Ali Pahlevani; Hamed Ebrahimian; Fariborz Abbasi
Abstract
Surface irrigation systems have been widely used in in arid and semi-arid regions of the world, but inappropriate design and management has led to high water losses and reduced water productivity. The objective of this research was to investigate the effect of plastic mulch placements in furrow irrigation ...
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Surface irrigation systems have been widely used in in arid and semi-arid regions of the world, but inappropriate design and management has led to high water losses and reduced water productivity. The objective of this research was to investigate the effect of plastic mulch placements in furrow irrigation on soil water distribution and water productivity under fodder corn production. Field experiments were carried out in Karaj in 2018. Four different treatments were considered in terms of plastic mulch placements including mulch on the ridge (R), mulch on the furrow bed (F), mulch on the ridges and the furrow bed (FR), and a treatment without mulch or control treatment (C). In order to measure water content, soil samples were taken one day before and three days after each specific irrigation event with 5 days intervals from four points (at 0-25 cm and 25-50 cm under the ridges and furrows) for all treatments. The mean values of volumetric water content during the growing season for the FR, F, R and C treatments were 24.8, 23.8, 18.0 and 17.1 percent, respectively. The results indicated that plastic mulch had substantial impact on retaining the soil moisture by reducing evaporation from the soil surface and the treatments with plastic mulch on the bed of the furrow (FR, F) had the highest soil moisture in comparison to the other treatments. Water productivity for dry matter of the FR, F, R and C treatments was 4.5, 4.4, 3.6, and 3.0 kg/m3, and for fresh matter of the FR, F, R and C treatments was 7.6, 7.4, 5.7, and 4.7 kg/m3, respectively. Based on the results, using plastic mulch on the furrow bed is recommended in order to reduce water loss and increase water productivity in furrow irrigation. Considering the effect of plastic mulch in maintaining soil water content, it is also recommended to utilize this method with the deficit irrigation method. Economic aspects should be taken into consideration in the future research on this topic.
Reza Delbaz; Hamed Ebrahimian; Fariborz Abbasi; Arezoo Nazi Ghameshlou
Abstract
The explosive growth of science and the dissemination of various results have confused researchers in various fields. Simple surveys and reviews of results collected in a specific area seem necessary. Meta-analysis as a structured method and using statistical methods aggregate the results of studies ...
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The explosive growth of science and the dissemination of various results have confused researchers in various fields. Simple surveys and reviews of results collected in a specific area seem necessary. Meta-analysis as a structured method and using statistical methods aggregate the results of studies on a subject. In this study, in order to assess the surface and drip fertigation based on crop yield and water and fertilizer productivity, a meta-analysis approach was used. For this purpose, studies of eight databases were recruited, and, after reviewing them, 21 studies had the conditions to enter the meta-analysis. Combined results showed that both surface and drip fertigation methods significantly increased the indicators of crop yield and water and fertilizer productivity. Measuring the effect size of the results for crop yield in surface and drip fertigation methods compared to surface irrigation with traditional fertilization method was equal to 1.32 and 1.25, respectively. The effect size of water productivity for surface and drip fertigation compared to surface irrigation with traditional fertilization methods was 1.24 and 1.74. These values were 2.12 and 1.43, respectively, in terms of fertilizer productivity. Therefore, both surface and drip fertigation methods increase crop yield and water and fertilizer productivity. The results of this study are derived from the quantitative data of preliminary studies, to achieve higher accuracy, it is suggested that further studies be examined by meta-analysis.
Mohammad saeid Jafari; Hamideh Noory; Abdol-Majid Liaghat; Hamed Ebrahimian
Abstract
Lettuce is one of the most important leafy vegetables used primarily for fresh and salad applications. The purpose of this study was to investigate the effect of different levels of water and nitrogen on lettuce yield and find the best irrigation and nitrogen fertilizer practices for producing this crop ...
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Lettuce is one of the most important leafy vegetables used primarily for fresh and salad applications. The purpose of this study was to investigate the effect of different levels of water and nitrogen on lettuce yield and find the best irrigation and nitrogen fertilizer practices for producing this crop in drip irrigation. Iceberg variety of lettuce was planted in 2018 with three irrigation treatments (I1, I2 and I3 to provide 100%, 80%, and 60% of crop evapotranspiration, ETa, respectively) and four nitrogen treatments (N1, N2, N3, and N4 to provide 105, 70, 35 and zero kg of nitrogen per hectare in total, respectively). In 2019, two irrigation treatments (I1 and I3) and two nitrogen treatments (N1 and N4) were used. The experiment had a randomized complete block design with three replications. The results indicated that the effect of irrigation and nitrogen treatments and their interactions on the marketable yield of lettuce; but the dry matter produced was only affected by irrigation and nitrogen treatments. Maximum marketable yield and dry matter production were 66.1 ton.ha-1 and 2728.2 kg.ha-1 for full irrigation treatment with 105 kg.ha-1 nitrogen (I1N1) treatment, respectively. The minimum marketable yield and dry matter were 37.5 ton.ha-1 and 1929.6 kg.ha-1 for 60% ETa treatment with 35 kg.ha-1 nitrogen (I3N3) treatment, respectively. The maximum and minimum irrigation water productivities for marketable yield were 21.63 and 15.38 kg.m-3 for I2N1 and I3N3 treatments, respectively. The linear and nonlinear production functions of yield-water and yield-nitrogen were obtained for lettuce variety Iceberg, which can be used in similar environmental conditions in research and practical applications.
