JWSS - Journal of Water and Soil Science

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Micronutrients such as Fe and Zn in adequate level are essential for plant growth cycle and impose a vital role in increasing yields of most agricultural crops. Using organic wastes such as sewage sludge, compost and manure is a proper practice for returning organic matter and some nutrients into the soil, particularly in arid and semi-arid regions. The objective of this study was to determine the effects of sewage sludge, compost and cow manure on availability of Fe and Zn in soil and their uptakes by corn, alfalfa and targetes flower. A completely randomized design with three treatments (sewage sludge, compost and cow manure at 25 Mg/ha) was used. Application of sewage sludge, compost and cow manure significantly increased availabile Fe and Zn of the soil. The application of organic wastes increased the dry matter yield of the plants. Fe and Zn concentration of plants shoots in organic amendments treatments were significantly greater than blank. The highest mean concentration of Fe in plant tissues was obtained in the cow manure and the highest mean concentration of Zn in plant tissues was obtained in the compost treatment.

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Heavy metals contamination of soil and plants has very important and vital role in relation to health and life of human and other organisms. The aim of this study was to assess the efficiency of sorghum (Sorghum bicolor) and sommon lambsquarter (Chenopodium album) in phytoremediation of Zn from soil. Efficiency of 0.01M CaCl2, 0.1M NaNO3, and 1M NH4NO3 for extraction of “bioavailable fraction of soil Zn was also compared. Correlation between the Zn concentrations extracted by these methods and plants response (relative yield and shoot Zn concentration) to soil Zn contamination was then evaluated. For this purpose, a calcareous soil sample was contaminated with different concentrations of Zn. Sorghum and common lambsquarter, were grown in pots containing the contaminated soil and were analysed for their Zn concentrations after harvest. Results of this study showed that, common lambsquarter was more tolerant to low and medium concentrations (≤900 mg/kg), but sorghum tolerated high concentration of Zn. Also sorghum was more capable in removal of Zn from soil in comparison to common lambsquarter, so that soils contaminated with low Zn levels (≤900 mg/kg) can be remediated by sorghum. In addition, there was a significant correlation between 1 M NH4NO3-extractable soil Zn and the plants response (relative yield and shoot Zn concentration) to soil Zn contamination.

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In order to assess the status of the iron (Fe) chlorosis of plane trees in green space of Isfahan city, the chlorosis intensity of 73 trees in different regions was recorded as (1): low (less than 5% of leaves), (2): moderate (less than 50% of leaves), (3): severe (more than 50% of leaves), and (4): very severe (more than 95% of leaves). The whole leaf (with petiole) samples were taken from the top and bottom of each tree, separately, during 2008 and 2009. Then selected chemical properties of the leaves were analyzed.  The results showed that in more than 95 and 71% of the young leaves, Fe concentration was less than the critical deficiency level (202 mg/kg). Concentration of Fe in the older leaves of all plane trees even those with slight symptoms of chlorosis was less than the critical level (382 mg/kg). No significant relationship was found between the leaf zinc concentrations and intensity of iron chlorosis. In more than 92 (in the first year) and 87% (in the second year) of the plane trees, Zn concentration of young leaves and in all trees, Zn concentration of old leaves were less than the critical deficiency concentration (23 mg/Kg). The comparison between concentrations of Cu in the leaves with its critical deficiency level showed that more than 90% of young and old leaves accumulated toxic levels of Cu in both sampling years. In regard with the sufficient range of P, about 79% of the trees in the first year and 53% in the second year accumulated excess levels of this nutrient in their young leaves. This condition was slightly modified for the older leaves so that excessive concentration of phosphorus in mature leaves was not observed in the first year and in the second year, only about 29% of the samples had concentrations higher than critical levels.