Iron is an essential trace element for plant organisms. It has an influence on photosynthesis and the formation of chlorophyll and carbohydrates. Iron overload can lead to iron toxicity. Iron is present at normal pH values in the form of Fe(OH)3 in soils. When the oxygen content in the soil is low, iron (III) is reduced to iron (II) and thereby converted into a soluble form available to plants. However, an excess of iron can damage plants under anaerobic conditions. One possible reason for this is soil compaction - a phenomenon that can particularly be observed in rice-growing areas.