BEGINNER’S CORNER
Understanding the Five
Most Important
Parameters on Your
Soil Test Report
by Guy Sela
Considering sending your soil off to
get tested at the lab? Good idea!
Professional soil testing is highly
recommended as it is more accurate
than simply using a hand-held meter in
the hopes of learning what’s going on
with your soil. Here are the five most
important things a soil test report
reveals, all of which are likely to
show up on your report.
Cation Exchange Capacity
The cation exchange capacity (CEC) listed on a soil test
report refers to the number of negatively charged sites on
the soil particles (mostly clay and organic matter) that can
retain plant nutrients. It is expressed in units of meq/100g
or cmolc/kg (1 meq/100g = 1 cmolc/kg). Positively charged
nutrients, such as potassium, calcium and magnesium, are
electrically attracted to clay particles in soil. Other positively
charged elements, such as sodium and hydrogen, are also
adsorbed on soil particles. Sodium can negatively affect soil
structure and hydrogen ions determine the soil pH.
Soils that have higher CECs are considered to be more fertile
than soils with lower CECs, as they can potentially hold more
nutrients for longer periods of time. These
soils also have a greater water-holding
capacity. Knowing the CEC of your
soil can help you decide on a
fertilizer application frequency,
as high CEC
soils require
less frequent
applications.
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Maximum Yield USA | June 2016