Journal of Water and Soil
Year:2013 | Volume:26 | Issue:6|Papers Count:27

Particle size distribution (PSD) is one of the most important soil physical properties. The Grey Model GM (1, 1) is a new method and different from empirical and parametrical models for description and estimation of soil particle size distribution. In this study, the models of Grey GM (1, 1) and Skaggs have been used to estimate PSD in five soil textural classes including 138 soil samples taken from Shahrekord Plain. For evaluating and comparison of two models, four statistical indices (MSE, MAPE, AAE, R2) and 1: 1 lines were used. The results showed that the performance of both models was relatively good in all five textures. However, Skaggs and Grey GM (1, 1) had the best performance in loam and clay textures, respectively. It seems that the performance of Skaggs and Grey GM (1, 1) models improved when soil textures changed to coarser and finer textures, respectively. Absolute cumulative error (AAE) of the Skaggs model in some textures tended to decrease while that of the Grey GM (1, 1) tended to slightly increase with increasing uniformity and curvature indices of soil.

Recently Application of municipal solid waste compost and sewage sludge on the farm land had received considerable attention. These organic wastes provides a valuable source of organic matter and enhances crop yield and soil fertility by improving soil physical, chemical and biological properties. To evaluate the influences of municipal solid waste compost (MSWC) and sewage sludge (SS) on chemical properties of soil an experiment was conducted with Municipal solid waste compost at 0, 15, 30 ton/ha (C0, C15 and C30) and sewage sludge at 0, 15, 30 ton/ha (S0, S15 and S30) in a factorial experiment based on completely randomized design with three replications in greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad. Results showed that municipal solid waste compost and sewage sludge and their interaction effects had significant effects on soil chemical properties. With increasing amounts of municipal solid waste compost and sewage sludge, organic carbon and electrical conductivity of soil increased. Portion of Sewage sludge compared to municipal solid waste compost in increasing of organic nitrogen is lower. The most amount of soil organic nitrogen was observed in municipal solid waste treatments. Also use of these wastes together decreased soil acidity.

This study was conducted to assess yield, water consumption, and water productivity of maize and the factors affecting it under farmers' management conditions at the Karkheh River Basin, Iran, during 2006 and 2007 growing seasons. The studied farms were in Evan Plain that is located in the northern part of the lands downstream of the Karkheh River Dam, where summer maize is planted in 75 cm spaced rows and irrigated by furrows. During the two years of the research and considering the prevailing diversity of the sources of irrigation water (Based on the ratio), seven irrigated field units were selected as follows: two units using groundwater (wells), three units receiving surface water from irrigation network, one unit taking water directly from the river, and one unit using network and well water. In each irrigation unit, three farms were chosen with regard to irrigation and farming management. In the field trials, some physical and chemical properties of the soil, soil test for nutrition (NPK) availability, the volume of inflow applied to the field by the farmer and runoff water in each irrigation, and total crop yield was measured and maize evapotranspiration was calculated. Then, the irrigation and rain water productivity (WP I+R), water application efficiency (WAE), and maize crop water productivity (CWP) was determined for each field. Based on the two years results, the average yield of maize kernel, WP I+R, WAE, and CWP values were, 4844 kg/ha, 0.38 kg/m3, 38.6, %, and 1.01 kg/m3, respectively. The results and observations made during this study indicated that the most important reasons for low water productivity were inadequate knowledge of farmers in irrigation, plant nutrient deficiencies, and improper crop management practices.

Optimal land utilization is important because of land degradation due to incorrect use and ever-increasing need for increasing yield per surface area unit. For this optimal use, crop specific land suitability evaluation is essential. The aim of this research was qualitative land suitability evaluation for maize production in Shahrekord area and validation of the applied land suitability evaluation methods. In this regards, land suitability class was determined by matching land characteristics with maize growth requirements, using parametric method and ALES program. For model making in ALES program, simple limitation method was used, a data base including soil units, land characteristics and maize growth requirements was established in the program and then land characteristics were matched with the maize growth requirements. The results showed that as the square root formula of parametric method and the ALES program are used, most of the land units are classified as S2c. As the storie formula of the parametric method is used, because of multiplication of the suitability ratings and not due to land characteristics limitations, most of the land units are classified as S3c. The most important limiting factors for irrigated maize production in the study area are average minimum temperature and mean ratio of sunshine hours to day length of the growing cycle. In some of the land units, soil pH is considered as limiting factor as well.

