JWSS - Journal of Water and Soil Science

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Iron and manganese oxides as well as hydroxide minerals are among active constituents in soils because they are sensitive to environmental changes and often move frequently along soil profile. Therefore, their chemical forms content and their ratios are used as a soil developmental criterion. The present study was conducted in order to evaluate the effects of topography and drainage conditions on chemical forms of Fe and Mn along a soil catena in Dasht-e- Roum plain, in Kohgilouye Province. According to the results, maximum pedogenic Fe and Mn (Fed and Mnd) was found in more stable geomorphic surfaces. Higher values of Fed and Mnd were mostly observed in surface horizons compared to soil depth. Aquic soils exhibited higher contents of poorly crystalline Fe and Mn (Feo and Mno) and higher contents of Fed and Mnd. A significant correlation between clay content and Feo, Mno, Fet and Mnt contents was found. In addition, aquic condition increased Feo/Fed, Mno/Mnd and Mnd/Fed, 3.1, 4.3 and 1.9 times respectively but decreased the Fe crystallinity index 2.6 times. Aquic soils seem to have more favorable conditions for the formation of pedogenic Mn compared to pedogenic Fe, hence higher content of Mnd/Fed was observed in these soils

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Stabilization of the silty sand soils which cover large areas of Iran and world is inevitable as their geotechnical properties are weak. In this research, the effects of different contents of lime and pozzolan admixtures on compressive strength of silty sand soil were investigated. To do this, different treatments were prepared by adding five levels of lime including 0, 1, 3, 5 and 7 percent by weight of silty sand soil, and four levels of pozzolan including 0, 5, 10, and 15 percent. Then, different specimens with 3 replications were remolded and cured for 7, 14 and 28 days and tested for determination of their unconfined compressive strength. Statistical analysis was made using SPSS software and the results showed that addition of lime and pozzolan increases optimum moisture content and decreases maximum dry density of the soil. Moreover, it was found that the addition of lime and pozzolan to the soil increases compressive strength considerably Compared with when applied individually. In this way, the compressive strength of the samples can be increased up to 16 times more than the natural soil strength. Based on the overall results of laboratory tests and statistical analysis, the combination of 3 percent lime and 15 percent pozzolan was determined as the optimum mixture for stabilization of silty sand soils

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In order to investigate the effects of municipal solid waste enriched with mineral fertilizers on some soil physical properties and lead (Pb) and chromium (Cr) concentration in plant organs of spinach, a field experiment was carried out in a factorial arrangement based on the randomized complete block design with three replications in 2008. The main plot included four levels of fertilizer, control without fertilizer, 20 tons of multiple solid waste + 50% chemical fertilizers and 40 tons of multiple solid waste + 50% chemical fertilizers per hectare and sub-plot consisted of a period of application in 3 levels of time (one, two and three years). The results showed that application of enriched municipal compost increased field capacity, soil porosity and moisture holding capacity, but particle and bulk density of soil decreased compared to the control. Also, the physical parameters in the two levels of emriched waste compost were higher than chemical fertilizer treatment. On the other hand, using for three-years the urban waste compost enriched fertilizer at all levels increased significantly (p 0.05) lead and chromium concentrations in spinach. The Pb and Cr accumulated in roots and shoots of spinach in urban using 40 tons of waste compost per hectare with 50 percent of chemical fertilizer for a period of three years and showed a significant increase. The amounts of fertilizer in all three levels were higher than the root element shoot.

