Potassium may help plants through a drought, but drought may also
prevent plants from getting enough potassium.
The mineral is abundant in most prairie soil, often at rates of more
than 10 tonnes per acre.
But plants can’t always get it.
“Often, early in the season, the soil is too cool to release much
potassium to the seedling,” says Adrian Johnston of the Potash and
Phosphate Institute.
“That is where replacing the 15 or 20 pounds that was taken off last
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year in the grain will help the plants get started.”
Cereals and oilseeds require 90 lb. or more per acre during the growing
season.
As well, dry soil particles are surrounded by thinner-than-normal
layers of water. Because potassium is found in these water layers,
plants need to absorb more water than normal to get enough of the
mineral. With water in short supply, the plants receive even less.
To overcome this early season potassium deficiency, placing potash with
the starter fertilizer will put it where the young plants need it most.
In soil that doesn’t have enough potassium, the mineral must be banded
or broadcast and incorporated to become available for the current
season.
Ross Mackenzie of Alberta Agriculture said farmers should soil test to
determine if potassium is needed.
“In many areas that are affected by this drought, there may not be a
crop potential that even warrants putting potassium on, provided you’re
not deficient in it. You’ve got to soil test to know. You may have
enough and you can save your money for a year with greater potential.”
Rich Szwydky of the Saskatchewan Soil Conservation Association said “a
little potash (10 lb. per acre) is cheap insurance for the growing
season …. Even 10 lb. can make a big difference early in the season.
The young plant can then go mining for its own sources.”
