جستجوی مقالات مرتبط با کلیدواژه « Localized irrigation » در نشریات گروه « آب و خاک »

In order to investigate the effect of different levels of water salinity and deficit irrigation in one-row strip tape irrigation on the chemical properties of the soil in grain maize cultivation, experiment was carried out in the research farm of the College of Agriculture, Shiraz University, Iran in 2018. Factorial experiment was performed in a randomized complete block design in three replications. Four levels of irrigation water salinity were including control (0.6), 2, 3.5 and 5 dS m-1 and three irrigation levels were full irrigation (FI), 75% and 50% of full irrigation. The results showed that the increase in salinity from 2 to 5 dS m-1 increased 57, 58, and 61 % in Ece, 35.76, 36, and 40 % in soil chloride, 62, 60, and 66 % in soil sodium, and 49, 45 and 53% in sodium absorption ratio at FI, 75 and 50% of full irrigation, respectively. The results related to the relationship between irrigation water salinity and soil chemical properties, including: salinity of saturated soil extract, chloride, potassium, sodium concentrations and sodium absorption ratio, showed that applying deficit irrigation reduced the slope of the regression line compared to full irrigation. In terms of water shortage, it is recommended to practice 50% FI with a salinity level of 2 dS m-1 from the perspective of water resources management and soil salinity management. This approach takes into consideration the need for salt leaching to prevent salt accumulation in the soil.

With the development of localized irrigation in arid and semi-arid areas, the soil is more susceptible to salinization. The salt accumulation in the soil can reduce crop yields, destruction of plants and even resulting the soil uncultivable. In this research, flood leaching and trickle leaching methods (tape) were investigated in a pistachio orchard. Comparing with the flood method, the results showed that, the amount of leaching water used in the trickle method was reduced by 62.7% for the first leaching leading to a total reduction of 26.7%. In the flood leaching method, the entire surface of the farm is leached, while in the 6-row method water to be directly use in saline accumulation areas, which saves leaching water. Also, in the trickle and flood methods the uniformity coefficient of salinity distribution increased by 7% and 3% respectively. In the trickle method, the salt mass balance added due to irrigation can be removed with only one washing step, while in the flood method, the mass of leached salt is less than the mass of added salt. For orchards leaching with localized irrigation, it is recommended to apply more leaching water to salts accumulation areas and for improving the salts management effectiveness low-leaching rates applied alternately is recommended.

Water and nitrogen fertilizer are the most important agricultural inputs in the production of tea leaves and shoots as yield. In some months (mid-June to early September), the amount of rainfall is less than the water requirement of tea plants and the amount and quality of the product due to water shortage stress is greatly reduced, which threatens the livelihood of farmers and the region's economy. Therefore, supplying the required water of the tea plant by using supplementary irrigation and correct principles of operation is the most important issue in increasing the quantity, quality and marketability of the tea produced and its economic efficiency. The use of conventional fertilizer application in the region, ie fertilizing mixed with soil in rainfed (without irrigation) and irrigated (sprinkler irrigation) fields had high losses and low efficiency. Reports show that more than 60% of tea plantations in Guilan and Mazandaran provinces are located in highlands and sloplands regions. Currently, sprinkler irrigation methods are used to irrigate less than 5% of the total tea growing regions (about 20,000 ha), while production in other regions is entirely dependent on precipitation. Technical limitations and restrictions related to the design and implementation of sprinkler irrigation methods in these regions are the main reasons for the underdevelopment of irrigated lands in tea growing regions. This issue and the lack of access to reliable water resources in these regions, highlights the importance of using drip irrigation in tea plantations. Therefore, the main challenge in this situation is the implementation and development of effective and low-cost irrigation methods that have high water productivity and are cost-effective for farmers.In order to optimize water and fertilizer use in drip irrigation system in tea fields, a field experiment was conducted in 2017-2018 in tea plantation in Bazkiagoorab region, Lahijan (Guilan province). The experiment was conducted as split plots in a randomized complete block design with two factors of irrigation water and nitrogen fertilizer in three replications. Fertilizer was considered as main factor in four levels of 0, 100, 150, 200 kg N ha-1 (N0 to N3) and irrigation as a sub-factor in five levels of 0, 25, 50, 75 and 100 water requirement percentage (I0 to I4). In the irrigation system of this research, on-line drippers (surface drip irrigation) of Netafim company with design flow rate of 4 L hr-1 were used. Sub-pipes (laterals) approximately 5 m long were placed in the middle of every two rows of tea plants throughout the experimental plot (except plots without irrigation). Seven drippers with a distance of 0.7 m (one dripper per plant) were installed on 16 mm laterals. Drip irrigation scheduling in water stress period was conducted twice a week based on soil moisture monitoring and fertilization (nitrogen) program once a week during growth period by fertigation at plant root depth. The maximum yield average (2581 kg ha-1 of made tea) and WP(I+P) (0.685 kg ha-1 m-3) with average water use of 3845 m3 and 150 kg N ha-1 was obtained during the growth period. The average water consumption of deficit irrigation levels I3, I2 and I1 was estimated to be 3380, 2917 and 2454 m-3, respectively. The biennial average of the highest yield of made tea for irrigation treatments I3 to I1 was 2640, 1449 and 1225 kg ha-1, respectively. At all levels of deficit irrigation of the experimental years, increasing the amount of nitrogen fertilizer increased water productivity, so that the productivity values related to deficit irrigation levels of 75% of water requirement (I3) were higher than the other two irrigation levels (50% and 25%). The highest water productivity for deficit irrigation levels I3, I2 and I1 was related to the use of 150 kg of nitrogen fertilizer equal to 0.625, 0.615 and 0.555 kg m-3, respectively. Top dressing of 100 kg N ha-1 in rain-fed/no-irrigation conditions (192.7 mm of effective rainfall) resulted in 803 kg of made tea with rain water productivity of 0.42 kg ha-1 m-3. Due to the increase in yield (300%) and water productivity (60%) resulting from the application of drip irrigation fertilizer system compared to rainfed conditions, the application of this irrigation method to produce tea economically with less water and fertilizer consumption in tea growing regions, especially sloplands and highlands are recommended. In general, for more than 8000 kg of green tea leaves per hectare, application of 150 kg of nitrogen fertilizer and lower yield, application of 100 to 120 kg of nitrogen fertilizer as a solution in drip irrigation system (fertigation) is recommended

