• Molybdenum (Mo)
    4294.95
    Mo
  • Ionic form
    Molybdenum (Mo) ionic formula image
  • Anion/Cation
    MoO42-
  • Molybdenum (Mo) influance image
    Leaf
  • Molybdenum (Mo) origin image
    Origine: Volcanic
  • Molybdenum (Mo) mobility image
    15mm around the root

Molybdenum

(Mo)

The availability of molybdenum differs from other trace elements in relation to soil pH. It is not available in acidic soil but becomes very soluble and can be mobilised in alkaline soil. The required quantities are very low and precision and moderation is needed when applying.

Mo
Plant
Plant
Soil
Soil
Crops
Crops
Origin
Origin
Keys
Keys
IMPORTANCE FOR THE PLANT
Molybdenum is involved mainly in enzymatic mechanisms related to the assimilation of nitrogen (nitrogenase and nitrate reductase).
ABSORPTION MECHANISMS
Molybdenum is absorbed via the soil solution as anion.
INTERACTIONS AND SPECIAL FEATURES
Molybdenum works well together with phosphorus. Sulphur has an acidifying effect in the soil which impedes the availability of Mo.

Unlike other trace elements, molybdenum is strongly bound to iron and therefore unavailable in acidic soils. As pH rises, molybdenum becomes mobile and its availability increases significantly. Fresh organic matter ensures a good supply of Mo. This is not the case for peat, which develops under acidic conditions. The graph shows the different forms of Mo depending on the pH value of the soil. It shows that the MoO42- content (the form which is taken up by plants) increases significantly as pH rises.

Molybdenum (Mo) related desktop image Molybdenum (Mo) related tablet image Molybdenum (Mo) related mobile image
SOIL ANALYSIS
Molybdenum is extracted specifically with oxalate. A soil analysis for Mo is not common but can be done upon request.

Sensitivity table

Sensitivity meter:
  • nutrient very sensible icon

    Very

  • nutrient very fairly icon

    Fairly

  • nutrient very moderately icon

    Moderately

Mo
Cabbage
Lettuce
Spring Barley
Sugar Beet
Tomato
Winter Barley
Winter Rapeseed
Cherries
Carrot
Cucumber
Apple
Grape Vine
Pear
Grain Maize
Silage Maize
Potatoes
Strawberry
Tomato
Fiber Flax
Sunflower
Winter Wheat

Sensibility table & Symptomes

Mo deficiency is often linked to nitrogen deficiency in legumes. Since Mo is necessary for the activity of nitrogenase and the fixation of N2, an N-deficiency can be observed. On crucifers, interveinal chlorotic plaques appear on the leaves, with a greyish colour and a soft consistency. In the most severe cases, the leaves of the plants are completely deformed.

Excess & Needs

Excess molybdenum blocks copper and may induce deficiencies in cereals and fodder grasses. Acidophilic crops, such as rubber, are sensitive to any excess of molybdenum.

SOIL CONTENT
Mo soil analyses are not routinely performed. Soils poor in Mo and rich in iron are prone to Mn deficiency.
ORGANIC MATTER CONTENT
A high organic matter content in low pH conditions may reduce the risk of deficiency. Regular inputs of organic matter can provide soluble Mo for crops. A high organic matter content in low pH conditions may reduce the risk of deficiency. Regular inputs of organic matter can provide soluble Mo for crops. Conversely, peat input creates a retention of Mo on humic acids.
CLIMATE
High temperatures above 25°C increase Mo solubility in soils. Dry conditions, on the other hand, cause deficiencies in Mo.
pH
This is the most important factor for the absorption of Mo by plants. At high pH, Mo is very mobile.
INTERACTION WITH OTHER ELEMENTS
Phosphorus facilitates the absorption and transport of molybdenum. This positive interaction is found when Mo is combined with P. High levels of iron are limiting the assimilability of Mo. An excess of copper as well as inputs of Cu decrease the absorption of Mo. An excess of manganese has the same effect.

The soil content varies greatly depending on the source rock, the iron content and the level of acidity. In general, assimilable Mo is higher in alkaline soils, soils rich in organic matter and young soils derived from volcanic rocks, whereas soils rich in iron have low Mo contents.