Leaching behaviour of azoxystrobin in sandy loam soil

The mobility of azoxystrobin in sandy loam soil was studied under continuous and discontinuous flow conditions in soil columns under laboratory conditions at two application rates (50 and 100 μg), with simulated rainfall of 300 mm. Residues of azoxystrobin in soil and leachate were estimated by gas-liquid chromatography and confirmed by gas chromatography-mass spectrometry. Though maximum concentration of azoxystrobin was found in the top 10 cm layer under both continuous and discontinuous flow conditions but azoxystrobin residues under continuous flow conditions were recorded down to a depth of 15-20 cm and under discontinuous flow conditions residues, were recorded at depths of up to 20 and 25 cm for the single and double dose treatments, respectively. The retention of azoxystrobin residues was greater under continuous flow conditions at the higher dose, whereas a low retention of azoxystrobin residues at the lower dose and under discontinuous flow conditions was observed. The low mobility of azoxystrobin in soil indicated that it represents a low risk to groundwater systems. Leachate fractions were free from azoxystrobin residues.   Key words: Leaching, azoxystrobin, sandy loam soil, column, residues.