Farm Progress

Lime is critical for high yielding pasturelandLime is critical for high yielding pastureland

January 3, 2008

3 Min Read

Are you losing extra yield from pasture and forage crops each season due to low soil pH?

“Lime needs to be applied on acid soils if you want a well-balanced fertility program and highest yields,” said Mark Keaton, Baxter County staff chair with the University of Arkansas Cooperative Extension Service.

Yields can be increased on many Arkansas farms by correcting acid soil conditions with lime. Most grasses will produce top yield on soils that are only moderately acid or slightly acid.

Most legumes, on the other hand, grow best on soils that are slightly acid to neutral in pH reaction, according to Keaton. Good yields of all forages are more attainable when proper levels of lime and fertilizer are applied to pastures and hay meadows.

In addition to increasing soil pH, lime supplies calcium or calcium and magnesium (dolomitic limestone), both essential nutrients for plant growth.

“Many forage producers are now trying to manage for species diversity. For example, two or three different grasses along with one or two legumes in the same pasture provide greater opportunity for producing available forage for a longer period of the growing season, and overall pasture quality can be improved.”

When considering all plant food elements in these pasture situations, the optimum pH level for availability is probably around 6.3 to 6.5.

“The only way to know how much lime or fertilizer is needed to produce a desired level of production for a given forage species or species mix is to soil test,” Keaton said.

Perennial pastures should be tested at least every two or three years. Fields used for hay production should probably be tested every two years at the minimum, particularly if the hay is fed on pastures other than the hay meadow.

The sampling process is the main source of error in soil testing. A single soil sample should be collected for each pasture. Typically, samples are taken to a depth of 4 inches. It’s a good idea to rake aside surface material before sampling. For each sample, 25 or more subsamples should be taken at random across the pasture.

Be sure to identify each sample so that you will be assured of matching the soil test recommendation to the appropriate pasture. Also, to ensure timely results, samples should be taken at least four weeks before the time you plan to apply lime and fertilizer. Once your soil samples are taken and have air-dried sufficiently, take them to your county Extension office.

There is no fee for soil samples tested at the University of Arkansas Soil Test Laboratory.

In forage production, as in the production of most crops, maintaining a satisfactory soil pH with lime and ensuring that nitrogen, phosphorus and potassium are available at levels necessary should be your goal.

Nitrogen produces the most dramatic growth response in forage grasses. However, for legume persistence in pastures, lime and potassium are more critical. Potassium also plays a vital role in plant winter hardiness for grasses and legumes.

There can be tremendous variability in the soil pH and nutrients from pasture to pasture. That’s why each pasture should have a soil test.

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