Root-soil interactions in biopores and their role in climate adaptation of cropping systems

The subsoil contains valuable nutrient and water resources for crop production, but high penetration resistance impedes root growth and therefore resource access. Large-sized biopores formed by deep-rooting perennial taprooted crop species such as chicory and lucerne can provide pathways through compacted subsoil layers. Different field and mesocosm experiments have shown that colonization by anecic earthworms modifies physical and biochemical properties of biopore networks and pore walls, further increasing attractivity of biopores for crop roots. The intensity of biopore exploration by crop roots and resulting nitrogen uptake from biopore walls as assessed with a combination of classical root-length density determination, in-situ endoscopy and 15N-labelling varies across different crop species and seems to be largely determined by root architecture. Long-term field observations show that benefits of precrops forming large-sized biopores for following crops in terms of water and nutrient uptake as well as grain yield generally in dry years and particularly pronounced for spring-sown cereals.