Journal of Water Research in Agriculture
Year:2017 | Volume:31 | Issue:2 |Papers Count:12

Optimal uses of water resources due to climate change and the recent drought conditions seem to be necessary. One of the most important and effective strategies is using the modern irrigation systems. Therefore, this experiment was conducted in Hamedan Agriculture and Natural Resources Research Center in a split plot arrangement based on a completely randomized block design with three replications. Main plots were irrigation systems (Sprinkler, Tape, and Furrow) and sub plots included wheat genotypes (Alvand, Toos, and two lines C-81-4 and CD-5009). In spite of different amounts of water used in the studied irrigation systems, results showed that grain yield of the evaluated genotypes did not have significant differences in different irrigation systems, although the difference between grain yield in the tape and the furrow irrigation system was around 1000 kg/ha. Also, differences among the evaluated genotypes were not significant. Water productivity in the tape, sprinkler, and furrow irrigation (regardless of effective rainfall), was 1.6, 1.1 and 0.69 kg per unit of water consumption, respectively. Water productivity in tape irrigation increased about 132% and 45 percent compared to furrow and sprinkler irrigation. Economic evaluation, however, showed that sprinkler and tape irrigation systems had economic justification for all of the evaluated genotypes in comparison with furrow irrigation. Besides, sprinkler irrigation had economic preferences in comparison to tape irrigation.

Effects of six irrigation treatments on vegetative characteristics, yield, and sugar content of sugar beet and water use efficiency were investigated. The experiment was conducted at Aleshtar in Lorestan province during growing seasons of 2014 and 2015, using a randomized complete block design. Irrigation treatments consisted of full irrigation (T1) as the control, T1 +cutting off the last irrigation (T2), 10% higher than the control (T3), 10% less than the control (T4), 20% (T5) and 30% less than the control (T6). The results of combined analysis of variance showed that the effects of different irrigation treatments on leaf area index, tuber dry weight, root yield, biomass, sugar content, sugar yield and water use efficiency on the basis of sugar yield was significant at 1% level. However, their effects on leaf dry weight and water use efficiency on the root yield basis was significant at 5% level. Although there were no significant differences between T2, T3, and T4 treatments in terms of crop vegetative characteristics, root yield, biomass and sugar yield, they increased these characteristics significantly compared to T5 and T6 treatments. Also, the highest water use efficiency on the basis of both root and sugar yield was obtained in T2 and T4 treatments. Therefore, to conserve water in sugar beet production in Lorestan province, decreasing the amount of water up to 10 % at each irrigation during the growing season or cutting off the last irrigation is recommended.

Iran has been faced with severe water resources scarcity and significant share of these scarce resources have been used in agricultural sector. One of the most important strategies for reducing the impact of these shortages is to improve the agricultural water productivity (WP) and to reduce utilization of water resources, which will be discussed in this article. This research is of both applied and development type and its methodology was based on library studies and field activities, using documentary study, survey and exploration. The statistical population consisted of experts and specialists of administrative institutions, university professors and research specialists in the field of agricultural WP, together with experienced farmers. All these stakeholders were selected by purposive sampling method. The study aimed to identify the most important processes for improving WP and to prioritize them. Through library and archival studies, and then by using the feedback obtained from professional meetings and interviews with the experts and stakeholders. Therefore, 2 centric process, 4 main processes, and 16 index processes were identified and were identified by means of questionnaire. The ranking of importance was determined on a LIKERT five option range, and then the results, questions, and hypotheses were examined by help of statistical software. Accordingly, the impacts of identified processes on improving WP were different, but all the processes had strong positive impact. Of the two centric process, "agricultural product reform processes" by a factor of 0.938, among the 4 main process, "reform process of agricultural production" by a coefficient of 0.786, and among the 16 indicators processes, the process of "reuse (recycling of) agricultural water" with a coefficient of 0.785, had the greatest impact on improving agricultural WP.

