Building soil sustainability from root–soil interface traits

Root hairs and rhizodeposits are root traits that vary between plant species and crop genotypes and have a large impact on both plants and soils. Targeting these traits may benefit both plants and soil, improving food and environmental security at the same time. Soils may store more carbon (greenhouse gas mitigation), trap more water (drought tolerance) and nutrients, and resist erosion. From limited research, rhizosheath size has been maintained or improved in modern crop varieties, but potential exists to increase it further. Whether this will lead to improved yield or soil properties, however, requires greater field testing to verify. Laboratory and glasshouse research using root trait ideotypes has found marked impacts on soil biophysical properties. Rhizodeposits vary in behaviour between species from hydrogels to surfactants, and as soil dispersers (miners) or aggregators (builders). Great potential exists to harness plant traits at the root–soil interface, mainly rhizodeposition and root hairs, to ‘build’ soils with better structure that can trap more carbon and resources, resist climate stresses, and promote a healthy microbiome. These traits appear to have been preserved in modern crop varieties, but scope exists to improve them further because they vary considerably between genotypes and respond to environmental conditions. From emerging evidence, rhizodeposition can act as a disperser, aggregator, and/or hydrogel in soil, and root hairs expand rhizosheath size. Future research should explore impacts of selecting these traits on plants and soils concurrently, expanding from model plants to commercial genotypes, and observing whether impacts currently limited to glasshouse studies occur in the field. Great potential exists to harness plant traits at the root–soil interface, mainly rhizodeposition and root hairs, to ‘build’ soils with better structure that can trap more carbon and resources, resist climate stresses, and promote a healthy microbiome. These traits appear to have been preserved in modern crop varieties, but scope exists to improve them further because they vary considerably between genotypes and respond to environmental conditions. From emerging evidence, rhizodeposition can act as a disperser, aggregator, and/or hydrogel in soil, and root hairs expand rhizosheath size. Future research should explore impacts of selecting these traits on plants and soils concurrently, expanding from model plants to commercial genotypes, and observing whether impacts currently limited to glasshouse studies occur in the field. fragmentation and aggregation of soil through the action of plant roots, soil fauna, and micro-organisms. substances secreted by roots, composed of a mix of sugars, amino acids, organic acids, and other organic substances. discrete spatial regions in soil where biological compounds alter water holding and transport properties. polysaccharide-rich compounds secreted at the root tip that are viscous. genes that influence specific traits. collective term for all materials exchanged from the plant to soil, dominated by exudates, mucilages, and sloughed cells. soil that adheres strongly to the root through the action of root hairs and rhizodeposits. It provides a rapid and easy approach to sample soil affected by plant roots. soil at the interface of plant roots that has been influenced by rhizodeposits. All resources capture by a plant from soil enters through the rhizosphere. It generally has greater carbon, biological activity, and stability than surrounding soil. single-cell outgrowths from the root epidermis that increase root surface area and soil exploration. the spatial arrangement of soil particles and pores, driven primarily by aggregation and dispersion from roots and soil biology.