Location: Forage-animal Production ResearchTitle: Nitrite oxidizing bacteria, Nitrobacter and Nitrospira, are differently influenced by season, fertilizer, and tillage in long-term maize culture
|LIU, SHUANG - University Of Kentucky|
|COYNE, MARK - University Of Kentucky|
|GROVE, JOHN - University Of Kentucky|
Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2022
Publication Date: N/A
Interpretive Summary: Nitrogen fertilizer is essential to the growth of many crop plants, including cereal grains, like corn (Zea Mays). However, nitrogen lost from the soil can be transported to water sources where it contributes to ecological problems, like algal blooms. The process of oxidation makes forms of nitrogen that leach more easily into the ground water. This study examined the soil bacteria that conduct the second step in oxidation, the conversion of nitrite to nitrate (nitrite oxidation) in long-term corn plots. There are two major types of bacteria that perform nitrate oxidation. The study determined that one type was more influenced by fertilizer application and the other more influenced by plowing. They were also influenced by season. It is important to understand what affects the bacteria that conduct nitrite oxidation so that we can make informed choices about nitrogen fertilizer application.
Technical Abstract: Nitrite (NO2-) oxidation is the second step in nitrification, following ammonia (NH3) oxidation, and catalyzed by nitrite oxidizing bacteria (NOB). Their activity is critical in preventing toxic accumulation of NO2-. The two major NOB genera in soil are Nitrobacter and Nitrospira. This study investigated how N fertilization and tillage management influenced these two NOB communities in long-term (>40 years) maize (Zea mays L.) cropping. To evaluate NOB community changes we used PCR and denaturing gradient gel electrophoresis (DGGE) to analyze Nitrobacter and Nitrospira NO2- oxidoreductase genes (nxr). Season, fertilizer rate, and tillage all influenced Nitrobacter and Nitrospira communities, but differentially for the two genera. Nitrobacter was more diverse in summer, whereas Nitrospira was more diverse in winter. Nitrobacter was more diverse in N-fertilized samples, whereas Nitrospira diversity decreased with increasing fertilizer rate in winter but not summer. The diversity of Nitrobacter was not significantly influenced by tillage, whereas no-tillage samples had more diverse Nitrospira, compared to plow tillage samples. In addition to providing evidence for better understanding the relationship between soil management and NOB communities, this study also helped to suggest linkages between ammonia oxidizing bacteria and Nitrobacter and between ammonia oxidizing archaea and Nitrospira that may facilitate future studies concerning ammonia-oxidizing nitrifiers and NOB.