Farm Talk

October 30, 2012

Consider legumes into soil tests


CNHI

Parsons, Kansas — If you’ve sent a pasture or hay soil test through your University of Missouri Extension Center, you’ve been asked what kind of forage you have. Pat Miller, area Extension agronomy specialist, recommends that next time, before you answer, think about whether you have a legume in there and how much of it there is, or do you want to add a legume. These things make quite a difference in the fertilizer and lime recommendation.

Legumes, like clover and lespedeza, add quality to the forage and provide most of the nitrogen that the field needs. They also dilute the effect of the fescue endophyte fungus. So Miller suggests that unless you’re going for a fescue seed crop (yet a different soil test code and recommendation) or you are in the process of cleaning up your fields with some broadleaf herbicides, you probably want legumes in your field.

According to Miller, “If your pH and fertility are in good shape, the legume should provide the needed nitrogen. Lespedeza can handle a lower pH than red or white clover.” So if your pHsalt is below 5.0, lespedeza may be a better choice than clover until your lime application has time to work. If you want a legume, don’t apply over 20 to 30 pounds of nitrogen, or the grass may crowd out the legumes. It is also best to have it closely clipped or grazed so the legume seedlings have adequate sunlight.

If you get a soil test recommendation for a legume/ grass mix, it assumes that you have at least a 25 percent legume stand. If you have less, your nitrogen recommendation may not be enough for good grass growth. If you are going from straight grass to legume/grass mix, you will have to cut your nitrogen application and sacrifice some grass yield that first year to get your legume established. In this case, use the overseeding recommendation on your test. This will recommend a little nitrogen and not recommend a potash amount that would hurt the seedlings.

Miller said, “If someone tells me they have trouble getting legumes to grow, my first two thoughts are that the soil pH and fertility are inadequate or they are applying too much nitrogen and the grass is crowding out the legume. A good soil test with the correct soil test codes should lead them in the right direction to correct the problem.”

For more information check out guides G4650, Establishing Forages: (http://extension.missouri.edu/p/G4650) and G4646, Tall Fescue: (http://extension.missouri.edu/p/G4646). These are available on-line and at your local University of Missouri Extension Center.

For more information, contact specialist’s name, number, e-mail or visit your local Extension Center or extension.missouri.edu.£