This fine 325 mesh 95% Gypsum contains 23% Calcium and 18.5% Sulfur. Apply through irrigation systems and sprayers. May be used as a side dressing around established crops or added to soil & soilless mixes. Use rates can vary from 25 - 100 lbs per acre. General foliage spray rates are from 1-10 lbs per acre. For greenhouse foliar applications, use 1 tsp - 2 tablespoons per gallon of water.