Plant micronutrient fertilization data

1. Although plants need many essential nutrients, nitrogen and phosphorus have been the major focus of theory and experimental studies seeking to understand plant limitation and community composition.2. As such, fertilization studies have usually ignored nutrients other than N and P, or added them as a group, obscuring any effects that other nutrients have individually.3. We fertilized a coastal tallgrass prairie in Texas by adding N and P together, crossed with separate Ca, K, and Na treatments, for a total of 16 treatments, with each replicated 8 times in large (30 x 30m) plots.4. As many other studies have found, N&amp;P fertilization had large effects on plant biomass and taxonomic and functional composition.5. However, the other elements also affected plant biomass as well as taxonomic and functional plant composition, pointing in particular to a role of Na and Ca in structuring plant communities at this coastal tallgrass prairie site.6. The effects of Na and Ca often interacted with N&amp;P: Na had positive effects on plant biomass in one year, but the combination of N&amp;P with Na had a suppressing effect on biomass in another year.7. There was also a small synergistic effect of Ca with N&amp;P with on plant biomass.8. Responses to Na and Ca were predicted by plant functional traits like plant life form, height, clonality, or stoichiometry.9. In particular, plants that had high amounts of tissue Ca relative to either N or P responded positively to Ca additions.10. At the species level, Na increased the abundance of one sedge, <i>Fimbrystilis puberula</i>, which may be a halophilic species, and Ca increased the abundance of several plants, especially understory species.11. Synthesis: These results argue for important roles for other elements besides N and P in structuring plant communities, especially Na and Ca at this tallgrass prairie site. Mounting evidence, including this study, necessitates that theory and experiments move beyond a focus on N and P to explicitly consider the roles of other elements in structuring plant communities in other ecosystems.