Agriculture Reference
In-Depth Information
Common Burdock
Burdock, Arctium minus , is a biennial herb that reproduces by seed only. Its existence on
a farm is generally a signal that the soil system is dominated by iron and is in need of calci-
um, and has a low pH. It is found all over the United States.
Burdock has fantastically enormous roots, big leaves and burs that stick to animals as
well as clothes of human beings. Common burdock, Arctium minus , is smaller than great
burdock, Arctium lappa . Gypsum soils frequently exhibit burdock and it can be suggested
that burdock is often a signal that soil has been incorrectly limed with magnesium carbon-
ate or subdued with great applications of sulfate of ammonia and lime, giving the effect of
calcium sulfate in the soil.
Burdock is a good phosphate feeder. It has to have a good available source of phosphate.
In the midwest there are a lot of soils low in calcium and high in magnesium, pH reading
being on the low side. Many times farmers apply gypsum or ammonium sulfate on soils
reading below pH 6.2. Unfortunately this has the effect of agitating the construction of the
pH, driving it down to pH 5.8 or 5.7 in terms of a colloidal position. A colloidal position
pH can be lower than the pH in terms of the entire environment, taking both colloidal and
soluble form pH ingredients into consideration. Remember that magnesium will raise pH
1.4 times as high as the same amount of calcium. When gypsum, calcium sulfate, is put on
soils at pH 6.2 or 6.1 — the resultant pH structure will still be too low to govern the proper
release of trace minerals regulated by calcium. At such pH levels there are mineral releases
on the surplus side. Often there is a surplus of aluminum. Moreover, there is a difference in
gypsums, depending on whether and where they are mined, or whether they are byproducts.
As a rule byproduct gypsum is more easily broken down to influence the reconstruction of
the pH equilibrium. It has a more fluffy particle surface (like a snowflake), which is quite
different from the usual product which is textured much like a pearly smooth grain of sand.
Many mined gypsums take a decade or more to break down. Heavy acid flushes both trace
minerals and heavy metals out of the soil. When calcium levels are low, aluminum is
flushed out very easily, as is iron. Burdock can tolerate more iron and aluminum than other
weeds and crops, but it is still a good phosphate feeder. It has a capacity for tolerating this
inventory of conditions without becoming toxic. By way of contrast, corn and grain crops
cannot tolerate the releases of aluminum and iron made mandatory by very low pH sys-
tems. Burdock will proliferate in an environment of iron and aluminum that is killing off
higher plants. In soils that are low in iron, or do not have a daily release of iron, burdock
will not grow. Soils that have a proper decay system going — and this will not happen at
low pH — will not give burdock permission for life. If a low pH soil is releasing a full
complement of iron, burdock will function. Iron in relationship to manganese is also an im-
portant factor. High iron in the presence of low manganese regulates the kind of fungi that
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