drip-tape irrigation (DTI) of row crops, so irrigation depth, wetted width, and irrigation frequency are the most important factors in managing the wetting front and keeping N in the root zone. Many farmers in arid regions who have changed their irrigation systems to DTI, but they are still applying N in two splits as they are used for surface and sprinkler irrigation. Crop models can be used to optimize the timing and amount of nitrogen fertilizer applied to minimize both N leaching and the amount of N remaining in the soil after harvest. The objectives of this study were to calibrate the Cropping System Model (CSM)-CERES-Maize for two maize hybrids and to evaluate the model under DTI with two different soil wetting widths. The single cross Hybrid 704 (SC704) grown in two experimental fields (Exp-1 and Exp-2) and the single cross Hybrid 606 (SC606) grown in one experimental field and two farmer fields (Exp-3, Ff-1 and Ff-2) were evaluated during three years (2016, 2017 and 2019). Plant traits including leaf area index (LAI), total biomass (TB), soil moisture (SM), nitrogen uptake (NU) and water productivity (WP) were measured. Soil NO3-N was measured at three distances from the planting row and three soil depths in Exp-1 and Exp-3 during two maize growth stages. The fraction of the wetted width (fw) along drip-tape was 70% in Exp-1% and 100% in Exp-3 (referred to as fw-70 and fw-100, respectively). The results showed good performance of the model for simulating TB and LAI with NRMSE < 21.9% for the two hybrids in the applied N fertilizer treatments. The accuracy of the simulation of SM and WP in fw-100 was better than that of fw-70. Simulated NO3-N followed the observed trend for fw-100, while model performance varied for the different irrigation and N levels in fw-70. Model accuracy for soil NO3-N prediction decreased for the high N fertilizer application under deficit irrigation management. These differences were related to the wetting pattern volume, the distribution of N in the soil profile, and accumulation of soil N under DTI. Overall, the model can simulate TB and NU with high accuracy, SM with good accuracy, and soil NO3-N with an acceptable accuracy under DTI. The accuracy of the model was also higher for the unlimited wetting width, as compared to the limited one. This study showed that the CSM-CERES-Maize model can be used for evaluation of nitrogen management practices for drip irrigated maize grown under arid conditions.

Drip-Tape-Following Approach Based on Machine Vision for a Two-Wheeled Robot Trailer in Strip Farming

Due to the complex environment in the field, using machine vision technology to enable the robot to travel autonomously was a challenging task. This study investigates a method based on mathematical morphology and Hough transformation for drip tape following by a two-wheeled robot trailer. First, an image processing technique was utilized to extract the drip tape in the image, including the selection of the region of interest (ROI), Red-Green-Blue (RGB) to Hue-Saturation-Value (HSV) color space conversion, color channel selection, Otsu’s binarization, and morphological operations. The line segments were obtained from the extracted drip tapes image by a Hough line transform operation. Next, the deviation angle between the line segment and the vertical line in the center of the image was estimated through the two-dimensional law of cosines. The steering control system could adjust the rotation speed of the left and right wheels of the robot to reduce the deviation angle, so that the robot could stably travel along the drip tape, including turning. The guiding performance was evaluated on the test path formed by a drip tape in the field. The experimental results show that the proposed method could achieve an average line detection rate of 97.3% and an average lateral error of 2.6 ± 1.1 cm, which was superior to other drip-tape-following methods combined with edge detection, such as Canny and Laplacian.

Moisture and Salinity Distribution around the Root of Drip-tape-irrigated Maize Cultivated in Heavy Soil of Khuzestan Province of Iran

