JWSS - Journal of Water and Soil Science

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During 1998-99, a field experiment was conducted to investigate the effects of residual Processed Municipal Waste Leachate (PMWL) on growth and yield of wheat (variety Roshan). The treatments consisted of residual amounts of 0, 150, 300 and 600 t/ha of PMWL and a residual N, P, K, and Zn fertilizer treatment in a randomized block design with 3 replications. In 1998, rice seedlings were transferred to 34 m plots. After harvesting the rice, wheat was seeded in the same plots without any new treatment. Processed municipal waste leachate and fertilizers were applied during the rice growth. Residual effects of PMWL increased the amounts of available macro- (N, P and K) and micronutrients (Fe, Cu, Zn and Mn) in soil which, in turn, promoted the grain and straw yield of wheat compared to the control. Straw and grain yield increased from 1.67 and 3.50 t/ha in control to 3.93 and 12.80 t/ha in 600 t/ha of PMWL, respectively. The residual effects of PMWL had no significant effect on heavy metals concentrations in plant. The effects of residual PMWL in the soil were proportional to the amount of leachate applied. However, more investigations are recommended to fully understand heavy metals effects on soil, plant, and environment.

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The ability of earthworms in recycling a wide range of organic solid wastes is well established. Only a few earthworm species are suitable for commercial vermicomposting. Two species, Eisenia foetida and Lumbricus rubellus, are common in temperate regions. Samples of earthworms were collected from manure pills and forest litter in North and Northwest of Iran. The samples were maintained in pots under greenhouse conditions. External morphological characteristics of mature worms were used in identifying earthworm species. These characteristics included: total number of body segments, numbers of clitellum and tubercula pubertatis (TP) segments, dorsal and external body color, body size, prestomium and prostomium shape, number of first segment with dorsal pore and patterns of clitellum and TP. All collected samples belonged to the species Eisenia foetida. Under incubation conditions in manure substrate (a moisture of 70% saturation at 24±2^oC), each worm produced 1-2 cocoons daily and each cocoon contained 2-7 worm embryos. The collected earthworm samples showed a good ability in vermicomposting of manure, plant residues, and some organic industrial refuses. The C:N ratio decreased during the vermicomposting process, which indicates the improved stage of decomposition and the vermicompost stability.

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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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Lintz-Donawitz (LD) converter slag, a by-product of the iron and steel-making industry is produced in large quantities in Isfahan, Iran. The slag contains 52.8 and 2.2% (w/w) CaO and MgO, respectively. To determine the influence of LD slag on the chemical characteristics of three acid soils from Gilan, an incubation study was conducted. The soil samples were collected from 0-30 cm of rice and tobacco fields and a tea garden. Treatments were 0, 0.5, 1, 2, 4, 8 and 16 % (w/w) of converter slag/kg soil. The slag was thoroughly mixed with 500g soil in plastic pots. Soil moisture content was adjusted to near field capacity and changes in pH, EC and AB-DTPA-extractable Fe, Mn, Zn, P and K were determined at 1, 10, 30 and 60 days. Results showed that soil pH increased with increasing slag rates. Slag increased AB-DTPA-extractable P and Mn, the magnitude increase depend on the amount of slag applied. However, the effect of slag on AB-DTPA-extractable Fe depended on initial pH, initially decreasing at the pH range of 7.4 - 8.5 and then increasing at higher pH levels. Slag decreased AB-DTPA-extractable K especially in highly acid soil. In the present study, soil pH and AB-DTPA-extractable Fe decreased with time, though the effect of incubation time on pH was not significant. The effect of incubation time on AB-DTPA extractable Mn and P was different. Time effect on EC and AB-DTPA-extractable K was not significant. In general, soil chemical characteristics were more affected by slag rates than by incubation time. In conclusion, it seems that converter slag is a suitable amendment for acid soils. It is suggested that the effect of LD converter slag on plant growth and chemical characteristics of acid soils be studied under field conditions.

