Maximo 363 Maxi-Granule Zinc Sulfate Fertilizer 50 pound bag AGRICULTURE Zinc is an excellent fertilizer for various crops where the soil presents Zinc deficiency. The presence of Zinc is critical to the production of growth hormones and chlorophyll, for the respiration process and for the synthesis of carbohydrates. Zinc is essential for the life of plants. Zinc sulfate is 100% water soluble and is used to correct zinc deficiencies in soil. It can be applied as fertilizer in granular form directly to the soil and in powder form for foliar and hydroponic applications.