Long-term phosphorus fertilization reveals the phosphorus limitation shaping the soil micro-food web stability in the Loess Plateau

Liangliang Li; Zhuzhu Luo; Lingling Li; Yining Niu; Yaoquan Zhang; Renyuan He; Jiahe Liu; Lili Nian

doi:10.3389/fmicb.2023.1256269

Long-term phosphorus fertilization reveals the phosphorus limitation shaping the soil micro-food web stability in the Loess Plateau

Front Microbiol. 2024 Jan 11:14:1256269. doi: 10.3389/fmicb.2023.1256269. eCollection 2023.

Authors

Liangliang Li¹, Zhuzhu Luo^{1

2}, Lingling Li², Yining Niu², Yaoquan Zhang³, Renyuan He³, Jiahe Liu³, Lili Nian³

Affiliations

¹ College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou, China.
² State Key Laboratory of Arid Habitat Crop Science, Lanzhou, China.
³ College of Forestry, Gansu Agricultural University, Lanzhou, China.

Abstract

The intricate decomposition pathways within soil micro-food webs are vital for cycling soil organic carbon and nutrients, influencing the quality, productivity, and sustainability of soil systems. However, the impact of diverse phosphorus addition on these organic decomposition pathways still needs to be explored. In an 8-year experiment, phosphorus (P) fertilizer was added at varying levels (0 kg ha^-1, CK; 60 kg ha^-1, P60; 120 kg ha^-1, P120; and 180 kg ha^-1, P180), to investigate the response of the soil micro-food web. The results revealed a significant effect of phosphorus addition on soil microorganisms and nematodes, with P60 exerting a greater influence than other treatments. At P60, the Shannon index of nematodes and fungi surpassed other treatments, indicating higher diversity, while the Shannon index of bacteria was lower. The Chao1 index of bacteria and fungi at P60 was higher, contrasting with the lower index for nematodes. Metabolic footprints of bacterivores and omnivores-predators (BFMF and OPMF) were higher at P60, while metabolic footprints of fungivores and plant parasites (FFMF and PPMF) were lower, signifying altered energy flow. Functional metabolic footprints and energy flow analysis unveiled a stable soil micro-food web structure at P60, with enhanced energy conversion efficiency. Network analysis illustrated positive correlations between fungi, fungivorous nematodes (FF), and omnivorous-predatory nematodes (OP) at P60, while P120 and P180 showed positive correlations among bacteria, bacterivorous nematodes (BF), and OP. Path analysis underscored the higher contribution rate of BF-C, FF-C, and OP-C to soil organic carbon at P60 compared with P120 and P180. These findings suggest that nutrient interactions between fungi and nematodes regulate soil micro-food web decomposition under low phosphorus concentrations. In contrast, interactions between bacteria and nematodes dominate at high phosphorus concentrations. The study indicates that adding phosphorus has nuanced bottom-up effects, intricately shaping the structure and activity of the pathways and underscoring the need for a comprehensive understanding of nutrient dynamics in soil ecosystems.

Keywords: Loess Plateau; decomposition pathway; nematode metabolic footprint; phosphorus; soil micro-food web.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the National Natural Science Foundation of China (31860364 and 32160526); the Science and Technology Program of Gansu Province (22JR5RA840); and the Special funds for the Central Government to guide local scientific and technological development of Gansu Province (YDZX20216200001473).