Data from: More diverse rhizobial communities can lead to higher symbiotic nitrogen fixation rates, even in nitrogen-rich soils

Symbiotic nitrogen fixation (SNF) by legumes and their rhizobial partners
is one of the most important sources of bioavailable nitrogen to
terrestrial ecosystems. While most work on the regulation of SNF has
focused on abiotic drivers such as light, water, and soil nutrients, the
diversity of rhizobia with which an individual legume partners may play an
important but under-recognized role in regulating nitrogen inputs from
SNF. By experimentally manipulating the diversity of rhizobia available to
legumes, we demonstrate that rhizobial diversity can increase average SNF
rates by more than 90%, and that high rhizobial diversity can induce
increased SNF even under conditions of high soil N fertilization. However,
the effects of rhizobial diversity, the conditions under which diversity
effects were strongest, and the likely mechanisms driving these diversity
effects differed between the two legume species we assessed. These results
provide evidence that biodiversity-ecosystem function relationships can
occur at scales of an individual plant, and that the effects of rhizobial
diversity may be as important as long-established abiotic factors, such as
nitrogen availability, in driving terrestrial nitrogen inputs via SNF.