JWSS - Journal of Water and Soil Science

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  Application of slag and converter sludge, major by-products of Esfahan Zob Ahan factory, to enrich two organic amendments for corn nutrition, was investigated. Farm manure and its vermicompost mixed with different rates of slag and sludge were incubated in 3 Kg pots at field capacity moisture and home temperature for three months. The applied rates of slag and sludge were 0, 5 and 10 percent (w/w) of pure iron from these compounds to the organic amendments. Iron sulfate with the above ratios was also examined for comparison. Sub-samples of the incubated materials were taken after 0, 10, 25, 45, 65 and 90 days of incubation and examined for DTPA extractable Fe, Mn, Zn and Cu. After the incubation, the enriched amendments were applied to a soil sample to grow corn. Three Kg soil samples, taken from Chah Anari experimental farm, Esfahan University of Technology, were mixed with 17 gr of the amendments (50 ton/ha) placed in 3 Kg pots. In each pot two corn seeds (single cross 704) were planted and after 70 days crop yield and concentration of Fe, Mn, Zn, Cu in the plant tissues were determined. Results showed that the use of iron sulfate strongly increased DTPA extractable Fe and Mn of the amendments. In enrichment by converter sludge, the best result was obtained in the mixture of 10 percent pure iron with the vermicompost on 60 days of incubation. Treatment of 5 percent pure iron from slag mixed with the manure increased DTPA extractable Fe and Mn with the time, but the 10 percent treatment was not much effective in this regard. The highest rates of iron uptake by the plants occurred in the iron sulfate and 10 percent converter sludge treatments, respectively however, the highest rate of the plant Mn uptake was observed in 5 percent iron from converter sludge mixed with vermicompost. In general, 10 percent pure iron from converter sludge was the most effective enrichment treatment, increasing the plant uptake of Fe, Mn, Zn and Cu micronutrients.

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  Applying of intensive cultivation especially in marginal and sensitive regions, after conversion of rangelands to cropland farms, commonly causes reduction in soil quality, and thus an increase in soil degradation, erosion and runoff. This study was conducted to evaluate the land use change effects on some soil physical and chemical properties such as mean weight diameter (MWD), soil organic matter (SOM), bulk density (BD) and saturated electrical conductivity (ECe). For the experiment, soil samples were collected from 8 regions (rangeland and cultivated range) from west and southwest of Isfahan. Samples were taken from two soil layers 0-15 and 15-30 cm. Results showed that after conversion of range to cultivated lands, in some regions, SOM content was increased about 39% but in some regions decreased about 26%. This is due to the initial conditions of the regions. The ECe also increased by 41% due to this conversion. However, no changes were observed to the MWD, BD and pH in different treatments. Although there were little change to the physical and chemical properties of soil as a result of this conversion, those properties which were changed, could have a degradation effect and lower the soil quality.

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The petroleum refinery sludge is an important source of environmental pollution. Burning and burying of the sludge may have adverse effects on environment and human health. Thus, other mechanisms for decreasing the toxic effects of hydrocarbon substances in the sludge must be used. In this study, Isfahan refinery sludge was dewatered, air dried and mixed by 0, 10, 20, 30 and 40% w/w ratio with two calcareous soils, viz., Mahmoud Abad (Typic Haplocalcids with clay texture) and Bagh Parandegan (Anthropic Torrifluvents with silty loam texture). Different mixtures of soil and sludge were farmed for 21 days and irrigated on a daily basis to field capacity. Then, 100 seeds of Tallfescue (Festuca arundinacea) and Agropyron were planted in polluted soils with 3 replicates in 3 kg pots for 5 months. Result showed that Tallfescue and Agropyron yields decreased in sludge contaminated treatments. In the 40% sludge treatment, Tallfescue decreased the total petroleum hydrocarbons content by 65 percent. The highest degradation for agropyron was in the 30% sludge treatment which showed about 55% reduction in total petroleum hydrocarbons. The 40% sludge treatment resulted in the minimum yields of root and shoot plants. The highest degradation of TPHs occurred in the Tallfescue rhizospher of 40% sludge. Maximum degradation of TPHs on the Agropyron rhizospher was in 30% sludge mixed with Bage parandegan soil, but maximum yield of plant was in 20% sludge. Our study shows that Tallfescue rhizospher is most effective for decreasing TPHs, and that the phytoremediation in soils with more clay can adsorb and fix the toxic components and then at higher levels of pollutions can let the plants grow.