“…Denitrifying bacterial populations in soil have been reported to be enhanced by PCP (pentachlorophenol) (Ishizawa and Hatsuguchi, 1966) and by 2,4-D (2,4-dichlorophenoxyacetic acid) (Sethunathan, 1970), but to be decreased by MCPA (2-methyl-4-chlorophenoxyacetic acid) and propanil (De and Hukhopadhyay, 1971). Denitrification by cultures of denitrifying bacteria has been reported to be inhibited by diquat (Atkinson, 1973), MCPA, 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) (Torstensson, 1974), 2,4-D, chlorbromuron, chloroxuron, fluometuron, metoxuron, neburon, diuron, linuron, siduron (Hart and Larson, 1966;Bollag and Nash, 1974;Bollag and Henninger, 1976), dalapon (Grant and Payne, 1982), simazine and atrazine (HcElhannon et al, 1984;Mills, 1984), to be enhanced by MCPA, 2,4,5-T, linuron and simazine (Torstensson, 1974), and to be .…”