Showing 2 results for Rezaee Nejad
M Karami, M Afyuni, Y Rezaee Nejad, A Khosh Goftarmanesh,
Volume 12, Issue 46 (1-2009)
Abstract
Sewage sludge application on farmland as fertilizer is commonly practiced in many countries. Sewage sludge is rich in macro and micronutrients. However, high concentration of heavy metals in sludge may cause pollution of soil, groundwater and human food chain because of toxic metals uptake by crops. The objective of this study was to determine residual and cumulative effects of sewage sludge on concentration of Zn and Cu in soil and wheat. Different levels of 0, 25, 50 and 100 Mg ha-1 of sewage sludge were applied to the soil for four years. To study the cumulative and residual effects of the sewage sludge, applications were repeated on three fourth of each plot in the second year, on one half of plots in the third year and on one fourth of plots in the fourth year. Wheat was grown in the plots. After the fourth year, soil samples from the 0-20 cm depth of the different parts of the plots were taken and analyzed. After harvesting the wheat, roots, stems and grains were separately analyzed for the heavy metal concentrations. Cumulative sewage sludge application significantly (P≤0.05) increased the total and DTPA-extractable concentration of Zn and Cu in soil. Residual sewage sludge in the soil also increased the total and DTPA-extractable concentration of Zn and Cu. Single sludge applications at different rates increased the DTPA-extractable concentrations of heavy metals. In subsequent years with no further sludge application, DTPA–extractable metal concentrations in soil decreased continuously, approaching the levels in the control. However, even after four years, DTPA-extractable concentration of Zn in plots receiving more than 50 Mg ha-1 and Cu in plots receiving more than 25 Mg ha-1 sludge, were still significantly higher than control. DTPA-extractable concentrations of metals were closely correlated with total concentrations. Sewage sludge had a significant effect on concentration of Zn and Cu in stems and grains. Cumulative effects on Zn and Cu uptake by stems were more than residual effects. The results of this study show that cumulative and residual effects of sewage sludge application increased concentrations of micronutrients in soil and wheat.
N Barahimi, M Afyuni, M Karami, Y Rezaee Nejad,
Volume 12, Issue 46 (1-2009)
Abstract
Compost and sewage sludge contain high concentration of plant nutrients and, thus, have been used extensively as an inexpensive fertilizer. The objective of this study was to evaluate cumulative and residual effects of compost, sewage sludge and cow manure on nitrogen, phosphorus and potassium in soil and wheat. The experiment included compost, sewage sludge and cow manure, each applied at 3 rates (25, 50 and 100 Mg ha-1), a chemical fertilizer (250 kg ha-1 amonium phosphate + urea) and a control plot with 3 replications. The experimental design consisted in completely randomized blocks with treatments arranged in split plots. To study the cumulative and residual effects of the organic amendments, application was repeated on four fifths of each plot in the second year. Wheat was grown in the plots. The results showed that one application (residual effect) of organic amendments had not significant effect on total N in soil and wheat leaves and stem, but it led to significant increase of available phosphorus and potassium in soil and wheat leaves and stem. Cumulative effects of organic amendments significantly (P≤ 0.05) increased the total N (in 50 and 100 Mg ha-1 Cow manure and 100 Mg ha-1 Compost treatments), available P in all organic treatments and K (in all Compost and Cow manure treatments) in soil. Also, cumulative effects of organic amendments significantly (P≤ 0.05) increased the N (in 100 Mg ha-1 sewage sludge), P (in 100 Mg ha-1 compost) and K (in all organic treatments with the exception of 25 Mg ha-1 Compost) concentrations in leaves and stem.
