A unique 3-in-1 combination of potassium, magnesium and sulfur - Langbeinite is a naturally occurring source of these three vital plant nutrients. Potassium is essential for high quality fruit. Magnesium is required for the synthesis of chlorophyll. Sulfur is needed for enzyme activation. Ideal to use on sensitive vegetables and fruit crops that require high fertilization rates but do not tolerate high levels of chlorine or soluble salts. OMRI listed for organic use. Comes in a compostable box.