In this study, a practical procedure was proposed for hydraulic analysis of flow in drip line lateral in the drip irrigation system to determine the major and minor losses of the driplines. In this method, the friction losses between the drippers and local head losses of the drippers were calculated step-by-step and the total pressure losses of the lateral were determined by summation of the head losses. To determine the minor losses of the emitters, the power relationship between the pipe discharge and the measured head losses related to simple and drip line pipes was determined by the nonlinear regression method. Then, the difference of the obtained head losses of these relationships in different discharges was calculated. Then, the power relationship between these results and discharge was determined by using nonlinear regression again. Also, Hazen–Williams equation and Darcy-Weisbach relationship used to determine the friction head losses. The friction coefficient (f) determined using Altshul, Blasius, and Moody diagram. Thus, four different methods of combining minor and friction head losses equations were obtained and evaluated using RE, MAE and RMAE indices. Experiments were conducted on three 60-meter samples of drip lines with emitter spacing of 0.20, 0.40 and 0.50 m and a simple sample with 16 mm diameter at 50, 100, 150, and 200 kPa pressures. The results indicated that the Darcy-Weisbach relationship based on the Blasius relationship was more accurate than the other methods. Also, the performance of the proposed experimental relationships were acceptable to estimate the local head losses. Therefore, the proposed method is recommended to calculate the head losses in the dripline laterals.

Pressurized irrigation methods can be a suitable solution for optimal use of water resources, provided that the selection, design, implementation and operation of irrigation systems are done with sufficient care and according to the principles. In decision-making and implementation of pressurized irrigation systems at the sub-regional and regional scale, several factors such as water, soil and climate along with socio-economic factors are of particular importance. Dez Plain (including Lor, Dimcheh, West Dez, East Dez and Sabili plains) is the largest plain and one of the most important agricultural hubs in Khuzestan Province. In this study, using AHP in GIS software, the suitability of various areas for implementing different irrigation systems (localized, solid set, wheel move, centre pivot, linear, Gun, low-pressure, and surface) was investigated in Dez Plain. For this purpose, effective criteria including socio-economic and field physical conditions were considered for implementation of each irrigation method. Socio-economic criteria included four sub-criteria, namely, operation and maintenance, costs, laborers skills, and local culture, and physical conditions included water, climate, soil, and topography. The final location map was prepared in GIS software. According to the results, Dez Plain areas with high suitability for each methods were as follows: 62.77% for all sprinkler systems, 14.6% for localized irrigation, 14.3% for low-pressure irrigation, and 8.3% for surface irrigation. Among all irrigation methods, the solid-set sprinkler obtained the highest score in all parts of the study area and, in total, 15.04% of the whole plain is highly suitable for this system.

