Characteristics of N[sub.2] and N[sub.2]O Fluxes from a Cultivated Black Soil: A Case Study through In Situ Measurement Using the [sup.15]N Gas Flux Method

• Published in: Agriculture (Basel) Vol. 12; no. 10
• Main Authors: Pan, Zhanlei, Wang, Rui, Liu, Yan, Wang, Lin, Zheng, Xunhua, Yao, Zhisheng, He, Hongbo, Zhang, Xiaochen
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.10.2022
• Subjects: Case studies; Conservation tillage; Methods; China; United Kingdom
• ISSN: 2077-0472; 2077-0472
• DOI: 10.3390/agriculture12101664

The magnitudes and source partitioning of soil dinitrogen (N[sub.2]) and nitrous oxide (N[sub.2]O) emissions are not well documented, yet. To address both issues for black soil subject to a typical cool temperate climate, soil N[sub.2]O and N[sub.2] fluxes following the basal application event of an ammonium-based fertilizer (labeled by [sup.15]N) for maize were simultaneously measured in situ by using the [sup.15]N gas flux ([sup.15]NFG) method. During the two-month field experiment, the measured N[sub.2] and N[sub.2]O fluxes cumulated to 1.61 ± 0.47 and 0.12 ± 0.01 kg N ha[sup.−1], respectively, showing N[sub.2]O to N[sub.2]O plus N[sub.2] ratios (R[sub.N2O]) of 0.02-0.31 (0.15 on average). Temperature was identified as a key factor regulating the total soil N[sub.2] fluxes (r[sup.2] = 0.27, p < 0.01), despite the N[sub.2] fluxes originated from nitrate denitrification related to dissolved organic carbon concentrations (r[sup.2] = 0.39, p < 0.01). Differently, both temperature and soil moisture jointly accounted for 85% and 74% of the variances in the N[sub.2]O fluxes and the R[sub.N2O] values, respectively (p < 0.01). Moreover, the process(es) other than autotrophic nitrification and heterotrophic denitrification could be of substantial importance for the soil N[sub.2]O emissions. Our findings emphasized the importance of temperature in regulating N[sub.2] emissions from black soil and the possible site- and/or time specificity of a soil factors-based parametrization of R[sub.N2O]. In addition, this study implicates that labeling a nitrogen substrate of nitrification while using the [sup.15]N enrichment of N[sub.2]O is necessary to more accurately quantify total soil N[sub.2] fluxes in situ by using the [sup.15]NFG approach even though further confirmation in future studies is still needed.