JWSS - Journal of Water and Soil Science

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Soil fertility measures such as cation exchange capacity (CEC) may be used in upgrading soil maps and improving their quality. Direct measurement of CEC is costly and laborious. Indirect estimation of CEC via pedotransfer functions, therefore, may be appropriate and effective. Several delineations of two consociation map units consisting of two soil families, Shahrak series and Chaharmahal series, located in Shahrekord plain were identified. Soil samples were taken from two depths of 0-20 and 30-50 cm and were analyzed for several physico-chemical properties. Clay and organic matter percentages as well as moisture content at -1500 kPa correlated best with CEC. Pedotransfer functions were successfully developed using regression and artificial neural networks. In this research, it seemed that one hidden layer with one node was sufficient for all neural networks models. The best regression model consisting of organic matter and clay variables showed R2=0.81 and RMSE=7.2 while best corresponding neural network with a learning coefficient of 0.3 and an epoch of 40 had R2=0.88 and RMSE=0.34. Data partitioning according to soil series and soil depths increased the accuracy and precision of the functions. Compared to regression, artificial neural network technique gave pedotransfer functions with greater R2 and smaller RMSE.

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Geopedology is a systematic approach of geomorphic analysis for soil mapping that construct field operation mainly upon the work in sample area. The main goal of this research is to determine the effect of location of sample area and expert knowledge on credibility of generalization of the results obtained from geopedological approach for similar landforms in south-east of Borujen area. Upon preparation of primary interpretation map of the study area on air photos (1:20,000 scale), and considering different locations of Pi111 unit that encompasses the maximum surface of the study area, the sample area was planned in three different locations. Then, a second-order soil survey was conducted and final soil map was prepared. Also, two different experts were considered to determine the amount of credibility of generalization of the results obtained through geopedological approach for the mentioned unit. Results showed that changing the location of sample area has taxonomic levels (order, subgroup and/or family) and map unit type (complex and consociation) differences in Pi111 unit. In spite of similarity of the profiles selected by the two experts, soil taxonomies of these profiles were different in comparison with representative pedons (at family level). Therefore, the use of landform phases is recommended to increase the accuracy of geopedological results.

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Although soil organic matter (SOM) constitutes a small portion of soil bulk weight, it has a tremendous effect on physico-chemical and biological properties of soils. It is also one of the most important indicators of soil quality and its production. Soil organic matter determination is required for soil fertility management and soil pollution purposes. Wet oxidation procedure of Walkley-Black is a routine, relatively accurate and popular method for the determination of soil organic matter, but it involves the use of chromate and high cost of analysis. Therefore, loss-on-ignition (LOI) procedure as a simple and cheap method of SOM estimation which also avoids chromic acid waste has got more attention. The aims of this study were (i) to establish the relationships between LOI method and SOM as determined by Walkley-Black method for four major plains of Chaharmahal-va-Bakhtiari province and (ii) to determine the optimal temperature of the LOI. To do this, 205 soil surface samples were randomly collected from 0-25 cm depth of Shahrekord, Farsan, Kohrang and Lordegan plains to determine soil organic matter by Walkley-Black method and LOI procedure at 300, 360, 400, 500 and 550 oC for two hours. To determine the optimum temperature for ignition, 40 soil samples were selected to compare the SOM and CCE before and after ignition for each temperature. Results showed a positive, linear significant relationship existed between LOI and wet oxidation in each plain. Coefficient of determination (R2) of the equations was higher for individual plain than the overall equation. Coefficient of determination and line slope decreased and error (RMSE) increased with increasing ignition temperature. At higher contents of calcium carbonate, the rate of line slope decrease with increasing ignition temperature was more noticeable. This may be due to the destruction of carbonates at higher temperature. A temperature of around 360 oC was identified as optimum as it burned most organic carbon, destroyed less inorganic carbon, caused less clay structural water loss and used less electrical energy.

