JWSS - Journal of Water and Soil Science

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The use of slot through a pier is a new method proposed to control local scour at bridge piers. In this study, control of local scour at bridge pier is studied using 20 pier models under clear water conditions. The models consist of one circular pier without slot, three round-nosed piers without slot, and 16 piers with slot. Two slot lengths were chosen (yl=b and yl=2b, where y1 is the length of slot and b is the width (diameter) of the pier). Furthermore, they were located at two positions (near the bed and near the water surface). The results showed that for a circular pier, the slots with the lengths of b and 2b, located near the water surface, had no influence on the equilibrium scour depth. It was also found that for all piers, maximum reduction in scour depth occurred for piers with a slot length yl=2b and close to the bed. Also, the efficacy of a slot for scour protection in the case of a round-nosed pier was more than a circular pier (with a diameter equal to the width of a round-nosed pier).

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This study included two experiments conducted in 2000-2001 for surveying the effects of saline water irrigation on yield and yield components in corn varieties. Experiments were conducted in a silty-clay soil in Ahwaz Agricultural Research Center. First experiment was conducted as a split plots and randomized complete blocks design in three replications. Main plots included salinity levels 2, 4, 6 and 8dS/m and subplots included three single cross hybrids of corn 704, 711 and 647. In the other experiment the effects of saline water 8dS/m at different growth stages including the stage of planting to plant establishment. (G1), flowering and pollination (G2) and grain filling (G3), were evaluated. The results of the first expriment showed that there was very significant difference among water salinity levels for yield, thousand kernel weight, percentage of corn fertility and percentage of plants containing corn. The highest and lowest grain yield were obtained for salinity levels 2 and 8dS/m treatments respectively. Differences among varieties and interaction of treatments were significant for grain yield, and highest grain yeild was obtained for 704 and 711 varieties on saline water 2dS/m. The results of the other expriment showed that highest and lowest tolerance to irrigation with saline water on corn were G3 and G1 growth stages respectively. Consequently, hybrids 704 and 711 were more sensitive than the 647, but the obtained yield, suggests that 704 and 711 hybrids can be cultivated under these conditions.

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  In order to study the effects of different levels of irrigation, nitrogen and plant population on yield, yield components and reserved dry matter remobilization of seed corn (SC. 704 hybrid) a research was conducted at the experimental field in Khuzestan Natural Resources and Agricultural Science University in summer, 2004. This research was made based on three split-plot field experiments, RCBD. Each of the irrigation treatments implemented separately in each experiment have been as follows: Optimum irrigation, Moderate stress and Severe stress (irrigation after drainage 50%, 75% and 100% of available water based on 70%, 60% and 50% of field capacity, respectively). In each experiment three nitrogen levels consisting of 140(N ₁ ), 180 (N ₂ ) and 220(N ₃ ) Kg N ha^-1 were applied in main plots and subplots which consisted of three plant populations (D ₁ =6, D ₂= 7.5 and D ₃= 9 plant m^-2). There were three replications for each experiment. The results of the combined analysis of variance indicated that the effect of water deficiency stress, nitrogen and plant population on grain and biological yield was significant. With increasing severity of drought stress, the grain and biological yield decreased. The maximum grain yield was estimated to be 1017.04 gm ^-2 which was related to optimum irrigation treatment. Grain yield reduction was mainly due to reduction of grain per ear and 1000 seed weight. The increase of nitrogen consumption caused an increase in grain yield. The positive effect of nitrogen application on grain yield considerably decreased as a result of the increased water deficiency in soil. The response of grain yield to plant population was positive. The contrary to interaction effects of irrigation and nitrogen, and irrigation, nitrogen and plant population, the interaction effects of irrigation and plant population and also nitrogen and plant population on grain yield were significant. The results indicated that the difference between different levels of irrigation in the case of dry matter remobilization rate was significant. The least and the highest remobilization rate of reserved dry matter was related to optimum irrigation and drought moderate stress treatment, respectively. The efficiency and contribution of remobilization in grain yield increased in response to increasing severity of drought stress, but these traits significantly reduced as a result of nitrogen consumption. Remobilization rate and contribution of reserved materials to grain yield in the highest density (D₃) were significantly more than other densities. According to the results of this study, under drought stress conditions, the decrease of inputs consumption, in addition to the decrease of costs, will be followed by the increasing efficiency use of the resources.

