measurement methods of soil, water, plant and fruit, in berry ... - NJF

LEAF- OR SAP ANALYSIS ?
A comparison of strong and weak points
Ingemar Månsson,
LMI AB, Sweden.
Abstract
Leaf analysis is compared with Sap analysis on general principles. The second half of the
article is a subjective evaluation of strong and weak points based on 55 years of experience.
Background
In all plants nutrients are present in 2 forms. Partly as dissolved inorganic salts, these are raw
material necessary for further growth. Partly as organic products such as proteins, chlorophyll
and enzymes.
The conventional leaf-analysis measures everything in the sample, both raw material and
finished products. Results are given / kg dry matter.
Sap analysis measures only the raw material and results are given as mg/l.
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Leaf analysis
% or mg/l, does it matter?
Plant material contains varying amounts of sugar, starch and cellulose. These carbohydrates
do not contain plant nutrients, but they affect the weight of the dry sample.
The practical effect of this is that leaf analysis will show lower nutrient levels as
carbohydrates increase. Normally carbohydrate content increases with age, why
optimumlevels of nutrients will change drastically during the year. This effect is so strong that
it is necessary to strict regulate what parts are to be sampled, also the developementstage has
to be included in order to evaluate the result. To get reliable references involves a lot of
analysis and work. Specific references for different varieties might be necessary.
Sap analysis is not affected by above variations. Differences in reference values between
varieties are rare.
Total content or raw material ?
OPTIMUM VALUES
Sap analysis
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