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Potato (Solanum tuberosum L.) has relatively weak root system and requires high nitrogen fertilizer which is costly and may pose environmental pollution. This study was conducted to compare root morphological characteristics and nitrogen uptake of some potato cultivars growing in Iran. A greenhouse experiment using a completely randomized design with 3 replications and 8 potato cultivars including: Arinda, Agria, Premiere, Diamant, Concord, Marfona, Marodana and Nevita was conducted at Isfahan University of Technology, Isfahan. Virus-free seed tubers were planted and grown up to flowering stage. The plants were then harvested and their root length (RL), root average diameter (RAD) and root surface area (RSA) were determined using a Delta-T Scan image analysis system and Windias software. Root length density (RLD), root length and shoot weight ratio (R/S) were also calculated. Dry mater production and nitrogen accumulation (total nitrogen uptake) (PNA) were also determined. Soil inorganic nitrogen was measured before planting and after harvest. All measured parameters, except RAD, were significantly (p<0.05) affected by cultivar. Large differences observed between cultivars for all traits indicated genetic diversity among the studied potato cultivars. The highest and the lowest values of RL, RLD, RSA, R/S, RDW and PNA were found in Marfona and Nevita respectively. Based on cluster analysis, cultivars were divided into four different groups. Under the condition of this study, Marfona was superior whereas Arinda, Nevita, Marodana and Agria were inferior. Due to the high differences in root morphological characteristics and nitrogen uptake among potato cultivars, plant breeders may produce cultivars with larger root volumes and high nitrogen uptake.

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Geologic and pedologic controls are the main factors determining the distribution of elements in natural soil environments. In order to assess the role of these factors in the content and distribution of major elements of soil, six parent materials including phyllite (Ph), tonalite (To), periditite (Pe), dolerite (Do), shale (Sh) and limestone (Li) were selected in Fuman-Masule region. Soil genesis and development of representive residual pedons were studied for each parent material. Total content of Si, Al, Ca, Mg, Fe, Mn, K, Na, Ti and P of soil horizons were measured and compared to the geochemical and mineralogical composition of parent materials. Maximum concentrations of Fe2O3 and MgO were found in the soils derived from Pe and Do however, these soils had low content of SiO2 and Al2O3, which is in conformity with the geochemical composition of the parent rocks. On the contrary, FeCBD content of these soils was lowest, indicating the low degree of soil development and, by the same fact, the importance of inheritance factor in soil Fe concentration. However, comparison of total Fe and FeCBD in Li1, Sh2 and To2 revealed that relative development of these pedons is higher than the others. Silicon depletion in Ph1, To2 and Sh2 pedons, relative to parent rocks, is higher than in Pe and Do pedons. However, this element is enriched in Li pedons. MnO content of Pe and Do pedons is governed by geogenic factors, while in Sh pedons, pedogenic factors, especially redox conditions, play the major role. Exchangeable forms of Ca and Na are determined by soil properties rather than by parent material type. Notwithstanding the redistribution of all major elements throughout pedons due to soil forming processes, the importance of inheritance factor in soil Si, Al, Mg, Fe, K, and Ti is higher than pedogenic factors.

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Iron deficiency is most widespread among plant nutrients. Nowadays, different materials such as inorganic salts, organic chelates, soil acidifying materials and industrial wastes are used to correct iron deficiency. Slag and convertor sludge of steel factories are among the industrials wastes for this purpose. These materials contain considerable amount of iron produced in large quantities every year. Application of slag and convertor sludge to soil may affect bioavailability and chemical forms of iron in soil. Sequential chemical extraction technique has been widely used to examine these chemical forms, and thus to better understand the processes that influence element availability. It was, therefore, the objective of this study to investigate the application effect of slag and convertor sludge of Esfahan Steel Mill on the chemical forms of iron, distribution of these forms and bioavailability of iron in surface (0-20cm) and subsurface (20-45cm) soil of three research fields. The results showed that more than 99% of the applied Fe occurred in residual, Fe oxide and hydroxide and free forms. Application of slag and convertor sludge for three consecutive years increased chemical forms and DTPA extractable iron in surface and subsurface soil of three fields.