It is known that intensive land use in agriculture causes acidification of soils due to harvest or leaching of cations. Wood ash is recommended instead of lime for improving acidic soils. The main objective of this study was to test the potential of wood ash to feed back the cations into the soils without risk of toxicity, and to examine the impact of bio fertilizer Phylazonit MC®. Corn (Zea mays L.) and cucumber (Cucumis sativus L.) seeds were grown in nutrient solution under controlled environmental conditions. The elements content was measured with ICP. The release of organic acids was examined by the root-disc-method and the amounts of organic acids were measured with HPLC. The use of living bacteria (bio-fertilizer Phylazonit MC) accelerates mineralization of organic residues in soil, therefore makes the nutrients more available. At the same time due to effect of living bacteria from bio-fertilizer, the uptake of heavy metals decreases. An application of Phylazonit was offered under heavy metal contaminated circumstances. According to our experiments bio fertilizers and wood ash can be effective tools in organic agriculture.