Organic Amendments to Enhance Atrazine and Metamitron Degradation in Two Contaminated Soils with Contrasting Textures

Gholam Hosain Haghnia, Ph.D. Head, Soil Science Department, College of Agriculture, Ferdowsi University, Mashhad, 91775-1163, Iran, Tel: +98 511 605 9478, Email: ghaghnia@yahoo.com

Mohsen Forouzangohar, M.Sc., Soil Science Department, College of Agriculture, Ferdowsi University, Mashhad, 91775-1163, Iran, Tel: +98 511 726 7792, Email: forouzangohar@yahoo.com

Accumulation of organic pollutants in the environment has potentially become a serious hazard in most parts of the world. Among all types of xenobiotics, pesticides such as herbicides play a significant role in soil and water pollution due to their widely usage all over the world. The ways by which environmental and soil factors affect the fate of pesticides in soil is of considerable importance. Because such studies will be useful to predict the environmental dangers of pesticides contamination, control the quality of the environment, and find the simple, low-cost probable techniques to remediate the contaminated sites. This study addresses the ability of organic amendments to enhance atrazine and metamitron degradation in two herbicide contaminated soils with contrasting textures in laboratory conditions. Soil samples were collected from surface soils with textures of sandy loam and silty clay, from northeastern part of Iran. Initial concentration of herbicides was 50 mg.kg^-1 soil. Contaminated soil samples were treated by manure, compost and vermicompost at rates of 0, 0.5, and 2 % (w/w). Remaining concentrations of atrazine and metamitron were determined by HPLC at the end of incubation periods of 20, 40, and 60 days. The experiment was performed as a 2´2´3 factorial completely randomized design for the two herbicides, replicated 3 times. Remaining concentrations of atrazine were 46.5, 38.9, and 36.2 mg.kg^-1 after 20, 40, and 60 days incubation, respectively. Residual metamitron concentrations were clearly lower than atrazine. After 20, 40, and 60 days, remained concentrations of metamitron were 2.9, 1.0, and 0.6 mg.kg^-1, respectively. Organic amendments at the rates of 0.5 and 2 % showed the similar effects on the enhancement of herbicides degradation in soils. However, no significant effect was observed between types of organic amendments. Degradation was clearly affected by soil textures. Remaining concentrations were higher in sandy loam than in silty clay soil.

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