In the present study, two methods of predicting evapotranspiration by the use of satellite images were compared. Field data in a corn site was measured at agricultural engineering research institute private farm in 6 days. Consequently MODIS images were used for predicting evapotranspiration by SEBAL and S-SEBI algorithms. These algorithms are different in predicting sensible heat flux. The results show that RSME value for the net radiation and soil heat flux was respectively 46 and 43 (w/m2). SEBAL algorithm is capable to estimate sensible heat flux more accurate than S-SEBI so it is able to estimate latent heat flux more accurate. The RSME amount in sensible heat flux and latent heat flux for SEBAL algorithm are 58 and 31 (w/m2) respectively. These amounts in S-SEBI algorithm are 111 and 74 (w/m2). The differences between two algorithms could be because of the use of meteorological data in predicting sensible heat flux and aerodynamic resistance in SEBAL algorithm. Also the results show that SEBAL algorithm estimates hourly evapotranspiration by the difference of 0.05 mm/hour which is about 1% of hourly evapotranspiration Whereas S-SEBI predicted it by the difference of 0.11 and 11%. The difference between measured daily evapotranspiration and SEBAL -based daily evapotranspiration was 0.4 mm that is about 1% less than measured. Whereas these differences by S_SEBI are 1mm and 12%.

The Madden-Julian Oscillation (MJO) is a tropical atmospheric phenomenon, associated with periods of active convection in the eastern hemisphere tropics. In its active stage, the MJO is associated with increased convective activity over the equatorial eastern Indian and western Pacific Oceans. The Oscillations cycle includes 8 different phases beginning with Phase 1 off the Indian Ocean coast of Africa, through to Phase 8 in the central Pacific before it fades out. We defined positive phase of the oscillation when the convective precipitation was centered over the areas denoted by phases 3, 4, 5 and 6. Conversely, the negative phase is signified as the period when the precipitation is highlighted over the regions denoted by phases, 1.2, 7, and 8. The relationships between the MJO indices and November-April precipitation data in seven stations spread over Fars and Sistan Balouchestan provinces were analyzed for the period 1979-2005. The influence of the MJO phases on rainfall amount and the frequency of wet or dry events were studied for daily timescales. Statistical examinations have shown that the precipitation amount during the negative phase was significantly greater than the corresponding values during the positive phase. In most stations, when negative MJO phase was prevalent, the occurrence probability of wet periods during phases 2 was greater than the corresponding probability during phases 1, 7 and 8. Moreover, at some stage in positive phase, the occurrence probability of dry periods in Fars and Sistan Balouchestan provinces, respectively, during phase 4 and 5 was greater than the corresponding probability during phases 3 and 6.

In recent years lots of studies have been done about modeling water scarcity and salinity stresses and analysis of their effects on different characteristics of agricultural crops. The aims of this study is to use phase I of response surface methodology for analysis of water scarcity and salinity stresses in different growth stages of spring wheat in Mashhad region for achieving the highest amount of yield. The experiment was carried out in the Research Field of Agricultural Faculty of Ferdowsi University of Mashhad in 2009-2010. The experiment was factorial 25: four variables consist to irrigation water requirement in different growth stages, which two levels were 20 and 100 % of water requirement, and one variable to water salinity, which two levels were 0.5 and 10 dS/m. The result showed that all of the variables have great, but different, effect on yield. The interaction effect of irrigation water and salinity on grain yield was negligible. The water use efficiency (WUE) in different optimization scenarios varied between 5.84-7.31 kg.h-1.m-1. The results of optimization revealed the necessity of considering non linear models and planning the further experiments in internal levels of variables in current study, 20 and 100% of water requirement, and inclines towards to upper half, the tensions less that 50 %. Also the non linear and important effect of salinity demonstrates more details of this tension should be considered in further studies.