In order to investigate the effect of different amounts of lead and chromium accumulation in soils and vegetables (cress and parsley), an experiment was conducted in pots in the research greenhouse of Sari Agricultural Sciences and Natural Resources University, in 2011. The pots had a height of 22 cm and diameter of 28 cm, filled with loamy soil.  The experiment had factorial arrangements based on randomized complete block design with three replications and sixteen treatments. Treatments consisted of four levels of lead in irrigation water (0, 500, 1000, 1500 mg l-1 of lead nitrate source (and four levels of chromium (0, 100, 200, 400 mg l-1 of chromium nitrate source), while treatments were studied as separate and combined. The correlation result showed that the application of different amounts of lead and chromium in water had significant effect on total and available concentration of lead and chromium in the soil. Increasing the amount of lead in irrigation water decreased the amount of chromium in surface soil and increased the amount of total and available lead in cress and parsley soil. Also, with increase in the amount of chromium in irrigation water and decrease in the amount of lead in combined treatments, the amount of total and available chromium increased. The result showed that with increasing the soil contamination by using a solution having 1000 mg l-1 Pb, lead concentration increased in shoot compared to the control and, at higher levels of contamination, lead concentration decreased in root. The reason might be the explained by saying that with increase in roots lead content, most probably, it deposited in root as insoluble compounds and did not transmit to the shoot. However, in the case of chromium, it is immobile due to remaining in the cation exchange sites and its tendency for hydrolysis and absorption.  The chromium bond to hydroxyl groups on the roots cell walls prevents movement of this ionic form to shoots. The highest accumulated lead in vegetables shoot was in 1000 mg l-1 lead treatment and the highest accumulation of chromium in the studied vegetable shoots was in 400 mg l-1 chromium treatment. It is obvious that there are significant health risks in use of polluted water for irrigation of vegetable fields and fruit gardens. Contamination of these products has caused a dilemma that, according to health professionals, is a catastrophe.

Innovative irrigation practices can enhance water consumption efficiency and economic returns. In this study, the effect of two irrigation methods and four different planting patterns on the yield and economic returns of potato crop were evaluated. For this purpose, an experiment was conducted in Ekbatana Agricultural Research Station in Hamedan for three years (2013-15), using a split plot randomized complete block design. The treatments included two main factors, sprinkler and drip irrigation, and four planting pattern in subplots. Economic analysis of the treatments was conducted by using Benefit-Cost Ratio (BCR), Internal Rate of Return (IRR), and Equivalent Uniform Annual Net Profit (EUANP) criteria. The results showed that the conventional planting in drip irrigation method was economically the superior treatment. For superior treatment, the calculated BCR was 1.48, with IRR of 287.49% and EUANP of 79.1 million Rials/ha. The impact of planting pattern in sprinkler irrigation method on economic return of the treatments was remarkable, such that the IRR and EUANP of all sprinkler treatments were more than double the conventional planting. The planting pattern with 60 cm distance in sprinkler irrigation method had the highest economic return.

Innovative irrigation practices can enhance water consumption efficiency and economic returns. In this study, the effect of two irrigation methods and four different planting patterns on the yield and economic returns of potato crop were evaluated.  For this purpose, an experiment was conducted in Ekbatana Agricultural Research Station in Hamedan for three years (2013-15), using a split plot randomized complete block design. The treatments included two main factors, sprinkler and drip irrigation, and four planting pattern in subplots. Economic analysis of the treatments was conducted by using Benefit-Cost Ratio (BCR), Internal Rate of Return (IRR), and Equivalent Uniform Annual Net Profit (EUANP) criteria. The results showed that the conventional planting in drip irrigation method was economically the superior treatment. For superior treatment, the calculated BCR was 1.48, with IRR of 287.49% and EUANP of 79.1 million Rials/ha. The impact of planting pattern in sprinkler irrigation method on economic return of the treatments was remarkable, such that the IRR and EUANP of all sprinkler treatments were more than double the conventional planting. The planting pattern with 60 cm distance in sprinkler irrigation method had the highest economic return.

The scarcity of freshwater and increasing water demand for irrigation has led to the application of new irrigation methods and also use of saline water resources. For this purpose, a field study was conducted in two crop seasons (2014 and 2015) for evaluating the effect of quantity and quality of irrigation water on morphological attributes and quality of sunflower in the experimental farm of Sari Agricultural Sciences and Natural Resources University. Treatments were arranged as factorial based on randomized complete block design with three replications. treatments included full irrigation with fresh water (FI), full irrigation with saline water (SI), full irrigation with alternative use of saline water and fresh water (FSI), partial root zone drying irrigation with fresh water (PRD1), partial root zone drying irrigation  with saline water (PRD2) and partial root zone drying irrigation with alternative use of saline and fresh water (PRD3). Saline water with an electrical conductivity of 5.4 dS/m was obtained from 20 percent mixing of Caspian seawater with fresh water. The results showed that, in most morphological characteristics, significant difference was not found between the treatments of PRD1, PRD3 and FSI compared with FI. The highest oil content (56%) was obtained from PRD2 and PRD3. SI treatment had the lowest oil content. The maximum oil yield was found in treatments FI and PRD1 with amounts of 1831 and 1783.5 kg per ha, respectively. The lowest level of oil and protein yield was found in PRD2 and SI treatments in both years. It could be concluded that in the water crisis condition and the need to use less water or saline water instead of fresh water, PRD3 and FSI methods are recommendable as the optimal management.

