Magnesium Sulphate salt for outdoor and glasshouse fertigation programmes - A foliar fertiliser for application to crops to help overcome magnesium deficiencies - Applications may be useful when conditions are very wet or cool where QuickTest Mg levels are less than 8-12 - MGSO4 is a cost-effective way of supplying magnesium via fertigation programmes. As a foliar application to broadacre crops it will provide a temporary relief of magnesium deficiency symptoms.