JWSS - Journal of Water and Soil Science

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Salinization and alkalization are considered spatiotemporal dynamic soil degradation processes. In order to investigate the effects of agricultural activities on land degradation and soil salinity, Shamsabad area in Qom province was selected. Aerial photos (1955) and satellite images (1990-2002) were used to examine the changes in land use. Soil samples were collected from 25 locations in the study area from 0-50 cm and 51-100 cm depth at each location. For comparative purposes, sampling locations in this study were similar to locations used for salinity study in 1983. For each sample, pH, electrical conductivity (ECe), base saturation percentage, exchangeable sodium, lime and texture were measured. Land use and salinity maps were created by using geographic information system (GIS) softwares. Results revealed an increase of 9.5 times in cultivated lands in 47 years. Increase in agricultural activities in the study area has also intensified the pressure on water resource in the area, lowering ground water tables and degrading water quality. In the 0-50 cm soil depth, the average soil ECe was 6.5 dS/m in 1983, which increased to 10.7 dS/m in 2005. If soil salinity trend and pressure on water resources continue, large part of Shamsabad area is expected to change to desert in near future years.

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Modeling plant response to salinity and nitrogen deficiency is very important for estimating optimum yield in arid and semi-arid regions. For this purpose, the models of Leibig-Sprengel (LS) and Mitscherlich-Baule (MB) originally proposed to explain plant response to nutrients only were modified to evaluate plant yield response to combined nitrogen and salinity stress conditions. Afterwards, in order to model canola (Brassica napus L.) response to combined salinity and nitrogen stress, an experiment was designed with different nitrogen and salinity levels. The water salinity treatments consisted of non-saline water, 3, 6, 9 and 12 dS m-1. The nitrogen treatments were 0, 75, 150 and 300 mg kg soil-1 added as ammonium nitrate. The results indicated that both modified models can satisfactorily predict canola yield. However, the modified MB model (R2=0.94) provided better estimation than the modified LS model (R2=0.87). The calculated statistics including Maximum Error, Root Mean Square Error, Modeling Efficiency, Coefficient of Determination and Coefficient of Residual Mass for the modified models indicated that the estimated relative grain yield for soil nitrogen, salinity and each rate of soil nitrogen in salinity levels by modified MB model compared with those by modified LS model is closer to the measured relative yield. Therefore, the use of modified MB model for estimating canola relative grain yield in salinity and nitrogen stresses is recommended. Using modified LS model showed that the salinity threshold value changes with the applied nitrogen. In this case, by application of each 75 mgN kg-1 soil, the salinity threshold value decreased 4 dS m-1 in saline conditions. Application of nitrogen decreased chloride concentration in grains under saline conditions. Nitrogen uptake also augmented with increasing canola transpiration, because nitrogen was carried over from soil to the uptake sites mainly by mass flow.

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Multi-environment trial data are required to obtain stability performance parameters as selection tools for effective cultivar evaluation. The interrelationship among several stability parameters and their associations with mean yield, along with the repeatability of these parameters in consecutive years was the objective of this study. Barley yield data of 18 cultivars, proprietary of Dryland Agricultural Research Institute, evaluated in 12 locations over 2005-2007 in three locations of Iran was used for the combined analysis of variance in three datasets. I: Across locations in a single evaluation year (dataset A), II: Across locations in each of two single evaluation year (dataset B), III: Across all locations in three years (dataset C). For each dataset, cultivar phenotypic variance and other statistics were appropriately partitioned in its components. The interrelationship among the parameters and their associations with mean yield based on Spearman rank correlation was studied in each of the three single evaluation years (dataset A). Rank correlation coefficients were also used as estimates of the repeatability of these stability parameters across two year combinations (dataset B). The parameters 2 σi Shukla and 2 Wi were consistently highly correlated with each other but not with mean yield in all single and pair evaluation years. The parameters bi , 2 Si and CV were consistently highly correlated with each other but not with mean yield in all single and pair evaluation years. Result showed that Shukla variance, Wricke ecovalence, SIPC1 and ASV AMMI stability statistics have high repeatability. Thus it is suggested that more stability statistics especially nonparametric methods be used for determination of repeatability methods.