Soil moisture characteristics curve has a great importance in soil and water researches related to irrigation and drainage, soil conservation and solute transport. Since the direct measurement of this characteristic of the soil is time-consuming and expensive, the estimation of soil moisture curve points by using pedotransfer functions and reliable soil properties can save cost and time. The aim of the present study was assessment and comparison of Ostovari-Beigi (2013) and Ghanbarian-Millán (2010) pedotransfer functions, both of which were derived from the same database (UNSODA), for estimating 8 points of soil moisture curve. For this purpose, data of 119 soil samples of Europe (HYPRES database) were used. Results revealed that functions of Ostovari-Beigi (2013) have a good and similarity performance with the function of Ghanbarian-Millán (2010) at low suctions. At high suctions and near the permanent wilting point, Ostovari-Beigi (2013) functions, which used the fractal dimension of soil texture as an independent variable input, had a higher performance than Ghanbarian-Millán (2010) functions. Also, at some suctions, both Ostovari-Beigi (2013) and Ghanbarian-Millán (2010) functions did not have appropriate performances for estimation of the soil moisture. Generally, it can be concluded that the performance of Ostovari-Beigi (2013) functions (with one input parameter, the fractal dimension) in predicting the retention curve points is similar to, and sometimes better, than the functions of Ghanbarian-Milan (2010) (with a large number of input variables).

Soil water content (SWC) plays an important role in plant growth, particularly in rainfed lands in arid and semi-arid regions. Knowledge of the variability of SWC is critical for understanding a range of hydrological processes including infiltration, runoff, and evapotranspiration. It is an integrative state variable affected by climate, soil properties, land cover, and topography. In this study, the variability of SWC was investigated in seven wheat rainfed lands with 4%, 8%, 11%, 15%, 18%, 20%, and 24% slope under fallow conditions in west of Zanjan province. The SWC was measured at a depth of 20 cm in three plots (1.5 m×2.5 m) with 5-day interval during the growing period of winter wheat from 2014 to 2015. The SWC showed a large variation during the study period which was associated with the monthly variation of precipitation. Significant (P< 0.01) difference in the SWC was found among the lands. The SWC steadily decreased from 4% to 11% slope and showed a negligible decline in higher slopes (15-24%). Decrease in the SWC in the lands was attributed to increases in the surface runoff. Correlation matrix (r) for determining the effects of land characteristics (slope gradient and soil properties) showed that the SWC was significantly correlated with slope gradient, sand, clay, organic matter contents, and soil infiltrability. Multiple regression analysis indicated the SWC was significantly (R2=0.78, P<0.01) related to slope gradient and sand content. The SWC in the semi-arid rainfed lands can be reliably estimated using the slope gradient and sand content in the soil.

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.

Most of the water in Iran is used in agricultural sector. In recent years, due to loss of attention to this scares production input and incorrect and excessive use, as well as the droughts, the water shortage issue has turned into a serious crisis. So, the planners should work to make a decision in order to minimizing water consumption and prevent the water  from wasted and misused by providing appropriate cropping pattern and also using advanced technologies of irrigation systems. In this study, the applied model is multi-objective genetic algorithms in MATLAB with nondominated sorting. For this study, for crop seasons 2011-12 to 2014-15, the data of cultivated areas, yield, price and the costs of productions of irrigated crops including wheat, barley, maize, alfalfa and sugar beet crops were obtained from Office of Agriculture in Zaveh plain, Khorasan-Razavi province. Also, the data of Regional Water Authority of Khorasan Razavi and the water supplied from Senobar Station was used. Some required data were obtained through consultation with experts. Comparing the results of the estimated cultivation areas with the actual statistics of cultivated areas for each crop in each year showed that the optimum cropping area of wheat and barley obtained from the model was lower than the actual cropped area. But, corn crop showed an increase in cultivation area which is highly desirable and increases the irrigation scheduling returns and sustainability of agriculture. Considering the importance of minimization of the deviation of the irrigation schedule presented by the experts and farmers, it is recommended that the irrigation scheduling plan for the farmers should take into account the viewpoints of both the farmers and the experts.

The use of pressurized irrigation technologies that significantly reduce water use is highly recommended, due to drought conditions in the agricultural sector which has the country's highest rate of water use. Since the most important issue in technology development is the adoption of these technologies by the stakeholders, this study attempted to examine the factors influencing the farmers’ adoption of pressurized irrigation. The research was done in four villages, namely, Ghochtapeh, Ahutapeh, Chenare Sofla, and Chenare Olya in Asadabad County. The research population was 90 farmers who were cultivating their farms under pressurized irrigation technology. Data of this study were collected through a questionnaire tool. Data processing was done through SPSS and AMOS software. The research findings showed that the variables including “perceived usefulness”, “perceived ease of use”, and “attitude to use” had a significant and positive impact on the decision to accept the use of pressurized irrigation systems. Finally, based on the research findings, it is recommended that more information should be prepared and awareness disseminated among farmers about pressurized irrigation systems through magazines, brochures, and other social media. Also, to promote adoption of the pressurized irrigation, some infrastructure and the required facilities for adoption should be provided for the farmers.