Effects of hexaconazole application on soil microbes community and nitrogen transformations in paddy soils
2017
Ju, Chao | Xu, Jun | Wu, Xiaohu | Dong, Fengshou | Liu, Xingang | Tian, Chunyan | Zheng, Yongquan
The ecological risks of widely used hexaconazole on soil microbes remain obscure. Thus, a 3-month-long experiment using two typical paddy soils in China (red soil and black soil) was conducted to assess the effects of hexaconazole (0.6 (T1) and 6 (T10) mgkg⁻¹ soil) on the overall microbial biomass, respiratory activity, bacterial abundance and community structure, and nitrogen transformations. Soil was sampled after 7, 15, 30, 60, and 90days of incubation. The half-lives of the two doses of hexaconazole varied from 122 to 135d in the black soil and from 270 to 845d in the red soil. Both dosages of hexaconazole did not affect NH⁺₄-N content, N₂-fixing bacterial populations, total bacterial diversity, and community structure, but transitorily decreased the populations of total bacteria in both soil types. In the black soil, T10 negatively affected microbial biomass carbon (MBC) and soil basal respiration (RB), but transitorily increased NO⁻₃–N concentration and ammonia-oxidizing bacteria populations, while T1 had almost no effect on most of the indicators. As for red soil, both concentrations of fungicide significantly, but transitorily, inhibited MBC and RB, while only T10 had a relatively long stimulatory effect on NO⁻₃–N concentration and ammonia-oxidizing archaea populations. This study showed that over application of hexaconazole is indeed harmful to soil microorganisms and may reduce soil quality and increase the risk of nitrogen loss in paddy soils.
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