Total iron as a useful index of the Fe‐status of crops

Abstract

Although the total Fe‐concent is sometimes a misleading index of the Fe‐status of crops, it would be nevertheless a desirable one, since it is obtained anyhow in the usual plant analysis. It can be shown for cereals and oilseed rape that the total Fe‐content provides an equivalent good information compared with several extractions of ‘active’ Fe, provided that the plants are carefully cleaned from dust. However, the ‘active’ Fe (obtained with chelates or weak organic acids) has the advantage that even samples of a doubtful degree of cleanliness can be evaluated.

Major field crops of Northern Germany seem to be well supplied with iron which is therefore apparently no minimum factor even under high yield conditions, since the contents are generally above the optimum nutrient level, i.e. 40 ppm of total Fe in dry matter of young oat plants or 50 ppm Fe in young oilseed rape leaves.

Key words:

• Fe‐status
• total Fe
• active Fe
• oats
• rape