Leaf sampling plays an important role in understanding the nutrient status of a sugarcane crop and helps growers make informed decisions about fertiliser use. Because fertiliser applications do not always translate into improved uptake, analysing the leaves gives a clearer picture of how well the crop is accessing nutrients under actual field conditions. Where imbalances or deficiencies are identified, growers can investigate the causes and apply corrective measures where possible.

Leaf sampling should take place when the crop is growing actively. The correct sampling period depends on the growing region and the crop age. In the Northern Irrigated areas and neighbouring African countries, sampling is best done between October and April on cane aged three to five months. In the Coastal Lowlands, the ideal window is November to March on cane four to seven months old, while in the Midlands the period runs from December to March on four- to nine-month-old cane. Sampling outside these windows may lead to misinterpretation of threshold values. At least four weeks must pass after any topdressing, foliar spray or chemical application, and the crop should not be under moisture stress.

Sampling must represent the field accurately. Growers should select the third fully expanded leaf (top visible dewlap leaf) from stalks of average height, avoiding shoots, unusually tall stalks or field edges. About 40 leaves should be collected while walking in a zig-zag pattern across the field. If the field contains clear areas of good and poor growth, each portion should be sampled separately. Once collected, the tops and bottoms are removed, the midrib is stripped out, and the remaining leaf blade is dried in a well-ventilated area or stored in a brown paper bag.

Correct labelling is essential. Each sample must have the required grower details, field identification and corresponding information on the Leaf Submission Form used by FAS.