Our methodological approach enabled differential cover crop root exudate collection from plants grown in presence of intra- and inter-specific neighbours. Biological tests were performed using root exudates of cover crops growing alone (BO-0 and BK-0) and in presence of P (BO-P and BK-P). P seeds treated with BO-P root exudates had significantly shorter seedling root length in comparison to seedlings treated with BO-0 root exudates. While performing biological tests in dark conditions resulted in elevated root growth suppression with BO root exudates, no difference was observed with BK root exudates. Presence neighbouring BK significantly changed the number of root tips and forks in BK and presence of P significantly changed the number of root forks in BK. No significant difference was observed in root tips and forks of BO. Average normalized cumulative total ion volume per number of tips were higher in presence of neighbours, the effect was more visible in BO than BK. BO = black oat, BK = buckwheat, P = pigweed