نشریه آب و خاک
سال بیست و دوم شماره 2 (پیاپی 4، تابستان 1387)

To compare the canola yield and chemical characteristics of soil under integrated and conventional fertilization systems, an experiment was conducted in Savadkooh region for 2 years. The fertilizer treatments concluded 0, 50,100, 150, 200 kg.N.ha-1 urea (F0 to F4), 150 kg.N.ha-1 urea + 50 kg.N.ha-1 manure (MF1), 100 kg.N.ha-1 urea + 50 kg.N.ha-1 manure (MF2), 50 kg.N.ha-1 urea + 100 kg.N.ha-1 manure (MF3), 150 kg.N.ha-1 manure (M). The results showed that for both years the highest yield was obtained from integrated system of 150 kg.N.ha-1 urea + 50 kg.N.ha-1 manure (MF1). For the first year no difference between seed yield of integrated and chemical treatments was observed, however, the integrated treatments seed yield was significantly higher than the chemical treatments for the 2nd year. In addition, in organic system (M) yield was lower than inorganic system (F3) for the first year, while this was reversed for the second year. The application of manure increased available phosphorus significantly. For example, in organic system the available phosphorus increased 115% as compared with chemical system. In both systems the organic carbon content increased, but this increase was 12% and 35% for the chemical and integrated systems, respectively. Total nitrogen had a similar trend and the correlation coefficient was very significant (R2=0.93). According to the results it can be concluded that the integrated fertilization can be suggested as a suitable strategy to increase the available phosphorus in soil and to obtain a sustainable yield of canola.

Genetic evidences have shown that the rhizobium bacteria nodulate the legume plants because of nod, sym and fix genes. Almost all members of rhizobaceae family harbor large plasmids, which are highly variable in number and size. Representative of nif, fix and nod genes have been located on the symbiotic plasmids of different rhizobium species. Therefore, the size and numbers of plasmids of bacterial isolates (by the plasmid profile technique) could be used as a diversity index in ecological studies. In this investigation, the diversity of 196 isolates of sinorhizobium sp isolated from Hamada soils was evaluated by using Plasmid profile technique. The results showed that the number of plasmids among all isolates varied from 1 to 4 and totally 13 different plasmids were identified. The size of plasmids varied from 50 to 200 kb. Isolates with 1, 2, 3 and 4 plasmids formed 63, 21, 13 and 2 percentage of the population. Isolates of sinorhizobium with 2 and 3 plasmids were clustered into 8 and 15 groups, respectively, based on plasmid patterns. Four isolates which contained 4 plasmids were grouped in four different clusters and finally all isolates of Sinorhizobium (196) were grouped in 28 different groups.

Some species of earthworms have great ability to breakdown the organic wastes and transform them to vermicompost. It is very important to optimize the growth conditions and earthworms reproduction to achieve high efficiency in vermicompost production. In this study the effect of aeration, soil and sugar beet molasses on the number of adult and juvenile worms, cocoons and earthworm biomass were studied in a completely randomized design with 8 treatments. Sugar beet molass had the highest influence on the number of adult and juvenile earthworms, cocoon and biomass. Aeration had a significant effect on the number of juvenile worms, cocoons, and earthworm biomass, although it had negative effect on adult worms. Treatments with soil increased the number of cocoons and biomass significantly, however, had no significant effect on the number of adult and juvenile earthworms. The highest amount of earthworm biomass was obtained during the seventh and eighth weeks of experiment and decreased afterwards. The earthworm growth rate in treatments with sugar beet molass was much higher than control.

Narrow tines are among the most important tillage tools, which are used in chisel plows, cultivators and subsoilers. The draft of these blades is highly dependent on their geometric shape and working depth. The most important geometric specifications of these blades are their aspect ratio (depth/width ratio) and rake angle. Researchers’ efforts have been aimed at minimizing energy consumption and maximizing soil-loosening efficiency in using these types of blades. The objective of conducting this research was to investigate the effect of narrow tine aspect ratio on draft force; soil disturbed area and loosening efficiency. The tests were conducted in the soil-bin facilities of the Agricultural Machinery Department at Shiraz University. The experiment was conducted using a complete randomized block design with factorial arrangement in three replications. The tools had the same rake angle (30 degree) with four aspect ratios (2, 3, 4 and 5) and three blade widths (2.5, 5 and 7.5 cm). Draft force was measured by a recording load cell, and the soil-disturbed area was measured by using a profilemeter and developed by using Curve Expert and Matlab Ver. 5.6 softwares. The soil loosening efficiency was calculated by dividing the soil disturbed area by the draft force. The results showed that the effect of aspect ratio (d/w) on draft force was highly significant (p)

In case the performance of irrigation and drainage systems could be monitored by using satellite data, which are taken in short intervals, the problems concerning these systems could be corrected. Roodasht region which is located in the lower part of the Zayanderood River Basin was considered as a pilot plain. The basin is struggling with salinity and waterlogging which started by construction of the Zayanderood Dam and consequently, doubling the share of irrigation water of the area. For this purpose the satellite images of Landsat MSS and TM of 1976 through 1990 were used. Modifications was performed after field works, reviewing the available reports and maps from the area, and then, the satellite data were classified. Temporal analysis of the satellite images showed that by doubling the irrigation water share during 14 years, soils with severe and no salinity risk were decreased by 5 and 16%, respectively, while 20% was added to the land with moderately salinity risk. During this time the area of waterlogged lands has been doubled. The images of 1990 showed that new waterlogged lands were developed in the vicinity of the drainage and irrigation canals.

