Iranian Journal of Irrigation and Drainage
Year:2007 | Volume:1 | Issue:1|Papers Count:7

In this investigation, five wheat cultivars (Ostad, Karbalaheidari, Zagrus, Omind and Kavir) and three triticale lines (Artclyt-33, Artclyt-35 and Artclyt-37) were studied under saline condition. Plants were planted in 6-Kg pots that were salinized at tillering stage with NaCl and different level of salt (S0, S1 and S2) which contained 0, 3000, 6000 mg NaCl per Kilogram soil, respectively. Five plants were remained in each pot. A factorial experiment was conducted in complete randomized design with three replications. Na+ and K+ were measured at stem elongation stage. Wheat cultivars and triticale lines had shown significant differences in Na and K+ contents and K+/Na+ ratio. Triticale lines had low Na+ in their leaves in comparison to wheat cultivars, but they had relatively high K+ and K+/Na+ because of their tolerance to salinity. K+/Na+ ratio is an important criterion for salt tolerance. In tolerant cultivars the ratio is higher than non-tolerant ones. Triticale lines and two wheat cultivars (Kavir and Zagrus) also showed relatively high value for K+/Na+ while that was low in Oastad, Omid and Karbalaheidari. According to cluster analysis, Kavir, Zagrus and triticale lines are classified in tolerant group, while Oastad, Omid and Karbalaheidari, were classified in non-tolerant group.

Quantitative description of infiltration process is crucial for many applications in hydrologic cycle. The direct measurement of infiltration is time consuming, expensive and often impractical because of the large spatial and temporal variability. Any indirect parametric estimation of this process would be quite useful. Although, the so-called pedotransfer functions (PTFs) are widely used as an indirect method to predict the soil hydraulic properties, no attention has made to indirect estimation of infiltration. The objective of this study was to develop and verify some parametric PTFs to predict the infiltration process under three different land uses; namely pasture, wheat and fallow. For this purpose, 123 double ring infiltration data were collected. The parameters of four infiltration models were then obtained, using sum of least squares error method. Basic soil properties of the two upper pedogenic layers such as initial water content, bulk density, particle-size distributions, organic carbon and gravel contents, CaC03 percent, field moisture capacity and penpanent wilting point water contents were measured for each sampling location. The parametric PTFs were then developed to predict the parameters of the infiltration models, using the step wise regression method. The accuracy of the derived PTFs was evaluated using MAMD, MRMSD, SDMRMSD and MPearson statistics. The results indicated that the PTFs derived for the land under fallow have the best performance on cumulative infiltration prediction. Under pasture, wheat and fallow land uses the derived PTFs for Philip, Horton and Kostiakov-Lewis models were the best predictor of infiltration, respectively.

A field study was conducted in Iran to evaluate the effects of water table management on quality of subsurface drain flows. Drain discharge volumes, N03-N concentrations, phosphorous concentrations and electric conductivity in drainage effluent were monitored during the growing seasons. Lysimetric site with drainage system and water table control system were prepared and annual alfalfa (Medicago Scatella) was cropped. The WTM treatments consisted of three subirrigation treatments with water table controls set at 0.3 m (CWT0.3), 0.5 m (CWT0.5), 0.7 m (CWT0.7) from the soil surface and a conventional free drainage (FD) treatment (water table more than 1.00 m below the soil surface). Drain flow volumes and N03-N concentrations were significantly reduced by WTM as compared with free drainage. Mean NO3-N concentrations in drainage water were reduced by 78.6%, 65.6% and 49.3% by the 0.3, 0.5 and 0.7 m controlled water table depths, respectively. Total drain flow was reduced by 49.6% and 41% by the 0.3 and 0.5 m controlled water table depths, respectively. Consequently, NO3-N loading was also reduced by 90% and 82% by the 0.3 and 0.5 controlled water table depths, respectively. Improvements in drainage water quality were attributed to both reduced drainage outflow and enhanced denitrification in the controlled water table treatments. Mean phosphorous concentrations in drainage water were reduced by 11.2% by the CWT treatments. Also mean electric conductivity in drainage water was lower than FD by the CWT treatments. In addition to significantly reduced NO3-N pollutions, economic benefits were achieved through fertilizer equivalent saving. Therefore, the practice of water table management in the region was demonstrated to be both environmentally and economically sustainable.

A greenhouse experiment was conducted in Ferdowsi University of Mashhad, IRAN in order to study the effects of sewage application on soil physical properties. Dried sewage sludge was mixed with the upper 30 cm layer of a sandy loam soil at rates of 0, 50, 100, 200 and 300 Mg/ha. Units were irrigated weekly by effluent and well water at the rate of 5-6 cm during the experimental period. Application of the sludge increased EC and organic carbon of the soil and decreased its pH, bulk density, penetration resistance and saturated hydraulic conductivity significantly. Application of effluent as irrigation water increased EC and soil water holding capacity significantly. But interaction effects of sewage sludge and effluent application on soil physical properties was not significant. There was no marked variation in soil texture, particle density and infiltration

With developing and advance in farm machinery and hydraulic science, many irrigation machines invented that can irrigate a wide range of fields with high efficiency. On the other hand the limitation of water resources and the necessity of water productivity made the use of these machines unavoidable. In this research the evaporation and wind drift losses of Center pivot irrigation system measured under different climate conditions. In order to determine evaporation and wind drift losses according to ASAE standard, four radial lines of cans with 6 m spacing were installed. Then the amount of water in the cans, soil moisture, climate and hydraulic parameters were measured under different speeds of center pivot system. Result showed that the average distribution uniformity during the growing season was 63 %, which indicates that this system is not suitable for the experimental site conditions. The average amount of PELQ during the growing season was 55% which shows that this system is not compatible with this farm condition. The evaporation and wind drift losses were between 2%-17 percent. The evaporation and wind drift losses calculated by Trimer method were much less than the measured value. This is because of not considering the effect of non-uniformity of water distribution in calculating the evaporation and wind drift losses by Frost, Schwalen and Trimer methods.