Data from: Long-term agricultural management does not alter the evolution of a soybean-rhizobium mutualism

Leguminous crops, like soybeans, often rely on biologically fixed nitrogen via their symbiosis with rhizobia rather than synthetic nitrogen inputs. However, agricultural management practices may influence the effectiveness of biological nitrogen fixation. While the ecological effects of agricultural management on rhizobia have received some attention, the evolutionary effects have been neglected in comparison. Resource mutualism theory predicts that evolutionary effects are likely, however. Both fertilization and tillage are predicted to cause the evolution of rhizobia that provide fewer growth benefits to plant hosts and fix less nitrogen. This study capitalized on an LTER (Long Term Ecological Research) experiment that manipulated agricultural management practices in a corn-soybean-wheat row crop system for 24 years to investigate whether four different management practices (conventional, no-till, low chemical input, and certified organic) cause rhizobia populations to evolve to become more or less cooperative. We found little evidence that 24 years of varying management practices affect the net growth benefits rhizobia provide to soybeans, although soybean plants inoculated with soils collected from conventional treatments tended to have lower biological nitrogen fixation rates than plants inoculated with soils from the no-till, low input, and organic management treatments. These findings suggest that rhizobia will continue to provide adequate growth benefits to leguminous crops in the future, even in intensively managed systems.Experiment 1 Plant growth and nodule dataPlant growth and nodule data from an experiment in which wildtype and non-nodulating mutant soybean plants were inoculated with soils collected from long-term agronomic treatments at the Kellogg Biological Station LTER site.Schmidt et al 2017 Experiment 1.csvSchmidt et al 2017 Experiment 2Plant growth and nodule data from an experiment in which wildtype soybean plants were inoculated with rhizobium strains isolated from long-term agronomic treatments.Schmidt et al 2017 BNFIsotope data and calculations estimating biological nitrogen fixation.Schmidt et al 2007 Data analysesSAS code used in the analyses presented in Schmidt et al. 2017.Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: DEB-1257756, DEB-1027253, DBI-093945