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  This research was carried out to study the impacts of geomorphologic characteristics of claypan on land use and land degradation. Databank of the study area was constructed and digital terrain model of claypan was prepared. By using GIS techniques spatial distributions of the subsurface drainage network, sediment transportation index and wetness index were calculated. The results indicate that the depth to the claypan is between 0 (where the pan is exposed at the surface) to 605 cm. There are several depressions in the claypan which are filled by new sediments. Each depression has a catchment which is charged by the drainage water of its attributed lands. While a depression drains naturally or synthetically, the attributed soils over the depression are in non saline or moderate salinity condition otherwise, a marshland, a waterlogging area or a salt crust zone develops over there. The results also indicated that soil surface salinity is a function of depth to claypan and drainage condition of area. The trends of salinity extension are different for closed and open catchments and the depth to the claypan could be estimated using electrical conductivity. The results also show that analysis of microtopography of soil surface and soil stratification should be considered for designing irrigation and drainage networks.

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Sorghum (Sorghum bicolor L. Var. Speedfeed) is a major forage crop in Birjand Region, and phosphorus (P) plays an important role in its nutritional value. During a field campaign, eighty soil samples from the region were collected and analyzed. Among them, 24 samples varying in physico-chemical properties and available P were selected. Five extractants were used for measuring sorghum available P as follows: 1) 0.5 M NaHCO3, pH=8.5, shaken for 30 minutes (Olsen's method), 2) 0.5 M NaHCO3, pH=8.5, shaken for 16 hours (Colwel's method), 3) 0.0025 M Na2-EDTA, pH=7 (EDTA method), 4) 1 M NH4HCO3, 0.005 N DTPA (Soltanpour and Schwab's method), and 5) Water (Paauw's method). A greenhouse experiment using a completely randomized design was carried out with 24 soil samples, two treatments of 0 and 90 mg P/kg soil and three replicates. Results indicated that all five extractants are suitable for prediction of sorghum available phosphorus, but Olson and Paauw's methods are preferable. The results also show ed that the critical levels of soil phosphorus for sorghum by Olsen, Colwel, EDTA, Soltanpour and Schwab and Paauw methods are 17, 24, 14, 7 and 2.5 mg P/kg soil, respectively. Statistical analysis indicated that soil pH, clay percentage and organic carbon significantly affected sorghum available phosphorus.

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Many studies have been carried out on the effect of organic matter on soil physical, chemical, biological, and nutritional properties, including the effect of organic matter on the availability of such elements as P, N and heavy metals. There is, however, no information on the effect of organic matter on potassium uptake from micaceous minerals. The objective of this study was to investigate the effect of organic matter on potassium uptake from micaceous minerals released by alfalfa. An experiment was laid out in a completely randomized design with factorial combination and three replicates. Growth medium was a mixture of quartz sand, micaceous mineral (muscovite or phlogopite) and organic matter (0, 0.5 and 1 %). Rehnani cultivar of alfalfa was used in the experiment. During 120 days of cultivation, plants were irrigated with either complete or K-free nutrient solution and distilled water as needed. At the end of cultivation, plant shoots and roots were separately harvested and their K concentration was measured by flame photometer following dry ash extraction. Under the K-free nutrient solution, a significant increase in biomass occurred in pots containing phlogopite and organic matter as compared to those with no organic matter amendment. Also, under K-free condition, potassium concentration in shoot was above the threshold value only in phlogopite amended pots. There was no significant difference in K concentration among different levels of organic matter in control treatment as well as in muscovite added treatment. Under both nutrient solutions treatments, significant increase of K uptake occurred in pots containing phlogopite and organic matter, as compared to those without it. In contrast, under K free nutrient solution, organic matter amendment could not enhance the K uptake in pots containing dioctahedral mica (muscovite). Root activities and organic matter decomposition appear to have increased rhizosphere acidity which, in turn, facilitate the K release from trioctahedral mica (phlogopite) in K deficient medium. Thus, the effect of organic matter on K release greatly depends on the type of micaceous mineral.

