Effects of the herbicide Topogard on soil respiration, nitrification, and denitrification in potato-cultivated soils differing in pH
2004
Kara, E.E. | Arli, M. | Uygur, V.
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 Karacakil) whereas soil respiration was initially increased in neutral and alkaline soils (Kasbasi and Baglar). The herbicide application significantly stimulated ammonification in Kasbasi and Baglar soils, while Tepedibi and Karacakil soils showed significantly lower NH4(+)-N contents than the control. The treatment inhibited the activity of nitrifying microorganisms and, thus it decreased the NO3(-)-N content in Tepedibi, Karacakil, and Kasbasi soils, whereas the NO3(-)-N content was increased in Baglar 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.
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