Application strategies in coffee production
Application strategies need to take into account the significant nutrient losses that occur, particularly in high rainfall, tropical plantations, as a result of surface run-off, leaching and volatilization.
All macronutrients – with the exception of phosphorus and some micronutrients - can be leached. Phosphorus, for example can be lost due to surface run-off. Nitrogen volatilization is a significant problem and losses of up to 50% have been measured. In the tropics, it is assumed that over half of the applied nitrogen and 25% of the potassium and magnesium can be lost.
Trials show that 60 – 85% of the total applied nitrogen, potassium, calcium and magnesium fertilizer can be lost on soils with a low CEC. Thus, it is common practice to apply small, but frequent amounts of fertilizer and to use mulches wherever possible to supplement applied nutrients.
As a result of the very high nutrient losses that occur in coffee plantations, the fertilizer rates required and commonly used are much higher than those suggested by theoretical calculation.
Basal fertilizers, especially phosphorus and potassium can be added to the planting hole when establishing the crop. They are also widely used in the coffee tree nursery.
Side-dressed fertilizers are commonly placed underneath the tree around the drip line or outer edge of the canopy, where finer root hairs are normally concentrated. It is important to keep fertilizer (and poorly composted mulches) at least 10cm away from the tree stem to avoid damage.
Foliar application is used to address an immediate nutritional need or where soil conditions restrict availability of specific nutrients. The use of adjuvants will improve the efficiency of foliar sprays onto the waxy coffee leaf. Berries are relatively sensitive to foliar sprays so it is important to ensure correct formulations are used to minimize risk of damage.
