Magnesium Sulphate in Agriculture: Why Growers Use It

Magnesium sulphate is one of the most widely used secondary-nutrient fertilizers because it supplies two nutrients in a single, fully water-soluble product: magnesium and sulphur.

What magnesium does in the plant

Magnesium sits at the centre of the chlorophyll molecule, so it is essential for photosynthesis. It also activates many enzymes and helps move sugars from leaves to fruit, tubers and grain. When magnesium is short, plants cannot make full use of the light and nitrogen they receive.

What sulphur does

Sulphur is a building block of proteins and is needed for oil formation in oilseeds. Sulphur deficiency has become more common as cleaner fuels have reduced atmospheric sulphur deposition and as high-analysis fertilizers carry less incidental sulphur.

Crops that respond well

Responses are commonly reported in citrus, bananas, potatoes, tomatoes and other vegetables, tea, coffee, oil palm, sugarcane and many fruit trees. Sandy, acidic or heavily leached soils, and soils high in potassium, are most likely to be short of magnesium.

How it is applied

• Soil application — broadcast or banded, often blended with other fertilizers. Monohydrate is common here.
• Fertigation — dissolved into drip or sprinkler systems. Heptahydrate is preferred for its fast solubility.
• Foliar spray — a quick correction of visible deficiency during the season.

Application rates depend on crop, soil test results and local recommendations, so growers should follow agronomic advice for their conditions.

Why buyers specify it carefully

For drip systems, insoluble matter must be low to avoid clogging emitters. For blending, crystal size should match the other granules to prevent segregation. Tell us how your customers apply it and we will match the form and crystal size.