Mechanistic modelling of the rhizosphere across scales

The rhizosphere, or the soil directly influenced by plant roots, is a complex and dynamic environment shaped by both plant and soil processes. Plant processes include root growth, rhizodeposition, root water and nutrient uptake or signalling; soil processes include water flow, reactive transport, organic matter decomposition or soil microbe and fauna-related processes. In this contribution, we focus on the soil-related aspects of modelling the interactions within the rhizosphere and how these interactions lead to the emergence of specific properties. Factors such as radial transport, root growth, and diurnal variation all play a role in the formation of patterns within the rhizosphere. However, modelling these processes is challenging due to their interconnected nature and the fact that they occur on multiple temporal and spatial scales. Recent research by Vetterlein et al. (2020) and Schnepf et al. (2022) have addressed these challenges and advances in our understanding of modelling the rhizosphere. For example can the effect of root elongation rate on the radial extension of the rhizosphere be quantified by means of the rhizosphere Péclet number, a dimensionless number that compares the importance of diffusive transport relative to root elongation rate. New findings of Kuppe et al. (2022), who have organized rhizosphere models within a collective framework that allows for the incorporation of microorganisms and their activity and motility, and Deckmyn et al. (2020), who combined soil carbon and food web ecosystem models, will further enhance a mechanistic description of the rhizosphere Deckmyn G, Flores O, Mayer M, Domene X, Schnepf A, Kuka K, Van Looy K, Rasse DP, Briones MJI, Barot S, Berg M, Vanguelova E, Ostonen I, Vereecken H, Suz LM, Frey B, Frossard A, Tiunov A, Frouz J, Grebenc T, Öpik M, Javaux M, Uvarov A, Vinduskova O, Henning Krogh P, Franklin O, Jiménez J, Curiel Yuste J. 2020. KEYLINK: towards a more integrative soil representation for inclusion in ecosystem scale models. I. review and model concept. PeerJ 8:e9750 DOI 10.7717/peerj.9750Kuppe CW, Schnepf A, von Lieres E, Watt M, Postma JA (2022) Rhizosphere models: their concepts and application to plant-soil ecosystems. Plant Soil 474, 17–55. doi: 10.1007/s11104-021-05201-7Schnepf A, Carminati A, Ahmed MA, Ani M, Benard P, Bentz J, Bonkowski M, Knott M, Diehl D, Duddek P, Kröner E, Javaux M, Landl M, Lehndorff E, Lippold E, Lieu A, Mueller CW, Oburger E, Otten W, Portell X, Phalempin M, Prechtel A, Schulz R, Vanderborght J, Vetterlein D (2022) Linking rhizosphere processes across scales: Opinion. Plant and Soil 478: 5-42. doi: 10.1007/s11104-022-05306-7.Vetterlein D, Carminati A, Kögel-Knabner I, Bienert GP, Smalla K, Oburger E, Schnepf A, Banitz T, Tarkka MT, Schlüter S (2020) Rhizosphere Spatiotemporal Organization–A Key to Rhizosphere Functions. Frontiers in Agronomy 2. doi: 10.3389/fagro.2020.00008.