ABSTRACT Limited water resources have increased the need for optimal use of water in agriculture. One solution in this regard is to employ modern irrigation methods, including drip tape irrigation. In this study, furrow surface irrigation (the standard method used in the local area) was compared with a drip tape irrigation system under three irrigation regimes (two-, three-, and four-day regimes). Soil moisture and salinity during every stage of plant development (primary, middle, and final) were monitored by collecting soil samples from 0–25, 25–50, and 50–75 cm depths before and after irrigation. Similar moisture distribution was achieved in the 2 consecutive crop years. Under the 2 day irrigation regime, the most substantial moisture changes were observed in the 0–25 cm deep layer and under 3 and 4-day irrigation regimes in the 0–50 cm depth. Soil moisture content before irrigation was around 16 wt.%, reaching 18% after the 2 day irrigation treatment and 23% after 3 and 4 day irrigation treatments. Salinity in the 2-day EC irrigation regime, the soil salinity has decreased from 9 to 5 dS/m in the first year and from 11.5 to 2.8 dS/m in the second year, and in 3- and 4-day irrigation regimes, soil EC has increased from 9 to 10 ds/m in the first year and from 11.5 to 4.5 dS/m in the second year. The study of salinity distribution at different depths of plant roots introduces the best soil depth to 0 to 25 cm with the lowest salinity in all three irrigation regimes. In contrast, by the end of the second crop year, salinity dropped to a quarter, which was primarily due to the better water quality of The Karun River compared to the previous year. A similar outcome was achieved with surface irrigation. The results show that replacing tape strip irrigation with surface irrigation, in addition to saving on the amount of irrigation water consumption, also controls the soil salinization process by applying irrigation management and choosing the best irrigation regime.

ТЕХНИЧЕСКИЕ СРЕДСТВА МЕХАНИЗИРОВАННОЙ УКЛАДКИ КАПЕЛЬНОЙ ЛЕНТЫ В КАРТОФЕЛЬНЫЙ ГРЕБЕНЬ

Purpose: development of technological equipment for drip tape installation, determining the installation resistance to assess the possibility of aggregation with agricultural machines. Materials and methods. The numerical values of the resistance to tape installation in a potato ridge are determined, the data obtained are refined in the process of laboratory studies with a working body model, and the possibility of installing technological equipment on agricultural machines is substantiated. Results and discussion. The Grimme GF-75/4 potato ridge former was upgraded to a drip tape stacker. For high-quality installation of the tape and preventing its twisting and breaking, it is necessary to maintain a constant tension of the tape at various speed rates of the basic machine. To do this, a brake device was introduced into the design of the stacker, which prevents the spool from unwinding by inertia during sudden braking and stopping the machine. Placement of equipment for drip tape installation on the Grimme GF-75/4 ridge former and the work on drip tape installation did not lead to a noticeable increase in traction resistance. The recommended tape laying depth was 20 mm. The brake device installed in the stacker structure prevents the drip tape spool from unwinding due to inertia when braking or stopping the machine. The optimal parameters of the braking device are determined: the spring diameter is 30 mm, the length is 200 mm. Conclusions. To reduce manual labor when carrying out work on installing a drip tape in the soil, the specialized stackers should be used. Due to the low laying resistance, these working bodies can be aggregated with various agricultural machines. To prevent the spool from spinning by inertia, a brake device should be introduced into the design, maintaining a constant tape tension and slowing down the spool in case of weakening the tension. This modernization will improve the quality of work on tape installation into the soil.

Mechanized Placement of Drip Tape in Potato Comb

Over the past two years, decrease in potato yield has been observed in the Moscow region. One of the main reasons is unfavorable weather conditions. To obtain a guaranteed yield, as well as to improve the quality of products, it is necessary to carry out reclamation works, including additional irrigation. Creation of the optimal water - air balance of the plant throughout the entire growing season will increase productivity, and improve the quality of agricultural products. Drip irrigation is the most economical method of irrigation, but its widespread use is hindered by the high proportion of manual labor when installing the drip tape. A mechanized method of laying the drip tape by placing the working equipment on the Grimme GF-75/4 comb former is offered. The existing methods for determining the irrigation rate do not consider the parameters of the humidification circuit, which leads to excessive irrigation and additional losses of irrigation water. The paper offers a method for determining the irrigation rate considering the shape of the humidification circuit and its geometric parameters.

