JWSS - Journal of Water and Soil Science

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Land application of sewage sludge is potentially beneficial as an inexpensive nutrient source. However, problem with the use of sludge may exist from high soil concentrations and subsequent uptake of heavy metals by plant and entering of the metals into the human and animal food chains. A field study with lettuce (_{Lactuca sativa} L.) and spinach (Spinacia oleracea L.) was conducted to examine uptake of heavy metals from a sludge amended soil as affected by sludge rate and time of sludge application. Sludge rates were 0, 22.5, and 45 ton/ha. To determine the effect of time on heavy metal uptake, a year after the first plants were harvested, one third of each plot was planted without sludge application and to the rest of each plot sludge was added in the same rates as before. Total and EDTA-extractable Cu, Zn, Pb, and Cd concentrations in soil were determined. The metal concentrations in shoots and roots of the plants were determined separately. Total metal concentrations showed an increasing trend with addition of sewage sludge. Copper, Zn, and Pb EDTA-extractable concentrations in soil and concentrations of these metals in the plants increased significantly with sludge rate. Time of sludge application did not have any significant effect on EDTA-extractable and plant uptake of metals. Sewage sludge also increased the crop yields significantly.

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Nitrogen is usually the most limiting nutrient for crop production. Manganese deficiency in some calcareous soils of Iran has been reported. The objective of this study was to evaluate the effect of N and Mn on the growth and chemical composition of spinach (Spinacia oleracea L.) under greenhouse conditions. The experiment was conducted in a soil from Chitgar series (Fine-loamy, carbonatic, thermic, Calcixerollic Xerochrepts). Treatments consisted of factorial arrangement of five N rates (0, 50, 100, 200 and 400 mg kg^-1 as NH₄NO₃) and three Mn rates (0, 15 and 30 mg kg^-1 as MnSO₄) in a completely randomized design with four replications. Plants were allowed to grow for 60 days and a hand-held SPAD-502 chlorophyll meter was used to evaluate leaf chlorophyll status at harvest.

 Results showed that N and Mn application increased shoot dry weight, N and Mn concentrations and total uptake, Mn:Fe ratios and chlorophyll readings, significantly. Nitrogen increased concentrations and total uptake of Zn, Cu and total uptake of Fe in plants, but decreased Fe concentration. Addition of Mn decreased Fe and Zn concentrations in spinach but increased total uptake of Fe and Cu. When maximum dry matter was obtained, the chlorophyll meter reading was about 40. A similar study should be carried out under field conditions before the N and Mn fertilizer recommendations for spinach can be made.

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Nitrogen is usually the most limiting nutrient for crop production. Thus, N fertilizer is widely used by farmers. Moreover, Mn deficiency in some calcareous soils of Iran with high pH has been reported. Therefore, the addition of nitrogen and manganese to achieve the optimum yield is necessary. The objective of this study was to evaluate the effect of N and Mn applications on the availability of some soil nutrients under wheat (Triticum aestivum L.), corn (Zea mays L.), and spinach (Spinacia oleracea L.) plants in greenhouse conditions. In a factorial test, five levels of N (0, 50, 100, 200 and 400 mg/kg soil as NH₄NO₃) and three levels of Mn (0, 15 and 30 mg/kg soil as MnSO₄) in a completely randomized design with four replication were applied. Corn, wheat and spinach varieties were sc₇₀₄ Falat and Spinacea spp., respectively. After eight weeks, total N content and DTPA-extractable Mn, Fe, Zn and Cu of soil were measured.

 The results indicated that N and Mn applications increased Mn-extractable of soil in three cultures but didn’t affect the soil total N. Nitrogen application in corn increased available Fe in soil. Mn application decreased extractable Zn and Cu of soil in wheat and soil extractable Cu in corn.

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Contamination of agricultural soils by heavy metals is a serious threat from both agricultural and environmental standpoints. Among heavy metals, cadmium (Cd) toxicity for humans and plants is of great concern due to its high mobility and phytoavailability in soil even at low concentrations. Opposite to Cd, Phosphorus (P) is an essential nutrient for plant growth. A greenhouse experiment was carried out in a completely randomized design to examine the influence of Cd, P and their interaction on the growth and chemical composition of spinach grown on a calcareous soil. Treatments consisted of four Cd levels (5, 10, 20 and 40 mg/kg soil as cadmium sulfate) and four P levels (0, 20, 40 and 80 mg/kg soil as mono-calcium phosphate) in three replicates. The results indicated that 40 mg Cd significantly decreased spinach dry weight by 47% but P application decreased detrimental effect of Cd on spinach dry weight. Also, phosphorus application significantly decreased Cd concentration in spinach aerial parts by 78%. Increasing Cd levels increased concentration of this element in spinach shoots. Addition of 40 mg Cd decreased P concentration by 21.5% in aerial parts. Zinc (Zn), manganese (Mn), calcium (Ca), and nitrogen (N) concentration significantly decreased with P application but increased concentration of sodium (Na). Cadmium application decreased Zn concentration but increased Ca, Na and N concentrations in spinach. Our tentative conclusion is that P application in P-deficient soils is probably effective in decreasing Cd concentration and the detrimental effect of Cd on spinach growth, indicating a negative interaction between these elements. Prior to any fertilizer recommendation, the results of this experiment should be verified under field conditions