Localized irrigation methods can be used to manage low water holding capacity in the sandy soils. In this research, the effects of different irrigation systems including pot, tape and drip irrigation with gravity pressures of 0.5, 1.5 and 3 meters on the sandy soil moisture distribution under watermelon cultivation were compared with the furrow irrigation as the control treatment. The moisture content of the soil at different depths and at the distance of 5 and 20 cm from the plant was measured using the TDR device. Water distribution study showed that in the pot irrigation method, the moisture content of different depths of soil was kept constant by 16% during the irrigation interval, but the highest moisture content was observed in gravitional drip irrigation treatment at the depths of 40, 50 and 60 cm; in contrast, the lowest amount of moisture was observed in the pot irrigation treatment. In tape and gravitional drip irrigation system with gravity pressure, in addition to the adjustment soil moisture up to 15 to 22% within the wetting front, soil moisture can be kept almost constant by pulsed irrigation technique. Therefore, while providing the use of drip irrigation system with minimum water pressure available in most of the agricultural land (0.5 m), using pot irrigation can ensure sandy soil moisture retention and soil for the cultivation of fruits such as watermelon plants.

In the present study, the state of pressurized irrigation systems in Qom province was investigated. Regarding the fact that by 2016, 81% of pressurized irrigation systems in this province are local and 19% are sprinkler, therefore, 11 local and 3 sprinkler irrigation systems (including solid-set with portable sprinklers, wheel move, and center pivot) were selected for investigation. First, the water and soil characteristics of the fields were studied then coefficient of uniformity (CU), distribution uniformity (DU), the yield of potential application efficiency of low quarter (PELQ), the yield of application efficiency of low quarter (AELQ) and adequacy of irrigation (ADirr) indexes were calculated. Obtained results showed that the mentioned indexes were 74.6, 60.8, 62.6, 62.6, 62% for solid-set with portable sprinkler, 57.6, 44.7, 76.1, 71.3, 86% for wheel move, and 81, 63, 85, 85, 71% for center pivot, respectively, and the weighted average of DU, PELQ and AELQ for local irrigation were 53.9, 45.3 and 53.9 %, respectively. Finally, the observed problems of system operation were analyzed and it was found that the main reasons of low performance were due to the management and some were due to the design and performance phases.

Given the diversity of pressurized irrigation systems, the matter of choosing the appropriate system is one important issue. The appropriate system(s) in each region could be determined considering several factors such as topography, soil characteristics, climate (especially temperature and wind), crop type, quantity and quality of water resource, labor requirement, farmer's skills, economic conditions and social and cultural contexts in the region. The aim of this research was ranking of the pressurized irrigation systems in the area of 6000 ha located in the Dinawar, Sahneh district in order to select the proper pressurized irrigation system(s) in the region. Analytical Hierarchy Process (AHP) was used for ranking of the systems. For this purpose, affecting factors on the choice of irrigation system classified to physical and socio-economic categories and for each category related indicators were defined. The score of each criterion for each system was determined in the scale of -3 to based on the analysis of available data and reports in the study area. The overall score for each system was determined by weighted summation of the score of indicators. Only applicable system for areas with slope over 20% is localized irrigation system. The semi-classic and solid set-portable sprinkler irrigation systems are determined as the most appropriate irrigation systems for the area with slope less than 20 percent.