In the Universal Soil Loss Equation (USLE), soil erodibility factor K can be estimated by using a regression equation that has been presented based on field erosion plots in relatively non-calcareous soils. Therefore, it seems necessary to determine the estimating error of the regression equation in calcareous soils of Iran. This study was conducted in an agricultural area with a dimension of 30 km in Hashtrood province, northwest of Iran during March 2005-2006. The studied soils had about 1.1% organic matter and 13% lime (TNV). In order to investigate the soil erodibility, 36 regular grids of 5×5 km were considered on the study area. On each grid, three standard plots with 1.2 m intervals were established in dryland farming area having a 9% south hill slope. The actual soil erodibility value of the plots was determined as the annual soil loss per annual rain erosivity factor under natural rainfall events. The K value was estimated using the USLE regression equation. Soil physical and chemical properties were measured in samples taken from 0 to 30 cm depth. The results indicated that mean actual value of the soil erodibility factor in the study area was 0.004258 Mg.h.MJ-1.mm-1 which is 10.75 times smaller than the estimated K-factor. There was a poor correlation (R2= 0.16) between the actual and estimated soil erodibility factor. The estimating error values of the soil erodibility varied from 3.173 to 39.298 with a mean error of 9.984. There was a significant correlation between the calcareous soil erodibility and the amount of coarse sand, silt, organic matter and lime (TNV) of the soil. Regression analysis showed that the calcareous soil erodibility significantly (R2= 0.80, p)

Flood is one of the destructive natural phenomena and being able to forecast it is of great importance. Simulation of rainfall-runoff and flood is difficult due to influence of several factors. So far, different methods have been suggested for their analysis. The aim of this study was to compare the efficiency of artificial neural networks (ANNs) in simulating rainfall-runoff process with HEC-HMS model. For this purpose, the Kardeh watershed which is located in northeast part of Great Khorasan province was chosen and based on several precipitation hyetographs and their runoff hydrographs (total of 450 data from 30 selected phenomena) the study was performed. Back-Propagation (BP) algorithm ANN was learnt to the data using sigmoid activation function. The criterion for selecting the network parameters in learning stage was producing the least RMSE in ANN outputs. Based on the SCS method and curve number (CN) the HMS model was performed. To evaluate the ANN performance, the simulated and observed data of total discharge and volume of runoff, peak discharges and peak times were compared. The results showed that based on Delta learning rule the multi layers Perceptron (MLP) network with 29 neurons, simulated the rainfall-runoff process with a high accuracy only in the middle (hidden) layer. The correlation coefficients of the total discharge and volume of runoff were found to be highly significant (r=0.98 and 0.99, respectively). The ANN model could significantly simulate the peak discharge and peak time values (r =0.98 and 0.83, respectively). By analyzing the HMS model performance, the correlation coefficients of the observed and simulated discharges and volumes of runoff were found to be 0.82 and 0.98, respectively. Also, the correlation coefficients of simulated peak discharges and peak times with this model were 0.97 and 0.70, respectively. By performing the T-test analysis at 99% confidence level no significant differences between observed and predicted data was observed. It can be concluded that although no significant differences was found between the two methods, however, the results of evaluated parameters showed that ANN predictions were more precise in comparison with those of HMS model.

Microirrigation has the potential to minimize water droplet evaporation and wind drift losses associated with sprinkler irrigation, improving the irrigation control by frequent applications, providing the needed nutrients for crops through the system, minimizing deep percolation and improving crop yield. This study was conducted to evaluate sugar beet yield under conventional and alternate tape and furrow irrigation. The sugar beet pp22 was cultivated with 0.3 m row spacing. There were four treatments of tape irrigation (tapes from Iranian and foreign manufacturers) and two treatments of furrow irrigation. In each treatment four rows of sugar beet were grown. Alternate and every row irrigation was applied for both tape and furrow irrigation treatments. The amount of water used, irrigation application efficiency (Ea), water use efficiency (WUE), coefficient of uniformity (CU) of applied water and fertilizer in tape irrigation, white sugar percentage, gross sugar percentage, root yield, white sugar yield, gross sugar yield, the WUE of root yield, and the WUE of white sugar and gross sugar were assessed in a field experiment near the College of Agriculture of Shiraz University. The results showed that the amount of water used in tape irrigation treatments was 50 percent less than furrow irrigation treatments. The average Ea of tape and furrow irrigation was 90.7% and 52%, respectively. The CU of Iranian and foreign tape was 97% and 98%, while the CU of applied fertilizer was 97.5% and 94.5%, respectively. The highest white sugar percentage was found in alternate tape irrigation; however, the highest gross sugar percentage belonged to alternate furrow irrigation treatment. The highest root yield was obtained from Iranian tape irrigation treatment of all rows. The highest gross sugar yield was found in furrow irrigation; however, there was no significant difference among all treatments for white sugar yield. The amount of water used in tape irrigation was 58% of furrow irrigation, while the highest WUE of root yield, white sugar yield and gross sugar yield was found in the alternate tape irrigation. These values were the least for conventional furrow irrigation.

Due to limitation of available water and soil resources in Iran, the challenge of optimizing the utilization of these resources has become more significant. In this study it was attempted to maximize the project benefit, estimating crop water requirements at different growth stages, and optimizing the cropping pattern and irrigation management. In order to achieve these objectives mathematical model was solved with simple genetic algorithm (GA) and linear programming (LP) methods. The proposed model was applied to an irrigation project with 7000 ha of farmland irrigated by the main canal network of Doroodzan dam (Fars province). Comparing the optimal cropping pattern proposed by this model (IPM) with those practiced by the farmers showed that the model had a good consistency with farmers’ decisions for cultivating different crops. The results of this model also indicated that optimal planting pattern (in the 1st and 2nd growing season) was the same for GA and LP models. To find the best response from GA in this study the number of generations of 800, population size of 100, probability of crossover of 0.6, and probability of mutation of 0.02 was considered.