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A greenhouse experiment was conducted in factorial experiment arranged as a completely randomized design (CRD) to evaluate the role of tree indigenous arbuscular mycorrhizal fungi (AMF) species originated from a polluted soil in phytoremediation of zinc polluted soils using maize as a host plant. The experiment consisted of plants inoculated with AMF (G1(Glomus intraradices), G2(Glomus mosseae) and G3(Glomus versiforme)) and G0 as non-inoculated plants and 5 levels of zinc (0, 10, 50, 100 and 500 mg kg -1) in non-sterilized sandy loam soil with three replications. According to the results of greenhouse experiment, the zinc and phosphorus uptake and also the biological yield of maize plants were significantly increased by inoculation with AMF in comparison with non-inoculated plants and also no zinc toxicity symptoms were observed. Uptake, translocation, and phytoextraction efficiency of plants inoculated with G. intraradices was more than the other treatments up to the level of 100 mg kg -1, but at the level of 50 mg kg -1 these amounts were highest in plants inoculated with G. mosseae. The efficicncy of three AMF in zinc uptake was highest at the low level of zinc. In general, under the high soil pollution (500 mg kg-1), G. mosseae was the most effective fungal species in Zn extraction and translocation while G. intraradices had the highest effectiveness for accumulation of Zn in the roots. The overall situation of G. versiforme was mostly between the two other fungal species.

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Crop residues are beneficial substances that can bring about important changes in soil biological, chemical and physical properties and can also increase or stabilize crops yield. A field experiment was carried out at Research Station of College of Agriculture, Shiraz University, Shiraz, Iran, to determine the effects of wheat (Triticum aestivum L.) residue rates in combination with N levels on some soil properties in common bean (Phaseolus vulgaris L.) cultivation for two years (2008-2009). The experiment was conducted as split split-plot arranged in a completely randomized blocks design with three replications. Treatments were two red bean cultivars as main plots, N levels (0, 34.5, 69, and 103.5 kg ha-1) as sub-plots and residue rates (0, 25, 50 and 75%) as sub sub-plots. The results showed that application of crop residues significantly increased soil organic carbon, N, K, and P contents. Heavy crop residue (75%) application had no effects on these soil properties. Thus, retaining 50% crop residue was optimum for proper soil quality. Increased N application increased soil N, decreased P and K contents, and had no effects on organic carbon.

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Soil characteristics are affected by climate. Available potassium is one of the most important soil fertility indices. This study was conducted to determine the availability of potassium using Quantity- Intensity (Q/I) relationships in Vertisols of Isfahan and Chaharmahal-Va-Bakhtiari provinces with aridic and xeric moisture regimes, respectively. Soil mineralogy showed that smectite was the dominant clay in Chaharmahal-Va-Bakhtiari soil. The results showed that the activity ratio of K (AReK) in the soil solution of the surface soil in Isfahan and Chaharmahal -Va -Bakhtiari soils, ranged from 0.019 to 0.11 and 0.0037 to 0.0078 mmol.L-1 respectively. The labile K (∆K0) in Isfahan and Chaharmahal Va Bakhtiari soils ranged from 0.23 to 3.8 and 0.72 to 1.6 mmolkg-1, respectively. Potassium on specific sites (KX) in Isfahan and Chaharmahal-Va-Bakhtiari soils ranged from 2.8 to 7.1 and 2.6 to 3.7 mmolkg-1 respectively. The potential buffering capacity (PBCK) in Isfahan and Chaharmahal-Va-Bakhtiari soils ranged from 12 to 36 and 191 to 201 mmolkg-1/(mmolL-1)0.5 respectively. The results suggested that the Q/I parameters were affected by soil depth. In all of the soils studied, PBCK increased with soil depth.

