|
The cost of
commercial nitrogen fertilizer has greatly increased recently, which has
in turn greatly increased the cost of producing grass forage. As a result,
many forage/livestock producers are actively seeking ways to reduce the
amount of nitrogen fertilizer they purchase. One very sensible strategy is
to grow forage legumes where possible, as they have the ability (in
association with Rhizobium bacteria) to capture nitrogen from the
air and fix it in nodules on their roots.
Consequently, it
seems likely this autumn there will be some producers who will be planting
legumes for the first time, and others who will be planting them for the
first time in a long while. In addition to biological nitrogen fixation,
legumes offer other benefits including excellent forage quality and the
possibility of increasing forage yield and/or distribution of growth. When
overseeded on the dormant sods of warm-season perennial grasses, like
bahiagrass and bermudagrass, they also tend to suppress winter weeds.
However, legumes require more precision and attention to detail than
grasses, so a review of some unique aspects of growing them should be in
order.
Herbicide residue -
Legumes are sensitive to some
herbicides, including some commonly-used pasture herbicides. Be sure to
check the labels of any materials used within the past year in any area
where the planting of legumes is being considered.
Soil Fertility - While
legumes do not require nitrogen fertilizer, it is quite important to apply
phosphorus and potassium according to soil test recommendations. It is
best to plant legumes in an area in which little or no nitrogen fertilizer
was applied during summer.
Soil pH -
Various legumes have differing pH requirements, but most pasture legumes
do best when the soil pH is in the range of 6.0 to 6.5. Alfalfa and
berseem clover do best when the soil pH is 7.0 or higher.
Fit Species To The
Site - No legume species is adapted
to all soils and sites. Information pertaining to requirements of various
legumes (as well as other forage information) is available on the website:
www.alabamaforages.com.
Seed Inoculation -
Much of the legume seed commercially available is coated seed containing
the proper inoculants and holds it tightly to the seed. If pre-inoculated
seed is not available, the proper type of inoculant should be purchased
and applied to the seed just prior to planting.
Stubble Height -
When legume seed is planted into warm-season perennial grass pastures, it
is important to have a short stubble height (less than two inches).
Planting Depth -
Small-seeded legumes, like ball clover and white clover, can be broadcast
over the soil surface. Medium-sized legume seeds, like those of arrowleaf
clover or crimson clover, should ideally be planted about one-fourth inch
deep. Large-seeded legumes, like vetch or Austrian winter pea, should be
planted about one inch deep.
Planting Date -
Legume plantings on a prepared seedbed can be made as early as
early-September in North Alabama or mid to late-September in South
Alabama. Guidelines for overseeding warm-season perennial grass pastures
are October 1-15 in North Alabama, October 15-30 in Central Alabama and
November 1-15 in South Alabama. |
