Soil properties shape the heterogeneity of denitrification and <scp>N<sub>2</sub>O</scp> emissions across large‐scale flooded paddy soils
Yijia Tang, Xiaoxuan Su, Teng Wen, Alex B. McBratney, Shu‐Yi‐Dan Zhou, Fu-Yi Huang, Yong‐Guan Zhu
Abstract
Abstract Flooded paddy soils after rewetting dry soils accompanied by extensive nitrogen fertilizer input are important anthropogenic N 2 O emitters due to the denitrification process. Owing to multiple complex denitrifying N 2 O sources, however, the extent to which biotic (fungal or bacterial) and abiotic (chemical) denitrification contribute to total N 2 O emissions remains largely unquantified. Here we sampled across eight provinces where most of the flooded paddy soils were in China to explore microbial and abiotic denitrification potentials and decipher N 2 O dynamics. N 2 O isotopocules and site preference (δ 15 N SP ) analyses found that in most of the sampled paddy soils, fungi‐mediated denitrification was the largest N 2 O contributor (51%–63%); while bacterial and chemical denitrifications contributed 12%–31% and 12%–28% of N 2 O emissions, respectively. Further, using 15 N labeling, a significant spatial heterogeneity of denitrification performance was observed among these flooded paddy soils. As indicated by variance partitioning and regression analyses, this heterogeneity was mainly determined by soil properties (especially soil organic carbon and total nitrogen) rather than by denitrifying communities. Our findings provide insights into the establishment of predictive models of future N 2 O emission from global paddy soils considering both the biotic and abiotic contributions.