Mohammad Hassanli; Peyman Afrasiab; Mahmoud Sabuhi; Hamed Ebrahimian
Abstract
The economic value of water is one of the most important factors for allocating water among various consumptions and encouraging users to take necessary actions to increase investments related to improving water productivity. There are several methods for economic valuation of water. In this study, due ...
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The economic value of water is one of the most important factors for allocating water among various consumptions and encouraging users to take necessary actions to increase investments related to improving water productivity. There are several methods for economic valuation of water. In this study, due to the key role of water in irrigation of agricultural products, residual valuation method was used for agricultural wells in Varamin County, with a wide range of water salinity. The average economic values of water for cucurbits, wheat, barley, and alfalfa were 2513.1, 5334.5, 1933.0 and 5647.6 Iranian Rials per cubic meters (IRR.m-3), respectively. The exchange price of water among the farmers in the study area was calculated as 5231.8 IRR.m-3, which was close to the calculated residual value for wheat and alfalfa crops. The coefficient of determination (R2) for the relationship of economic value and salinity of irrigation water for the above crops was 0.806, 0.878, 0.865 and 0.702, respectively, which indicates that the main changes of economic value of water is related to salinity of water. According to the relationship between salinity and irrigation water value in the study area, the residual value of water was zero in the electrical conductivity of 3.61, 7.30, 6.05, and 8.24 dS.m-1 for cucurbits, wheat, barley, and alfalfa, respectively. As a result, the water pricing policy in the study area should be such that for water salinities higher than the mentioned values, the selling price of water is set lower than the current value, so that the farmers do not suffer losses. Another option is that choice of crop should be based on greater resistance to salinity and its economic value.
Arash Ranjbar; Ali Rahimikhoob; H E; Maryam Varavipour
Abstract
Transport and transformation of urea, nitrate, and ammonium in the soil take place as a sequential decay chain reactions which should be considered altogether for more precise management of water and fertilizer in agricultural farms. In this study, HYDRUS-2D model was evaluated to predict distribution ...
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Transport and transformation of urea, nitrate, and ammonium in the soil take place as a sequential decay chain reactions which should be considered altogether for more precise management of water and fertilizer in agricultural farms. In this study, HYDRUS-2D model was evaluated to predict distribution of water, nitrate and ammonium under furrow and ridge during the growing period of maize. Thus, maize was planted in the treatments with nitrogen rates of 0, 150, and 250 kg ha-1. The amounts of nitrogen uptake, soil water, nitrate, and ammonium concentrations during the growing season, before and after fertilization, and after harvesting were measured over different depths under ridges and furrows. Results showed suitable agreement between predicted and measured water, nitrate and ammonium distribution in soil during validation stage. NRMSE and R2 as evaluation indexes for the predicted soil water were calculated as 0.772 and 4.37%, respectively. Besides, these indexes were calculated for the predicted ammonium concentration under furrow and ridge for all treatments and were found to be in the range of 0.645-0.798 and 14.23%-29.4%, and for the predicted nitrate concentration, they were in the range of 0.716- 0.829 and 23.57%- 25.2%, respectively. According to the results of this study, the HYDRUS model is a useful tool for management of water and fertilizer in furrow irrigation.
A J; M M; H E
Abstract
In management of surface irrigation, infiltration function is important. Quantitative understanding of this phenomenon is essential in preventing soil erosion and water losses. The main objective of this study was to estimate the coefficients of infiltration equations (Kostiakov-Lewis, Philip, and Horton) ...
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In management of surface irrigation, infiltration function is important. Quantitative understanding of this phenomenon is essential in preventing soil erosion and water losses. The main objective of this study was to estimate the coefficients of infiltration equations (Kostiakov-Lewis, Philip, and Horton) and evaluate the sensitivity and performance of these equations under various initial (initial soil moisture) and boundary conditions (water head on soil surface). Therefore, two-dimensional infiltration for furrow irrigation were simulated by changing the initial soil moisture (before irrigation) and water head on soil surface (during irrigation) using the solution of the Richards’ equation (HYDRUS model). To determine the coefficients of infiltration equations, outputs of the HYDRUS model (cumulative infiltration over time) were fitted. Evaluating the performance of infiltration equations via statistical evaluation indicators showed that infiltration empirical equations (Kostiakov-Lewis and Horton) had better performance than the physical equation (Philip) to estimate the cumulative infiltration under various initial and boundary conditions. Kostiakov-Lewis equation ranked the first in all cases of estimating infiltration by simulations, followed by Horton and Philip equations. Sensitivity assessment of the coefficients of the equations showed the power coefficient (b) of Kostiakov-Lewis equation as the most sensitive coefficient, while the final infiltration rate coefficient ( 15ff"> ) in Horton equation was the least sensitive. The results also showed that Horton equation was the most sensitive equation in evaluation of infiltration equations sensitivity.