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In order to study the effect of deficit irrigation at reproductive growth stages on water use efficiency and drought tolerance of four sunflower cultivars, including Azargol, Allstar, Alison and Euroflor, an experiment was conducted during 2007 growing season at experimental field of Agricultural Faculty of Bu-Ali Sina University, Hamadan, Iran. The experiment was a split plot based on randomized complete block design with three replications. The irrigation levels included full irrigation, deficit irrigation at heading, deficit irrigation at flowering, deficit irrigation at seed filling, deficit irrigation at heading and seed filling and deficit irrigation at flowering and seed filling stages. The biological and economic yield (BY and EY), harvest index (HI), water used, water use efficiency (WUE) and water stress indexes were measured. The results indicated that the highest BY (11681.7 kg.ha-1), EY (4854.0 kg.ha-1) and HI (42%) were obtained from full irrigation treatment. The lowest negative effects in cultivars belonged to deficit irrigation at seed filling stage. Euroflor obtained the highest of these parameters with 10127.1 Kg.ha-1, 4081.5 Kg.ha-1 and 40% respectively. Highest WUE was related to twice cutoff of irrigation in flowering and seed formation stages and then without irrigation in seed formation stage by 1.09 and 0.96 Kg.m-3. Allstar and then Euroflor had highest WUE among sunflower cultivars by 1.01 and 0.94 Kg.m-3 respectively. Results also indicated that Euroflor was a tolerant cultivar and STI (Stress Tolerant Index) and GMP (Geometric Mean Productivity) were acceptable indexes for selection. Finally, deficit irrigation at seed formation stage had the lowest negative effect on yield and HI with suitable WUE. In addition, Euroflor showed the highest yield, drought tolerance and HI with suitable WUE.

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The effect of phosphorus (P) (0, 25, and 50 mg kg-1 soil as Ca(H2PO4)2) and organic matter (OM) (0, and 2% w/w feedlot cattle manure) on P and zinc (Zn) distribution in different parts of wheat plant (Triticum aestivum L.) at various growth stages and its relationship with soil P and Zn were determined in greenhouse condition. In all pots, shoot P concentration decreased as plant growth proceeded. Phosphorus concentration of shoot and flag leaf decreased from 7th to 9th stage of growth, whereas that of spickle increased. Spickle P uptake and Zn uptake of stem, shoot, flag leaf, and spickle increased with proceeding of wheat growth. Phosphorus uptake of shoot increased from 3th to 9th growth stages, whereas P uptake of stem and flag leaf decreased from 7th to 9th growth stages. Soil P and Zn concentrations increased with application of P and OM and plant growth. The trend of P and Zn changes in shoot, stem and flag leaf was similar. It is, therefore, concluded that analyzing flag leaf for P and Zn concentrations be used for prediction of plant nutritional status of those nutrient elements in cases where such information is needed.

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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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Fertilizers in agriculture are potential sources of environmental pollution, especially in ground water quality and soil resources. Studying factors effective in water and nutrient transport through soil profile is helpful for nutrient management to minimize adverse impacts on environment and nitrate leaching below the root zone. In this study, the ground water level and nitrate leaching transportation below the root zone were measured in a paddy rice field and the data were simulated with the DRAINMOD-N model. For evaluating DRAINMOD-N software in a paddy rice field under surface drainage in Mazandaran, the ground water level and nitrate transportation were measured during four months (June, July, August and September) in 2008. The DRAINMOD-N model was calibrated by adjusting nitrification and denitrification rate constants to reach the best fit between measured and predicted data. Results indicate that predicted ground water level and nitrate concentration by model were significant at one percent level. The statistical comparison was done by model efficiency (EF) 0.84 for estimation of ground water level and 0.97 for estimation of nitrate concentration, respectively. The DRAINMOD-N model can be used as a tool to manage environmental pollution of nitrate in paddy rice fields.

