مجله آبیاری و زهکشی ایران
سال ششم شماره 1 (بهار 1391)

The research has been tested over four long-date onion cultivars for purpose of studying 3 methods of irrigation (drip, furrow and basin) on the yield, germination, water use efficiency (WUE) of onion produce at the Neyshabur Agricultural and Natural Resources Research Center for two years (2005- 2007). Three methods of irrigation were taken as main factor in three levels and cultivars of onion (Azarshahr red, Kashan White, Neyshabur Red and Neyshabur White) were sub factor in four levels. According to the essence of experiment, the treatments were analyzed in a Strip Plot design based on randomized complete blocks in three repetitions and finally the means were compared on basis of Duncan multi-domain test. The results showed that, yield average in drip irrigation method was more than another irrigation methods. Different between yields on irrigation systems were significant at the 5% level and basin irrigation had least yield. Different between yield cultivars was statistically significant at 5%. So that, Kashan with cultivar with a 19% increase compared to the other cultivars, had the highest yield. WUE in drip irrigation method was higher than other methods in 28% more than furrow method and 52% more than basin method. Economical analysis results showed that expense increment was along income decrement, so basin and furrow treatments in each row of comparisons had negative final income, and finally treatment of drip irrigation was the best among other cultivars.

Despite daily increasing water requirement, it is necessary that environmental adverse effects of each project be controlled, so revision of ability of traditional drainage systems is unavoidable. Controlled drainage is an environment friendly water management practice that conserves water and reduces nitrogen losses through reduced drainage water volume. This research was conducted in order to determine the controlled water table depth and its effects on irrigation water productivity and yield of soybean crop, by using lysimeter in 2008 in Shahrekord University. A completely randomized experimental design with three replicates, consisting of four water table treatments were used: Free Drainage/ traditional drainage (FD) as control, and depth of water table in 60-65, 40-45 and 20-25 cm from the soil surface, which named CD60,CD40 CD20, respectively. Results of variance analysis showed that the effects of drainage treatments were significant on yield components. The highest yield observed in CD60 treatment (2774 kg/ha). Lack of rapid depletion in this controlleddrainage treatment may caused water and nutrient be more available for plant. The least yield obtained in CD20 treatment with the average of 1798 kg/ha. It may be explained by water logging in the most part of root. Also lack of oxygen and creating the situations to denitrification limited efficient use of water and nutrients for plant. The maximum and minimum of irrigation water productivity obtained in CD60 and CD20 treatments. The seed production rates of these treatments were 0.45 and 0.29 Kg/m3, respectively, in comparision 0.4 in control treatment.

In this study, the water distribution uniformity of different sprinkler used in solid set systems were determined at different operating pressures, sprinkler spacing and under varying wind speed conditions The experiment was conducted in the Agricultural Experimental Station of Seed and Plant Improvement Institute (SPII) in Karaj, near the meteorological station during 2008-2009. The experimental design was randomized complete blocks design (RCBD) in factorial layout with different replications. The experimental treatments were combinations of 8 sprinklers (Farm-RC180, Jaleh 5, Komet 162, Luxor, VYR 155, Nelson24F80 with one nozzle, Rain Bird 80EHD and Nelson F80,18with two nozzle), 3 operation pressures (3, 4 and 5 Kg/cm2), 4 wind speed range (0-5, >5-10, >10-15, >15-20 Km/hr) and 7 sprinkler spacing (22.5*22.5, 22. *25, 22.5*27.5, 25*20, 25*25, 25*27.5 and 25*30 meter). The outdoor single sprinkler test method was used to determine the water distribution pattern distorted by wind action uniformity. In order to determine the water distribution uniformity under varying wind speed conditions, a set of catch-cans was set around the individual sprinkler in 2.5*2.5 arrays. The volume of water in the catch-cans was measured after 1 hour operation for each treatment. The overlapping of sprinklers was simulated and water distribution uniformity for seven sprinkler layout was calculated and the Christiansen’s coefficient of uniformity (CU) and distribution uniformity (DU) values for each treatments were determined Results showed that the sprinkler type, sprinkler spacing, operating pressures and wind speed treatments had significant effect on water distribution uniformity (P 0.01). Sprinklers type were classified in five group from A to E. Sprinklers type of Komet 162 and Nelson F80 with two nozzle had high water distribution uniformity and classified in group A. Nelson F80 with one nozzle and VYR 155 types classified in second group. Based on the results, with increasing the operation pressures, water distribution uniformity was increased non-linearly. Also, water distribution uniformity was decreased when wind speed increased more than 5 Km/hr. According to the results, the sprinkler type that classified in group A and B with the operation pressures of 4 to 5 kg/cm2 and 20*25 meters spacing was recommended for overall agricultural conditions.

Return flow is one of the main factors in reduction of water efficiency within the irrigation networks. Hence, an accurate prediction of return flow and providing the managerial strategies to reduce it’s quantity or reuse it in an optimal way could improve the efficiency of irrigation systems. In the present study, a regression tree model is developed to predict daily return flow discharge for Salimeh Irrigation Area, SIA, in Dez Irrigation Network. The daily inflow to the irrigation area, effective rainfall, consumptive water demand, percolation loss and evaporation from the surface canals are taken as predictor variables and return flow is treated as the target variable. Four sub-models of regression tree are evaluated. Model training, validation and testing carried out based on the observed data of 1386 and 1388. The model performance shows a good match between the simulated and the field measured return flow values. Results of statistical analysis indicated that the correlation coefficients are high for all sub-models and it can be concluded that the model performs satisfactorily in simulating the return flow. Accordingly, all tree regression sub-models may be recommended in the monitoring process of the SIA. The sensitivity of the model to the predictor variables is evaluated as; daily inflow> consumptive water demand> percolation loss> effective rainfall> evaporation from the surface canals. The findings demonstrate that the model has also a desirable accuracy in spite of deleting effective rainfall and evaporation from the surface canals as predictor variables.

To determine the effect of salinity imposed by saline water on the yield and water use efficiency of maize an experiment was carried out in Eshtehard-Karaj during 2000-2001. The experimental design was based on a randomized complete block design with 4 replications. The treatments were four salinity levels of irrigation water (3, 5, 7 and 9 dS/m) as vertical factors and five corn hybrids (SC301, POPEN, TWC647, S 647 and SC704) as horizontal factors. According to the results, the threshold level of irrigation water salinity in sprinkler irrigation methods for corn yield was equal to 5 dS/m and the yield decreased rapidly by increasing salinity.Among the variety of the maize, high average yield potential belong to SC704 with 2.84 ton per hectare under all salinity levels and SC301 showed lowest yield of 1.67 ton/ha. SC704 was more resistance to salinity stress and showed less leaves damages. Accordingly, maize water use efficiency was highest in SC704 and lowest in SC301. As a result, pre-ripping cultivars such as SC301 are not recommended where irrigation water is saline.

In this study, regard to sustainable use of water resources of Mashhad – Chenaran plain, wasattempted in a ten-years planning period with emphasis to achieve a non-negative balance of groundwater resources at the last year of the planning period, optimum crop pattern regard to farmers subjective priorities be examined. To achieve this objective, were used optimization methods of Non- Linear Programming (NLP) and Non-Linear Multi-objective Goal Programming (NL-MOGP) in various environmental, social and economic structures. Study results showed that applying of specified crop pattern in horizon ten years planning in addition to achieve multi- maximization of gross margin, minimizing of water use, capital costs and chemical fertilizer and pesticide consumption and remaining labor employment cause to reduction of groundwater shortage of region from 38 107m3 in base year to zero in end of plan period.