Conventional graded granular filters which are commonly used in subsurface drainage projects in Iran, encounter various difficulties such as huge costs and long distances from source of gravels and led to use of other materials as envelopes. Synthetic products can be justified over granular filters due to their comparable performance, improved economy and ease of placement. Considering that, it's essential to assess selected synthetic envelopes performance before setting them in the field. The objective of this study is assessment of permeameter test proccessing (based on ASTM D-5101 standard), using 3 different PLM synthetic envelopes (PP450, PP700 and PP900) in application of water with different salinity (EC=22.2 dS/m and 0.78 dS/m) and saline-sodic soil (EC=169.3 dS/m and SAR=45.18 (meq/lit)0.5), prepared from north Khoram-Shahr drainage project located in Khuzestan Provience. This study deal with evaluation of permeability tests results by applying saline water and soil which is not common in permeameter standard tests. So, a distinctive point of this research is using drainage water with high salinity, in comparison with applying normal water and also saline soil. For this purpose, two physical models of permeameter used to do a series of permeability tests by varying synthetic envelope types and saline and normal water. Permeability tests were done at 5 different hydraulic gradients (1, 2.5, 5, 7.5 and 10). Variations of discharge, hydraulic conductivity and gradient ratio (GR) were measured and investigated statically as factorial experiments in the form of randomized complete design. The results demonstrated that the more salinity the lower the hydraulic conductivity in all synthetic envelopes. The average hydraulic conductivity by applying normal water were 1.29, 1.36 and 1.26 times more than the average hydraulic conductivity by applying saline water for PP450, PP700 and PP900 samples respectively. Based on all tests of gradient ratios, it can be concluded that none of the envelope samples were susceptible to clogging, even in application of saline soil and water, even though the probability of clogging by applying saline water was higher. Also, it should be noticed that water quality is essential to encounter in permeability tests.

Soil contamination by heavy metals and its long-term detrimental effects on environment and human health is a present-day concern of environmental scientists. The aims of this paper is to present the results of spatial distribution mapping of heavy metals in topsoils (0-10 cm) using 315 georeferenced soil samples regularly spaced grid pattern with an interval of 500 meters from Anguran area located in the Zanjan province. Total and available forms of Pb, Zn, and Cd were extracted by HNO3 and DTPA-TEA and measured for the samples. The average for total concentrations of Pb, Zn, and Cd were 109.96, 165.57 and 6.02 mg/kg and for available forms were 46.36, 61.54 and 2.63 mg/kg, respectively. The heavy metal concentration data tended to be positively skewed and outlying values were observed. The Box-Cox transformation technique was applied to normalize the data. Strong positive correlations were observed between the concentrations of heavy metals studied. The results showed that spherical model revealed the best result for describing the spatial variability of Pb, Zn, and Cd. The ranges of influence for variograms of Pb, Zn, and Cd were 4800m, 3987m and 4845m, respectively. The application of the Ordinary Kriging method showed a good performance for estimating heavy metals concentration in the areas not being sampled. The results based on the Kriging Maps showed that the concentration of heavy metals increased around the procreation factories, while decreased in longer distances from the factories. The Kriging Maps of total heavy metals concentration indicate a strong spatial pattern in the Southeast and Center of the study area. These maps can provide valuable information for assessing the pollution hazard.

To decree evapotranspiration from soil surface and improving irrigation efficiency and reduce water usage in cotton cultivation, plastic mulch was applied in furrow irrigation. This study was performed as a split plot experiment in capability randomized complete block design, in 3 replications. The experiment was located in Khorasan Razavi-Kashmar-Kashmar agricultural research station and was applied in 2 years, 2004-2005. The treatments were consist of irrigation period at three levels, 6, 9 and 12 days as main plot and plastic mulch at three levels I-black plastic mulch, II- white plastic mulch and III- control (without plastic mulch) as a subplot on furrow irrigation. Each treatment was irrigated up to field capacity. The results showed that application of plastic mulch used better water usage and black plastic mulch was more effective. Meanwhile The results showed that the use of plastic mulch had significant effect on reducing of weed growth, plant height increasing, yield and water use efficiency in respect with control.