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Nowadays, due to drought and water shortage, use of unconventional waters, particularly sewage, has become usual in agriculture whereas they often contain heavy metals. The present study was employed to evaluate the effect of urban wastewater of Shahrekord on growth, yield and accumulation of heavy metals (lead and cadmium) in balm (Melissa officinalis) as a medicinal plant with five treatments (0, 25, 50, 75 and 100 percent wastewater) and three replications in a completely randomized experimental design. The results showed that the highest shoot length, stem diameter and stem number, number of leaves and tillers are achieved in the treatment of 100 percent. The wet and dry weight of shoots and roots was highest in 100 % of wastewater. Oil percentage of the leaves was also the highest amount (1.23 %) in 100 % of wastewater. Accumulation of lead in roots and aerial parts and its transmission factor was not significant for the treatments. However, the highest concentration of lead in root (0.057 mg/kg) and shoots (0.013 mg/kg) was observed in 100 % of wastewater and the lowest one was related to zero percent of wastewater treatment. The lead concentration was less than the critical limit for all the treatments. The amount of cadmium was undetectable in all the plant samples. The results of this study demonstrated that urban wastewater of Shahrekord, in addition to providing water, increases plant growth and essential oil.

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Discrete Models of Spatial Variability (DMSV) have limitations for soil identification in traditional soil maps. New approaches, generally called digital soil mapping (DSM), using continuous methods (CMSV), try to predict soil classes or soil properties based on easily-available environmental variables. The objective of this study was to map the soil classes of the Borujen area, Chaharmahal-va-Bakhtiari province, using digital elevation model (DEM) and its attributes and Soil-Land Inference Model (SoLIM). To do this, eighteen terrain attributes were derived from the DEM of the area. The primary analysis showed seven attributes are the most important derivatives. These derivatives as well as three dominant soil subgroups and seven soil families of the region (41 profiles from 125 profiles) were used to construct the input data matrix of the model. Then, output fuzzy soil maps of SoLIM were converted to polygonal soil map, using ArcGIS. Results showed that different combinations of DEM attributes have different accuracy rates for soil prediction. The accuracy of the interpolation was twice that of the extrapolation. Although SoLIM had an acceptable accuracy for soil nomination, and identification of soil map units’ types, it did not have enough accuracy for the location of soil classes. It seems that using other data like parent material and geomorphic surface maps will increase the accuracy of the model prediction.

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As pressurized irrigation is not possible for all circumstances, the use of modern techniques in surface irrigation is essential. In this paper, BISEDOM, a new mathematical model for evaluation, design and optimization of border irrigation is introduced. The effects of weighting coefficients of indicators are investigated based on the potential to improve and the most appropriate weighting scheme in optimization process is presented. In this model, volume balance equations for hydrodynamic simulation and SA method for optimization steps are used. Due to the nature of the SA, its parameters are determined by the method of sensitivity analysis. In this model, evaluation of different combinations of decision variables (inlet flow, length, width and slope of the strip) and consequently the performance of irrigation efficiencies reagent strip in an objective function is possible. Finally, the results indicate that the proposed method for weighted indicators has significant effects on improving performance of border irrigation. Model validation results in three parts of design, evaluation and optimization in comparison with SIRMOD and asymptote method showed that the results are very close to each other. The results also indicate that the proposed model has a good efficiency in comparison with other existing models especially for optimization purposes.

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Regards to the importance of using safe vegetables, controlling the concentrations of heavy metals is necessary for consumer's health. Therefore, this study was aimed to evaluate the potential risk of heavy metals on human health for non-cancerous and cancerous diseases through consumption of agricultural products in Isfahan province. The samples were included wheat, rice, carrots, onions, leafy vegetables and potatoes which were collected randomly from the studied area. In order to assess the risk of non-cancerous diseases, Target Hazard Quotient (THQ) and Hazard Index (HI) were calculated for a specific element as well as combinations of different elements. The results showed that the THQ for arsenic was more than one in wheat and was less than one for other heavy metals if one product is consumed. This indicates that the likely effects of arsenic for noncancerous diseases of wheat are not alone, rather they are for other elements in various products. Risk indicators for men and women are 2.6 and 2.9 respectively, which indicates the effects of noncancerous diseases resulting from consumption of products. Cancer risk due to arsenic in samples of wheat consumption is higher than the Onion and potential cancer risk for this disease for this element is in the middle. The parameters for the lead element in both cases is low.

