Fractionation and Risk Assessment Zinc in Calcareous Soils under Dry Farm and Irrigated Cultivation in Province Zanjan
Subject Areas :
Ali Afshari
1
(دانشجوی دکتری علوم خاک - دانشکده کشاورزی - دانشگاه زنجان)
Keywords: Soil properties, Zinc, Dry farming, Sequential extraction, Irrigated farming,
Abstract :
The present research aims at evaluate the concentration and distribution chemicals (fractions) in dry farm and irrigated soil in Zanjan province. For this purpose, 120 samples of surface soil (0 to 10 cm depth) were taken at 24 and 96 dry farm and irrigated soils respectively. After determining the total concentration of the sample, 36 soil samples for chemical and physical analysis and sequential extraction were selected. According to the results, total Zn and DTPA-extractable for dry farm and irrigated soils were 142.8, 1.66 and 230.1, 15.30 mg/kg respectively. Not significantly different were found between the two soils and the chemical fractions in descending order were: soluble + exchangeable fraction < bound to carbonate > bound to organic matter > bound to iron and manganese oxides < residual. Although the contribution of each fraction in the two soils was different. The physical and chemical properties of soils, the greatest influence on the distribution of chemical organic matter fraction was found. The DTPA-extractable Zn was affected mostly by organic matter and pH. Because of the dynamic equilibrium is established between the different phases, so different fractions are correlated strongly. To determine risk assessment in Zn risk assessment code (RAC) was used for dry farm and irrigated soils with 4.1 and 5.5 percent respectively which fall into low risk limit.
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