plant analysis
The plant analysis lab report generated usually
states each of the macroelements (N, P, K, Ca, Mg, and
S) as a percentage of dry matter, while microelements
(Fe, Mn, B, Zn, and Cu), present in much lower
concentrations, are expressed as either parts per
million (ppm), milligrams per kilogram (mg/k), or
micrograms per gram (μg/g). Some lab reports will
also include a guide to the ideal foliar level range of
each nutrient for specific crops to compare the results
against, but not all do. Instead, guidelines for the most
commonly grown hydroponic plants can be found
in plant nutrition books and websites that indicate
ideal levels for different species at different stages
of growth. A list of foliar mineral levels at which
deficiency or toxicity symptoms would be expected
to occur are also useful to have on-hand when
comparing plant analysis reports.
When to Use Foliar Analysis
“BY COMPARING
the foliar mineral levels
returned on a recent lab
analysis to the healthy
range for the plant
species being grown, it’s
possible to see which
nutrients fall outside the
recommended range.”
Plant analysis can be used for different purposes. It
has a vital role in crop research, where nutritional
programs for new crops may be determined by
analyzing the mineral content of well-grown, healthy
plants. This data can then be used to formulate
nutrient solutions or soil programs specifically
aimed at maximizing plant nutrition for that crop. For
those running small trials, foliar mineral analysis
may be used to determine how different treatments,
supplements, products, growing environments, and
formulations affect the nutritional content of the plant.
For growers, the most common use of foliar
analysis is for when suspected deficiency or toxicity
symptoms are starting to show on plants. Since many
physiological, disease, and nutritional disorders can
look quite similar, plant analysis is often used to rule
out or confirm specific nutrient issues so that these
can be rectified quickly and correctly.
Foliar analysis is often used alongside nutrient
solution analysis to determine necessary changes
or supplements to prevent deficiencies from
continuing to occur. It is also commonly used to
confirm that nutrition has been optimal and that
the nutrient formulation is suitable for the current
stage of growth. Growers experiencing unexplained
symptoms such as an overall lack of plant vigor,
plant stunting, or low yields may use plant analysis
to rule out nutrition as the specific cause of any
issues, or to diagnose nutritional problems before
they become more severe.
Interpretation of Plant Analysis Lab Reports
Top: Many disorders and diseases can have symptoms similar to mineral
deficiency/toxicities. Bottom: Foliar mineral analysis doesn’t take into
account nutrients incorporated into other parts of the plant, such as fruit.
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feature
Recommendations for the ideal level of each nutrient
in foliar samples vary slightly, depending on the
reference source. For this reason, ideal levels are
simply given as a range within which most healthy
plants should fall. Typically, this is somewhat species
dependant. For example, normal foliar levels of
nitrogen in crisp head lettuce are often stated as
being three to 4.5 per cent, while in tomato, a crop
requiring a higher level of nutrition, are 4.5-5.5 per
cent; deficient levels would be less than two per cent.
For potassium, ideal foliar levels are 4.5 to eight per
cent in crisp head lettuce and four to six per cent in
tomato, with deficient levels being below two per cent.