Concentration of total fenamiphos residue over time in the profile of two sandy soils
1990
Minton, N.A. | Leonard, R.A. | Parker, M.B.
A field experiment was conducted to monitor concentrations of fenamiphos and and its oxidation products, fenamiphos sulfoxide and fenamiphos sulfone [total fenamiphos residues (TFR)] in two soils over a 5-month period under two verse tillage systems to determine the persistence and movement of applied fenamiphos over time. Concentrations of TFR were measured to a depth of 100 cm (39.4 in.) in the profiles of a Dothan sand (fine loamy, siliceous, thermic Plinthic Paleudults) in 1984 and a Fuquay sand (loamy, siliceous, thermic Arenic Plinthic Paleudults) in 1985. Soybean (Glycine max (L.) Merr.) planted in rye (Secale cereale L.) stubble by the subsoil-plant method and in moldboard plow prepared seed beds was grown both years. Yields were affected by tillage treatments only on the Fuquay soil where yields were greater for the subsoil-plant plant method than for the moldboard plow method. The persistence and vertical movement of TFR was not significantly affected by tillage treatments when fenamiphos was applied at 2.2 kg ai/ha (2.0 lb ai/A) at planting in a 17.9-cm wide band. Total fenamiphos residues exhibited an initial soil half-life of 7 to 10 days. More TFR moved below the 10-cm depth in the Fuquay than in the Dothan soil, but less than 1% of the fenamiphos applied moved below the 75- to 100-cm depth interval in both soils.
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