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One of the main objectives of soil classification systems is to identify the differences of soil properties for management purposes. In this study, the efficiency of American and WRB soil classification systems were compared in order to describe some of soil physical, chemical and mineralogical properties in arid and semiarid regions of central Iran. Khatoon-Abad and Mobarekeh plains as arid regions and Koohrang and Shahrekord plains as semiarid regions were selected. Then, representative pedons of each plain were chosen from 16 excavated pedons and soil samples were taken from the genetic horizons to determine soil classification. Results showed that soil orders of both Koohrang and Khatoon-Abad plains are vertisols according to American soil classification system whereas based on WRB system, these soils are classified as cambisols and calcisols, respectively. On the other hand, both Mobarekeh and Shahrekord soils are classified as calcisols in WRB system whereas these soils are classified as aridisols and inceptisols, respectively, according to American soil taxonomy. None of soil classification systems could show the existence of gypsum in horizons lower than 100 cm of the soil surface for Mobarekeh soil. Clay mineralogy indicates that smectite is the dominant clay mineral in Koohrang soil as explains well at the family level of American soil classification system. Results suggest that WRB has somewhat higher efficiency rather than American soil classification system for the studied soils.

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  Many studies have been carried out on pure minerals to study the effect of plant roots on minerals weathering, but information on mineral weathering that normally occurs in different soil fractions is limited. To investigate the effect of

German Chamomile (Matricaria chamomilla L.) cultivation on mineral weathering of clay and silt fractions in five different soil series amended or not amended (control) with cattle manure, a factorial experiment was performed in a randomized complete block design (RCBD) with three replications. At harvest time, rhizosphere soil was separated and mineralogical studies were performed through X-ray diffraction (XRD) and compared to before cultivation Results showed that in clay sized particles, trioctahedral chlorite transformed to di-octahedral chlorite while kaolinite disappeared. In silt sized particles, feldspar transformed to amphibole and vice versa The pots amended with manure showed the same changes for clay and silt sized particles as the pots without manure.

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In order to investigate the effect of pest and water stresses on different growing stages of cowpea (Vigna sinensis) and pest occurrence, an experiment was conducted in Khazaneh Research station of Isfahan University of Technology. The experiment was carried out in a factorial complete randomized block design, in two different farms, with and without insecticide application. The treatments included severe water stress (50% water requirement), moderate water stress (75% water requirement) in four stages of cowpea growth, the first stage (from seed germination until flower in, second stage (from flowering until pod-filling), third stage (from pod-filling until harvesting) and the whole period of cowpea growth, in three replications. There was a control treatment in each farm with no stress in the whole period of cowpea growth, in three replications. The results showed that water stress had no significant effect on percentage of protein and mineral material. Result also showed that water stress had a significant effect (P≤ 0.01) on population of insects. Water stress significantly (P≤ 0.01) reduced the population of nymphs and adults of Empoasca decipiens Paoli and leaf minor damages, but water stress increased population of Thrips tabaci Lind. Considering the duration of first stage of growth (63 days), it is concluded that this stage had less sensitivity to water stress than the other stages. In regions, where farmers encounter water shortage for cowpea planting, the best performance can be obtained when moderate water stress (75% water requirement) is applied at the first stage of growth.