Comparing Overhead versus Drip Irrigation for Production of Three Cultivars of Romaine Lettuce on Biodegradable Plastic Mulch

Growers seeking alternatives to traditional polyethylene plastic mulch may use biodegradable plastic mulches (BDMs). However, plasticulture systems typically also use plastic drip tape underneath the mulch, which must be removed from the field and disposed of at the end of the season, making tilling the BDM into the soil more difficult and expensive. A potential solution to this dilemma may be to use other irrigation methods, such as overhead sprinklers, that could be more easily removed from the field and reused from year to year. At Knoxville, TN, in 2019 and 2020, we grew three cultivars of romaine lettuce (Lactuca sativa) on BDM with two irrigation systems (overhead sprinklers above the mulch and drip irrigation tape under the mulch) to compare water use, disease, and yield in these two irrigation systems. Water use was higher in overhead vs. drip irrigation in both years; however, the difference in water use was much smaller in 2019 due to higher rainfall amounts during the time period the lettuce was growing in the field (March to May). Disease incidence and severity were very low both years for both irrigation systems. There were no differences in marketable yield (number of heads) between irrigation treatment in 2019. In 2020, marketable yield by number was greater in the drip vs. overhead irrigation treatment. Unmarketable yield in 2019 was due to heads that were too small; in 2020, unmarketability was predominantly due to tipburn in overhead irrigated ‘Jericho’. Overall, marketable lettuce yield did not differ between irrigation treatments in 2019 and was similar for ‘Parris Island Cos’ in 2020. Although quantitative weed counts were not made, observations of weed pressure between rows showed that weed pressure was higher in overhead irrigated compared with drip irrigated subplots. This highlights the need to have a between-row weed management program in place. The results of this study suggest that with attention to cultivar and weed management, overhead irrigation could be a viable alternative to drip irrigation for lettuce production on BDM, especially for early spring lettuce when rainfall is historically more plentiful.

Mechanized method of laying drop tape when growing potatoes in the Moscow region

The use of a drip irrigation system allows the most efficient use of irrigation water, since it is delivered directly to the root space. In recent years, the production of drip tape at domestic enterprises has significantly increased by introducing additional capacities at existing plants and commissioning new production facilities, which will halve the import of drip tape and related equipment and fittings. However, the share of lands occupied by drip irrigation among the territories using irrigation measures has practically not increased and amounts to 2-4 %. The design of drip irrigation systems, taking into account the peculiarities of the growing season of a particular agricultural crop, its dynamics of water consumption throughout the life cycle, and the planting scheme, will help to change the situation and expand the use of drip irrigation. One of the limiting factors is the low degree of mechanization when laying the drip tape. The use of handicraft devices for these purposes leads to an uneven tension of the tape and, as a consequence, its breakage and twisting during the laying process. To eliminate this drawback, the working equipment for laying the drip tape into the potato comb was developed and installed on the Grimme GF-75/4 comb shaper. Traction resistance increased by 6-8 %, without affecting the performance of the machine. During the tests, a brake system was installed that maintains the belt tension within acceptable limits and prevents the coil from spinning when the machine stops suddenly. The use of a drip tape stacker based on the Grimme GF-75/4 ridge former has increased the productivity of work by 32–36 %.

Irrigation Regime for Protection on Root Intrusion for Subsurface Drip Irrigation

Root intrusion into emitters poses a threat to the service lives of subsurface drip irrigation systems. In an attempt to address this problem, an experiment was conducted on spring wheat grown in soil columns installed in a greenhouse to study the effects of irrigation regimes in protecting against root intrusion into emitters. Spring wheat was planted in soil columns. The specifications of the soil column were 15-cm width, 60-cm length and 100-cm depth. Drip tapes were buried manually in the center of the soil columns at a -40-cm depth. The soil matrix potential at a 20-cm depth immediately over the drip emitters was used to schedule the subsurface drip irrigation regime. Five different irrigation arrangements, with targeted soil matrix potentials of -10, -20, -30, -40 and -50 kPa, were maintained. The soil matrix potential influenced the spring wheat root distribution, emitter flow rate, root intrusion, and spring wheat yield and quality. The total root dry weight increased as the soil matrix potential decreased. Root length density at 35-45-cm increased as the soil matrix potential increased. The decrease in the emitter flow rate increased along with the soil matrix potential. All the treatments had root intrusion, but its severity was correlated with the soil matrix potential. Root intrusion first decreased as the soil matrix potential decreased but then increased as the soil matrix potential continued to decrease. The lowest root intrusion rate (22.22%), as well as the greatest relative yield and relative thousand-grain weight values, were achieved with a soil matrix potential of -40 kPa.

