再精准的实验室，也无法从劣质样品中得出正确结论。混合取样实用指南。
In many of the cases referred to us there is a prior soil analysis on file, but its results do not match what is visible in the orchard. Almost always the problem is not the laboratory — it is how the sample was taken.
Composite, not single
A handful of soil from one spot represents nothing. Soil can differ meaningfully over a few metres. For each homogeneous block, take at least 10–15 sub-samples from scattered points, mix them in a clean bucket, and send about one kilogram of the final mix to the laboratory.
Two depths, not one
In orchards, sampling at two depths is essential: 0–30 cm and 30–60 cm. Many problems — salt accumulation and deep-layer deficiencies in particular — are only detectable in the second layer.
Common mistakes
- Sampling immediately after fertilisation, which gives an unrealistic picture of soil status.
- Sampling right at the trunk or under an emitter; those points do not represent the wider root zone.
- Using rusty tools or a used fertiliser bag, contaminating the sample with iron or residues.
- Not blocking the orchard: if part of the site has different soil, it needs its own sample.
Do not skip the leaf sample
Soil analysis tells you what is in the soil; leaf analysis tells you what was actually taken up. The two are complementary, and reading one without the other is often misleading. The correct leaf sampling window differs by species and must be observed precisely.