Biopore characterization with in situ endoscopy: Influence of earthworms on carbon and nitrogen contents

Summary

Biopores have been shown to be enriched with plant available nutrients as compared to the surrounding bulk soil and therefore are considered hot spots for the nutrient acquisition especially in the otherwise nutrient-poor subsoil. However, depending on their individual biography, i.e. colonization by plant roots or earthworms, different nutrient status can be assumed. In this study, individual biopores were characterized with respect to signs of earthworm passage using in situ endoscopy, a non-destructive technique for display of pore wall characteristics. Subsequent sampling and analysis of biopore linings and blockages revealed that only biopores with visible earthworm coatings had significantly higher C and N contents as compared to the surrounding bulk soil. The results of this study highlight the special role of earthworms for enriching biopores with nutrients and underline the value of biopores for the nutrient acquisition from the subsoil.