Effects of drip tape modes on soil hydrothermal conditions and cotton yield (Gossypium hirsutum L.) under machine-harvest patterns.

BackgroundThe layout of drip tapes under mulch has changed in Xinjiang, China, with the development of machine-harvest cotton (Gossypium hirsutum L.) planting technology. This study aims to demonstrate the effects of drip tape modes on soil hydrothermal conditions, cotton yield, and water use efficiency (WUE) of machine-harvest cotton under mulch in Xinjiang.MethodsA field experiment was conducted to set up two machine-harvest cotton planting patterns (T1: the cotton planting model with one film, two drip tapes and six rows; T2: the cotton planting model with one film, three drip tapes and six rows), and a conventional planting mode (T3: the cotton planting model with one film, two drip tapes and four rows) as a control.ResultsOur results showed that the heat preservation and warming effects of the cotton planting model with one film, two drip tapes and six rows and the cotton planting model with one film, three drip tapes and six rows were better than that of the conventional planting mode. Soil temperature under the mulching film quickly increased and slowly decreased, which was beneficial to the early growth and development of cotton. The mean soil moisture content of the 0–60 cm soil layer in the cotton planting model with one film, three drip tapes and six rows was significantly higher than the other two treatments at the middle and late stage of cotton growth (90 days after sowing (DAS) and 135 DAS). Moreover, the water holding capacity of the middle and upper part of the tillage layer in the cotton planting model with one film, three drip tapes and six rows was the best. At the medium cotton growth stage, the main root layer in the cotton planting model with one film, three drip tapes and six rows formed a desalination zone. At the late cotton growth stage, the soil salinity content of the 0–60 cm soil layer showed that the cotton planting model with one film, three drip tapes and six rows was the lowest, the cotton planting model with one film, two drip tapes and six rows was the highest, and the conventional planting pattern was in the middle. Among these three modes, the cotton planting model with one film, three drip tapes and six rows was more efficient in controlling soil salt accumulation. The agronomic traits and cotton quality in the cotton planting model with one film, three drip tapes and six rows were better than that for the other two treatments. Compared with the other treatments, the cotton yield in the cotton planting model with one film, three drip tapes and six rows increased by 6.15% and 11.0% and 8.1% and 12.3%, in 2017 and 2018, respectively, and WUE increased by 17.4% and 22.7% and 20.9% and 22.8%, in 2017 and 2018 respectively. In conclusion, the cotton planting model with one film, three drip tapes and six rows can be recommended for machine-harvest cotton planting for arid areas in Xinjiang, considering water conservation and improving cotton yield.

Effect of EVA and DCP addition on injection moldability and tensile properties of recycled PE from disposable drip tapes

Abstract The effects of ethylene-vinyl acetate copolymer (EVA) and dicumyl peroxide (DCP) addition on injection moldability and tensile properties of recycled polyethylene (PE) from disposable drip tapes were studied. DCP showed an adverse impact on the injection moldability of recycled PE materials, while EVA had positive effects on it. Tensile properties of the reproduced PE increased with the increasing amount of EVA up to 10 wt.% and decreased beyond it. The DCP addition reduced the elastic properties of the reproduced PE, while it enhanced the tensile strength. Overall, the co-addition of 6 wt.% EVA + 0.4 wt.% DCP could improve the tensile strength of the reproduced PE materials.

Tomato tolerance and purple nutsedge control with sulfuryl fluoride mixes

AbstractSulfuryl fluoride (SF) is currently used as a fumigant for control of drywood termites and insects in building structures, vehicles, wood products, postharvest commodities, and food processing facilities. This research investigated the feasibility of using SF as a preplant soil fumigant for purple nutsedge control in plastic-mulched tomato production. SF treatments included SF injected through drip tapes or SF injected through drip tapes a few hours following shank injection of chloropicrin (Pic). Results revealed that SF alone at 224, 336, or 448 kg ha−1 was generally less effective compared with when it was applied in conjunction with Pic at 168 kg ha−1. SF alone provided inconsistent control of purple nutsedge. In contrast, SF + Pic was as efficacious or more efficacious on purple nutsedge than the industry standards, including 1,3-dichloropropene (1,3-D) plus Pic and metam potassium. None of the fumigant treatments visually injured tomato plants, stunted growth, or adversely affected tomato yield. In one of the four tomato seasons, tomato plants growing in plots fumigated with SF + Pic resulted in taller tomato plants and higher markable yields. Results indicate that soil fumigation with SF + Pic is safe on plastic-mulched tomato and effectively controls purple nutsedge.

