All twenty one nutrients required by the plant, including macronutrients (nitrogen, phosphorus, potassium), micronutrients (boron, zinc, molybdenum, manganese, copper, iron), and secondary nutrients (calcium, magnesium, sulfur), must be in balance in order for the plant to maintain its utmost health to defend against unfavourable environmental conditions. A proper soil and tissue sampling program is key tool in managing plant nutrition. Micronutrient deficiencies are likely when one of the following conditions apply:
- Removal of large amounts by high yielding crops
- Leaching from sandy soils
- Naturally high pH soils
- Over-limed soils resulting in a high pH
- Land leveling
- Additions of high rates of phosphorus
- Soil compaction
- Cool, wet growing conditions
- Tie-up by the soil
- Use of sensitive crop varieties