Growth of barley (Hordeum vulgare L.) roots in biopores with differing carbon and nitrogen contents

Summary

Large sized, vertical biopores can provide preferential pathways for root growth, hence facilitating the exploration of great soil depths by crop roots. This is of particular importance for organic production systems, where crops are more dependent on nutrient acquisition from the solid soil phase than under conditions of mainstream agriculture. The relevance of biopores for nutrient acquisition from the subsoil can possibly depend on their individual properties. The aim of this study was to test how different chemical pore wall properties affect the growth of barley (Hordeum vulgare L.) roots in large sized biopores. Bulk soil, pore wall material and roots from individual biopores were collected from three depth layers in 45-75 cm soil depth. C and N contents in the pore walls were up to 3 times higher than in the bulk soil. A large variation of C and N contents between the walls of individual biopores indicated that the quality of the pore wall is a function of pore colonization by earthworms over time. N-rich pores hosted more roots than N-poor pores. It is concluded that elevated C and N concentrations in pore walls can facilitate the exploration of the subsoil by crop roots.