Undular flow on broad-crested weirs is a phenomenon occurs under certain hydraulic conditions. In this case the flow surface on the weir transforms to a sinusoidal wave and the number of waves may vary from one to over 10. Forming of this phenomenon leads to error in measurement of flow discharge by weirs. In this study in addition to introduction of the most effective parameters on undular flow formation, effect of geometric properties of rectangular broad-crested weirs was also investigated when only one wave formed. The results show that reducing the upstream slope from standard angle to 21 degree, decreases the relative wave height by 78 percent and increases the relative wave length by 55 percent. The position of undular wave also displaced toward the downstream. With changing in upstream edge shape from sharp edge to a relative radius of curvature equal to 0.5, the relative height of wave decreased up to 80 percent. Roughening the surface of the weir crest led to attenuation and elimination of undular wave, depending on the position of roughness surface.

In recent decades, using drip irrigation has been developed because of water resources deficiency. As irrigation system design and its installation is expensive and time consuming, so its designing should be in a way which the system can supply plant water requirement. Nowadays, there are models that can simulate the soil moisture, according to different conditions. In this study, the performance of HYDRUS-2D has been assessed, by considering temporal variability of soil hydraulic properties. In a field under corn crop and irrigated with tape in south of France, soil moisture at every 10 cm depth until 150 cm of soil measured by a neutron probe was compared to simulated moistures by model according to two statistic indices, i.e. Root Mean Square Error (RMSE) and efficiency factor (EF). By considering soil hydraulic properties variation, RMSE values reduced from 0.061 to 0.022 cm3/cm3 and efficiency factor of model increased from 8% to 88%. Significant effect of these differences has been evaluated by using SPSS software and the result showed that the variation of soil hydraulic parameters in first irrigation was considerable and HYDRUS-2D model has a good performance in simulating the soil moisture at different depths. It is suggested that before installing system or implement of irrigation management, the system performance was evaluated by this model, and the best system management and design would be chosen.

The low irrigation application efficiency is the major problem of surface irrigation systems due to weak management and poor design. In this research, in order to analyze the performance of furrow irrigation system, a field experiment was conducted during maize growing season. Three furrow irrigation methods, conventional furrow irrigation, fixed alternate furrow irrigation and variable alternate furrow irrigation were considered to collect field data and, then, to evaluate the performance of WinSRFR (surface irrigation model). This model was calibrated and evaluated based on the experimental data with Zero-Inertia (ZI) and Kinematic Wave (KW) solutions. The sensitivity analysis of WinSRFR showed that the most sensitive parameters were inflow rate, cutoff time and parameters of the infiltration equation, respectively. There was a small difference between ZI and KW to estimate advance time, runoff and infiltration due to high field slope. The minimum absolute error for estimation of advance times was obtained about 1.5% (0.8 minute). The minimum absolute error in estimating runoff and infiltration were 5.7 and 5.0%, respectively. Using operations analysis of WinSRFR, the isoperformance contour plots of furrow irrigation system was obtained to optimize cutoff time and inflow rate under maximizing of application efficiency and distribution uniformity and minimizing of runoff and deep percolation. Application efficiency iso-performance contour plot of fixed alternate furrow irrigation, indicated by managing of cutoff time and inflow rate, application efficiency could be increasing from 54.5% in current evaluation to 74%, provided water supply of Dreq. Also based on this contour plot, increasing of application efficiency more than 74% was impossible provided water supply of Dreq, under current furrow geometry parameters and it was possible with changing furrow geometry parameters.

In this research chemical forms of lead and zinc in bulk and rhizosphere soil of different cultivars of maize and canola were determined by sequential and single step extraction methods. Some factors affecting chemical transformation of the two elements such as pH, dissolved organic carbon (DOC), their uptake by plant and also cat ion exchange capacity in the rhizosphere and bulk soil were also assessed. Rhizosphere was obtained with gentle shaking and separating the soil around plant roots. Results showed that zinc uptake was more than lead in both plant cultivars. Zinc and lead accumulation in all cultivars roots were also more than shoots. Translocation index (The ratio of element concentration in shoot to root) in the com cultivars was higher than canola cultivars (significant correlation=1%) while the ratio was higher for lead in canola cultivars. Metal concentration in shoots to total metal concentrations in soil (Accumulation factor) showed a similar trend like the translocation index. In total, the com ability in zinc and lead absorption and extraction in soil was higher compared to canola. There weren't any significant changes in rhizosphere pH compared to bulk soil. Dissolved organic carbon in the rhizosphere of different cultivars was more than bulk soil and the amount of it in canola was significantly more than com cultivars. Among each plant cultivars, the absorption rate increased with increasing root exudates. The results of sequential and single step extraction methods showed that the general trend and the soil system tendency (Root-Soil interface) is toward zinc availability in the rhizosphere, The amount of lead in rhizosphere showed no significant changes to bulk soil with none of the extractants in single step extraction method but with regards to the results of sequential extraction method, rhizosphere processes tend to reduce the availability of this element in both plant cultivars.

