Application of Fertilizers

The primary goal is to have sufficient magnesium, relative to other nutrients, readily available for plant uptake throughout crop development. The type and rate of magnesium to apply depends upon the crop, soil type, and method of production (field, container, or hydroponics). If plants are grown hydroponically, a completely soluble form of magnesium would be required. For container-grown nursery crops, Whitcomb (119,120) suggested injecting dissolved Epsom salts (magnesium sulfate) into irrigation water at a rate to produce a calcium/magnesium ratio from 1:1 up to 5:1. In preliminary studies with juniper (Juniperus spp. L.), increased vegetative growth occurred when magnesium was supplied by applications of magnesium sulfate in the irrigation water versus equivalent magnesium applications through the incorporation of fine dolomitic lime into the planting media (119-121). Obatolu (226) reported that magnesium deficiency resulted in a loss of yield and quality of tea (Camellia sinensis O. Kuntze) in Nigerian plantations. A spray of 30% magnesium oxide corrected magnesium deficiency within 14 days and increased growth from 16 to 134%. Two applications of a 20% solution were required to correct deficiencies. A second application of the 30% solution was toxic to the tea plants.