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Remote sensing has been considered as an appropriate tool for temporal monitoring of some natural phenomena. Ardestan Region is prone to land degradation and masked by sand sheets, sand dunes, clay flats, desert pavement and different kinds of salt crust due to dry climate. To study the trends of land degradation in last three decades, four satellite data sets of Landsat MSS, Landsat TM, Landsat ETM+ and IRS acquired in 1976, 1990, 2001 and 2008, respectively were analyzed. The time series analysis revealed that the bare clayflats have decreased and clayflats with vegetation cover have expanded over 32 years. During this period, the areas which are covered by gravel have decreased 13 percent and both the area covered by salt crusts and aeolians have extended 2 percent. Puffy grounds have developed by 2001 but their magnitudes have decreased between 2001 and 2008 as they have been masked by the moving sand ripples. Reduction of 13 percent of sand sheets between 1990 and 2008 indicates that soil conservation practices have efficiently controlled land degradation and desertification in the area.

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This research was carried out to determine spatial distribution of heavy metals concentration in soil particle size classes using Landsat ETM+ reflectance in Southern Isfahan city in the vicinity of Bama mine. To fulfill this goal, 100 compound soil surface samples were collected randomly from the area. The samples were air dried and soil particle size classes 250-500, 125-250, 75-125, 50-75 and <50 μm were determined using appropriate sieves after dispersion of the bulk samples of soil using ultrasonic apparatus. Total Zn, Pb and Cd concentrations were measured using Atomic Absorption Spectrophotometer after wet digestion of samples in acid nitric. The results indicated significant negative correlation coefficients between heavy metals concentrations of soil particle size classes and soil spectral reflectance in the visible, near infrared and panchromatic bands of Landsat ETM+ satellite. Stepwise multiple regression models were used for estimating heavy metals concentration in soil particle classes through satellite data. Furthermore, spatial distributions of heavy metals were mapped using stepwise multiple regression equations. Results also showed heavy metals concentrations in all soil particle size classes were maximum close to the mines and decreased by increasing the distance from these sources.

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It is necessary that ETr (Alfalfa-reference evapotranspiration) values be converted to ETo (Grass-reference evapotranspiration) or vice versa. The main objective of this study was to develop ETr to ETo ratios (Kr values) for a growing season in Shahrekord plain, Shahrekord, Iran. Mean monthly and total (growing season) values of Kr were calculated based on 185 daily ET data set in Chaharthakhteh Agricultural Resaerch Station of Shahrekord. The ETr and ETo values were calculated using six models for developing Kr values. The models included the Standardized American Society of civil Engineers Penman-Monteith (ASCE-stPM), American Society of Civil Engineers Penman-Monteith (ASCE-PM), 1982 Kimberly-Penman (KP), and modified Jensen-Haise (JH). Kr values as a function of some of the climatic variables in FAO56 Irrigation and Drainage Paper were compared with lysimeter ETr values. For the growing season, Kr values based on lysimeter study was 1.12, which was comparable to 1.12, and 1.16 for ASCE-PM, and JH, respectively, but was far from 1.27 for 1982 KP models. ETr values in each method compared to ASCE-stPM-ETo were not comparable to 1.40 derived from Kr value based on FAO56 method.

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Landslide as a global disaster causes great human and financial damages. Identification of landslide causes and zonation assist in instability control and construction projects siting. This study aimed to identify landslide causes and instability zonation in Ardal county, Chaharmahal va Bakhtiari province, Iran, using Analytical Hierarchy Process (AHP). Current landslides were delineated through field survey and interpretation of Earth Google images and geologic maps. By using Digital Elevation Model (DEM), slope, aspect, geologic, soil, distance to faults, distance to roads, distance to rivers and landuse/landcover maps and expert knowledge, the pairwise comparison matrix was designed. The weights for all the involved thematic maps were calculated and susceptible zones were mapped. The hazard map indicated more than 77% of current landslides are located in the severe and very severe hazard classes. Comparing landslide hazard map and trigger maps revealed the most influential factors in landslides are distance to roads and slope maps while distance to faults and aspect show the lowest impacts on landslides.