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This study was conducted to study and compare the effects of different tillage systems on soil physical properties and wheat yield in dryland conditions. The experiment was carried out in Maragheh Dryland Research Station with 5 treatments and 4 replications based on RCBD for 3 years (2001-2003). The results showed that difference between the treatments in terms of wheat yield was significant, and stubble chopping and chisel plow tillage in fall + sweep in spring + seed drill planting had the maximum yield (i.e. 1452 kg/ha), lower value for yield (1.077kg/ha) blonged to T1 treatment. Also the results showed that spike/plant and spike length were the main characters in yield increase. For the soil bulk density and water content, the difference between treatments was significant and in planting and flowering stages stubble chopping and chisel plow in fall + sweep in spring + planting by seed drill had the highest soil water content and the lowest bulk density

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Knowing about the way water is distributed in the soil is essential for designing and managing the Subsurface Drip Irrigation systems (SDI). Since carrying out experiments to recognize the form of moisture distribution in the soil is too complicated and time-consuming, using numerical simulations can be an efficient, effective substitute method to design these systems. One of these models is HYDRUS-2D, which is able to simulate the movement of water, heat and solute in saturated and unsaturated conditions in soil. This research aims to figure out the extent to which the HYDRUS-2D model is able to estimate wetting pattern in soil around a dripper. The simulations’ findings were compared to the data gathered from the field, including SDI system in different irrigation times, and 72 hours after irrigation. Moreover, the rates of error were measured for all points and distances from the dripper in all times of irrigation and also beyond that. The results indicated that the model can simulate the changes, trend similar to what happened in the soil profile. However, it estimated the rate of soil moisture with higher errors in those points in which the wetting took place, with the maximum error rate being RMSE= 0.05 per every 1.5 hours after irrigation starting point in the depth of 30 centimeters where dripper is placed. Also, with an increase in the irrigation time, and soil moisture evening which resulted from redistribution of moisture, the model resulted in better estimations. 72 hours after finishing the irrigation, the estimates were closer to real figures with an average error estimate of RMSE= 0.002.

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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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Magnetic susceptibility measurement is a simple and quick technique for characterizing soils and sediments and describing soil-forming processes. The interpretation of soil magnetic susceptibility data needs sufficient knowledge about the factors affecting this parameter. To identify the effects of parent material, gypsum and calcium carbonate equivalent, 42 samples were taken from horizons of soils developed on loessial, alluvial, granitic and marly materials in southern Mashhad. Gypsum and carbonates of soil samples were removed by successive washing with distilled water and diluted HCl, respectively. Magnetic susceptibility of bulk samples (lfbulk), gypsum free samples (lfGf), gypsum and carbonates free samples (lfGCf) and gypsum, carbonates and sand free samples (lfGCSf) was measured. The results revealed a strong 1:1 correlation between the measured and calculated lfGf and lfGCf. Despite the high amounts of gypsum and carbonates in soils developed on marls, their lfbulk was much more than that of the other soils and reached up to 121.8×10-8m3 kg-1. In contrast, the lfbulk values of saprolitic granite were less than 10.4×10-8m3 kg-1. The lfbulk values of loessial and alluvial soils were less than those of marly soils but higher than those of soils developed on saprolitic granite. lfbulk values were negatively correlated with the amount of sand. However, reduction in magnetic susceptibility values of marly soils after removing sand reflects the different nature of this soil. The correlation between lfbulk and amount of silt and clay is positive, but the magnetic susceptibility values are more sensitive to clay percentage, indicating the more important contribution of clay to magnetic susceptibility values. The results of this study highlight the role of parent materials, gypsum and carbonates in the soil magnetic susceptibility values that should be considered.