To calculate the index and optimal depths of crop water use, and maximizing the profit under deficit irrigation practices, this study was performed using a split plot design. In this experiment three cultivars of early maturing corns (301, 303 and 315) were set as the main treatments with 3 replications, while the irrigation levels were considered to be the minor treatments. A line source irrigation method (after Hanks) with 6 irrigation levels on both sides of the line was used. In this research, three sub-functions such as yield Y(w), cost C(w), and benefit B(w) were developed initially. Then, the optimal depths of irrigation were extracted from these functions. The results indicated that: a) although the complete irrigation had the maximum yield, however, the marginal net profit was not maximum because of the cost rise, b) with deficit irrigation under land restriction conditions and aiming to maximize the use of unit land, the optimized water depth for all cultivars was 3% less than the complete irrigation, and c) using deficit irrigation under water limitations and aiming to maximize the use of unit volume of water, the optimized irrigation depth would be 19% less than the complete irrigation practices. Also, the results showed that the net benefit was the same for the equivalent depth and the maximum water depth; therefore, it is logical to use the equivalent depth. Meanwhile, applying 17.5% deficit irrigation for cultivar 301, 20.4% for cultivar 303 and 19.1% for cultivar 315, the highest earning return (Rials per m3 of water) will be 1011.2, 1206.1 and 1543.6 Rials, respectively. It can be concluded that with the savings of water under deficit irrigation practices, the planting area would increase and ultimately the marginal net profit increases substantially. Also, the most net profit among the cultivars was obtained for cultivar 315.

Due to the necessity of wastewater reuse in arid regions and the necessity of investigation on the fate of added materials into the soil, a greenhouse experiment was carried out with polyethylene columns (150 cm in length and 11 cm in diameter) filled with a sandy loam soil during 7 periods of 15 days. A statistical factorial design was used. Raw and treated wastewaters from Parkandabad treatment plant were applied to the columns under continuous and intermittent flood irrigations. The results showed that PO4-P and Cd were retained by the soil while a large portion of soluble cations and anions, NO3-N and TOC as well as a part of Ni were leached out. The type of wastewater had a significant effect on transport percentage of elements except K and Mg. The transport percentage of all elements (with the exception of NO3-N and PO4-P) was higher for treated as compared to raw wastewater. Ca, HCO3 and Ni were significantly affected by the mode of application. For the intermittent flood conditions more Ca was leached out, while a reverse case was observed for the other two elements. Due to relatively rapid leaching of soluble cations especially Ca and Mg, NO3-N and TOC from the soil, and also high amount of heavy metals and TOC in raw wastewater, disposal of wastewaters (especially raw wastewater) should be managed carefully.

In order to determine the critical level and classify the soil Zn in Western Azerbaijan, Eastern Azerbaijan, Kurdistan and Kermanshah dryland areas, a study was conducted in a complete randomized block design having 4 treatments (0, 5, 10 and 15 kg.ha-1 of zinc sulfate) with three replications for four years (1998-2002).When the experiment ended, the crop and soil data uniformity test were performed for all experimental sites. The results of these experiments were interpreted by different methods including: Cate-Nelson graphical method, Cate-Nelson two and three classes ANOVA models, Mitshcherlich equation, plant response column order procedure and interaction chi-square methods. The results showed that the Zn critical levels using the mentioned methods were 0.75, 0.55, 0.65, 0.61, 0.80 and 0.66 mg.kg-1, respectively. Different Zn critical levels calculated by different soil testing interpretation methods were compared by using contingency table. The results showed that Cate-Nelson two classes ANOVA model with 0.55 mg.kg-1 Zn and 0.47 predictability value was a better model for determining the Zn critical level than all other models for Northwestern dryland region of Iran. Using different soil testing interpretation methods for determining the Zn critical levels it was concluded that all the values were to some extent similar; however, Cate-Nelson two classes ANOVA model seemed to be more suitable for this purpose.

Sediment load-discharge data of hydrometric stations in the north of Great Khorasan province were studied. Twenty nine stations were selected and the mean annual sediment yield was computed using sediment rating curves. The total annual sediment yield for these catchments (61.5 to 16800 km2) varied between 4.8 to 19500 M ton/year and the specific sediment yield varied between 62 to about 4000 ton/year/km2. Due to large variations in the total and specific sediment yield, 29 selected catchments were divided in two groups: 17 large catchments (area>500 km2) and 12 smaller ones (area)

Topography is the most important parameter which produces minimum temperatures in complex terrain. Radiative inversion occurs in the mountains and produces radiative freezing. When the land surface is cooled, a boundary layer forms. Since cold air is heavier than warm air, therefore, it flows toward the down slope, which is named Katabolic flow. When Katabolic flows are formed, cold air accumulates in the valleys and thereafter in places which do not have a good drainage of air. Based on thermodynamic equations a model was developed to consider the accumulation of cold air in each point of a complex terrain. Minimum temperature prediction model (MTPM) was developed and used to predict the minimum temperature in complex terrains. This thermodynamic model uses digital elevation model to produce minimum temperature maps. Running MTPM for North Mountains of Tehran showed a good correlation between modeled and actual minimum temperatures.

