... are calcium, sulfur, magnesium, and other elements are boron, manganese, iron, zinc, copper and molybdenum. Fertilizers enhance the natural ... , is made from plant materials mixed with manure and some soil. Green manure is a herbaceous plant material ... phosphorus and potassium (N, P and K) for various crops and growing conditions. N (nitrogen) promotes leaf growth and forms proteins and chlorophyll. ...