Higher fertilizer prices have spiked interest in interseeding pastures with legumes and Kansas State University Extension Agronomist Doug Shoup discussed that issue with producers attending last week’s KOMA Beef Cattle Conference in Oswego, Kan.

Shoup noted that legumes in pastures have the potential to reduce spring fertilizer cost, increase animal performance and extend the grazing season, although maintaining a stand requires management.

Shoup said producers often ask whether legumes actually feed nitrogen to grass.

Generally, there is not a direct relationship, he said, explaining that the legume has to die and decompose before any of its nitrogen is available to grass. Citing a University of Minnesota study involving white clover in a grass stand, he said that in the first year of establishment there was no extra N available to the grass. In the second year, however, there was an additional 47 pounds of nitrogen and that figure decreased as the legume stand decreased.

Producers can, however, reduce spring fertilizer costs without giving up tonnage and still maintain forage quality compared with fertilized fescue.

Relating the results of a Southeast Agricultural Research Center study, the K-State area agronomist said cattle summer grazing fertilized endophyte-infected fescue had an average daily gain of .72 pounds compared to a 1.18-lb. ADG on fescue interseeded with ladino clover while winter gains were similar.

Much of the additional gain from grazing fescue pastures interseeded with legumes is attained by diluting the amount of toxin consumed from endophyte-infected fescue.

To establish legumes in fescue, Shoup said anything a producer can do to reduce springtime grass competition, will be beneficial. Grazing fescue down in early spring and then reducing stocking rates to allow the legume to grow can aid to success.

Even though, legumes require no additional nitrogen, phosphorus, potassium and proper pH are critical to stand establishment. P and K should be added to soil test recommendations and pH should be 6.4 or above.

No-till, Shoup said, is probably the best way to plant legumes but, if a broadcast approach is applied, rates should be increased. A split seeding with half being planted in the fall and half in the spring is a consideration to hedge weather issues.

Producers should also plan on reseeding annually or biannually, he said.

Shoup suggested the following seeding rates:

•Ladino—3-5 lbs./acre

•Red clover—10-15 lbs./acre

•Annual lespedeza—10-15 lbs./acre

•Alfalfa—10-12 lbs./acre

•Birdsfoot trefoil—8 lbs./acre

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