Frequency of application
The best way to ensure that added nutrients are used efficiently by plants and to reduce the risk of nutrient loss to the environment is to match nutrient availability to plant demand over time. Annual crops, perennial crops and pastures all have different patterns of nutrient demand over time, and respond differently according to soil moisture status and temperature. These factors should be considered in planning fertiliser applications.
Mobile nutrients such as nitrogen or potassium are most effectively used when split applications of fertiliser are applied frequently during the periods of crop or pasture growth. This is usually preferable to one large application. However, crops and pastures may have short periods of very high nutrient demand and so a larger application will be required at that time.
Fertigation systems (adding nutrients in irrigation water) provide flexibility in applying nutrients to meet plant demand but regular top-dressing or side dressing of fertiliser can have similar effects, provided that there is sufficient moisture to move nutrients into the soil.