Low phosphorus use efficiency in calcareous soils is one of the problems of wheat production in the fields, all over the world. This experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP) and phosphorus (P) levels on the yield and P use efficiency of wheat (Triticum aestivum L.). A factorial experiment in randomized complete block design was carried out with two factors of type of nitrogen fertilizer (1- control: with no added N fertilizer, 2 and 3- ammonium sulfate fertilizer (ASF) with and without nitrification inhibitor DMPP, 4 and 5- ammonium sulphate nitrate fertilizer (ASNF) with and without nitrification inhibitor DMPP with rate of 100 mg N Kg-1 soil) and different levels of P (0, 30, 60 and 90 mg P kg-1 soil) on spring wheat cv. Pishtaz during 2010 at ShahreKord University with three replicates. According to results, application of nitrification inhibitor DMPP with both of ASF and ASNF resulted to meaningful increase of soil available P at the end of experiment as well as significant increase of NH4+and also significant decrease of NO3- in the soil during experiment as compared to similar treatments but without NI. The results indicated that application of nitrification inhibitor DMPP with ASNF at all P applied led to significant increase (P<0.05) of biological yield and grain yield of wheat and also P agronomic efficiency of aerial part and grain of wheat compared to ASNF but without NI. In conclusion: application of nitrification inhibitor DMPP with ammonium sulfate nitrate fertilizer is recommendable to improve yield and P use efficiency of wheat.

Most of medicinal plants are able to grow in low P supply as well. In order to study the ability of some medicinal plant species, a greenhouse experiment was conducted with Salvia virgata, Achillea millefolium and Ziziphora clinopodioides Lamin a low P soil. The experiment was undertaken with three levels of P (0, 15, 150 mg kg-1), two harvests and three replications as a randomized complete block design. In the second harvest and low P treatment, all species showed a high relative shoot dry matter (above 80%) which indicated a high P use efficiency of them. The range of shoot P concentration in low P treatment at the first harvest was between 0.23% and 0.29%. In this case, no significant difference was observed among different P treatments. In addition, the shoot P content of plants was almost high. As a result, all three plant species were P uptake efficient plants. The P influx in Ziziphora clinopodioides Lam was more than two other plant species. The results of the root- shoot ratio of plants at low P supplied was indicated that high P uptake efficiency of Salvia virgata was mostly due to its extensive root system, whilst, for Ziziphora clinopodioides Lam it was mostly due to its high P influx.

Rhizosphere is a small zone and has quite different chemical, physical and biological properties from bulk soil. This research was conducted to investigate the availability and fractionation of copper in the wheat rhizosphere and bulk soils by using rhizobox at greenhouse conditions. Three seeds of wheat were plant in the rhizobox. After 8 weeks, plants were harvested and rhizosphere and bulk soils were separated. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and available Cu (by using 7 chemical procedures) and Cu-fractions were determined in the rhizosphere and bulk soils. The results indicated that TOC, DOC and MBC in the rhizosphere were increased significantly (p<0.01). Cu extracted using several chemical extractants in the rhizosphere were significantly (p<0.05) lower than in the bulk soils. In the rhizosphere soils exchangeable Cu, Cu associated with carbonates and Cu associated with manganese-iron oxides were decreased and Cu associated with organic matter and residual Cu were increased. Moreover, results indicated that correlation between Cu associated with iron-manganese oxides and residual fraction with extracted Cu using DTPA-TEA, AB-DTPA and Mehlich 3 with were significant (p<0.05) in the rhizosphere and bulk soils. Correlation between concentration index and extracted Cu using AB-DTPA and Mehlich 3 were significantly (p<0.05) in the rhizosphere and bulk soils. In addition, correlation between uptake index and extracted Cu using 0.01 M CaCl2 was significantly (p<0.05) in the rhizosphere and bulk soils. The result showed that significant correlation (p<0.05) between concentration and uptake indices and Cu associated with iron manganese and residual fractions in the wheat rhizosphere and bulk soils were found. Result revealed that coefficients in the rhizosphere soils were higher than in the bulk soils.

