Marl refers to a type of muddy or clayey soil that is formed from limestone or other calcareous rocks. It contains calcium carbonate and can be found in various parts of the world, including Europe, North America, South America, Africa, Asia, and Australia. Marl is often used as a fertilizer due to its high nutrient content, which includes nitrogen, phosphorus, potassium, magnesium, calcium, and sulfur. In addition, marl can also be used for soil conditioning, horticulture, and as a component in cement production.