Phosphorus deficiency made worse by
- Acidic or very alkaline (calcareaus) soils
 - Low organic matter
 - Cold or wet conditions
 - Crops with a poorly developed root system
 - Soils with low P reserves
 - Soils with a high phosphate capacity
 - Iron rich soils
 
Phosphorus is important for
- Part of nucleic acids, phospholipids and energy storing and transferring systems in plants
 - Important for root growth, flower development and fruit set