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Soil characteristics are the most powerful factors in desertification phenomenon. The purpose of this study was investigating soil characteristics as indices for evaluating desertification intensity. The most important indicators of the soil that affect desertification were selected in the present study. Soil samples were taken from Segzi desert vicinity located in the east of Isfahan city with surface area of 112,167 ha. Soil indices such as Soil texture, soil gypsum percentage, the content of HCO3-1, electrical conductivity (EC), pH, the percentage of the organic matter, the content of the soil sodium, chloral and sodium absorption ratio (SAR) were selected. All of these indices were calculated on the thirty four soil samples. After ensuring of the normality of the samples by Klomogrov-Smirnov test, the mentioned indices were imported into GIS for delineating soil characteristics maps. To delineate distribution maps of each soil indice, inverse distance weighting and ordinary and discrete Kriging methods were applied, and appropriate method was selected. Each layer was scored based on MEDALUS model, and the final characteristic maps were then generated using soil geometric mean indices. Results showed that the affected areas of the average, severe and very severe classes of desertification were calculated about 66000, 45650 and 517 ha, respectively. The results also revealed that the indices of the organic matter, soil gypsum percentage, electrical conductivity and SAR were the most influential indicators, which affected desertification in the study 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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Organic carbon is the most important component of terrestrial ecosystems and any change in its abundance can have a major impact on the processes that take place in ecosystem. The aim of this study was to estimate carbon sequestration in three different elevations (200 to 1200 m from sea level) and according to vegetation type in the Khairoodkenar forest. The highest carbon sequestration was observed in the surface layer of a soil with Fig-Carpinus betulus vegetative cover and it was estimated to be 167.4 ton/ha. But when carbon sequestration was measured in soil solum, it was found that soils with Fagus orientalis-Carpinus betulus vegetation cover had the highest amount of organic carbon (514.4 ton/ ha). The results showed that clay fraction had the highest carbon content but the highest enrichment factor (1.59) was measured for sand fraction in soils with Fagus orientalis- Carpinus betulus vegetative cover. The highest organic carbon content (7.89%) and aggregate stability (MWD= 7.79mm) and lowest bulk density (1.21 g/cm3) were measured in soils with Figs- Carpinus betulus vegetative cover.

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Hydraulic conductivity is an important parameter in the design of geotechnical structures such as earth dam, floor construction, retaining walls and environmental structures. In unsaturated soils, hydraulic conductivity is a function of moisture content and soil water suction i.e. soil moisture characteristic curve. In this study, the values of unsaturated hydraulic conductivity in two soil types (Ramjerdi and Molasadra core dam series) at 5 different compactions using Gardner method were measured. Then, the unsaturated hydraulic conductivity was estimated by different models using the soil moisture characteristic curve and was compared with measured values. The results showed that Fredlund and Xing models predict the soil moisture characteristic curves more accurately compared with van Genuchten model. For Ramjerdi soil series and up to nearly 0.25 volumetric water content, (VGM) and (FM) models indicated a good estimation for unsaturated soil conductivity. Also, for Molasadra core dam none of the models resulted in acceptable estimations for unsaturated hydraulic conductivity.

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In order to describe soils polluted with hydrocarbons, the amount and distribution pattern of soil heavy metals (Ni, Cd) in soils were studied. Soil samples were taken from one of the western oil field of Iran. The field was naturally exposed to crude oil spillage into soil and consequently was environmentally polluted during the development, production, transportation and storage of crude oil. Sampling was started near the oil wells with maximum relative contamination and continued to the remote places based on grid sampling pattern. Samples were characterized by physicochemical analysis. The results revealed different levels of total hydrocarbons (from 0.12 to 2.99 mg/kg of dry soil), Ni (from 32 to 136 mg/kg. of dry soil) and Cd (from 0 to 4mg/kg of dry soil). In addition, the role of soil agents such as pH and EC and sedimentary indexes was considerable in controlling the pollution trend in the studied area. Finally, by interpolation module and prediction of unknown values via Kriging techniques, the expansion plans were created. The extracted plans obviously illustrated the decrease in the levels of pollution indexes with the increase in distance from the given centers of pollution

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The type and intensity of soil erosion in a region generally depend on climatic conditions, ups and downs, soil and land use. Of these, land use is most important. Using different systems of ploughing after unconscious and non-scientific change of land use affects soil physicochemical characteristics. This fact especially in marginal lands and mountainous regions is more visible. In order to investigate sensitivity to soil loss and erosion in various land uses of Aghajary deposits, part of Margha catchment with an area of 1609 hectares in Izeh city was selected. This was to determine the relationship between soil loss by rain simulator and some soil physicochemical characteristics like percentage of very fine sand, sand, clay, silt, pH, Ec, moisture, Calcium Carbonate and organic materials in different land uses. Then, sediment sampling in 7 points, three replicates and in various intensities of 0.75, 1 and 1.25 millimeters in minute in range, residential and agricultural land uses was done using rain simulator. In order to investigate effective factors in sediment production and erosion, samples of soil layers (in depth range of 0-20 cm meters) equal to the number of sediments were taken. For statistical analysis, EXCEL and SPSS 11.5 software were used. In total, the amount of runoff in residential land use was highest and in agriculture land use was lowest. The amount of sediment in agriculture land use was highest and in residential land use was lowest. Then, the most important factors in sediment yield were diagnosed by multi regression. The results showed that sediment yield and erodibility in land uses have meaningful differences in various intensities of precipitation. Regression models showed that in the production of sediment in various land uses, from among the measured factors, silt, sand very fine, lime, Ec, organic materials and pH had the greatest role. Sand percentage in the residential land use, and very fine sand and organic matter in agriculture land use had the most important role in sediment production. But in range land use, moisture percentage and pH had the biggest role in sediment production.

