JWSS - Journal of Water and Soil Science

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The possibility of using a steel plant by-product (converter sludge) as an iron fertilizer was investigated. This compound consists of 64% Fe oxides. Considerable amounts of elements such as Ca, Si, Mn, P, and K are also present in the sludge. To study the converter sludge, an incubation experiment was carried out on three calcareous soils. Treatments were 0, 4, and 8 percent of converter sludge mixed with soils plus mixtures of 4% converter sludge with elemental sulfur, thiobacillus inoculum and sulfuric acid. Soil samples (400 g) were kept at field capacity and room temperature in capped, aerated plastic containers for two months. Sub-samples were taken at 1, 10, 30, and 60 days of incubation and analyzed for Fe, Mn, Zn, P, and K contents as well as EC and pH. Results showed that converter sludge increased significantly extractable Fe proportional to the rate of sludge used. Sulfuric acid application increased Fe availability significantly, but the availability of this nutrient generally decreased with the incubation time. Application of the sludge also increased the pH slightly at the beginning of incubation. Elemental sulfur and sulfuric acid application increased Fe and Mn availability significantly. Application of the sludge without and with elemental sulfur and sulfuric acid slightly increased availability of P. The results of this study revealed that converter sludge might be used as an iron fertilizer. However, further investigation in greenhouse and field experiments is needed.

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Temporal and spatial distribution of water components in watersheds, estimation of water quality, and uncertainties

associated with these estimations are important issues in freshwater studies. In this study, Soil and Water Assessment

Tool (SWAT) model was used to estimate components of freshwater availability: blue water (surface runoff plus deep

aquifer recharge), green water flow (actual evapotranspiration) and green water storage (soil water), in Hamadan-Bahar

watershed. Also, the Sequential Uncertainty Fitting program (SUFI2) was used to calibrate and validate the SWAT

model and do the uncertainty analysis. Degree of uncertainty is calculated by R-factor and P-factor parameters. In this

paper, results of calibration and validation are given for the river monthly discharge. In most stations, especially in

outlet of the watershed (Koshkabad station), simulation of river discharge was satisfactory. Values of R-factor in

calibration of monthly runoff were 0.4-0.8. These small values show good calibration of runoff in this watershed.

Values of P-factor were 20-60%. These small values show high uncertainty in estimations. For most stations of the

watershed, lack of data on river-water withdrawal caused poor simulation of base-flow and therefore the P-factor values

were low. Nash-Sutcliff (NS) coefficient was 0.3-0.8 after calibration, which shows good model calibration of outlet.

This study provided good information on the components of freshwater availability at spatial (sub-basin) and temporal

(monthly) scales with 95% prediction uncertainty ranges. The results of uncertainty analysis of components of

freshwater availability show that uncertainty ranges of average monthly blue water are larger than the other

components, because of its sensitivity to more parameters.

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With the advent of advanced geographical informational systems (GIS) and remote sensing technologies in recent years, topographic (elevation, slope, and aspect) and vegetation attributes are routinely available from digital elevation models (DEMs) and normalized difference vegetation index (NDVI) at different spatial (watershed, regional) scales. This study explores the use of topographic and vegetation attributes in addition to soil attributes to develop pedotransfer functions (PTFs) for estimating soil saturated hydraulic conductivity in the rangeland of central Zagros. We investigated the use of artificial neural networks (ANNs) in estimating soil saturated hydraulic conductivity from measured particle size distribution, bulk density, topographic attributes, normalized difference vegetation index (NDVI), soil organic carbon (SOC), and CaCo3 in topsoil and subsoil horizon. Three neural networks structures were used and compared with conventional multiple linear regression analysis. The performances of the models were evaluated using spearman’s correlation coefficient (r) based on the observed and the estimated values and normalized mean square error (NMSE). Topographic and vegetation attributes were found to be the most sensitive variables to estimate soil saturated hydraulic conductivity in the rangeland of central Zagros. Improvements were achieved with neural network (r=0.87) models compared with the conventional multiple linear regression (MLR) model (r=0.69).

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Soil contamination by Pb leads to a reduction in the quality and quantity of crop yield, because it is highly toxic in soluble ionic forms. The availability of this element for plant roots can reduce by the formation of compounds with low solubility and their sedimentation by phosphorous amendments.. Root symbiosis with mycorrhizal fungi can also increase plant resistance against heavy metals. This study was carried out as a factorial experiment in a randomized complete block design asa greenhouse experiment on sunflower plant at Shahrood University. Treatments included mycorrhizal fungi with two levels of inoculation, (with and without inoculation), organic and inorganic phosphorous fertilizers such as humic acid, diammonium phosphate, bone meal and bone meal+humic acid. The results showed that inoculation with mycorrhizal fungi resulted in a significant increase (P&ge0.05) in percentage of mycorrhizal colonization and an increase in soil EC,shootdry weight and phosphous uptake by the plant. Phosphorus fertilizers significantly increased the available phosphorus in soil, dry weight and uptake of phosphorus by the shoots. The interaction effects of mycorrhiza and phosphorus fertilizers on soil exchange able Pbwere significant. The application of diammonium phosphate and mycorrhiza had the greatest impacton the reduction of Pb (by 25.48percent) in the soil exchange. Mycorrhizal plants had a lower rate of lead concentrations in shoots, which was equal to 78/14%, and also the application of phosphorus fertilizers significantly reduced Pb in plant shoots.