South
Florida
Beef -
Forage
Program
"Article of the Month"
March 2000
Fertilization and Liming
of Limpograss (Hemarthria) For Summer Grazing
Jack Rechcigl Professor- Soil and Environmental Quality
UF, IFAS, Range Cattle REC
Limpograss (Hemarthria) is a popular grass grown for cattle in Florida.
When managed correctly, limpograss can be a high yielding and good quality grass.
Few studies have been conducted to evaluate the fertilizer and limestone requirements
for limpograss. Thus, growers were forced to guess as to how much fertilizer and lime to
apply to limpograss pastures. It is essential that we carefully evaluate how much to
spend on pasture management in the hope of obtaining a profit. Pasture fertilization
is one of the most expensive costs in beef production. It is no longer realistic to apply
high rates of fertilizer on pastures and expect greater profits from increased pasture and
cattle production.
Over the past five years the Range Cattle Research and Education Center evaluated
the fertilization and lime requirements for limpograss. Results indicated that limpograss
can respond to small amounts of either phosphorus (P) or potassium (K). The results show
that approximately 15 to 20 pounds of P2O5 and 30 to 40 pounds of K2O should be applied
per acre in a one time application in early spring. Our nitrogen (N) studies show that
limpograss will respond to as high as 300 pounds of nitrogen per acre. Our results
indicate that nitrogen be applied in two or three applications throughout the growing
season. Higher limpograss production was also obtained with ammonium sulfate as compared
to ammonium nitrate fertilizer. This increase in production is probably a result of the
ammonium sulfate supplying needed sulfur for the limpograss.
Limestone is important for crop production by increasing soil pH and providing
calcium (Ca) and /or magnesium (Mg). The majority of soils in Florida are acid,
coarse-textured sands. These soils tend to be low in calcium and magnesium, both
are required for plant growth. Acid mineral soils found in Florida can contain toxic
aluminum which stunts plant root systems and reduces nutrient and water uptake. Addition
of limestone can also affect nutrient availability to crops. It is important to take soil
samples to determine pH and lime requirements prior to applying limestone. The amount
of limestone needed depends upon the initial soil pH, soil texture and the crop to be
grown. Whenever it is cost effective one should use dolomitic limestone. Ordinary
calcitic limestone only increases soil pH and calcium, while dolomite limestone provides
magnesium in addition to increasing soil pH and calcium.
Results of a field trial evaluating the lime requirements of limpograss showed
that there is a yield response from a one-time application of one ton of limestone
per acre which increased the soil pH to 5.0. Addition of one ton of limestone per acre
increased average annual limpograss production by as much as 0.8 tons of dry matter per
acre over three years. The application of two and four tons of lime per acre increased
the soil pH to 5.9 and 6.5 respectively but did not increase limpograss yield.
Assuming you need summer grazing this research suggests that one should apply about
300 Ibs/A of a 20-5-10 fertilizer in the spring with an additional 50 pounds of nitrogen
applied one or two times during the growing season, and apply approximately one ton per
acre of limestone to limpograss when the soil pH is less than 5.0. In new plantings of
limpograss, limestone needs to be applied at least six months prior to planting to allow
ample time for the soil pH to increase.
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Fertilization and Liming
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