• Manganese (Mn)
    2554.938
    Mn
  • Forme ionique
    Manganese (Mn) ionic formula image
  • Anion/Cation
    Mn2+
  • Manganese (Mn) influance image
    Leaf
  • Manganese (Mn) origin image
    Origine: Volcanic
  • Manganese (Mn) mobility image
    4-6mm around the root

Manganese

(Mn)

This trace element is worth knowing, both for its performance and for the way it works. Unlike other elements, under optimal growth conditions , manganese becomes involved in crop growth with negative effects. In properly aerated and drained soils, and during growth, it temporarily switches to a less available form, at the very moment when plants need it the most. It is therefore important to consider “soil-climate” interactions, in order to assess the deficiency risk and to interfere, essentially with foliar application, to support the crop and alleviate the critical phase.
Mn
Plante
Plante
Sol
Sol
Culture
Culture
Origine
Origine
Clés
Clés
METABOLISM:
Manganese is involved in the reduction of nitrates and the synthesis of amino acids for building up proteins. A deficiency always leads to growth disruption, in this case to a lack of dry matter, and therefore to a loss of yield. In enzymes, it plays an essential role in the synthesis of chlorophyll, which explains why chlorosis can develop between the veins of young leaves when a deficiency occurs. During the full vegetative development manganese, together with nitrogen and magnesium, can be a determining factor in the success of most crops.
ABSORPTION MECHANISMS:
Manganese is absorbed by plants in the manganous state (Mn 2+ ).. In the presence of oxygen, it passes to the manganic state Mn 3+ ; it no longer solubilises and becomes unavailable. This is a reversible reaction, under the effect of rain or compaction. This may sound paradox, but in properly drained and aerated soils, favourable to the soil’s biological activities and the growth of plants, manganese becomes the first limiting factor.
INTERACTIONS, SPECIFICITY:
Soil applications are useless since it is the soil and climate conditions that determine manganese availability. It is therefore necessary to intervene by foliar application, while fractioning the applications as much as possible.
Soils with a high granite and sandstone content are naturally poorer than volcanic or sedimentary soils. High organic matter content lightens the structure and negatively affects the solubility of manganese. Liming has the same effect. Finally, dry weather is not conducive to the presence of absorbable manganese. In damp soils, possibly soaked in water during the winter months, manganese is identified by bluish gley stains, signalling this temporary clogging phenomenon.
LE MANGANÈSE DANS LE SOL PEUT SE RETROUVER SOUS DIFFÉRENTES FORMES :

- The oxidised, trivalent or tetravalent forms, which are very hard to assimilate, are the most important: Mn 3+ and Mn 4+

- The divalent Mn 2+ form, which can be assimilated by crops, is absorbed in clay minerals and in organic matter, and is also contained in the soil solution.

Tableau de sensibilité

Echelle de sensibilité:
  • nutrient very sensible icon

    Hautement

  • nutrient very fairly icon

    Moyennement

  • nutrient very moderately icon

    Modérément

Mn
Orge de printemps
Orge d
Betterave sucrière
Pomme
Vignes
Concombre
Lettue
Pomme de terre
Blé d
Carotte
Poire
Cerise et cerise acide
Fraise
Tomate
Lin Fibre
Colza d
Chou
Maïs grain
Maïs ensilage
Tournesol

Tableau sensibilités & Symptômes

Sur céréales, les plantes atteintes de carences en Manganèse sont généralement réparties en foyer irréguliers dans la parcelle. Les zones où le sol est soufflé sont les plus atteintes, les symptômes sont visibles à côtés des passages de roues du tracteur. La différence de couleur se voit aisément, les passages de roues sont verts foncés tandis que les abords sont vert clairs. En vigne par exemple, la carence se caractérise par une chlorose internervaire.

Les cultures de blé sur blé sont particulièrement sensibles. Un apport en manganèse préventif est souvent nécessaire.

Excès & Besoins

L’excès de manganèse au sol peut être préjudiciable aux cultures en cas de sol humide, de temps pluvieux, de milieu anaérobie.

To meet the goal of absorption through foliar application, the use of sulphates, or better still of oxides, nitrates and carbonates is quite adequate. Generally, manganese penetrates into the leaves in a few days, which ensures nutrient complementation that can be renewed several times during the vegetative growth phase. The choice of formulations aims to maintain the efficiency of foliar applications over a sufficiently long period, in order to limit the number of applications.
SOIL CONTENT:
Although most of the manganese present in soils is in the form of oxides, the manganese analysis through an EDTA or DTPA extractive is a good indicator for the potential of absorbable manganese.
ORGANIC MATTER CONTENT:
High organic matter content causes a blockage of the manganese by the formation of a manganese/organic matter complex.
TEXTURE:
Light sandy textures are subject to constant aeration, which causes manganese oxidation. Surface clay and limestone, in addition to their filtering effect contain a quantity of calcium, which can cause a manganese blockage.
CLIMATE:
Climate has a strong influence on the availability of Mn 2+. The deficiency worsens under cold and damp conditions. Low soil temperatures further compound the phenomenon. It has been observed that under conditions of strong luminosity, the manganese demand of the crop is reduced. Finally, in favourable growth, aeration, and damp conditions, the manganese is oxidised and no longer absorbable.
pH:
The pH value strongly determines the availability of manganese. At pH<6 the risk of manganese deficiency is low, but the amount of Mn 2+ in absorbable form decreases by 100 times when the pH-value rises by one unit. At pH 7 and above, the trivalent forms represent the majority, and the risk of deficiency is elevated. However, in very acid and manganese-rich soils, the element can become toxic. Frequent liming causes a blockage of manganese, due to the rapid pH increase.