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Biology and Fertility of Soils, vol.39, no.6, pp.474-478, 2004 (SCI-Expanded, Scopus)
We investigated the effects of Topogard 50 WP (3 kg ha-1) on soil respiration, mineral N content, and number of denitrifying and total bacteria in four coarse-textured volcanic soils for 91 days. Topogard application decreased CO2 evolution in acid soils (Tepedibi and Karaçakil) whereas soil respiration was initially increased in neutral and alkaline soils (Kaşbaşi and Baǧlar). The herbicide application significantly stimulated ammonification in Kaşbaşi and Baǧlar soils, while Tepedibi and Karaçakil soils showed significantly lower NE4+-N contents than the control. The treatment inhibited the activity of nitrifying microorganisms and, thus it decreased the NO3--N content in Tepedibi, Karaçakil, and Kaşbaşi soils, whereas the NO 3--N content was increased in Baǧlar soil. The NO2--N content of soils was not affected by the treatment. The activity of denitrifying bacteria was stimulated by the addition of herbicide in all soils, whereas the total number of bacteria was not influenced. It may be concluded that the effects of Topogard on the microbiological characteristics of coarse-textured soils are likely to be dependent on soil pH. © Springer-Verlag 2004.