Economic nitrogen doses via fertigation for corn cultivation in a semiarid environment

Producers in the northeastern semiarid region of Brazil have been cultivating irrigated corn. The commercialized product comprises mainly green ears and silage. However, the irrigation of crops for dry grain has been questioned regarding costs and price competitiveness in relation to the same non-irrigated product cultivated in other regions. In recent years, the use of drip tapes and fertigation has spread among corn producers in the region. The aim of this study was to determine the N dose, via fertigation, which provides the maximum economic production of corn for dry grain, in two crop seasons (summer and winter), in the semiarid region of Brazil. The experimental design was performed in randomized blocks, with four replications. In both crops, the treatments consisted of four doses of N (0, 80, 160, and 240 kg ha-1) applied in the form of urea. In the hybrid corn (Bt Feroz), the N content was evaluated in terms of leaves, grain yield, gross and net incomes, the rate of return, and the profitability index. Independent of the crop season, the yield of dry grain (5,441.03 kg ha-1) was highest when the corn was fertigated with a dose of 104.05 kg ha-1 N. The highest net incomes of the dry grain were obtained with 80 kg ha-1 N in summer (R$ 1,190.78 ha-1) and 160 kg ha-1 N in winter (R$ 2,757.54 ha-1). The winter crop was more favorable to the economic production of dry grain.

Effect of different production types on the yield and ß-carotene content of sweet potato /cultivar Ásotthalmi- 12/

Production of sweet potato is extending in Hungary, despite the fact that there is no field-specific production technology. Therefore, many growers cannot utilize potential yields and quality. The goal of this study was to determine the optimal production method of the Ásotthalmi 12, a Hungarian sweet potato cultivar which can adapt to the Hungarian climate. The effect of single and twin rows production on the yield of this cultivar was examined. The planting was carried out on June 24th, the harvesting on October 20th and the growing-season was 120 days long. Uniform nutrient supply was applied to the whole field experiment. During basic fertilization, 206 kg Knd 20 kg N, 36 kg P ha-1 were used on the soil. While forming the ridges, we used an additional 25 kg N, 45 kg P and 62.5 kg K ha-1. We adopted drip tape irrigation on the experimental field. After the planting, from the 8th week of the vegetation, another 21 kg ha-1 K, 10 kg ha-1 MgSO4, and 2 kg ha-1 Ca(NO3)2 was added in one dosage weekly, until the 13th week of vegetation. At the evaluation of the experiment, we examined the yield regarding the whole experimental plot. SPAD and fluorescence measurements were carried out on 08.16. 2019, 08.28.2019, and on 09.13.2019, during the watering break. To demonstrate the difference between the dates, we applied ANOVA and Tukey post-hoc tests. For the measurement of phytonutrients HPLC, a liquid chromatograph was used, where the carotenoid content of the Ásotthalmi 12 cultivar was determined in connection with the different production methods. Test results showed that twin rows production leads to a nearly 30% greater yield, than single row production. We determined, that the growth of yield correlates negatively to the ß-carotene content of the Ásotthalmi 12 cultivar sweet potato.

Simulation analysis of the effects of friction on the performance of pressure regulator for drip tape

