Plant–soil feedback relationships depend on nutrient availability and stoichiometry

Plant–soil feedback (PSF) significantly influences plant species abundance and community composition. Negative PSF arises from pathogen accumulation, autotoxicity, and nutrient depletion, often being species‐specific. Conversely, cultivating mutualistic microbes like mycorrhizal fungi can enhance PSF positively. While PSF relationships are typically studied in mesocosms under optimal nutrient conditions, natural ecosystems often face nutrient limitations, particularly nitrogen (N) and phosphorus (P). The impact of nutrient availability and N:P stoichiometry on PSF remains largely unexplored. In our study, we examined the PSF of six plant species across six nutrient treatments, combining three N:P ratios (3, 15 and 75) with two nutrient levels (high and low). The selected species represented distinct natural stoichiometric niches: two from P‐limited soils, two from N:P co‐limited soils, and two from N‐limited soils. Our findings revealed that nutrient supply level and N:P ratio affected PSF in five out of six species. Two species exhibited more positive PSF at high nutrient supply, while one species showed a more positive PSF at low nutrient levels. Similarly, two species experienced higher PSF at low N:P ratios, and one at higher N:P ratios. Notably, the observed effects were not correlated with the species' natural stoichiometric N:P niches. In some cases, PSFs shifted from negative to positive within a single plant species, depending on nutrient levels and ratios. These results suggest that the effects of soil nutrient availability on PSF are common among plant species but are species‐specific. Such nutrient‐dependent PSF effects likely influence species coexistence in natural plant communities and are also impacted by human interferences in nutrient cycles, such as enhanced atmospheric N deposition rates.