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In order to investigate the effect of different levels of irrigation on qualitative and quantitative yield and determine the corn's optimum depth of Irrigation in sShahrekord, a randomized complete block design experiment was done with 7 treatments including 40, 55, 70, 85, 100, 115 and 130 percent of soil moisture deficit and three replications in furrow irrigation. Effects of irrigation levels on yield, water use efficiency, weight of dry matter, plant height, stem diameter, median diameter, length and weight of corn were significant. Different levels of irrigation had no significant effect on seed oil and protein content, but their impact on plant fiber content was significant. With increasing depth of irrigation, stem length, grain weight and plant fiber content increased. The minimum and maximum corn yield were related to 40 and 130% of full irrigation with the yield of 43.1 and 88.1 tons per hectare, respectively. The maximum and minimum use efficiencies were 55 and 130% of full irrigation treatments with values ​​of 16.17 and 10.1 Kg per cubic meter, respectively. The result of economic analysis showed that the water consumption is 5/582 mm, equivalent to 86% full irrigation depth.

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Conventional methods for estimating evapotranspiration are based on point measurement and suitable for local areas, therefore, cannot be generalized for larger areas or watershed basins. The remote sensing technology is capable of using satellite images and meteorological data to estimate evapotranspiration in a wider area. In this study, estimates of evapotranspiration (ET) by SEBAL and METRIC models based on Landsat 7 ETM+ sensor were compared against ET measured by lysimeter on seven satellites passing time over Shahrekord plain located in Karun basin. The results showed that the lowest indices of NRMSE, MAE and MBE (respectively, 0.317, 1.503 and -0.973 mm per day) and the maximum of d index (0.768) belonged to SEBAL. These indices were 0.420, 2.120, 2.023 and 0.646 for METRIC, respectively. The results showed that the SEBAL was more accurate than METRIC model for estimating ET under Shahrekord plain conditions. As long as the possibility of getting complete hourly meteorological data be provided, or some modifications on METRIC model were done, SEBAL show closer results to reality, and therefore is recommended.
 

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In order to investigate the persistence of organic amendments, nitrogen and zinc effects on soil characteristics in rapeseed-wheat rotation, a factor analysis was conducted in a complete random design with three replications in two consecutive years in a greenhouse. Treatments in the first year consisted of N fertilizer, municipal waste compost, vermicompost, sheep manure. The control consisted of zinc and two rapeseed cultivars. In the second year of the experiment, two cultivars of durum wheat were sown in the same pots as the first year of the experiment. Results showed that two years after application of cattle manure, a significant increase in soil electrical conductivity (41.81 %), available K (59.45 %) and available Mn (79.82 %) compared to the control were found.  Saturated soil moisture (48.57%), total N (94.66 %), available Fe (46.49 %) and available Cu (47.51 %) significantly increased by municipal waste compost compared to the control. Also, Zinc had a significant effect on soil total N (0.28 %), available K (218.4 mg/kg) and available Mn (12.89 mg/kg). Generally, the results showed that application of organic amendments can change many soil characteristics which some of their impacts might last for next upcoming years. Therefore, it is necessary to monitor the soil characteristics and nutrients availability of the fields that were treated with organic amendments in the years after application.
 

