PO 1 and PO 2. List the 18 elements essential for plant nutrition, and classify the essential elements as macronutrients or micronutrients.

Plants require eighteen elements found in nature to properly grow and develop.  Some of these elements are utilized within the physical plant structure, namely carbon (C), hydrogen (H), and oxygen (O).  These elements, obtained from the air (CO₂) and water (H₂O), are the basis for carbohydrates such as sugars and starch, which provide the strength of cell walls, stems, and leaves, and are also sources of energy for the plant and organisms that consume the plant.

Elements used in large quantities by the plant are termed macronutrients, which can be further defined as primary or secondary.  The primary nutrients include nitrogen (N), phosphorus (P), and potassium (K).  These elements contribute to plant nutrient content, function of plant enzymes and biochemical processes, and integrity of plant cells.  Deficiency of these nutrients contributes to reduced plant growth, health, and yield; thus they are the three most important nutrients supplied by fertilizers.  The secondary nutrients include calcium (Ca), magnesium (Mg), and sulfur (S).

The final essential elements are used in small quantities by the plant, but nevertheless are necessary for plant survival.  These micronutrients include iron (Fe), boron (B), copper (Cu), chlorine (Cl), Manganese (Mn), molybdenum (Mo), zinc (Zn), cobalt (Co), and nickel (Ni).

The table on the next page lists the essential elements, their status as macro- or micronutrients, their uptake forms, and their plant mobility.