Although foliar applications are possible, we have had maximum success using soil drenches. 3-4 oz per 100 gallons is generally enough to solve iron related deficiencies in herbaceous crops. Apply as a normal irrigation to plants not under water stress. Magnesium supplements - magnesium is a mobile element, therefore deficiency symptoms appear first on the lower leaves. Watch for intervienal chlorosis starting with the lowest leaves.
Epsom salts is an inexpensive and safe way to supplement magnesium.
Soil drench applications of 8 oz per 100 gallons supply ample amounts of water-soluble magnesium. This can be repeated as needed without risk of burning. Griffin provides water tests free of charge to our customers to help match up fertilizer and acid injection programs with the crops you are growing. Soil pH is critical to the availability of micronutrients, making it well worth your while to monitor and adjust this parameter as needed. Lowering soil pH is usually best accomplished by injecting sulfuric acid through your irrigation water.