Magnesium variations don’t affect corn yields
UNIVERSITY PARK - Far
mers growing com on high
magnesium soils should apply the
cheapest source of high quality
lime available and not worry about
the magnesium ratio of the lime.
That statement comes from the
experiments at Penn State’s
College of Agriculture. Test sites
ranged from fields low to high in
soil magnesium levels with wide
ranges in calcium to magnesium
ratios. There were not significant
differences in com gram or silage
yields among any of the treat
ments at any site.
Richard H. Fox, crop scientist in
charge of the research, indicated
maximum grain yields were ob
tained with magnesium saturation
values as low as 1.8 percent or as
high as 29 percent. When the soil
magnesium content was expressed
as a calcium to magnesium ratio,
the range of ratios varied from 1.8
to 37.
“There is no evidence from trials
in the U.S. that corn yield is
depressed by high soil magnesium
levels,” Fox affirmed. “There is
no need to add gypsum or calcitic
lime to high magnesium soils in
Pennsylvania to increase corn
yields,” he added.
At the same time, it was men
tioned that some private soil test
laboratories recommend that
farmers apply gypsum or high
calcium, calcitic lime to their soil
when the soil magnesium levels
are higher than specified values,
or when the calcium to magnesium
ratios are lower than specified
values.
“It is obviously uneconomical
for farmers in areas where only
dolomitic lime is produced locally
to import calcitic lime or apply
sypsum when it does not improve
yields or crop quality,” Fox
declared.
Maximum gram yields in the
experiments ranged from 103 to 147
bushels per acre. Silage yields
went from 8.0 to 10.1 tons per acre.
Three experiments were carried
out in 1980 at the Agronomy
Research Farm of Penn State in
Centre County. The testing was
repeated in 1981 on one of the low
magnesium sites, with no new
treatments added.
Two of the test sites had low soil
magnesium levels, 4.5 to 5.0 per
cent saturation; one was high with
20.0 percent magnesium
saturation. To create a wide range
of magnesium levels and calcium
to magnesium rations, the soils
were treated with clacitic and
dolomitic lime, magnesium
sulfate, and potassium chloride.
Other essential nutrients, in
cluding potassium, were either at
high enough levels or were added
to ensure that yields would not be
affected. Assisting with the project
was William P. Piekielek, senior
research aide.
“We do not know how low the
magnesium saturation can go
before lack of magnesium begins
to limit corn yields,” Dr. Fox
commented. “However, we
suggest that the lower limit for
magnesium saturation of soil
should be 5 percent for corn grown
for grain,” he added.
On the other hand, no one knows
how high the soil magnesium level
can be before it damages yields, it
was pointed out. Even soils limed
PFA favors milk pricing
CAMP HILL - Keith Eckel,
president of the Pennsylvania
Farmers’ Association (PFA) said,
“After examining the Sunset
Review audit of the Pennsylvania
Milk Marketing Board we believe
the report is on target in its
recommendations and valid as a
tool for improving the board’s
Lancaster Farming, Saturday, March 10,1984—A23
continuously with pure dolomite
should always have calcium-to
magnesium rations high enough
that calcium deficiency or
magnesium toxicities will not limit
yields.
“This lack of yield response to
wide variations in calcium-to
magnesium rations applies only to
com and probably most other
agronomic crops,” Fox stated.
“There are a number of hor
ticultural crops such as apples,
tomatoes, and celery where the
ratio of calcium to magnesium
must be kept within a narrow
range to maintain optimum crop
yields and quality,” he added.
Similar results at the University
of Wisconsin confirm Penn State
findings. Wisconsin scientists
observed that both corn and alfalfa
future role in Pennsylvania’s milk
industry.”
The Sunset Review report was
prepared by the Legislative
Budget and Finance Committee.
Eckel said PFA agrees with the
Sunset Review recommendations
that the Pennsylvania Milk
Marketing Board should consider
can produce maximum yields over
a wide range of' soil calcium and
magnesium levels. The Wisconsin
researchers also found reports of
greenhouse experiments where the
soil had twice as mcuh ex
changeable magnesium as
calcium. Yields were still not
affected by high magnesium.
Penn State’s current ex
periments confirm previous
research showing that a
magnesium saturation of 10 per
cent ensures that the silage will
have 0.2 percent magnesium. The
National Research Council
recommends this level of
magnesium for dairy cattle
feeding. Soils maintained at this
level will have adequate
magnesium to prevent grass
tetany.
change
discontinuing the setting of
mandatory minimum resale prices
for milk.
Eckel said, “Our members
adopted policy in 1982 calling for
the Milk Marketing Board to
eliminate control of retail sale
prices. We believe retailers should
have the opportunity to sell milk at
prices they determine themselves.
However, we also agree with the
Sunset Review recommendation
that milk should not be priced
below the cost of production. After
all, consumers can’t rely on an
adequate supply if dairymen and
processors are forced out of
business by below-cost pricing.”
PFA also agrees with the Sunset
Review finding that the Pa. Milk
Marketing Board performs a
necessary function in maintaining
economic stability in the milk
industry and in protecting the
public’s health and welfare. Eckel
said, “This report reaffirms our
faith in the milk board’s valuable
service in providing a means for
the orderly marketing of Penn
sylvania’s milk products.”
PFA also agrees with the Sunset
Review finding that the Milk
Producers’ Security Fund is not
working at the present time to
protect dairymen from
bankruptcies and defaults by milk
dealers. PFA is currently seeking
legislation to improve security
fund protection.
Zoning meeting
on Monday
HONESDALE - Stanford M.
Lembeck, Penn State Extension
Service Specialist in Community
Affairs, will be the speaker at an
educational meeting on zoning
Monday at 8 p.m. in the Knights of
Columbus Hall, Rt 191, south of
Honesdale.
Lembeck has been a member of
the Penn State faculty since
February, 1965. He assumed his
present position as community
housing and planning specialist in
January, 1972. In that role he
conducts educational workshops
and assistance on planning
practices for planning com
missioners and local officials, and
is a resource person for county
Extension staff throughout Penn
sylvania providing assistance and
in-service education programs. He
also teaches in the Graduate
Regional Planning Program.
Lembeck will attempt to identify
local land use issues and suggest
techniques to solve these
problems. In addition he will
outline the provisions of a zoning
ordinance. All interested persons
are welcome.