This study was conducted to determine the best micro irrigation system for pepper cultivation during two years. The goal of this study was water saving and reduction the disease progress (Phytophthora capsici) in the field condition. Experimental design was split plot based on randomized complete blocks design with four replications. Three different drip irrigation methods, drip irrigation with in-line emitter tubes, drip irrigation (tape), and drip irrigation with porous pipes as main plot and three different amount of water (50, 75 & 100% water requirement) were as sub-plot. The result showed that the drip irrigation had the highest effect on disease control. The drip irrigation (tape) with 100% and 75% water requirement treatments had the lowest progress of Phytophthora capsici. In the first year the effect of irrigation method on yield and progress of Phytophthora capsiciwas significant. The effect of irrigation levels on the characteristics of plant except yield was no significant (a<0.01), but the effect of irrigation methods on water use efficiency was significant (a<0.05). The drip irrigation (tape) with 100% and 75% water requirement treatment had the highest water use efficiency. In the second year the effect of irrigation levels and irrigation methods on yield was significant (a<0.05), but the effects of combination of irrigation levels and methods on yield was not significant. The drip irrigation (tape) with 100% water requirement treatment had the highest yield. The result in two years showed that the pepper is a sensitive plant to water deficit. The drip irrigation (tape) and 100% water requirement treatment had the highest yield (7214 Kg) and water use efficiency (1.311 Kg/m3). The result also showed that the porous pipes had no good efficiency. According to the results, the best option for pepper is drip irrigation (tape) with using 100% water requirement.

Deficit irrigation is an optimization strategy for water use efficiency in irrigation. This research was conducted to evaluation effect of deficit irrigation (DI) and partial root zone drying (PRD) on yield, yield components and water use efficiency of corn. Research was conducted on Shahid Bahonar University of Kerman in the spring of 2010 using a completely randomized block design with one control, 18 deficit irrigation treatment and three blocks. Deficit irrigation treatments were included: mild water stress (irrigation with %75 ETP), high water stress (irrigation with %50 ETP), fixed every other furrow irrigation and three partial root zone drying (Change the wet furrows in every irrigation, Change the wet furrows in every other irrigation and change the wet furrows in every second irrigations). Every treatment was applied at three growth stages of corn (all periods of growth, vegetative growth stage and reproductive growth stage). The highest biological yield obtained 32431 and the lowest was 17654 kg per hectare. The highest grain yield was 12115 kg per hectare and the lowest was 7163. Water use efficiency (km grain yield per cubic meter of water) for the control treatment was equal to 1.16 and for partial root zone drying with change the wet furrows in every irrigation (14 days) in all periods of growth treatment was equal to 2.13. Results showed that partial root zone drying with one interval irrigation (14-day) was the best choice to apply deficit irrigation on corn.

In recent years, quantity and quality of groundwater in most country is reduced due to over-withdrawal of water. It is important to use new tools and technology to manage these water resources. The purpose of this study was to manage the groundwater resource using a Bayesian Decision Network (BDN). The Kordkooy region in North of Iran (Golestan province) has been selected as the study area. The region has been divided to three parts based on transmisivity (T) and electrical conductivity (EC) values. The BDN parameters-marginal probabilities and Conditional Probability Tables (CPTs)-have been identified for each of the three zones. Three groups of management scenarios have been developed based on the two decision variables including "Crop pattern" and "Domestic water demand" across the three zones of the study area. Arising from implementing each scenario have been predicted using the functional BDN for each of the zones. The results showed that unmanaged operation causing irreparable damage to the groundwater of study area. In conclusion, we can propose that the use of BDNs in groundwater management studies is a practical and effective approach for assessing and managing these valuable water resources in a probabilistic context representing the uncertainties.

