The influence of soil nitrogen and phosphorus content on biodiversity has been well documented during the last decades. It was shown that low biodiverstity arises when high levels of these nutrients are encountered. Nitrogen is an extremely mobile element in the soil and therefore it won't be a problem unless organic matter content and the rate of mineralization of the soil are high. It is not the case with phosphorus that can still be available for organisms several years after the soil enrichment. Iron oxides are well know for their role in phosphate adsorption in soils and are naturally present into them but only in small amounts. In order to reduce the available phosphorus of soil to a level compatible with high biodiversity the use of synthetic and potentially extremely reactive iron oxides is investigated.