Blood meal contains large amount of nitrogen and iron that can be supplied to plants instead of chemical fertilizers. Nitrogen is the most important nutrient for corn plant. The main objective of this study was to determine the capability of blood meal to release nitrogen and iron and its consequence effect on corn growth. An experiment under laboratory and greenhouse conditions was conducted in the form of a completely randomized design with 6 treatments and 3 replications. The treatments included 3 levels of blood meal (1.5, 3 and 6 ton/h), urea fertilizer (200 kg/h), Fe EDDHA (5 kg/h), and the control. The results of soil incubation demonstrated that release of iron from blood meal was similar to Fe EDDHA and the amount of iron reached to its highest level after 30 days of adding to the soil. Nitrogen was released from all levels of blood meal slower than urea, and the amount of inorganic nitrogen in blood meal was less than urea. The results of corn growth showed that the application of blood meal one month before planting could provide the needed nitrogen and iron and have a positive effect on its growth.

Due to good climatic condition for producing spinach during autumn in Bushehr province, a study was carried out in Borazjan Agricultural Center during 2001–2002 to determine the effects of irrigation regimes, plant density and cultivation method on spinach. The experiment was based on a complete randomized block design having split factorials with three replications with the following treatments: three methods of cultivation (plant rows in basin (B1), ordinary bed and furrow (B2), and on upper part of furrow (B3)); three plant densities (40×15 (C1), 50×15 (C2), and 60×15 (C3) centimeters); and three irrigation intervals (I1=25mm, I2=35mm, and I3=45mm based on cumulative evaporation from a class A pan). Results showed that the effects of all main factors and their interactions were significant at P

The diversion flow pattern is quite 3-D and nonuniform. In general, diversion flow occurs either naturally like streams or artificially like lateral intakes. According to the performed investigations the intake location affects the rate of diversion discharge and entry of sediments to the diversion channel. Since the main purpose of lateral intakes is to facilitate water transfer without sediments, and most rivers are zigzagged through their path, therefore, more research on the location of the lateral intake and its angle in the bending channels seems necessary. For this purpose, to determine the velocity and secondary flow fluctuations caused by hydraulic parameters changes in domain of lateral intakes with no diversion dam in winding channels a U-shaped flume with rectangular cross section was built. A straight channel with rectangular cross-section was used as a diversion channel. Based on the past researches, water intake was performed from the outer bend with 60˚ diversion angle at different locations (40˚, 75˚, 115˚) and with Froude numbers 0.27, 0.41, and 0.55, respectively. The obtained results of velocity distribution, secondary flow strength and radial flow momentum in a bend channel with diversion channel showed that the maximum variation of the above hydraulic parameters occur in the intake entrance.

Naturally, rivers are rarely straight and more likely to take a winding course, called meandering. Because of presence of strong secondary currents in meanders, flow in river meanders is a complicated phenomenon, making it interesting for many researchers and engineers to investigate the equations governing this kind of flow. Many studies have been carried out by different researches during the last 45 years, and consequently, different relations have been published to determine the hydraulic parameters of the flow. In this research, a laboratory trapezoidal channel with a central radius curve of 5 m and central angle of 94 degrees was used to measure the hydraulic parameters for 120, 180, and 230 l/sec flows over a sandy movable bed having rigid walls. The results of this experiment were compared to the results of different models developed to estimate the flow characteristics. Finally, the most suitable model to determine the flow characteristics was introduced.

In this study the role of hillside direction and plot length of experimental plots on the accuracy of soil erosion estimation was studied. For this purpose 12 experimental plots with length of 2, 5, 10, 15, 20 and 25 meters were established on the north and south facing hillside of Sanganeh watershed having sandy loam soil texture and mean slope of 30%, located in the northeastern part of Khorasan Razavi province. The sediment of Sanganeh watershed having an area of about 1 ha was collected in concrete ponds and was used for comparison with the test plots. During the research period (November 2006 to June 2007), 12 storms causing runoff occurred and the sediments were collected in metal containers and were analyzed later. The results revealed that the amount of sediment per unit area collected from the south hillside plots was nonlinearly and adversely dependent on the plot length. However, the variation among sediment collected from the north hillside plots was not significant due to difference in crop cover and soil type. In addition, the variation in soil loss was reduced as the plot length increased. According to statistical analyses, the 20 meter plot length was found as the optimal plot length for estimation of soil erosion in the studied watershed.

To investigate the effective parameters and simulate the conditions under which sediments are transported in ephemeral rivers and compare it to perennial rivers a series of experiments were performed in a laboratory flume. The hydrodynamic equations were solved for initial and boundary conditions using numerical method. Triangle hydrographs with time duration of 40, 60 and 80 seconds and five different flow rates for each situation were considered. Three slopes of 0.006, 0.014 and 0.018 were selected. A fine and uniform sand with d50 of 1.5, 2.1 and 3 mm from river materials was used as the mobile bed. Clean water (with no sediment) was used. The results of 85 experiments showed that the bed slope was the most important parameter in sediment transportation and it could be used for predicting the sediment transport. The base time of hydrograph was also found to have an effective role in sediment transport, and the results showed that by increasing the base time the transported sediment was decreased. The bed form had a big role on the flow resistance and also affected the sediment transport. The sediment ratio of unsteady to steady flow found in this research was found to be similar with those of Tun Lee.