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The incorporation of plant residues in soils of arid and semiarid regions is a major principle of sustainable agriculture. This study was conducted at the research farm of Urmia University (37° 32’N and 45° 5’ E), Urmia, Iran during the 2009 and 2010 growing seasons. Five green manure crops were grown in four replications arranged in a randomized complete block design. The treatments included white clover (T.repens), sainfoin (Onobrychis viciaefolia), pearl millet (Panicum miliaceum), sorghum (Sorghum bicolor) and turnip (Eruca sativa). Changes in soil nutrient elements and nitrogen mineralization were measured during different time periods after plant residues incorporation to soil. The plants were irrigated 50% of field capacity during growing period. The results showed that the total nitrogen and NH4-N were influenced by type of green manure in both years. The lignin and cellulose were the main factors controlling N mineralization and residue decomposition. In the first and second year, the results indicated that pearl millet green residues resulted in the highest amount of soil organic carbon. Nitrate-N content reached the highest amount in sainfoin and white clover. In conclusion, white clover and sainfoin due to increasing total and mineral nitrogen for subsequent plants could be introduced as a proper green manure in water deficit conditions.

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Soil erosion is one of the most important factors affecting soil quantity and quality and is environmental problems in developing countries like Iran. It can have deteriorating effects on ecosystems. This research was carried out in farm lands of the Chehel-Chai watershed, Golestan province to investigate the effect of soil properties on runoff and soil loss. Runoff and soil loss were measured in a completely randomized design in 36 plots with 10×10 m sizes in farm lands. For this reason, this study was conducted using rainfall simulator with 2 mm/min intensity and 15 min duration in 4 replicates. Soil samples were also taken in each plot. Sampling was conducted in October 2009. Results of the Pearson correlation showed that among soil properties, the contents of the lime, silt and fine sand had positive correlations with runoff at 1% confidence level. Also, soil surface resistance at 1% confidence level, the contents of the organic matter and nitrogen at 5% confidence level had negative correlations with soil loss. Finally, the results of multiple linear models showed that the content of lime is effective in estimating runoff and soil surface resistance, and organic matter is effective in estimating soil loss.

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Study of land use effects on soil quality indicators leads to sustainable management and preventing progressive land degradation. The TM (1987) and ETM+ (2000 and 2005) data were used to study land use change effects in Mahan-Joopar area on soil quality indicators. Fifty random soil samples from 0-30 cm depth of each land use were taken using provided maps. Organic matter, microbial respiration potential, bulk density, pH, EC, and soil texture were investigated as soil quality indicators. Eight land uses including fruit orchards, woodlands, pistachio orchards, cultivated, barren, bare land, fallowed, and haloxylone land were detected. Results showed overall accuracies of 89.4, 95.2, and 91.7 % with kappa coefficients of 85, 92, and 88% for maps provided in 1987, 2000, and 2005, respectively. Generally, the investigated quality indicators showed that woodlands, fruit orchards, cultivated land, and pistachio orchards enhanced soil quality better than other land uses.

