When crops are harvested, the nutrients follow the crop.
In nature there are 17 critical plant nutrients: The macronutrients nitrogen, phosphorus, potassium, calcium, sulphur, magnesium, oxygen, hydrogen, carbon, and the micronutrients iron, boron, chlorine, manganese, zinc, copper, molybdenum and nickel.
All the nutrients contained in different fertilizers are found in nature. The most common sources of nutrients in mineral fertilizers are nitrogen, potassium and phosphate.
Source: Yara International