2021 journal article
Nitrapyrin-based nitrification inhibitors shaped the soil microbial community via controls on soil pH and inorganic N composition
APPLIED SOIL ECOLOGY, 170.
author keywords: Nitrification; Ammonia oxidizing microbes; soil microbiome; Non-target effects; Nitrogen stabilizers
UN Sustainable Development Goal Categories
2. Zero Hunger
(Web of Science)
13. Climate Action
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14. Life Below Water
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Source: Web Of Science
Added: November 23, 2021
Nitrate is a major source of N nutrition for plant production, but it is prone to loss from an arable soil via leaching and denitrification. Chemicals that inhibit biological NO3− production, known as nitrification inhibitors or N stabilizers, have been widely applied to slow nitrification and therefore minimize soil NO3− accumulation. However, the impacts of nitrification inhibitors on microbes other than nitrifying bacteria and archaea are largely unknown. Here we examined the diversity, abundance, and composition of the soil microbial community following the addition of two nitrification inhibitors, both containing nitrapyrin as the active ingredient but different solvents or emulsifying agents. Two silt loam soils of different acidities were used for a two-month microcosm incubation. Each soil was subjected to six treatments of soil alone, soil with the addition of each nitrification inhibitor at 4 μg nitrapyrin g−1 soil, soil with the addition of ammonium sulfate at 60 μg N g−1 soil, and soil with the addition of both ammonium sulfate and each nitrification inhibitor. Periodically during the incubation, soil NH4+ and NO3− were quantified. In addition to measurements of soil pH and potential rate of nitrification at the end of incubation, 16S rRNA and ITS marker gene libraries were prepared for high throughput sequencing. Our data showed clear targeted effects of nitrapyrin-based nitrification inhibitors on nitrification as well as ammonia oxidizing bacteria and archaea; and these effects were little affected by different solvents for dissolving or emulsifying nitrapyrin. However, the use of a nitrification inhibitor generated some non-target effects on the soil microbial community. Microbes of copiotrophic life strategy, e.g., Alphaproteobacteria, Betaproteobacteria, and Ascomycota were promoted, whereas microbes of oligotrophic life strategy, e.g., Acidobacteria, Planctomycetes, and Basidiomycota were suppressed. The degree of non-target effects appeared to be soil and microbial domain specific, with stronger effects in the acidic soil than neutral soil on the bacterial community and yet comparable effects on the fungal community between the two soils. Spearman's rank correlations suggested that non-target effects of nitrification inhibitors were primarily attributed to changes in soil pH as well as soil inorganic N composition, i.e., the percentage of ammonium (or nitrate) in inorganic N. Further research is needed for better understanding soil microbial ecology under high NH4+ concentrations so that the management practice of keeping more NH4+ in soil can be well adopted to improve crop N use efficiency and soil sustainability.