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 sandyrich
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.