Author(s): S. K. NAG AND S. K. DAS

Abstract: Atrazine was applied @ 1.5 kg ai/ha in soil before emergence of fodder sorghum (cv.PC-6) grown during kharif season in two successive years 2006 and 2007 under two different nitrogen sources viz., sole inorganic (T2) and organic and inorganic in the ratio of 50:50 (T4) keeping T1 and T3 as their respective controls. Samples collected at different intervals from two depths of soil i.e. 0-15 and 15-30 cm were analysed for atrazine residues in both the years. The average initial zero day deposition in 0-15 cm depth soil was 0.4779 and 0.4619mg/kg which dissipated by 62% (0.1823mg/kg) and 65% (0.1619mg/kg) in 15 days in T2 and T4 respectively. However, after elapse of 30 days about 86-88% residues disappeared in both the treatments. In samples of 15-30 cm depth the initial zero day deposits were 0.1935 and 0.2005 mg/kg in T2 and T4 respectively which dissipated down to 0.066mg/kg in 15 days in both the treatments. Residues were below detectable level in samples collected at 30 days from 15-30 cm depth and at 45 days from 0-15cm depth. In plant foliage collected at harvest we could detect traces of atrazine in few samples only in first year but in the second year’s sample it was totally absent, thus the fodder at harvest was absolutely safe for animal feeding. The dissipation pattern followed first order rate kinetics with high correlation coefficients (r = - 0.98 to – 0.99). The statistically calculated half-life values were found to be 10.27, 9.35 days in 0-15 cm and 9.65, 9.38 days in 15-30 cm depth soil in T2 and T4 respectively.

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