Translations:AY Honors/Agriculture/Answer Key/70/en

Fertilizers can be divided into macronutrients or micronutrients based on their concentrations in plant dry matter. There are six macronutrients: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Nitrogen, phosphorus, and potassium are often termed "primary macronutrients" because their availability is usually managed with NPK fertilizers. The "secondary macronutrients" — calcium, magnesium, and sulfur are required in roughly similar quantities, but their availability is often managed as part of liming and manuring practices rather than fertilizers. The macronutrients are consumed in larger quantities and normally present as a whole number or tenths of percentages in plant tissues (on a dry matter weight basis). There are many micronutrients (such as boron, chlorine, manganese, iron, zinc, copper, and molybdenum), required in concentrations ranging from 5 to 100 parts per million (ppm) by mass.