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This study was designed to investigate the possibility of using the surface energy balance algorithm for land (SEBAL) and mapping evapotranspiration at high resolution with internalized calibration (METRIC) models to estimate evapotranspiration (ET) in Shahrekord  plain (Chaharmahal va Bakhtiari province, Iran). Two sets of Landsat ETM+ data dated June 30^th and August 21^st, 1999 were provided to estimate and compare reference evapotranspiration (alfalfa) at regional scale using Landsat ETM+ data to ET estimations by five mathematical methods (experimental and combined) known as standardized Penman-Monteith by American Society of Civil Engineers (ASCE-stPM), Penman-Monteith (F56PM), Blaney-Cridle (F24BC), Hargreaves-Samani (HS) and evaporation pan (F24P). Results showed that ET at cold anchor pixel for SEBAL were 6.97 and 6.77 millimeters per day and for METRIC were 10.27 and 9.31 millimeters per day, on days when the satellite passed over. Hargreaves-Samani ET values, as the suitable mathematical model for the studied area, were 8.0 and 7.5 millimeters per day, respectively, on two satellite passes. Results showed that, in the first pass all statistical indices for SEBAL were less than the second pass, maybe due to higher air temperature and wind speed. On the other way, statistical indices in METRIC on the alternate pass, however, showed higher values over the corresponding values in SEBAL. ET values on two satellite passes for anchor pixels were 5.65 and 5.93 mm/day in SEBAL, and 5.22 and 6.65 mm/day in METRIC, respectively. ET values on the same days of satellite overpass for Hargreaves – Samani (HS) were 8.0 and 7.5 mm/day. Consequently, based on the results, both RS-ET models were comparable to empirical models such as (HS). Generally, the results showed that SEBAL had higher accuracy than METRIC, presumably due to lack of accurate weather data (hourly data), so SEBAL is recommended in similar conditions. Generally, the results showed that SEBAL had higher accuracy in comparison to HS and lysimeters data than METRIC, so SEBAL is recommended in similar conditions.
 
 
 

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The aim of this work was to study distribution of some heavy metals in different soil particle-size fractions and to assess their spatial distribution. The study was carried out in Kafe Moor (Kerman, Iran) where the Gol-Gohar Iron Mine is located. One hundred twenty composite soil samples were randomly collected and transferred to the laboratory in bags. After air-drying, the samples were fractionated into six classes including 2- 0.5, 0.5-0.25, 0.25-0.125, 0.125- 0.075, 0.075-0.05 and <0.05 mm. Elemental concentrations (Fe, Mn, Cu, Zn, Pb and Ni) were determined using acid digestion method (HNO₃, 4.0 N) and an atomic absorption spectrophotometer in each class. Ordinary Kriging technique was used for predicting spatial distribution of heavy metals. The results showed that content of metals in soil increased with decreasing particle size. The results also showed that the concentration of Fe, Mn, Cu, Zn, Pb and Ni in <0.05 mm size fraction were 2.13, 1.70, 4.79,2.43, 1.42, and 3.47 times higher than in 2-0.05 mm size fraction, respectively. In addition, mapping the concentrations of heavy metals with kiriging showed that metals pollution decreased with increasing distance from mines area.
 

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Due to limited access to water, it is necessary to determine the comparative advantage of crops and horticultural products in different parts of the province and identify products that lack the desired productivity. Then, find ways to improve water productivity or replace products with higher comparative advantage with low-yield products. Based on this, the crop and economic productivity index of the province's agricultural and horticultural products under surface irrigation systems was determined. Based on the results of gross economic productivity of horticultural products, pistachio with 48690 Rials per cubic meter had the highest economic productivity, and grapes with 30220 Rials per cubic meter (62% of pistachios) was in second place. In addition, water quality for pistachios can never be generalized for grapes and other crops, and this is a tremendous advantage for pistachios that low-quality water resources can also be used. The lowest gross economic productivity of water for barley, alfalfa, and wheat is equal to 3790, 3990, and 4570 Rials per cubic meter, respectively. The study of fodder corn shows that the net profit from the cultivation of this crop in the surface irrigation system is equal to 51.78 million Rials per hectare and its net profit in the strip drip irrigation system (tape) is equal to 110.87 million Rials, which it has a 2.14-fold increase compared to the conventional irrigation method. The comparative advantage of horticultural products was higher than that of crops, and the replacement and development of orchards instead of some crops is recommended as a solution. In addition, solutions that can be recommended to improve the productivity index include the use of a drip irrigation system (tape) for crops (fodder corn, tomatoes, summer crops, and potatoes) and the use of drip irrigation (normal, subsurface, and subsurface modified drip) for horticultural products. Examination of practical experiences of using tape irrigation system for wheat and barley showed that this method has not improved the agricultural and economic productivity index, which indicates the lack of comparative advantage of wheat and barley cultivation in Semnan Province even with tape irrigation system.