After
crops are harvested, fall is a good time to apply lime. While lime can
be applied any time, ideally, the soil should be dry to allow good
spreading with out rutting up a field. Here are some tips for fall lime
spreading.
First, get a good soil test to evaluate soil pH. Dr.
Steve Culman, Ohio State University says the ideal pH is dependent upon
the crop and the subsoil pH. In western Ohio with calcareous soils
(subsoils with limestone), lime is usually not needed until the subsoil
pH for mineral soils gets below 6.0 for corn and soybeans and 6.2 for
alfalfa. In other parts of the state (eastern and southern Ohio), where
the subsoil pH is less than 6.0 for mineral soils, additional lime is
recommended after the soil pH drops to 6.2 for corn and soybean, and 6.5
for alfalfa. Western Ohio soils needs less lime to buffer soil pH.
Second,
lime regularly. Soils that are regularly limed are not as critical as
soils that seldom get limed and the pH gets too low. Regular liming
maintenance gives a farmer more flexibility to lime when time and soil
conditions are ideal. Usually, farmers time liming applications to when
they take a soil test, which is every 3-4 years.
Third, lime may
be slow to break down and release, so make applications before they are
needed. Most limestone, depending upon grade and fineness, take at least
6 months to break down to correct the soil pH. When the soil pH is
really low, it may take even longer and multiple lime applications may
be needed. Generally, no more than 2 tons of lime are applied per acre.
Fourth,
consider the soil conditions. Lime trucks and lime hauling equipment is
heavy and may compact the soil. Dry soils and long-term no-till soil
have higher structural stability for heavy equipment then wet soils or
tilled soils. About 80% of the compaction occurs on a tilled soil with
the first wheel pass.
Sometimes, lime is applied to frozen soils
which limits soil compaction. As long as the lime stays in place, this
should not be a problem but lime applied to a no-till field with residue
and/or a cover crop is less likely to move then lime applied to a bare
soil. Lime applied in the fall and early winter will freeze and thaw and
to be shallowly soil incorporated. On sloping fields or fields prone to
flooding, lime can be washed away. Again, residue and cover crops allow
lime to stay in place. On conventional fields, farmers often do some
tillage to incorporate the lime, however; the soil is loose and may
erode away.
Fifth, to be effective, lime must be applied evenly.
Sometimes lime and that is dumped in a filed can gather moisture and
freeze, becoming lumpy when it is spread. Non-uniform application may
cause uneven pH changes across a field. One way to avoid this is to
apply the lime quickly after being dumped in a field and before it gets
wet and freezes.
Sixth, consider the Effective Neutralizing Power
(ENP) of any lime source which allows a producer to compare lime
quality. ENP considers the purity, neutralizing power (including
fineness) and moisture content. ENP tells how much the lime neutralizes
soil acidity and is measured in pounds/ton. ENP is a required on any
liming source and allows producers to compare liming sources as price
per pound of neutralizing material.
Seventh, what is the best
source of lime? Is high calcium lime better than dolomitic lime (higher
in magnesium)? Check your soil test and compare transportation line
hauling costs. Dr. Steve Culman says, soil test magnesium levels need to
be greater than 50 ppm (100 lb) for optimal corn, soybean, wheat, and
alfalfa production on fine (clay) to medium textured (silty) soils and
greater than 35 ppm on coarse textured (sandy) soils.
On sandy
soil (often lower in magnesium), dolomitic lime may be a better buy
depending upon transportation costs. Magnesium can be applied with other
magnesium fertilizers, so compare costs. Too much magnesium tends to
tighten and compact clay soils. Ideally, calcium base saturation should
be 65%-68% on sandy soils and up 72% on clay soils. Magnesium base
saturation needs to be a minimum of 15% on sandy soils but ideally not
more than 20% on clay soils. Calcium activates at least 146 key enzymes
while magnesium is needed to make chlorophyll. If your pH is OK, adding
gypsum (calcium sulphate) can increase calcium base saturation without
affecting pH. Keeping these two elements in balance is a key to keeping
soils healthy.