Converting the forests and pastures to cultivated land results in loss of soil organic matter, deteriorating the soil structure, lowering hydraulic conductivity and increasing soil bulk density, which all cause increase in surface runoff and soil erosion. One of the soil physical properties which intensify runoff is soil water repellency. To examine the effects of land use change on water repellency, soil samples were taken from two areas of central Zagros (e.g. pasture in Fereydunshar and forest in Lurdegan). In each area two different land uses were selected. One under cultivation and the other was unaltered and for each land use three sites were randomly selected. The effects of organic matter and soil water content on water repellency were investigated during January and July. The degree of water repellency of a soil was measured by using the water drop penetration time (WDPT) test. There was a strong relationship between soil water repellency and percentage organic matter in surface soils under forested areas. In January when the soil water content was between 18 to 22%, no actual water repellency was found in the forest. However, in July the water drop penetration time in sites 1, 2 and 3 in the 5 cm of the top soil was 130, 50 and 150 second, respectively, when the soil water content was only 5%. No soil water repellency was found in cultivated forest and pasture (cultivated pasture and undisturbed pasture). Changes in land use induced negative effects on water repellency. In this study, changing forest to cultivated land decreased organic matter content; mean weight diameter of soil aggregates, total porosity and hydraulic conductivity by 23, 55, 11 and 40%, respectively. Changing pasture to cultivated land decreased organic matter content; mean weight diameter and total porosity by 22, 40 and 9%, respectively. Changing forest and pasture to cultivated land increased bulk density of soil by 7 and 6%, respectively.

Application of empirical models is a must owing to complexity of process, different features, spatial and temporal variation of soil erosion and non-existence or lack of pertaining data. In this study, the efficiency of rainfall and runoff variables of 11 storms during winter 2006 and spring 2007 in explanation of storm-wise sediment yield in Chehelgazi watershed of Gheshlagh Dam basin in Kurdistan province was evaluated with the help of bivariate and multivariate regression models by using different transformed data. The models’ efficacy was then assessed by using coefficient of determination, error of estimation and verification. The results showed that bivariate regression models, using different transformed data with determination coefficient of beyond 66%, and respective error of estimation and verification of below 40 and 30%, had a better efficiency in estimation of storm-wise sediment yield than multivariate regression models. The results also verified that the rainfall variables could explain storm-wise sediment yield variations better than runoff relating factors with overall contribution of some 80%.

Furrow irrigation is one of the oldest methods of irrigation in which soil surface is used to convey and infiltrate water. The furrow geometry data are used for design, evaluation and simulation of furrow irrigation. With furrow geometry data, the furrow infiltration, irrigation efficiency and furrow erosion and sedimentation can be estimated more precisely. Furrow geometry is expressed with some power functions and the coefficients of these functions are used as input for surface irrigation models. In this article, a computer program with Matlab version 7 was written to calculate the furrow cross section functions. The functions are power functions and second order polynomial. To evaluate the model, two cross section data of a furrow irrigation field were used. The model predictions were compared with the two-point method of Elliott and Walker and the results showed that the coefficients of furrow cross section equations obtained by the Elliott and Walker are different with the model output. The results showed that the model is capable to predict the field cross-sectional data with high accuracy. The comparison of coefficient of determinations of the fitted power function and second order polynomial function to the field data showed that both functions can predict the field data closely.

There is a gradual decline in the availability of fresh water to be used for irrigation in Iran. As a consequence, the use of treated wastewater and other unconventional sources of water for landscape irrigation are on the rise in arid and semi arid areas. Irrigation with wastewater changes the soil properties. Hence, a case study was performed to assess the effects of treated wastewater irrigation on nutrient and heavy metal absorption of a turf cover (DALZJ1 variety). In this research, the advanced treated wastewater (TW) of Shahinshahr Wastewater Treatment Plant was used and the effects of different percentages of water and TW (100% water, 50% water and 50% TW, and 100% TW) on three soil textures (sandy loam, loam and clay loam) for a period of 10 months was studied. Statistical design was based on a completely randomized design with factorial arrangement, with three replications. The results indicated that using TW for irrigating turf grass increased plant uptake of N and Cd. The maximum amount of K, Ni, Co and Pb was absorbed by turf grass from soils irrigated with 50% TW. Also, the absorption of P, Fe and Zn was not affected by TW in the irrigation water. Analysis of variance showed that there was no significant difference between soil textures on plant uptake of N, P, K, Cd, Co, Ni, Fe and Zn. The comparison of means showed that there was significant difference in grass Pb content among soil textures. The interaction effects of soil texture and percent TW showed that variation of uptake with increasing TW percentage in irrigation water was not linear and soil texture had no effect on the uptake of elements by this Zoysia variety.

Deficit irrigation is a method to promote water use efficiency (WUE) in a farm under water shortage conditions, however, the consequences is that yield per area decreases. To determine production functions for three cotton cultivars, an experiment was conducted during 1381 growing season on a silty clay loam soil in HashemAbad Agricultural Research Station in Gorgan. This study was performed using a split-plot design with 3 replications on three cotton cultivars. A line-source sprinkler irrigation system was used with 54 plots in each side of the line (3cultivars* 6treatments* 3replications). To estimate root zone water deficit, climatic data and cotton crop coefficients during the growing season were used. For each cultivar second order equations were derived to relate yield and applied water. However, linear relationships were established to relate yield and evapotranspiration. In addition, based on Doorenbos and Kassam formula yield response factors were found to be 1.02, 0.96 and 1.01 for Sahel, Say Ocra, and 818-312 cultivars, respectively. Such yield response factors can be used to optimize irrigation planning under water shortage conditions.

