Basic guidelines for sampling plants for chemical analysis
WHERE TO SAMPLE
Fresh plant tissue never be placed in “zip lock” or in airtight containers.
Clean paper bags and envelopes are ideal plant tissue containers even for moist samples.
It is not necessary to maintain the tissue sample in the fresh state for plant analysis.
WHAT TO SAMPLE
Plants that have been:
– under a nutrient element stress for some time with dead tissue;
– mechanically injured;
SHOULD NOT be included in a composite sample for analysis.
WHEN TO SAMPLE
For the purpose of monitoring the nutrient levels in plants, the proper sampling time is at the flowering stage. The beginning of the flowering stage is easily identified. Therefore, researchers have used this growing stage for establishing interpretation guidelines. Research has found that the nutrient concentrations in plants change as plant growth develops. Testing earlier than flowering stage will show higher nutrient levels than at flowering and testing after grain formation will show lower nutrient levels than at flowering.
For each crop sampling stage is strictly defined.
Scheme of plant sampling for most crops you can – download below