Select Mag S
  • Advantages
  • Description
  • Directions for use
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  • Select Mag S is one of the magnesium-richest, fully-soluble and non-chloride fertilizers. It is made up of plant nutrients exclusively, 16% of magnesium, in the form of MgO, equivalent to 9.6% Mg, and 32% of sulphite (SO3), equivalent to 12.8% S.
  • Select Mag S has a considerable solubility of 337 g/L of water at 200C.
  • Select Mag S can be applied by fertigation with practically all other soluble fertilizers, but when concentrated stock solutions are prepared, it should not be dissolved with fertilizers containing phosphates, e.g. MAP, MKP, urea-phosphate or phosphoric acid, nor with calcium fertilizers. Its combination with potassic fertilizers is limited too. Therefore, it should be dissolved in a separate dissolving tank, e.g. the tank used for adding the acids or the trace elements.
  • Select Mag S can be bulk-blended with other specialty-, or commodity- fertilizers, to enrich them with magnesium and sulfur nutrients.
  • Select Mag S is considerably less expensive than magnesium-nitrate products.

Select Mag S is ideal for use in fertigation and foliar feeding schemes of all crops, and can be equally successfully used for field crops, orchards, flower crops and protected crops in tunnels or greenhouses. It has a relatively low salt-index of ~50. Select Mag S has a chemical formula of MgSO4 x 7H2O and a molecular weight of 246,5.

Magnesium has many functions in the plant. It is a central structural component of the green chlorophyll molecule, which is responsible for capturing light energy and using it to split the water molecule into its hydrogen and oxygen parts. It is an activator of several enzymes, and specifically required, by a large number of enzymes involved in phosphate transfer. Mg is also related to stimulation of P uptake.

Product benefits:

  • Select Mag S is an excellent source of magnesium for plants. Magnesium is the central atom in the chlorophyll molecule, see figure. Therefore, suboptimal availability of magnesium to the crop reduces the photosynthetic capacity of the plants, and hence, their agronomic performances will be impaired. 
  • Select Mag S is practically free of chloride, fluoride, sodium, heavy-metals, and other harmful elements for plants and people.
  • Select Mag S produces neutral solutions, e.g. a 5% w/w concentration solution has a pH=7.2, so, when slightly acidified it promotes its fast absorption in the foliage of the sprayed target crops. Also, when applied by fertigation, it can be slightly acidified to help maintaining optimal environment for chelated trace elements that are tank-mixed with the Select Mag S.
  • As opposed to other magnesium carriers that contain nitrogen, Select Mag S does not contain this element, and is an excellent magnesium product for correcting magnesium deficiency when nitrogen application can be unfavorable, such as during fruit bulking-up and maturation.
  • Select Mag S is optimal for hydroponics growth systems because it does not contain ammoniacal nitrogen.
  • Select Mag S is an excellent magnesium carrier for soil applications, because it will release its nutritional ingredients for an extended period of time.
Directions for use

Select Mag S is recommended as a magnesium and sulphur carrier in many field crops and plantations, such as cereals, oil-seed rape, potatoes, sugar-beets, asparagus, hops and Christmas trees. It can be applied by soil application, fertigation and foliar feeding. Application rates by fertigation are 50-200 kg/hectare. Application rates by foliar feeding are around 3-8 kg/hectare/application, at 2-3 split applications of 1-1.5%, depending on the application rate of the solution, and on crop's development stage.
Contact Everris or your professional advisor for specific advice and recommendations.

Select Mag S is a fully soluble fertilizer, formulated as free-flowing whitish crystals. It is highly beneficial in preventing and correcting magnesium (Mg) deficiencies in crops, and in growth stages, when the crops require high Mg rates.