Sample the third or fourth pair of coffee leaves
Monitor nutrient levels in the trees by taking leaf samples once or twice a year. Leaf samples should be taken just before the rapid vegetative growth phase (September to December) and again after harvesting (May to July).
Adjust fertiliser rates if large differences occur between the actual levels and the optimum nutrient levels (see optimum leaf nutrient levels table below).
Procedure for taking leaf samples
1. Take the third or fourth pair of leaves from the tip of an actively growing branch. Sample leaves from either bearing or non-bearing branches, but not a mixture, in the middle part of the tree. Take only leaves free from insect or physical damage and disease.
2. Take four pairs of leaves from each tree and sample at least 15 trees over an area.
3. Place sample leaves into clean plastic bag and label the bag.
4. Take leaf samples to a chemical analysis laboratory such as QDPI Ag.Chem., Incitec or Soil-Tec Alstonville for complete nutrient analysis.
Note: Do not store leaf samples for more than 24 hours before analysis.
Optimum leaf nutrient levels (Reuter Robinson, 1986)
You can use visual symptoms of nutrient deficiencies as a tool to estimate fertiliser needs. The following table is a guide to deficiency symptoms:
Nutrient deficiency symptoms (adapted from Nagao et al., 1986)
Source
James Drinnan and Ted Winston