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In order to determine optimum equilibrium solution phosphorus (P) concentration using P adsorption isotherm and obtain model(s) by integrating soil solution P concentration, physicochemical properties, and soil P test (available P) which predict standard P requirements to achieve maximum yield, laboratory and glasshouse experiments were conducted on 36 soil samples belonging to 15 soil series and 14 soil samples, respectively. Using wheat as a test crop, the glasshouse experiment was laid out with five P levels in a completely randomized design with three replications. Concentrations of P in solution established by adding P in the pots estimated from the sorption curve ranged from 0.2 to 1.2 mg P/L including check treatment (no P). The results showed that equilibrium solution P concentration (EPC) was almost low in comparison with the requirement for most crops (<0.2 mg/L). The amount of P adsorbed by the soils at 0.2 mg/L EPC ranged from 5 to 114 mg/kg soil. The phosphate adsorption was well described by Freundlich (R2 = 0.96) and Langmuir (R2 = 0.88) isotherms. Langmuir maximum adsorption (Xm) and Freundlich coefficient (aF) estimated from Langmuir and Freundlich equations ranged from 127 to 238 mg P /kg soil and from 43 to 211 mg P/kg, respectively. Yield of wheat in all soils approached maximum as adjusted P levels were increased to 0.4 mg P/L. The results showed that some soils studied were adequate in available P by the NaHCO3 test, but required an amount of P fertilizer by the isotherm P requirement test to obtain maximum biomass production. Soil clay content was significantly related to the soil P sorption indices, P0.4 (P sorbed at 0.4 mg P/L EPC) (R = 0.40, P<0.01), PBC (P buffering capacity) (R = 0.54, P<0.001), aF (R = 0.48, P<0.01), and Xm (R = 0.40, P<0.01). Total CaCO3 and Active CaCO3 were found to be less important factors affecting P adsorption. Using stepwise regression analysis resulted in a useful regression model including the combination of Olsen P and clay content for the prediction of standard P requirement (P0.4).

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Different root water uptake models have recently been used. In this article, we use evapotranspiration data and soil water content data obtained from lysimeter measurements and root distribution in soil data obtained from olive tree to evaluate the accuracy of root water uptake models in predicting the soil water content profiles. Depth of lysimeter was 120 cm which was filled with clay-loam. Lysimeter recorded values of input and output of water and accurate value of evapotranspiration was also calculated. Soil water content distribution was measured using a TDR probe in lysimeter during the experiment. Feddes model with the root length density was used to account for the role of root distribution in soil. The flow equations were solved numerically with the measured evapotranspiration data as input, and the predicted soil water content profiles were compared with the measured profiles to evaluate the validity of the root water uptake models. The comparison showed that the average of relative error index for Feddes model was 10 %. Based on the results, about 90% of root uptake in olive tree happened at the depth of 40 centimeter

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Soil erodibility and gully erosion and their expansion occur under geological formation and soil characteristics. This study aims to find the rate of soil and formation effects on gully erosion in Seifabad watershed. To that end, aerial and field work were used together to determine the rate & expansion of 17 gullies in 12 years' period from 1997 to 2009. The soils were sampled for each gully in 50% interval distance with 0-30 cm horizontal surfaces and >30 cm depth. Some factors were estimated from the soil such as EC, PH, Silt, Clay, Sand & limeston percentages. Statistical analysis was done using SPSS 14 through non-parametric tests such as Kruskal-Wallis & Mann-Whitney. Spearman coefficient was used to investigate the relation between volume of gully & litological factors. The results showed a positive correlation at 1% level for the PH with the gully erodibility in surface soil, but for the depth of soil this relation belonged to the silt percentage, and sand showed a negative relation at 5%level with the volume of the gully sediments. Finally, there was no statistical relationship between geological formation and the sediment yield in gullies.

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The quantity and variability of soil organic carbon (SOC) is one of the most important indices to determine the effect of land use changes on the soil quality. Regarding long-term changes from rangeland to dry farming in the Roin area of North Khorasan, the objectives of this study were to investigate the effect of long-term land use changes on the SOC in different slope faces and use SOC as an index to make a proper decision about the future of land use in this area. 140 soil samples were taken from 0-15 cm soil depth of back slope position of north-, south-, west- and east-facing slopes of rangeland, dry farming, alfalfa dry farming and garden in 7 points. 14 soil samples were taken from irrigated farming, too. The results showed that garden and irrigation farming with averages of 2.03 and 0.78% have the maximum and minimum SOC content. The average of SOC content in rangeland was 1.40% that decreased by land use change to 1.04 and 1.27% in dry farming and alfalfa dry farming, respectively. SOC content in southern slope aspects showed a significant difference compared to other slope aspects. The most SOC content occurred in east aspects. It seems that after long-term land use changes, the SOC content have equilibrated to environmental and land use conditions. The average SOC content in different slope aspects except south one changed from 1.4% in rangeland to 1.11% in dry farming and 1.32% in alfalfa dry farming, which are a suitable value for semiarid regions. In conclusion, to protect land from degradation and considering this fact that dry farming is the main income of the people in the study area, it is recommended to stop dry farming on south aspects and continue on east, north and west aspects with conservation practices.