In order to evaluate the effects of limited irrigation on forage of two local populations of Kochia scoparia a field experiment was conducted in Research Field of Center of Excellence for Special Plants at Ferdowsi University of Mashhad during 2007 growing season. The experiment was performed as a split plot design based on complete randomized block arrangement. In the main plots four irrigation levels were applied including complete irrigation, 80%, 60% and 40% of water plant requirements. Two local populations of Kochia including Sabzevar and Borujerd were used in the subplots with 3 replications. The plant characteristics were studied in terms of plant height, branch number, fresh and dry matter weight, green area index (GAI), and leaf and stem dry weight. Results indicated that the different irrigation regimes had a significant effect on all plant characteristics. Maximum forage yield was obtained from complete irrigation with 13.22 t/ha dry matter and 31.81 t/ha fresh materials. Sabzevar's local population represented a better performance on all of the characteristics; however, there was no significant difference among the two populations on dry matter per plant. The interaction effects of limited irrigation and variety showed a significant difference on fresh matter weight, stem dry weight, leaf dry weight, and green area index. The stem dry weight and green area index showed the highest correlation with dry matter and fresh matter weight, respectively. It can be concluded that due to high Kochia’s resistance in the presence of drought, salinity and other desert stresses such as high temperatures this plant has the potential to be used as a forage crop in harsh environmental conditions.

Drainage water created from irrigation and drainage projects in south of Khuzestan province are saline and its disposal to rivers such as Karoon river is faced with certain constraints. One of drainage water disposal strategies is using evaporation ponds, in which the most important outlet is evaporation. Evaporation rate of saline water of these ponds is lower than fresh water. In this study the evaporation rate of implicit ponds for drainage water control in Mirza Kuchak Khan Project was estimated by adjusting the saturation vapor pressure equation of saline water with regard to pure water and by using of Penman equation. Finally, using the evaporation and the annual drain water volume, the required area of evaporation ponds was determined. By evaporation of water from ponds the salinity of water increases. This increase of salinity continues until the salt saturation threshold is reached, and then salts precipitate. The most common salt in drainage water of Khuzestan province is NaCl which has a saturation threshold of 300 g/lit. The results showed that the average annual evaporation of water with 300 g/lit salt is 1903 mm. The drainage water volume produced from Mirza Kuchak Khan Project (12,000 ha area), requires evaporation ponds as big as 7740 ha. This study showed that disposal of the drainage water of sugarcane projects is impossible if only evaporation ponds are used, and therefore, other management options should be considered for reducing the volume and salinity of drainage water.

The estimation of reference evapotranspiration (ETo) is of great importance due to its applications in water resource management as well as irrigation scheduling. Difficulties associated with using lysimeters have encouraged researchers to use various ETo models, while the shortage of actual radiation data seems the main obstacle for users of radiation-based models. In this research the output of four radiation-based evapotranspiration models including: Penman-Montieth-FAO56 (PMF56), Penman-Montieth FAO-Irmak (PMFI), modified Jensen-Haise (JH1), and Jensen-Haise (JH2) are evaluated for a cold semi-arid climate. The daily ETo values were generated for 16 different scenarios and the results were compared against a two-year lysimeter data during the growing season (May to November). Deviations of model results were investigated using mean of R2, RMSE, MBE and t-test criteria. The results indicated that the JH2 model which uses radiation model of Daneshyar, can generate the most accurate ETo values (R2>0.85, P<O.05) in cold semi-arid climates. Although, the Angstrom radiation models are widely being used to generate radiation data in recent years, this research showed that other radiation models can provide more accurate radiation data for radiationbased ETo models. In places with lack or shortage of meteorological data, using an accurate radiation model might significantly reduce the errors generated by certain ETo models. The mentioned radiation models and ETo models should be examined for other climates.

Efficient water use in agriculture is a priority in arid and semi-arid regions where water for irrigation is scarce. Super absorption polymers (SAP) could be considered as an approach to increase water productivity in rainfed and irrigated farming. The present study was carried out to evaluate the effect of stockosorb super absorption polymer on the Kostiakov-Lewis Equation parameters and the flow advance curve in the furrow irrigation method. The experiment was conducted based on a randomized block design with factorial arrangement having 3 replications. The main plots included four levels of SAP included 0 (control), 5, 7, and 9 g m-2 polymer into 25 cm of soil depth, and two levels of inflow rate included 0.5 and 0.7 l/s as sub main plots. The data were collected during four irrigation events. The results showed that applying SAP had a significant effect on the flow advance time and cumulative infiltration depth. Flow advance time and cumulative infiltration depth values were increased because of using SAP. Using SAP may have suitable effects on infiltration rate especially after the first irrigation event that reduces the cumulative infiltration substantially. Hence, the performance of surface irrigation methods and its water productivity can be improved. The results of statistical analysis also indicated that the effect of SAP and inflow rate levels on the improvement of infiltration was significant at 1% level. Using 9 g.m-2 SAP into 25 cm of soil with inflow rate of 0.5 l/s in plots having 90 m length increased the cumulative infiltration by 67% as compared to the control treatment. In addition, decreasing of inflow rate increased cumulative infiltration.

An estimate of the groundwater budget at the aquifer scale is particularly important for the sustainable management of available water resources. Water resources are generally subjected to over-exploitation for agricultural and domestic purposes in agrarian economies like Iran. Using water table fluctuations in dry and wet seasons of a hydrological year is a reliable method for calculating the water budget. In this method, the existence of a piezometric network with careful monitoring and measurements is essential. The objective of this study was to develop a methodology for optimizing the piezometric network so that the groundwater budget could be estimated accurately. In this method the priority of each well and its effects on estimation of water budget was determined by using geostatistics. Using this analysis an optimal network could be determined. In order to demonstrate the applicability of proposed methodology, the Astane-Koochesfahan aquifer with an area of about 1173 km2 in north of Iran was selected. Fifty seven observation wells were analyzed using geostatistical methods and results showed that spherical variogram model had the best performance. It was recognized that such an optimized network provides far fewer measurement points, i.e. 33 wells, without considerably changing the conclusions regarding groundwater budget.

