EAPSI:Effect of Humic Substances on Ammonium Oxidation Coupled to Iron Reduction in Paddy Soils

Healy Olivia, Lincoln NE

Investigators

Abstract

Humic substances could have a significant impact on iron cycling in paddy soils, resulting in impacts on nitrogen loss and retention in terrestrial ecosystems. This project will determine the effect of humic substances on the process of iron reduction coupled to ammonium oxidation and subsequent nitrogen loss in paddy soils. The abundance of humic substances in soils indicates the significant potential impact of humic substances on iron cycling and on nitrogen loss from paddy soils in China, where one-third of the world?s synthesized nitrogen fertilizer is produced. To determine the impact of humic substances on iron and nitrogen cycling in paddy soils, humic substance, iron, and nitrogen cycling will be stimulated in paddy soils and nitrogen loss will be measured. In addition, the stimulated microbial community will be analyzed to improve the understanding of the microorganisms responsible for nitrogen loss and retention and iron cycling in terrestrial ecosystems. This project will be completed in collaboration with Dr. Yong-Guan Zhu at the Institute for Urban Environment, Chinese Academy of Sciences. Dr. Zhu has extensive experience analyzing paddy soil iron and nitrogen cycling and microbial communities. The stimulated microbial community will be analyzed by stimulating iron reduction coupled to ammonium oxidation in paddy soils and employing culture-independent (sequencing-by-synthesis of 16S rRNA gene sequences) and culture-dependent (soil enrichment followed by colony isolation) microbial community analysis of the paddy soils. The proposed research will improve the mechanistic understanding of terrestrial nitrogen and iron cycling and estimations of global nitrogen loss. This NSF EAPSI award supports the research of a U.S. graduate student and is funded in collaboration with the Chinese Ministry of Science and Technology.