Iran is a vast country with limited water resources. Iran is located in arid areas and average precipitation is estimated to be 250 mm. In recent years, water shortage has created many problems for Iranian farmers. In these conditions, surface and ground water use is excessive. High consumption, low irrigation efficiency, bad time and geographical distribution of precipitation, population growth and increasing agricultural land are one of the main reasons for the irrigation water crisis. Therefore, the main problem of drought and water shortages still remains. The area of agricultural land in Golestan province is high, but most of them are rain-fed cultivation or left fallow. Due to the loss of irrigation water in traditional agriculture, development of pressurized irrigation as a solution to increase productivity and reduction of strain on water resources was raised. With government support, the use of pressurized irrigation systems is increasing.
To evaluate the effect of different amounts of water on new variety of cotton-Sepid, a two-year study was conducted using drip irrigation at Hashemabad Cotton Research Station, Gorgan, Iran.The Hashemabad Cotton Research Station is located in north of Iran at 36° 51' N latitude and 54° 16' E longitude at the south-east corner of Caspian Sea and its height from sea level is 13.3 meters. That station has a Mediterranean climate with relatively mild winters and relatively dry summers. The station's annual evaporation, precipitation and relative humidity are 1311mm, 525 mm and 71%, respectively. Soil texture of Hashem Abad station is silty clay loam. In this study, four levels of irrigation water: 0%, 40%, 70% and 100% evaporation of class A pan were studied in a randomized complete block design. Land was plowed in autumn last year and was ready for planting in April with the disc. During tillage, manure fertilizer on the soil surface was sprayed based on the soil test recommendations. At this stage, for combating weeds, herbicide trifluralin (2.5 liters per hectare) was used. Planting new varieties of cotton - Sepid was in the first decade of May. Each plot consists of 8 lines which was ten meters. After evaporation of 50 mm from Class A evaporation pan, irrigation is done. Irrigation tapes were placed just alternate between planting rows. Water consumption was measured using a volumetric water meter. To measure the product, cotton-seed of four rows of each plot were harvested. Yield components were measured in the same four rows. Product wastaken in October and early November during two harvesting.
Cotton as thermophilic plants, especially in humid areas, is strongly influenced by farm management. Among the controllable factors, irrigation management had very effective role in the balance between vegetative and reproductive growth. In other words, water stress control in cotton fields is essential for economic output. Through advanced techniques, drip irrigation despite high initial cost, will be the first choice. Because in addition to irrigation efficiency, with earliness management, mechanization harvesting is done better. According to the analysis of variance, the effect of different amounts of water on the total yield was significant at the level of one percent. The lack of statistical significant differences between treatments in terms of total yield of I100 and I70, the second treatment due to a 30% saving in water consumption and earliness as the best in the normal condition. One of the parameters that are usually affected by irrigation management is earliness. Average comparison shows in term of earliness, three treatments of I70¡ I40 and I0 in group A and treatment I100 are in the latter group. Thus, from this aspect I70 can be recommended. In terms of water use efficiency I40 and I70 with 1.44 and 1.17 kg per cubic meter had the highest WUE, respectively.
The results shown that irrigation water had significantly effects on first pic, second pic and total yield. But irrigation water treatments had no significant effect on earliness and boll weight. According to the combined analysis table (two years data), as much as % 70 of cumulative evaporation from class A pan, will be recommended for cotton farming in north of Iran in normal weather. In dry years, % 100 of cumulative evaporation from class Apan is suggested.

Drip irrigation is one of the effective ways to conserve water and increase water use efficiency (WUE). Despite the many benefits of drip irrigation system, a substantial amount of irrigation water is wasted through evaporation from the soil and transpiration by weeds growing between the rows. Using mulch between planting rows can maintain soil moisture, reduce evaporation from the soil and transpiration from weeds, reduce irrigation water consumption, and increase crop yield. The purpose of this study was to evaluate irrigation depth and mulching effects on potato yield and water use efficiency in Dehgolan plain of Kurdistan Province. For this propose, a field experiment was conducted in the spring season of 2014, using a split plot scheme based on randomized complete blocks design with three replications. The main plots and subplots included the amount of irrigation water at four levels (60%, 80%, 100%, and 120% of the potato water requirement) and three mulch treatments (without mulch, straw mulch, and plastic mulch), respectively. Results showed that the effect of irrigation water and mulch on yield was significant (P<0.01). The maximum and minimum amounts of potato tuber yield were related to 120% and 60% water requirement, respectively. The results also showed that the effect of mulch on potato WUE was significant (P<0.01). The highest WUE (14.96 kg.m-3) was related to plastic mulch. It is to be noted that the use of plastic mulch compared to the biodegradable straw mulch will lead to environmental problems.

The objectives of this study were to investigate the effect of dripper discharge and irrigation time on the wetted width in the sandy loam soil with high percentage of gravel and to evaluate previously developed models of estimation of the wetted width in the previous researches. The treatments included three irrigation times (T) of 4, 8 and 12 h and three dripper discharge rates (q) of 2, 4 and 8 l/h, with three replications. The wetted width of each dripper was measured 24 hours after irrigation application. The maximum and minimum wetted widths were 159.8 and 63.5 cm for T12q8 and T4q2, respectively. A linear model was developed as a function of two variables of irrigation time and dripper discharge rate was developed to predict the wetted width in sandy loam soil with high percentage of gravel. The evaluation of recommended models of wetted width for the studied soil showed that only one of six models was accurate enough to estimate wetted width. It can be concluded that the presence of gravels in the soil has a complex effect on width and depth of wetted zone. Thus, it is necessary to measure the wetted width and wetted depth in the field.