AUTHOR=Li Chunpei , Fan Maopan , Wang Xuan , Li Xue , Zhao Guang , Liu Gangcai , Zhao Jixia 

TITLE=Effects of nitrogen fertilizers on the bacterial community diversity and the weathering of purple mudstone in Southwest China

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1164826

DOI=10.3389/fmicb.2023.1164826

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>Rock weathering is crucial in the development of soil. Yet the role of bacteria in the fine particle-forming process of purple mudstone is not fully understood, especially under nitrogen fertilization.</p></sec><sec><title>Methods</title><p>In this study, the particles (0.25 mm to 1 mm) of purple mudstone from Penglai Group (J<sub>3</sub>p) were selected as the test material. Two nitrogen fertilizers, i.e., urea (U) and ammonium bicarbonate (AB), and four application levels (0, 280, 560, and 840 N kg∙ha<sup>−1</sup>) with 18 replications were designed in an incubation experiment. The weathering indices and bacterial community structure of the purple mudstone particles were investigated after 120 days of incubation.</p></sec><sec><title>Results</title><p>The results showed that the weathering indices of purple mudstone particles in the AB treatment were higher than that in the U treatment at the same fertilization levels and a reducing trend was observed with increasing nitrogen fertilizer levels under the same nitrogen fertilizer application types. The diversities of the bacterial community were extremely significantly altered by nitrogen fertilizer application (<italic>p</italic> &lt; 0.01). The effect of the nitrogen fertilizer application level on the beta diversity of the bacterial community (<italic>R<sup>2</sup></italic> = 0.34) was greater than that of the nitrogen fertilizer application type (<italic>R<sup>2</sup></italic> = 0.20). Through stepwise regression analysis, the positive effects of nitrification of Nitrobacter (<italic>Nitrolancea</italic>) (<italic>R<sup>2</sup></italic> = 0.36), the Phosphorous-dissolving bacteria (<italic>Massilia</italic>) (<italic>R<sup>2</sup></italic> = 0.12), and N-NO<sub>3</sub><sup>−</sup> (<italic>R<sup>2</sup></italic> = 0.35) on the weathering indices of J<sub>3</sub>p purple mudstone particles could be observed. Structural equation modelling indicated that nitrogen fertilizer application level affects the abundance of the dominant species at the genus level (<italic>Nitrolancea</italic> and <italic>Massilia</italic>), and key environmental factor (N-NO<sub>3</sub><sup>−</sup>), which in turn accelerated the weathering indices (59%).</p></sec><sec><title>Discussion and Conclusion</title><p>Our findings imply that the enhancements of nitrification of Nitrobacter (<italic>Nitrolancea</italic>) and of phosphorus solubilization of Phosphorous-dissolving bacteria (<italic>Massilia</italic>) by nitrogen fertilization are the key factors affecting the weathering indices of J<sub>3</sub>p purple mudstone particles.</p></sec>