Nutrients and timing

Nitrogen - tends not to accumulate in plants and so needs to be supplied constantly. Ideally, nitrogen application rates should be matched to the growth stage of the crop.
Phosphorus – phosphate fertilisers should be broadcast and incorporated before planting, except on Bassendean sands where phosphorus may leach.
Potassium - to promote optimum early growth, sufficient potassium should be applied. Later in the crop’s life, applications are not as critical because potassium can be stored in the plants’ leaves and stems.
Sulphur and Calcium - are generally incorporated into fertilisers in a quantity sufficient to meet crop needs.
Magnesium - can be side dressed regularly, at the appropriate rate, during the life of a crop to avoid deficiency.
Boron - leaches readily in sandy soils so soil applications may be required before planting and a number of times during crop growth
Zinc and Manganese - deficiencies can be corrected with foliar sprays, though recovery from symptoms can be very slow.