Aims

The theory of ecological stoichiometry mostly builds on studies of natural terrestrial ecosystems, whereas only limited stoichiometry information is available in response to agronomic practices.

Methods

We designed a greenhouse experiment in order to disentangle the specific role of cover crop identity and soil characteristic in affecting nutrient stoichiometry of a plant-microbe-soil system.

Results

Nutrient ratios of cover crop biomass were species-specific and the growth rate explained, for most species considered, the stoichiometric differences in response to soil type. In contrast, the nutrient stoichiometry of soil microbes was more homeostatic and did not respond to either cover crop identity or soil type. Compared to bare soil, the presence of cover crop enhanced microbial phosphorus immobilization in the clay-rich soil, whereas it promoted microbial carbon biomass and microbial nitrogen immobilization in the sandy-rich soil. A greater microbial cumulative respiration in clay soils, where a higher microbial biomass C at the beginning of the incubation was observed, suggested a major role of soil type, compared to cover crop identity, in affecting microbial metabolism.

Conclusions

By understanding the stoichiometric constraints in the plant-microbe-soil system, our findings can help to implement agro-ecological practices by selecting appropriate cover crop species in relation to soil type in order, for example, to avoid nutrient limitation due to microbial nutrient immobilization.

中文翻译：

---

覆盖作物物种和土壤类型的植物-微生物-土壤系统的营养化学计量

目的

生态化学计量学的理论主要建立在对自然陆地生态系统的研究上，而只有有限的化学计量学信息可用于农学实践。

方法

我们设计了一个温室实验，以弄清覆盖作物身份和土壤特性在影响植物-微生物-土壤系统养分化学计量方面的特定作用。

结果

覆盖作物生物量的养分比是特定于物种的，对于大多数物种而言，其生长速率可以解释其对土壤类型的化学计量差异。相反，土壤微生物的营养化学计量更趋于稳态，对覆盖作物的身份或土壤类型均无反应。与裸土相比，覆盖作物的存在增强了富含粘土的土壤中微生物对磷的固定化，而促进了富含沙质土壤中微生物的碳生物量和微生物对氮的固定化。粘土土壤中微生物的累积呼吸作用更大，在培养开始时观察到较高的微生物生物量碳，这表明与覆盖作物身份相比，土壤类型在影响微生物代谢方面起着主要作用。

结论

通过了解植物-微生物-土壤系统中的化学计量约束，我们的发现可以通过根据土壤类型选择合适的覆盖作物来帮助实施农业生态实践，例如，以避免由于微生物养分的固定化而造成养分限制。