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Urease is one of the most important enzymes in nitrogen cycle. The clay particles (with high surface area) play an important role in the stability of these protein compounds (enzymes) against various environmental factors. In order to examine the interactions between urease with sepiolite and vermiculite, three in vitro experiments were conducted separately in a completely randomized design. Two experiments were carried out with two replications. Treatments included six incubation times (0, 1, 2, 5, 10 and 20 days) and five levels of temperature (10, 20, 30, 40 and 50 ˚C). The third experiment was carried out in a factorial arrangement with two replications. Factors included three levels of pH (5, 7 and 9), and six-levels of enzyme concentrations (0.05, 0.25, 1, 5, 15 and 30 units). The results showed that the activity of adsorbed enzyme was more than free enzyme during the incubation time. The optimum temperatures for activity of free and adsorbed enzymes were 30 and 50 ˚C, respectively. It was concluded that enzyme adsorption on clay surfaces increases enzyme stability against environmental changes. Also, the results showed that the highest levels of urease adsorption on sepiolite and vermiculite occurred at pH 9 and 7, respectively. Adsorption isotherms of Enzyme showed that Vermiculite adsorbed urease with higher affinity compared to Sepiolite.

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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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A study was conducted to evaluate the effect of vermicompost and nitrogen (N) on growth, nutrient concentration and uptake of N, phosphorus (P), potassium (K), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) in sunflower shoots as a factorial experiment arranged in completely randomized design (CRD) with three replications under greenhouse conditions. Treatments included three levels of vermicompost (0, 2.5, and 5 % by w/w) and three N levels (0, 90, and 180 mg kg-1) as urea. Application of 2.5% vermicompost significantly increased the average fresh and dry weights, and uptake of K, Fe, Zn, Mn, and Cu of shoots as compared when no vermicompost was applied, but decreased Zn and Cu concentrations. Application of 90 mg N, increased fresh and dry weights, and concentration of N, Zn, and Mn, total uptake of N, P, K, Fe, Zn, Mn, and Cu in sunflower shoots, but decreased P concentration. Application of 180 mg N increased total N uptake than that of 90 mg N kg-1 treatment. Combination of 2.5% vermicompost with 90 mg N, significantly (p<0.05) increased dry matter yield of sunflower as compared to 2.5% vermicompost without N treatment

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The aim of this study was to investigate the effect of parent materials and pedogenic processes on distribution of Pb, Zn, Cu, and Ni in the residual soils derived from different parent materials in the Binaloud zone, western Mashhad. Two soil profiles on the summit of granitic, ultrabasic and metamorphic rocks were described and sampled from their genetic horizons. Pseudototal concentrations of selected heavy metals and fractions of these metals were determined using aqua-regia and sequential extraction methods, respectively. 178.1-419.7 mg kg-1of Ni in ultrabasic soil versus 0.7-27.5 mg kg-1 in the granitic soil make the Ni a distinctive element in the studied area. Cu with the average contents of 60 and 56.3 mg kg-1 in the ultrabasic and metamorphic soils respectively showed more concentration in comparison to granitic soils with 12.1 mg kg-1. The amount of Zn was not significantly different among the soils, although the average of this element in the granitic soil (55 mg kg-1) is slightly more than the other soils. Pb was only detectable in the surface layers of all pedons reaching up to 6 mg kg-1. Residual fraction except Ni and Cu in granitic soil was the main fraction for all of the studied heavy elements that was expectable according to the low weathering intensity of the soils. The eolain addition of gypsum and carbonates have influenced heavy metals concentration, especially in surface horizons. In conclusion, the amount of heavy metals was significantly affected by parent materials and the eolian deposition must be considered as the secondary influencing factor.

