RHP
The various roles and effects of magnesium in cultivation
What is the function of magnesium?
Magnesium is absorbed by the plant roots as magnesium ion (Mg2 +) and is mobile inside the plant. Magnesium is an important building block of the green leaf color of plants (the chlorophyll). This is in the green leaf granules, the so-called chloroplasts. Magnesium is also indispensable for the enzyme in the plant that ensures that proteins can be formed from amino acids. In the dry matter, the magnesium content varies from 0.1 to 3 percent.
In what forms does magnesium occur?
Most potting soil fertilizers contain a small amount of magnesium. Like calcium and the other cations, magnesium is also bound to the adsorption complex. The extent to which this happens with magnesium is significantly less than with calcium. In potting soil, the level of soluble magnesium is determined by the amount of metered fertilizer. The supply of magnesium comes mainly from the lime if it contains magnesium. In unprocessed coconut dust, magnesium is adsorbed along with calcium, making it poorly available to the plant without further fertilization. Coconut products (raw materials) under the RHP quality mark must be processed in order to obtain a good nutritional balance.
What is the effect of magnesium?
In the past, magnesium deficiency regularly occurred in crops. Especially tomatoes that were cultivated in open soil were affected. Due to a shortage of magnesium, the leaf between the veins (through degradation of leaf green) turns yellow-green to yellow, while the veins themselves remain green. This phenomenon is called chlorosis and, in the case of a magnesium deficiency, is mainly expressed in the oldest leaf. A magnesium deficiency manifests itself in monocots in a spotty appearance (tiger ring). The absorption of magnesium is hampered by a low temperature of the growth medium and by a high potassium concentration. Magnesium excess manifests itself as salt damage, but this is rare.
Magnesium deficiency in tomato and Cordyline
What is the RHP standard for magnesium?
Magnesium is contained in most potting soil fertilizers, but mainly comes from the lime if it contains magnesium. RHP-certified products are checked for application in a substrate for the magnesium content. Lime is a mineral and is also checked for contamination with trace elements. For substrates with the RHP Horticulture quality mark, the substrate producer and grower determine together what the magnesium content should be, fitting with the cultivation.
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