By evaluating the performance of the current drainage systems and exploration of their strengths and weaknesses a comprehensive perspective can be given to designers and organizers for optimum design and implementation of drainage systems for future plans. This study was conducted to evaluate the performance of subsurface drainage systems using rice husk as envelope in Behshahr, a coastal region in the northern part of Iran. For this purpose, eleven piezometers were installed between two subsurface drains designated as S3PD14 and S3PD15. Subsurface drainage system was monitored during rainfall seasons in 1383 and 1385. Parameters such as daily water table fluctuations and drain discharge rate were recorded. The overall conclusion was that subsurface drainage system performance was not satisfactory due to poor control of water table depth and low water discharge, which was mainly because of the drain envelope clogging. Therefore, the Hooghoudt’s equation should not be used for evaluation of design parameters, due to the fact that this equation is only valid for normal conditions (envelope without clogging).

Puddling is the most common method of land preparation of paddy fields in lowland rice cultivation. Puddling affects the physical, chemical and biological properties of soil and these changes are effective on rice growth. The soil that is more susceptible to changes in structure is easier to puddle. This research was aimed to investigate the effects of different puddling levels on moisture content and bulk density of three dominant soil textures of paddy fields in Guilan province. The experiment was designed as factorial with completely randomized blocks having three replications. Undisturbed soil samples were taken from 3 different soils (silty clay, clay loam and loam) with cylindrical samplers with diameter and height of 50 cm. The soil samples were puddled by a laboratory apparatus. The puddling treatments were: P0 (no puddling), P1 (low puddling), P2 (medium puddling) and P3 (high puddling). Soil moisture content and bulk density of all soil samples was measured every 24 hrs for six days. Analysis of variance showed that puddling had significant effect (p < 0.05) on soil moisture content and bulk density. The water content of the puddled layers decreased with an increase in settling time. During drying period, P0 dried faster than P1, P2 and P3. In P0 to P3 treatments of the loamy soil, the moisture content decreased about 22.6, 16.3, 14.8 and 9.6% after 144 hrs past puddling, respectively. The trend was similar for other two soils. Measurement of bulk density in 0-15 cm depth showed that P1 caused bulk density of silty clay and clay loam soils to decrease 23.8 and 22.8%, respectively; however, it caused the bulk density of loamy soil to increase 4.1%. Bulk density increased with time in all the three soils. Bulk density increased with depth and this increase was higher for lower puddling levels. It seems that higher puddling levels are more suitable for paddy fields preparation because they loose water more slowly. To determine what puddling level is appropriate for different soil textures, parameters such as water infiltration, water retention and amount of water used should be investigated.

Spent mushroom compost (SMC) is a by-product of the mushroom industries. It is made from straw, manure, gypsum and horse-bedded straw, hay and poultry manure. SMC has been used as a soil amendment, particularly for intensive horticultural production. In this study the effects of various SMC's types (fresh, one year old, two years old) on changes of chemical characteristics of a loamy soil was studied for 12 weeks in a laboratory column incubation under controlled conditions. Different rates of each SMC (0, 15, 30, 60 t ha-1) were mixed with a loamy soil. The columns were leached with deionized water every week. Leachates were collected and analyzed for EC, pH, soluble cations (Sodium, Potassium, Calcium, and Magnesium), and anions (Chloride, Bicarbonate, Nitrate) content. Similar data collection was conducted on the soil samples at the beginning and at the end of the test. The results showed that EC and concentration of nutrients was the lowest in two years old SMC. It is probably due to the amount of salts leached out during the weathering of SMC. The leachate contained a higher amount of Calcium and Magnesium over the 12 week period. Two years old SMC had less Cl and Na and had less effect on soil salinity and sodification. Since the slow inorganic-N release rate from SMC-amended soil is predominantly the result of the slow mineralization of recalcitrant organic- N in SMC, therefore, nitrate content in two years old SMC can provide the primary requirements of plants. Comparison of different levels of SMC showed that using 30 t ha -1 is more favorable as compared with other levels. The 60 t ha -1 level caused higher EC and salinity in the soil. As a general rule if SMC with proper aging is used at an appropriate level it can affect the chemical and physical characteristics of the soil and can be used as a soil amendment.

The shape factor is one of the most important physical characteristics of a dam’s reservoir. This factor is equal to the reciprocal of the slope of a line obtained by plotting reservoir depth against reservoir capacity on a log-log paper. The shape factor is used for reservoir classification and sediment distribution. In this study, a new method is proposed for determination of the reservoir shape factor. In this method, the normalized depth-capacity curve is plotted on log-log paper and then the value of shape factor could be derived as the reciprocal of the line slope. In this study, the original depth-capacity data and reservoir sedimentation data of 4 dams in Iran (Dez, Kardeh, Latian and Shahid Abbaspour) and 4 dams in the USA (Cedar Bluff, Kirwin, Nambe Falls, and Theodore Roosevelt) were used. The results showed that reservoir shape factor of all reservoirs decreased 2 to 2.5 for the first or second sedimentation measurements. In addition, the type of reservoirs was changed to type III. Therefore, prediction of reservoir sedimentation by area reduction method should be performed with reservoir type III. The most important advantage of the proposed method is the capability of plotting and comparing the normalized depth-capacity data of several reservoirs (or several sedimentation measurements of a single reservoir) on individual log-log paper. While in the old method, the depth-capacity data of each reservoir should be plotted on a separate log-log paper.