Geopedology which is a systematic approach to analyze the influence of the geomorphic levels on soil mapping, makes it possible to generalize the soil survey results in one geomorphic unit to the other similar units of a studied area that resulted in reducing the time and costs of soil survey. The main question, in this regard, is to what extent the soil data generalization can be valid? To answer this question the effect of landform's kind on the reliability of the geopedology approach was studied in an area of about 1500 ha on the east of Damavand. For this purpose, the geomorphic units were determined by interpreting the 1:55000 scale air-photos of the study area. In the next step, two similar delineations were selected in the piedmont landscape and two similar ones were selected in the hill-land landscape as well. Then, according to semi-detail soil surveys, some pedons were studied in each of similar delineations. Through the description and sampling of all of pedons and through physical and chemical analyses on all of the pedons' master horizons, the pedons were classified up to the family level according to Soil Taxonomy system. The results indicated a significant effect of landform's kind on the results of geopedology approach. Although the kind of map unit for similar landforms was the same, the similarity was lower among the pedons in the hill-land landscape than the piedmont in all levels of Soil Taxonomy system. It was probably due to the more slope variations in the hill-land (compared to piedmont areas), and as a result, a greater spatial variation of the nature of exist soils on this landscape.

One of the important factors that limits the maintenance and expansion of agriculture in irrigated lands of arid areas is the water shortage. Reuse of the municipal waste water effluent as one of the uncommon water resources especially around the big cities has received a lot of attention. One of the most important physical properties of the soil affected by using wastewater is the saturated soil hydraulic conductivity (Ks). In order to investigate the effect of wastewater on Ks, the farms with sand, silty loam and clay were selected from the area around Parkand Abad (2) refinery in Mashhad that has been irrigated during the past 5 years with wastewater. Undistirbed sample was selected and saturated with water, wastewater and mixture of them was used to determine the amount of ks (with constant head method) and the pbof soil in laboratory. The results showed that the farms with wastewater with total suspended solids of 60 mg per litere floating in water limits the ks in different textures. The reduction in soil with clay texture as about 9 Percent and in silty loam and sand was about 4.5 and 2 Percent respectively. Using water as the liquid of experiment didn't have any effect on increasing the amount Ks so that leaching the soil under the irrigation with wastewater increased the soil saturation up to 3 percent That shows no effect of leaching in improving the water direction. The most change of pb was observed in clay soil about 11 percent and the least in sand texture soil about 0.6 percent that with respect to the amount of floating materials in wastewater (60 mg) per liter the use of wastewater has been effective in blocking the soil openings. It seems that the floating material in waste water soil aggregation and the duration of continuous use of wastewater are effective factors in changing the physical properties of soil such as Conductivity of water saturated soil.

This study was conducted to identify the most effective agroclimatic variables (indices) which are detrimental for wheat production (irrigated and rainfed) in Hamedan Province. For this purpose, statistical correlation analysis were performed for seven sites between wheat performance (WP) (Kg. per hectare) and various agroclimatic indices namely: annual rainfall (Pa), seasonal rainfall (Ps), monthly rainfall (Pm), 10-day rainfall (Pd), reference precipitation deficit (RPD), crop precipitation deficit (CPD), monthly growing degree-day (GDDm) and 10-day growing degree-day (temperature thresholds of 5, 10, 15 and 20 degrees centigrade). To evaluate the degree of correlations, correlation coefficients and coefficients of determination (R2) were determined for all steps using two-variable and multi-variable (Pearson) approaches. For two-variable correlations, 462 scenarios were constructed. For mulit-variable Pearson correlations, 55 scenarios were defined at statistical significant levels of p<0.01 and p<0.05 respectively. The results showed that crop precipitation deficit index (CPD) is the most effective factor affecting wheat performance in Hamedan (R2=0.36). It was found that the rainfall events in March and April are more effective than other months. On average, the rainfed wheat was more sensitive to agroclimatic variables than irrigated wheat. The analysis of two-variable correlations (WP-GDD) revealed that the spring time GDD at 5oC (GDD5) is more effective than other temperature thresholds. In general, the results of two–variable correlation analysis and multi-variable analysis both showed that the RPD and CPD are the most effective agroclimatic indices governing WP. By contrast, the multi–variable analysis of GDD showed insignificant correlation coefficients. For multi-variable method, more than %90 of the correlation coefficients were positive (0.67<r<0.97) and statistically significant (P<0.05). On average, the western areas of the province were more susceptible for wheat production (rainfed and irrigated) than the other areas.