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In order to investigate the effects of municipal solid waste enriched with mineral fertilizers on some soil physical properties and lead (Pb) and chromium (Cr) concentration in plant organs of spinach, a field experiment was carried out in a factorial arrangement based on the randomized complete block design with three replications in 2008. The main plot included four levels of fertilizer, control without fertilizer, 20 tons of multiple solid waste + 50% chemical fertilizers and 40 tons of multiple solid waste + 50% chemical fertilizers per hectare and sub-plot consisted of a period of application in 3 levels of time (one, two and three years). The results showed that application of enriched municipal compost increased field capacity, soil porosity and moisture holding capacity, but particle and bulk density of soil decreased compared to the control. Also, the physical parameters in the two levels of emriched waste compost were higher than chemical fertilizer treatment. On the other hand, using for three-years the urban waste compost enriched fertilizer at all levels increased significantly (p 0.05) lead and chromium concentrations in spinach. The Pb and Cr accumulated in roots and shoots of spinach in urban using 40 tons of waste compost per hectare with 50 percent of chemical fertilizer for a period of three years and showed a significant increase. The amounts of fertilizer in all three levels were higher than the root element shoot.

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Heavy metals in water resources are one of the most important environmental problems in most of countries. Up to now, various methods for removing these metals including using low price materials have been used. In this study, two new absorbents (zizyphus spinachristi leaf and its fly ash) were studied for adsorption of cadmium from aqueous solutions using batch experiments. The effect of contact time, pH, and amount of adsorbent on adsorption efficiency was evaluated and the best kinetic and isotherm model was determined. Results showed that optimal absorption of pH was 5 and 6 for zizyphus spinachristi leaf and its fly ash, respectively. The equilibrium time was 45 min for zizyphus spinachristi leaf and 30 min for ash. Adsorption efficiency was increased by increasing the adsorbent dose. By comparing the parameters of isotherm models, it was observed that the cadmium adsorption capacity of fly ash (4.27 mg/gr) was higher than that of zizyphus spinachristi (3.91 mg/gr).

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Fluoride (F) is an essential element for humans and animals. The continuous ingestion of fluoride by humans and animals in excessive amounts has damaging effects. The objective of this study was to investigate the uptake of fluoride in spinach and alfalfa in an alkaline soil of Isfahan, Iran. Two plants were planted in lysimeters at Isfahan University of Technology research station site. The treatments consisted of two plants and three concentrations of F. Each treatment was performed in triplicate. All the plants were harvested after 125 days and the total plants' F concentrations were determined. The F concentration in both plants' roots were higher significantly (p<0.05) than the plants' shoots at both treatments. The F concentration in spinach root was 2.5 to 3 times greater than those values in alfalfa root. Totally, the RCFs and SCFs values of F were very low. This showed that these plants did not uptake much fluoride from the soil.

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Water scarcity forced farmers to use wastewater as water source, without considering its effects on environment and resultant contamination of soils and plants especially with heavy metals. The objectives of this study are to evaluate the application effects of zeolite as soil amendments on the uptake of Cd by spinach (Spinach Oleares L.) irrigated with wastewater (containing 10 ppm Cd). Different levels amounts of zeoilte (0, 1% and 5% w/w) were added to the soil and the experiment was conducted as a completely randomized design in a green house with 3 replications. The results indicated that, the addition of zeolite 1% (w/w) in soil treated with wastewater reduced cadmium concentration in plant, and consequently the percentage of extractable Cd using DTPA was decreased. However, application of zeolite 5% (w/w) increased the soil salinity, and as a result increased Cd concentration in the plant but this increase was not statistically significant, comparing with control. Spinach biomass did not differ significantly under irrigation with wastewater, but the Cd available in wastewater caused a decrease in Spinach biomass yield.