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Paddy soils provide the staple diet for nearly half of the world's population. The formation of the Anthrosols is induced by tilling the wet soil (puddling), flooding and drainage regimes associated with the development of a plow pan and specific redoximorphic features. The aim of this study was to evaluate the effects of long-term rice cultivation on physico-chemical properties and clay mineralogy of soils of three rice farms and compare the results with adjacent virgin lands in Yasouj region. Paddy soils exhibited larger contents of clay, organic carbon, saturation percentage, cation exchangeable capacity, cation exchange activity classes, electrical conductivity and lower content of calcium carbonate equivalent compared to non-paddy soils. This land use showed higher proportions of Feo, Fet and lower content of Fed. No such differences were noticed with the type of clay minerals in both land uses. Paddy soils contained greater amount of smectite, particularly in the surface horizons. Smectite in paddy soils exhibited lower layer charge and higher degree of crystallinity compared to non-paddy soils. Transformation of illite and chlorite to expandable minerals is a possible mechanism for lower amounts of these minerals in paddy soils.

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The objective of this study was to evaluate the effects of crop residues management on soil physical and biological properties. The impacts of residue management on yield of forage corn and barley and soil micro-organisms population were also studied. The results showed that application of crop residues increased soil organic matter (22.2 %), saturated hydraulic conductivity (51.9 %), porosity (3.7 %), mean weight diameter (MWD) of the aggregates (5.4 %), and field capacity (5.8 %) and decreased bulk density (3.7 %) Whereas crop residues burring decreased soil organic matter (31.8 %), saturated hydraulic conductivity (36.6 %), porosity (0.5 %), mean weight diameter (MWD) of the aggregates (5.1 %), and field capacity (4.1 %) and increased soil bulk density (1 %). Soil water characteristic curves showed that the observed differences in soil water retention of application and burning residues treatments were higher at low matric suctions than those at high water matric suction. The results demonstrated that micro-organisms population significantly (P<0.05) decreased in residues burning treatment compared with the residues application treatment. Therefore, based on the results of this study residues' burning is not recommended in Ardabil.

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In order to study the precision of qualitative land suitability classification method for main irrigated crops (i.e. potato, sugar beet, wheat and alfalfa) in the Shahrekord plain, qualitative land suitability maps were obtained for all the studied crops according to representative pedon analysis using simple limitation method. In the next step, a regular grid sampling consisting of 100 sample points with a distance of 375 m was designed. Then all required analyses were done to recognize the suitability class of these sites for each land use. Finally, land suitability results for all the observation points in each map unit were compared with the results of its representative pedon. The results showed the average of measured compatibility between representative pedon and other observation points in each map unit in class and subclass levels was about 60 % and 38 %, respectively. Due to the generalization of representative pedon analyses to all unit area, the use of soil map units as land suitability units may lead to unsatisfactory results. Therefore, the use of representative pedon is not recommended in sustainable land management and precision agriculture. However, new techniques like geostatistics can be used to improve the conventional soil mapping methods.

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The reclamation of salt-affected soils which occur on 831×106 ha can be effective in increasing agricultural production. Cultivation of plant species which are resistant to salinity can improve the soil by increasing the solubility of calcite and releasing the calcium in soil solution. This study was conducted as a column experiment with a saline-sodic soil (SAR = 23.8, EC= 12.88 dS m-1, pH= 7.7, CaCO3= 15.15 %). Three plant treatments including Sesbania acuelata, Cyanodon dactylon and Rubia tinctorum, and three chemical treatments including gypsum in two levels (50% and 100% gypsum requirement) and sulfuric acid with a control were arranged. All treatments were replicated 3 times. The soil columns were similarly leached by 41 liters of tap water during 30 days in 8 stages. After leaching, SAR and EC in soil, the amounts of sodium in leachate and total amount of sodium in plants shoot were determined. Results showed that the SAR was decreased compared to control by the plant treatments and the chemical amendments by about 59% and 65%, respectively. Moreover, two plants of Cyanodon dactylon and Rubia tinctorum had maximum amount of leachate sodium, which shows an impressive role of these plants in dissolution and leaching of exchangeable or sediment sodium in comparison with the other treatments. According to salient performance of phytoremediation in improvement of physicochemical properties of soil compared to chemical amendments, phytoremediation can be recommended as a profitable low-cost and effective method for remediation of saline-sodic soils.