Soil Nutrient management
Micronutrients
Molybdenum
In soil solution, molybdenum may exist in several forms depending on the pH. At pH >5.0, molybdenum exists primarily as molybdate ion (MoO42¯), which is the available form for plants, but at a lower pH the hydrogen molybdate (HMoO4¯) and molybdic acid (H2MoO4) forms dominate.
Since adequate molybdenum is essential for proper nitrogen metabolism, deficiencies commonly appear as stunted plants and failure of leaves to develop a dark green color. In more severe deficiencies, the leaves may develop a pale green or yellow area around the edges and between the veins.
Molybdenum toxicity in plants seldom occurs under field conditions. However, because molybdenum availability is high under alkaline conditions, molybdenum toxicity may be a problem in some arid climates.
In acid soils, molybdate anions are subject to adsorption processes on clays, metal oxides of iron, aluminum, and manganese as well as organic compounds and carbonates. Unlike most other micronutrients, molybdenum availability increases with increasing soil pH.
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