Imazamox is a post-emergence herbicide used to control weedy rice weeds in combination with tolerant rice varieties. This study, carried out in 2010 at Vercelli, Italy, was aimed at assessing the behavior of imazamox in water and sediment of rice fields managed, since 2002, according to the following different cultivation systems: A) straw and liquid manure incorporated in autumn and rice seeded in flooded field, B) straw incorporated in autumn and rice seeded in flooded field, C) straw incorporated in autumn and rice seeded in dry field. Imazamox was applied at 35 g/ha twice at 2-4 leaf stage. Water (from flooded fields and inlet/outlet floodgates), and soil samples were collected at different intervals from herbicide application. Extraction of imazamox from water and soil was performed with SPE and by using a CaCl2 solution, respectively. Extracts were analyzed by HPLC. Imazamox was found in inlet water (≤1 μg/L), while in outlet water its concentration ranged between 0.2 to 10.6μg/L. In paddy water, high concentrations of imazamox (up to 10.6μg/L) were found in the first days after treatments. After the second treatment, the highest concentration of imazamox was observed in paddy water of system C), likely due to the great crop canopy and thus to the gradual release of the chemical from rice foliage. In soil, the highest concentration after the first treatment, was 130.9 μg/kg in system C). Two weeks after the second treatment, the herbicide was not longer detected. Dissipation of imazamox in soil and water was influenced by timing of herbicide application and by the crop canopy, in particular in system C). Its presence in inlet water indicate a discharge from paddies upstream.
Environmental fate of imazamox in paddy fields
MILAN, MARCO;VIDOTTO, Francesco;DE PALO, FERNANDO;NEGRE, Michèle;FERRERO, Aldo
2012-01-01
Abstract
Imazamox is a post-emergence herbicide used to control weedy rice weeds in combination with tolerant rice varieties. This study, carried out in 2010 at Vercelli, Italy, was aimed at assessing the behavior of imazamox in water and sediment of rice fields managed, since 2002, according to the following different cultivation systems: A) straw and liquid manure incorporated in autumn and rice seeded in flooded field, B) straw incorporated in autumn and rice seeded in flooded field, C) straw incorporated in autumn and rice seeded in dry field. Imazamox was applied at 35 g/ha twice at 2-4 leaf stage. Water (from flooded fields and inlet/outlet floodgates), and soil samples were collected at different intervals from herbicide application. Extraction of imazamox from water and soil was performed with SPE and by using a CaCl2 solution, respectively. Extracts were analyzed by HPLC. Imazamox was found in inlet water (≤1 μg/L), while in outlet water its concentration ranged between 0.2 to 10.6μg/L. In paddy water, high concentrations of imazamox (up to 10.6μg/L) were found in the first days after treatments. After the second treatment, the highest concentration of imazamox was observed in paddy water of system C), likely due to the great crop canopy and thus to the gradual release of the chemical from rice foliage. In soil, the highest concentration after the first treatment, was 130.9 μg/kg in system C). Two weeks after the second treatment, the herbicide was not longer detected. Dissipation of imazamox in soil and water was influenced by timing of herbicide application and by the crop canopy, in particular in system C). Its presence in inlet water indicate a discharge from paddies upstream.
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