Molybdenum uptake by beets in Dutch soils

In the Netherlands a soil may induce Mo-deficiency symptoms in beet if it contains more than 1 or 2% iron; whether such deficiency did occur depended primarily on pH, but particle size and kind of iron also played a role: αFe _{<font size="-1">2</font>} O _{<font size="-1">3</font>} and αFeOOH sharply reduced Mo content of the plant; γFe _{<font size="-1">2</font>} O _{<font size="-1">3</font>} had only little effect. When no molybdenum was supplied, three groups of soils could be distinguished by the interaction Mo X P: soils where P almost completely prevented Mo deficiency; soils where P aggravated deficiency; and soils where P dressing hardly affected response to Mo. Steaming soils influenced Mo content of the plant. The effect of adding Mo differed when it was supplied before from when it was supplied after steaming. Applying Mo before steaming reduced its availability but after steaming increased it. Application of manganese sulphate reduced Mo content of the plant to a degree depending on the amount of available Mo in soil. Beet could take up Mo as a cation, the cation was less effective within the plant. A scheme summarizes processes affecting the availability of Mo in Dutch soils