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Fertilizer shortages require
making best use of supplies
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[OCT.
5, 2004]
URBANA --
Continued worldwide demand for
fertilizer could result in limited supplies for the 2005 growing
season, according to Bob Hoeft, soil fertility specialist with
University of Illinois Extension.
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"With potentially short supplies, it is
important for producers to make the best use of available fertilizer
to ensure maximum production on their fields," Hoeft said. "Growers
who have not had a recent soil test should consider having a sample
from each 2½ acres of their fields analyzed for pH, phosphorus and
potassium." He suggests
applying lime, which will not be in short supply, to any field with
less than 6.0 soil pH. Growers should also consider adding
phosphorus and potassium to low-testing fields first.
"The allocation should be made to
fields that have phosphorus test levels less than 40 pounds per acre
or potassium levels less than 260 pounds per acre," Hoeft said.
"Research has shown that application of an amount equal to about 1½
times crop removal will often optimize yields, even on low-testing
soils. If supplies are limited, growers should think about delaying
the buildup portion until the quantities are more plentiful."
Hoeft points out that various crops
can differ considerably in their ability to extract nutrients from
the soil.
"Corn and soybeans yields will be at
near-maximum at phosphorus test levels greater than 25 pounds per
acre with supplemental applications," he said. "Failure to add
phosphorus to wheat will result in yield losses when test levels are
below 50 to 70 pounds per acre. At the same time, wheat has a low
demand for potassium compared to corn and soybeans."
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Hoeft advises growers to spread
limited supplies of fertilizer over all the acres rather than adding
full rates to some fields and none to others. The exception would be
only when phosphorus test are greater than 70 pounds per acre and
potassium levels are greater than 400 pounds per acre.
"When test levels are low and soil
pH is high, limited supplies of phosphorus can be applied in a band
2 inches below and 2 inches to side of the seed," Hoeft said. "It
is, however, important to remember that the high yields in 2004 will
remove more phosphorus and potassium from the soil than during an
average year."
Hoeft notes that nitrogen will
likely not be in short supply, although prices could be higher than
normal.
[University
of Illinois news release]
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