Crops need nutrients just like people do. A fertile soil will contain all the major nutrients for basic plant nutrition (e.g., nitrogen, phosphorus, and potassium), as well as other nutrients needed in smaller quantities (e.g., calcium, magnesium, sulfur, iron, zinc, copper, boron, molybdenum, nickel). Usually a fertile soil will also have some organic matter that improves soil structure, soil moisture retention, and also nutrient retention, and a pH between 6 and 7. Unfortunately, many soils do not have adequate levels of all the necessary plant nutrients, or conditions in the soil are unfavorable for plant uptake of certain nutrients.