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Biocalcite infilling and bridging in a sandy soil was studied in the present research. Effects of 2 bacterial species (Sporosarcina pasteurii and Sporosarcina ureae), 3 reactant concentrations (0.5, 1.0, and 1.5 M of urea and CaCl₂ mixture), and 6 reaction times (12, 24, 48, 96, 192, and 288 hr) on saturated hydraulic conductivity and mechanical strength of a sandy soil were studied as a factorial experiment. Soil samples were selected from sand dunes of Joopar area, Kerman Province. Bacterial inoculums and reactant solutions were daily added to soil columns. Results of the study showed that S. pasteuriihad had a higher effect on decreasing hydraulic conductivity of the treated samples (11.57 cm/h) compared to the blank (41.61 cm/h) than S. ureae. Increasing reaction times (from 12 to 288 hrs) and reactant concentrations (from 0.5 to 1.5 M) decreased hydraulic conductivity by 49 and 16 %, respectively. S. pasteurii increased strength of treated samples up to 2.6 Mpa pressure compared to S. ureae. Reactant concentrations and reaction times increased soil strength significantly (2.13 and 4.1 Mpa, respectively). Micromorphological observation showed calcite crystals bridging soil particles and filling pore spaces.

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In recent years, due to the increased population, urbanization and changes in human consumption patterns, urban, industrial and agricultural soils have been exposed to various pollutants such as heavy metals. The objective of this research was to identify hotspots of Pb by using global and local Moran Indices in urban and suburban soils of Kashafrood catchment. A total of 261 surface soil samples (0-15 cm deep) were taken using irregular girding network method and their total Pb concentrations were measured. The positive Moran index at confidence level of more than 99 percent showed the spatial clusters between observations. On the basis of local Moran index results, 15 samples were introduced as hotspots (high-high value) located southeast of Mashhad plain. Exclusion of extreme values resulted in the addition of high-high cluster (hotspots) leading to the extension of these areas to the West of the Mashhad city. These areas are introduced as hotspots due to the urban land use, the direction of prevailing wind, and the area being close to Mashhad airport.

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Organic acids play an important role in improving the bioavailability of soil nutrients. The objectives of this study were to determine the effect of oxalic acid on the release of soluble, exchangeable and non-exchangeable forms of K from micaceous minerals and potassium feldspars, and also to investigate the trend of K release by time. A laboratory study was carried out using a completely randomized design with two replicates. Biotite, phlogopite, muscovite, Zanjan and Yazd K-feldspars (< 50 &mu;m size) were treated with 0, 10 and 100 mM of oxalic acid solutions for a period of 5 hours and 20, 60 and 90 days. The amount of K was determined by flame photometer. The results indicated that most amount of soluble, exchangeable and no-exchangeable K was released by 100 mM of oxalic acid. The maximum soluble K (0.86 gKg-1) was released from phlogopite, and the maximum exchangeable and non-exchangeable K (1.5 and 29.6 gKg-1, respectively) were released from biotite. Muscovite with 0.19, 0.34 and 1.41 gKg-1 of soluble, exchangeable and non-exchangeable K, respectively, had the lowest release of K among the studied minerals. The kinetics K release from minerals consisted of two phases. The first phase was relatively rapid and then it had a slow rate until the end of the experiment. Given that the applied concentration of organic acid was high, potassium release during the experiment period did not reach the steady state. Therefore, a longer period of release experiment is suggested.

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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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By modifying plants at genetical, physiological and ecological levels, entophytic fungi as the most important soil microorganisms have a pronounced growth-promoting activity and also increase plant resistance to biotic and abiotic stresses. This research was undertaken to evaluate the potential of P. indica to increase barley (Hordeumvulgare L.) resistance to lead (pb). Therefore, a greenhouse experiment with two fungus treatments (non-inoculated and P. indica inoculated) and five levels of pb (0, 25, 50, 100 and 500 mg/kg) with three replications was conducted based on a factorial design. Measurement of shoot and root dry weight showed that the growth of P. indica-colonized plants at all levels of pb treatments was higher (P < 0.05) than that of the corresponding controls. Also, chlorophyll concentration of inoculated plants with P. indica was superior to non-inoculated plants. In addition, the results showed that in contrast to the plant shoot, lead concentration in the root of P. indica-colonized plants was higher than the non-inoculated controls.