Micro-mining of soil phosphorus by means of root-exudate induced rhizobacteria

Phosphorus availability to plants can be limited due to its high sorption to soil particles. Many fields have accumulated large fertilizer-phosphorus reserves (legacy P) during decades of agriculture. Aim of this work is to study how phosphorus-mining bacteria and thus phosphorus utility from field reserves is affected by mixed cropping of special crops and their root exudates. Faba bean, buckwheat, camelina and yellow mustard are cultivated mixed with oats in settings where their growth parameters are measured, and root exudates sampled. Hypothesis is that the crop mixtures produce various exudates, in response to P-availability, which enhance enrichment of beneficial microbes and phosphorus mining. Plant-growth-promoting properties of the bacteria are tested on the crops in laboratory setting. The work is done in Natural Resources Institute (Luke) in Jokioinen, in collaboration with French National Research Institute for Agriculture, Food and Environment (INRAE) in France.