Abstract
Background and aims
Root exudation is a key process for plant nutrient acquisition, but the controls on root exudation and its relationship to soil C and N processes in agroecosystems are unclear. We hypothesized that root exudation rates would be related to root morphological traits, N fertilization, and soil moisture. We also anticipated that root exudation would be correlated with bulk soil enzyme activity.
Methods
Root exudation, root traits, and bulk soil extracellular enzyme activity were assessed in maize (Zea mays L.), soybean (Glycine max (L.) Merr.), biomass sorghum (Sorghum bicolor (L.) Moench), giant miscanthus (Miscanthus × giganteus), and switchgrass (Panicum virgatum L.). Measurements were taken in situ during two growing seasons with contrasting precipitation regimes, and N fertilization rate was varied in sorghum during one year.
Results
Specific root exudation (per unit root surface area) was negatively related to root diameter and was generally higher in annuals than perennials. Sorghum N fertilization did not affect root exudation rates, and soil moisture regime had no effect on annual root exudation rates within maize, sorghum, and miscanthus. Specific root exudation was negatively related to bulk soil C- and N-degrading soil enzyme activities.
Conclusion
Intrinsic plant characteristics appeared more important than environmental variables in controlling in situ root exudation rates. The relationships between root diameter, root exudation, and soil C and N processes link root morphological traits to soil functions and demonstrate the potential tradeoffs among plant nutrient acquisition strategies in agroecosystems.
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Data availability
Data supporting this study are provided in the Supplementary Information. Additional datasets are available from the corresponding author upon reasonable request.
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Acknowledgements
This material is based upon work supported by the DOE Center for Advanced Bioenergy and Bioproducts Innovation (U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research under Award Number DE-SC0018420). Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the U.S. Department of Energy. The authors thank Tim Mies, Trace Elliot, Lucienne Burrus, Rachel Van Allen, Corben Andrews, Jack Goldman, Haley Ware, Kelly Purtell, Ingrid Holstrom, Mike Masters, Ilsa Kantola, and Joanna Ridgeway and others for assisting in the field and lab. The authors also thank Bill Rooney for providing sorghum germplasm and DK Lee and August Schetter for facilitating access to the bioenergy sorghum nitrogen fertilization experiment.
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Adam C von Haden: design of the research; performance of the research; data analysis and interpretation; writing the manuscript. William C. Eddy: performance of the research; writing the manuscript. Mark. B. Burnham: design of the research; writing the manuscript. Edward R. Brzostek: design of the research; writing the manuscript. Wendy H. Yang: design of the research; writing the manuscript. Evan H. DeLucia: design of the research; writing the manuscript.
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von Haden, A.C., Eddy, W.C., Burnham, M.B. et al. Root exudation links root traits to soil functioning in agroecosystems. Plant Soil (2024). https://doi.org/10.1007/s11104-024-06491-3
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DOI: https://doi.org/10.1007/s11104-024-06491-3