Biopores in the subsoil: Formation, nutrient turnover and implications for root growth of field crops

• Applicant: Professor Dr. Ulrich Köpke
• Subject Area: Plant Cultivation, Plant Nutrition, Agricultural Technology ; Soil Sciences
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 259988109

In preliminary studies our working group has shown that after growing fodder crops with taproot systems the density of large sized biopores in the subsoil increased within quite a short period of time. Anecic earthworms did not contribute to primary biopore generation that much, although their abundance was increased by soil rest and crop residues. Stabilizing biopores and influencing their pore wall characteristics are potential effects of earthworm activity that under favorable habitat conditions may take place in the short-term; however this assumption needs further investigation. C and N contents of individual biopores vary largely, presumably as a consequence of the pores genesis and colonization history. Roots of field crops frequently colonize biopores and establish contact with the biopore wall, regardless of the root architecture. However, more research is needed on the question how biopore properties influence root growth. Our new proposal aims to quantify the effects of crop sequences with fodder crops on biopore properties and the performance of subsequent crops. For this purpose we will use previously established field experiments, including the monitoring systems for soil temperature and moisture. Continued investigation will allow understanding the lasting effects generated by fodder cropping. Monitoring three field trials with similar design but established in a series from 2007 to 2012 enables taking into account the effect of different years with different weather conditions. In addition, we aim to quantify the interactions of precipitation, nutrient concentration in the topsoil and biopore systems for nutrient acquisition from the subsoil in subplots with rain shelter and topsoil exchange. Furthermore, we will quantify the properties of walls of biopores with known history (colonization by earthworms vs. colonization by roots) and the effect of earthworm activity on pore wall properties. Harvesting roots and pore wall material from individual biopores combined with in situ-endoscopy will provide new insights about the attractiveness of biopores with different pore wall properties for crop roots. We expect our research to give new insights on how cultivation of crops with taproots and earthworm activity affect biopore density and pore wall properties and which properties are beneficial for allowing crop roots to use biopores as pathways for elongation and hot spots for nutrient acquisition.

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Timo Kautz