Labile carbon inputs offset nitrogen-induced soil aggregate destabilization via enhanced growth of saprophytic fungi in a meadow steppe

• Published in: Geoderma 2024-03, Vol.443, p.116841, Article 116841
• Main Authors: Zhao, Ruonan, Kuzyakov, Yakov, Zhang, Haiyang, Wang, Zhirui, Li, Tianpeng, Shao, Lingyu, Jiang, Liangchao, Wang, Ruzhen, Li, Maihe, Jianxin Sun, Osbert, Jiang, Yong, Han, Xingguo
• Format: Article
• Language: English
• Subjects: Grassland ecosystems; Labile carbon; Nitrogen deposition; Soil aggregate size distribution; Soil fungi; Soil physical structure
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2024.116841

[Display omitted] •High dose of N addition decreased macroaggregates (>2000 μm) in meadow grassland soils.•Short-term labile carbon did not alter soil pH and exchangeable Ca2+.•Labile carbon inputs offset the negative effects of N addition on soil aggregates.•Enhanced saprotrophic fungi explains restoration of macroaggregates by labile carbon. The formation and stability of soil aggregates affect plant growth, carbon sequestration, and many other physiological and biogeochemical processes. Aggregates may be destabilized by nitrogen (N) deposition due to decreased inputs of binding materials; however, the legacy effects of which are unknown. An increase in labile carbon (C) input could mitigate the negative impacts of N addition on soil aggregate stability through the improvement of soil physical, chemical and biological conditions. Using a field experiment with the addition of NH4NO3 at multiple levels in a meadow steppe, we terminated the addition of N at the sixth year and shifted to applying labile C in the form of sucrose at three levels (C-0, C-200, and C-2000 g C m−2 y−1) to soil for two years. Then we examined the aggregate size distribution and the associated soil properties. The high historical N addition rates decreased the proportion of macroaggregates (>2000 μm) and increased microaggregates (