Pressure regulators (PRs) are critical equipment to ensure the safety and uniformity of irrigation systems, and their performance and stability are affected by the friction produced by the seal rings. This paper addresses the effects of friction on the performance of a drip tape inlet PR sealed by an O-ring. A dynamic numerical model considering the friction force was developed. The performance of the PR and characteristics of motion of the internal moving parts under different friction levels, inlet pressures, and flow conditions were calculated and analyzed. The results show that the simulated precision for outlet pressure is improved by considering the friction and depends on the magnitude of the friction force and working stages of the PR. Compared with a corresponding model where the friction is neglected, for friction levels of 2.5 N and 5 N, the normalized root mean square error (nRMSE) of the outlet pressure decreases by 3.8% and 6.9% in the transition stage and by 0.8% and 4% in the regulating stage, respectively. According to the response characteristics of the displacement curve of the regulating cup with respect to the variation in the regulation performance curve, the performance curve can be divided into three stages: the pressure raising stage, the transition stage and the regulating stage. Friction causes obvious outlet pressure fluctuations in the latter two stages by affecting the displacement increments of the moving parts, especially in the transition stage. Greater friction corresponds to greater fluctuations (expressed in terms of the variation coefficient of outlet pressure, CV) in the regulation performance curve, and the fluctuation amplitude increases with increasing flow rate. A PR with greater friction has a smaller applicable flow rate range to remain below a certain CV limit. When the friction is less than 7.5 N, the PR is suitable for a flow range of 400–1000 L/h. The rate of variation in the outlet pressure (δPout) increases as the friction increment and flow rate increase and the inlet pressure decreases. δPout can be greater than 20%, mainly in the transition stage and when the friction increment is greater than 7.5 N. Considering the changes in outlet pressure caused by the lubricant loss and O-ring aging during long-term use of PRs, regular inspection and maintenance are recommended for PRs installed downstream of a submain, especially ones with long drip tapes.

Effect of allowable flow-rate variation and local head loss on maximum length of non-pressure compensated drip tape

A challenge for the design of drip irrigation systems with non-pressure compensated emitters is to increase the maximum length of the lateral lines without significantly reducing water application uniformity. This work evaluated the effect of the flow-rate variation and the local head loss in the maximum length of drip tape with a non-pressure compensated flat emitter. The tests were carried out in a laboratory, using a collapsible drip tape non-pressure compensated in three 50-meter segments. The production line was configured to generate drip tapes without insertion of emitters and with closed emitters (0.30 m spacing). The experimental local head loss was compared with the Darcy-Weisbach equation's estimates using the Blasius friction factor. In the sequence, simulations were generated for the flow-rate variations of 10 and 20% for the emitter spacings of 0.30, 0.40, and 0.50m. The results showed that the local head loss had little influence on the lateral line's maximum length, generating variations of 2.5% on average. However, increasing the allowable flow rate variation from 10 to 20% resulted in a 34% increase in the lateral line maximum length. Also, the reduction in uniformity coefficients was less than 5%, enabling the indexes to remain above 90%. The adoption of higher flow rate variation values allowed gains in the lateral line length with a small decrease in uniformity, making it an alternative to reduce design and operational costs.

Effects of wheat row spacing layout and drip tape spacing on yield and water productivity in sandy clay loam soil in a semi-arid region

Recent droughts and subsequent reduction of water resources in arid and semi-arid regions have highlighted the necessity of altering surface irrigation techniques to modern methods of irrigation. The present study compares drip irrigation tubes with 60 and 75 cm spacing with the furrow irrigation prevalent in Hamedan province, Iran and investigates the effects of the former form of irrigation on the productivity of wheat crops with various cropping layouts. This experiment was implemented as a field-scale experiment in sandy clay loam texture soil and consisted of the following treatments: 4 cultivated rows with 15 cm spacing on both sides of the drip tape, and 75 cm spacing between tapes (T1); 4 cultivated rows with 20-cm row spacing, and 75 cm drip tape spacing (T2); 3 cultivated rows with 20 cm row spacing and 60-cm drip tape spacing (T3); 4 cultivated rows with 15 cm row spacing and 60 cm drip tape spacing (T4); 2 cultivated rows with 30 cm row spacing and 60 cm drip tape spacing (T5); and furrow irrigation which consisted of 4 cultivated rows with 12 cm spacing on the ridge and 60 cm furrow spacing (F). The results showed that the maximum and minimum value of the two-year average grain yield and irrigation water productivity were those of T1 and F treatments at 7443 and 5996 kg ha−1 and 1.91 and 1.02 kg m−3, respectively. The maximum and minimum values of two-year average weight of 1000 kernels were also obtained from T1 and F treatments at 44.3 and 42.1 g, respectively. The mean irrigation water productivity obtained for drip and furrow irrigation treatments were 1.74 and 1.01 kg m−3, respectively. Results indicated that drip irrigation caused a 33% reduction in applied irrigation water use and a 72% increase in irrigation water productivity in comparison to the furrow irrigation method.