DOI: 10.5061/dryad.x3ffbg7rx
title: Relative importance between nitrification and denitrification to N2O from a global perspective

description: Nitrous oxide (N2O) is a potent greenhouse gas and its mitigation is a
 pressing task in the coming decade. However, it remains unclear which
 specific process between concurrent nitrification and denitrification
 dominates worldwide N2O emission. We snagged an opportunity to ascertain
 whence the N2O came and which were the controlling factors on the basis of
 1315 soil N2O observations from 74 peer-reviewed articles. The average N2O
 emission derived from nitrification (N2On) was higher than that from
 denitrification (N2Od) worldwide. The ratios of nitrification-derived N2O
 to denitrification-derived N2O, hereof N2On:N2Od, exhibited large
 variations across terrestrial ecosystems. Although soil carbon and
 nitrogen content, pH, moisture, and clay content accounted for a part of
 the geographical variations in the N2On:N2Od ratio, ammonia-oxidizing
 microorganisms (AOM):denitrifier ratio was the pivotal driver for the
 N2On:N2Od ratios, since the AOM:denitrifier ratio accounted for 53.7% of
 geographical variations in N2On:N2Od ratios. Compared with natural
 ecosystems, soil pH exerted a more remarkable role in dictating the
 N2On:N2Od ratio in croplands. This study emphasizes the vital role of
 functional soil microorganisms in geographical variations of N2On:N2Od
 ratio, and lays the foundation for the incorporation of soil
 AOM:denitrfier ratio into models to better predict N2On:N2Od ratio.
 Identifying soil N2O derivation will provide a global potential benchmark
 for N2O mitigation by manipulating the nitrification or denitrification.
description: # Readme **Title** Relative importance between nitrification and
 denitrification to N2O from a global perspective **Athour** Bingbing Han,
 Yanzhong Yao, Bin Liu ,Yini Wang, Xiaoxuan Su, Lihua Ma, Dunyi Liu, Shuli
 Niu, Xinping Chen, Zhaolei Li * **Corresponding author:** Zhaolei Li,
 Professor E-mail: **Correspondence address:**
 College of Resources and Environment, and Academy of Agricultural
 Sciences, Southwest University, Chongqing 400715, China **Data abstract**
 Nitrous oxide (N2O) is a potent green-house gas and its mitigation is a
 pressing task in the coming decade. However, it remains unclear which
 specific process between concurrent nitrification and denitrification
 dominates worldwide N2O emission. We snagged an opportunity to ascertain
 whence the N2O came and which were the controlling factors on the basis of
 1315 soil N2O observations from 74 peer-reviewed articles. The average N2O
 emission derived from nitrification (N2On) was higher than that from
 denitrification (N2Od) worldwide. The ratios of nitrification-derived N2O
 to denitrification-derived N2O, hereof N2On:N2Od, exhibited large
 variations across terrestrial ecosystems.** **Although soil carbon and
 nitrogen content, pH, moisture, and clay content accounted for a part of
 the geographical variations in the N2On:N2Od ratio, ammonia-oxidizing
 microorganisms (AOM):denitrifier ratio was the pivotal driver for the
 N2On:N2Od ratios, since the AOM:denitrfier ratio accounted for 53.7% of
 geographical variations in N2On:N2Od ratios. Compared with natural
 ecosystems, soil pH exerted a more remarkable role to dictate the
 N2On:N2Od ratio in croplands. This study emphasizes the vital role of
 functional soil microorganisms in geographical variations of N2On:N2Od
 ratio, and lays the foundation for the incorporation of soil
 AOM:denitrfier ratio into models to better predict N2On:N2Od ratio.
 Identifying soil N2O derivation will provide a global potential benchmark
 for N2O mitigation by manipulating the nitrification or denitrification.  
 **Data collect** The data were collected from published peer-reviewed
 papers obtained from two libraries: Web of Science
 () and China National Knowledge
 Infrastructure Database (). The string of
 keywords for surveying the papers was ‘soil AND nitrification AND
 denitrification AND N2O’. Additional papers were supplemented using Google
 Scholar. The publication time for the papers was up to July 1, 2022.
 Initially, 1009 papers were gotten (323 papers in Chinese and 686 papers
 in English), and the dataset was compiled following the guidelines of
 PRISMA (Preferred Reporting Items for Systematic Reviews and
 Data-Analyses; Fig. S1). The criteria for screening papers were: 1. The
 N2On and N2Od were measured. 2. The topsoil were used to measure N2O
 emission (e.g., soil depth was top 0-30 cm). Data from the soil profile
 were excluded as it is sporadic. Accordingly, 74 studies met the criteria,
 in which 56 studies came from laboratory incubation and 18 studies came
 from field experiment. We compared the N2On, N2Od, and N2On:N2Od ratio
 between laboratory incubation and field experiment using t-test, and no
 significant differences were observed in N2On, N2Od, and N2On:N2Od ratio
 between laboratory incubation and field experiment (all p &gt; 0.05;
 Figure S2). Notably, there are some empty cells in the dataset, indicating
 that there were no values or missing values, i.e., NA. To make it easier
 to run R (version4.2.2.) we don't fill the null value with NA or
 Null. In sheet2 (i.e., the Readme) of the uploaded dataset, we provide the
 specific meaning of each heading and its unit of expression. The details
 of experimental site were also extracted from papers, including the
 geographic information of experiment site (i.e., latitude and longitude),
 climate conditions (i.e., mean annual temperature (MAT) and mean annual
 precipitation (MAP)) and ecosystem types (i.e., grasslands, forests and
 croplands). Additionally, soil physicochemical properties [soil pH, the
 ratio of carbon to nitrogen (soil C:N), total nitrogen (TN), bulk density
 (BD), clay content and ammonium content (NH4+), nitrate (NO3-), soil
 moisture (WHC%), Nitrification-derived N2O (N2On), Denitrification-derived
 N2O (N2Od), Percentage of nitrification-derived N2O (N2On proportion),
 Percentage of denitrification-derived N2O (N2Od proportion), AOA
 (ammonia-oxidizing archaea), AOB (ammonia-oxidizing bacteria), nirS (S
 type nitrite reductase), and nirK (K type nitrite reductase)].  **Data
 processing software** We processed the entire set of data by utilizing the
 R language, version4.2.2., R Core Team. **Contact Information**
 **Corresponding author:** Zhaolei Li, Professor **E-mail:**
 **ORCID:**