The rate and duration of downward flow during redistribution process determines the effective soil water storage at any time. This property is vitally important, particularly in arid and semi-arid regions where plants must rely for long periods of time on the remained soil water of the root zone. In this study a new approach for scaling of soil moisture redistribution process based on the Green-Ampt redistribution theory was developed. Using the scaled results of numerical solution of the general flow (Richards’ equation), an empirical equation for predicting the soil moisture profile during redistribution process was derived. An important advantage of the empirical equation is adopting the effect of hysteresis in soil retention curve on redistribution process. To validate the proposed empirical equation, its outputs were compared with those of Richards’ solution for 11 soil textural classes (from sand to clay). The comparison showed negligible amount of error for all of the 11 soil textural classes and for a wide range of initial conditions. However, some deviations from results of Richards’ solution were observed under high initial infiltrated water depth and/or high initial soil water content. Therefore, a model which can estimate the soil moisture content at any depth and time during redistribution phase with accuracy of numerical models and simplicity in application of analytical models was obtained.

Analysis and interpreting spatial variability of soil hydraulic and physical properties on a catchment scale is important in hydrological modeling and decision making. This study was conducted to analyze and interpret spatial distribution of selected soil hydraulic and physical properties including clay, silt, and sand content, bulk density (BD), infiltration rate (IR) and saturated hydraulic conductivity (Ks) in Marghmalek watershed. In this research, 111 soil samples were collected in a regular spaced grid pattern of 1 km from 0-30 cm depth in order to determine the soil size distribution. In addition, at each sampling site undisturbed soil samples were obtained from the topsoil using cylinder method to determine soil bulk density and consequently the saturated hydraulic conductivity. Saturated hydraulic conductivity was determined using the falling head method. Infiltration tests were conducted on all 111 sample sites using double-ring infiltrometers. Maximum coefficient of variation (CV) was found for IR (72%) and Ks (67%). In contrast, the minimum CV value of 8% was found for BD. Statistical analysis illustrated that there was a significant difference (P)

The initial assumption of many laboratory, greenhouse and lysimetric experiments is the longtitudal and latitudal homogeneity of repacked soil columns as well as homogeneity between different replications. Despite the great importance of these assumptions, a few reports, especially among domestic studies, have discussed the details of packing procedure. On the other hand, in most cases no criterion is introduced as verification standards, while the methods introduced are dependent on soil sampling which itself is destructive. This paper has discussed the details of packing procedure used for filling 36 cylindrical lysimeters having 39.5 cm internal diameter and 150 cm height. In addition, 3 nondestructive criteria have been introduced to verify the packing procedure and homogeneity in repacked soil columns. These criteria include the soil surface depression, variation in field capacity (FC) point, and the slope of breakthrough curves (BTCs). Based on all introduced criteria, the introduced packing procedure produced longtitudal and latitudal homogeneity in repacked soil columns and similarity between 36 replications.

In order to estimate the freezing depth and developing a simple and rational relationship between air temperatures at the screen and soil temperature at different depths a study was conducted during 1386. The maximum and minimum daily air temperatures (2 meter above ground) and the soil temperature at 5, 10, 20, 30, 50 and 100 centimeter depths were measured at 12 stations of Khorasan Razavi province. Functional relationships were developed between air and soil temperatures for each station. Also, soil freezing depths were estimated by four standard methods. The estimated depths were compared with actual freezing depths which were measured during the year of observation. The results showed that the Finnish and Norway methods were more reliable than U.S. and SNipll – 15 – 74 methods.

Since the majority of dryland farming area in eastern Azerbaijan is devoted to wheat production, therefore, climate zoning of dryland wheat was set as the goal of this research. For this reason long term climatic data of 39 meteorological stations inside the province and 7 synoptic stations out of the province were used. The most proper planting date was suggested based on the commencement of rainy season in each part of the province, and the different growth stages of dryland wheat were determined. Using the precipitation data, the climatic isohyetal maps of the following were derived: annual rain, rain during germination, rain during flowering, and rain during seed filling stage. In addition, using temperature data the climatic isothermal maps for germination, thermal stress during flowering and seed filling stages were developed for the province. Finally, these maps were compiled in GIS and afterward the climatic zoning of dryland wheat was derived. The areas with no potential of wheat dryland farming were omitted. The final map showed the most appropriate, appropriate, medium, and poor climatic zoning. The zoning in the map indicated that areas in the north part of the province had the most appropriate climatic conditions for dryland farming. The concentration of medium to poor climatic zoning was located in a strip which was stretched from east to west part of the province.

To explore the on-farm strategies which result in higher economic gains and water productivity (WP), a physically based agro-hydrological model, Soil Water Atmosphere Plant (SWAP), was calibrated and validated using intensive measured data at 8 selected farmer fields (wheat, fodder maize, sunflower and sugar beet) in the Borkhar district, Isfahan during the growing seasons of 2004-05. The WP values for the main crops were computed using the SWAP simulated water balance components i.e. transpiration (T), evapotranspiration (ET), irrigation (I), and the marketable yield (Y)M in terms of YM T -1, YM ET -1 and YM I -1. The average WP, expressed as YM T -1 (kg m-3) was 1.18 for wheat, 3.38 for fodder maize, 0.33 for sunflower and 1.72 for sugar beet. This indicated that fodder maize provided the highest economic benefit in the Borkhar irrigation district. Soil evaporation caused the average WP values, expressed as YM ET-1 (kg m-3), to be at least 11 to 27% lower than the average WP, expressed as YM T-1. Furthermore, due to percolation from root zone and stored moisture content in the root zone, the average WP values expressed as YM I-1 (kg m-3), had a 24 to 42 % reduction as compared with WP expressed as YM ET-1. Improved irrigation practices in terms of irrigation timing and amount, increased WP in terms of YM I-1 (kg m-3) by a factor of 1.5 for wheat and maize, 1.3 for sunflower and 1.1 for sugar beet.