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Improper use of rangelands may lead to their destruction. Therefore, the conversion of these degraded rangelands to agricultural lands and other land uses may improve their soil quality. The purpose of the present study was to evaluate the impact of cultivation in the degraded rangelands on some soil characteristics in Safashahr region of Fars province. Four land uses including the rangeland with sparse vegetation (degraded rangeland), the rangeland converted to agricultural land over 17 years, the agricultural land converted to apple orchard for 4 years and also to an apple orchard for 40 years were selected. Samples were randomly taken from each land use at two depths (0-20 and 20-50 cm) with five replications. The results revealed that land use change significantly increased organic matter and MWD in both soil depths. Bulk density and water dispersible clay increased in agricultural land and new orchard while a decrease was observed for old apple orchard. It is suggested the traditional farming to be replaced with new cultivation methods like minimum tillage and no tillage. Overgrazing of the rangelands must also be avoided.

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Flood irrigation after planting induces wetting and drying cycles in arable soils. For this reason, the effect of this process on load-bearing capacity (pre-compaction stress pc) of a fine textured soil (silty clay) was studied. In this research, large air-dry disturbed soil specimens were prepared and some of them were exposed to five wetting and drying cycles. Next, the large soil specimens with/without wetting and drying cycles were compressed under three preloads (0, 100 or 200 kPa) and then the centre section of the preloaded soil specimen was firstly submitted to a plate sinkage test (PST). Then immediately one cylindrical sample was cored for confined compression test (CCT). The results showed that for reconstructed soil samples without wetting-drying cycles, the predicted pc using PST didn't significantly differ from the applied preload. Therefore, the PST can be used to determine the load-support capacity of the tilled soils. In PST, with an increase in soil water content from 0.9PL to 1.1PL, the amount of over-prediction in pc decreased. However, wetting-drying process significantly increased over-prediction in pc at the same water content. Hence, soil compressibility does not simply depend on the actual soil water content but also on the previous history of water content changes (i.e., wetting-drying cycles).

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The present study was conducted in order to investigate the effects of silicon and salinity on growth, chemical composition and physiological properties of rice var. Hashemi, in the greenhouse of agricultural college of University of Tabriz during 2011. It was arranged as factorial based on a completely randomized design with three factors consisting of silicon at four levels (control, 100, 200 and 300 mg/kg soil), salinity at four levels (control, 2, 4 and 8 dS/m) and source of salinity at two levels (NaCl and combination of different salts) with three replications. The results showed that increasing soil salinity resulted in a decrease in shoot dry weight, catalase activity and concentrations of phosphorus, potassium and reducing sugars, and an increase in glycine betaine content in the plants. The comparison between two sources of salinity also revealed that plants treated with a combination of salts experienced less vigorous decrease in dry weight and potassium, and reducing sugars' concentrations. Meanwhile, the enhancement in glycine betaine content appeared to be less intense in these plants. Hence, it could be concluded that the salinity resulting from a combination of different salts caused less damage to plants than NaCl salinity. Silicon supplementation resulted in increasing of shoot dry weight, catalase activity and concentrations of reducing sugars, glycine betaine, phosphorus and potassium. Therefore, silicon nutrition alleviated suppression effects resulting from the presence of soil salts, which means, enhanced the salt tolerance of rice.

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Potassium (K) fixation in soil is an important process which affects the availability of K to plants. There is limited information on K fixation capacity (PFC) of soils in Chahar Mahal & Bakhtiary province. This study was carried out with the aim of determining PFC and its relation with soil characteristics in 10 samples of surface soils in Chahar Mahal & Bakhtiary province. PFC was determined by adding six different levels of K by using KCl salt and measuring cation exchange capacity (CEC) in mineral, organic and clay fraction of soils. The results showed that the CEC in the mineral, organic and clay soils changes from 16.02-19.38, 1.71-3.27 to 29.3-39.8 cmol+/kg consequently. Potassium availability index (PAI) in the soils changes from 0.36 to 0.7 and Potassium fixation index (PFI) changes from 0.29 to 0.63. According to the results PFI and PAI showed significant correlation with whole and mineral fraction of the soil CEC, clay percent, pH and CaCO₃ percent. The results of this study also showed that fixation of K fertilizer in the studied soils plays an important role in K dynamic of soil and K availability to plants.

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