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Alfalfa (Medicago sativa)

Plant Characteristics: Perennial legume with up to 36 inches of growth and a deep taproot. Most tillers arise from the crown. Leaves are trifoliloate with serrated leaflets at the tip. It should not be confused with sweet clover with which leaf serration occurs around the entire leaf margin.

Establishment: Alfalfa can be adapted in the state, but recommended to the northern part. It should be planted between mid-August to early September with the opportunity for spring seeding in the upper part of the state. Seed should be planted at a rate of 15 to 20 lbs/ac in a well-prepared bed using a cultipacker-seeder at 1/4 to 1/2 inches deep. Stand persistence is still questionable but 2-3 years is acceptable, and it does better in well-drained soils. Several diseases and pests such as Sclerotenia crown, stem rot, alfalfa weevil, leafhoppers could be a problem if they are not controlled. Nematodes are a major problem in the sandy Coastal Plain soils.

Fertilization: Alfalfa is very sensitive to soil acidity and pH levels should be maintained about 6.5. N is not required but requires P, K, S, and B. Optimum soil test indices for alfalfa are 65 lb P/ac and 350 lb K/ac. Split applications, one-half in the fall and one-half after the first cutting, may result in more efficient use of fertilizer, especially K. If the soil test shows 1 part per million (ppm) or less of boron (B), or if plant tissue has 25 ppm or less B, then topdress with a fertilizer containing at least 2 pounds of B per acre.

Grazing/Hay Management: Alfalfa productivity in the southern part can occur from March to November while in the northern part could be April to October. It could be used for pasture, hay, or silage. Up to 6 cuts could be possible in the southern part of the state and should be harvest at the bloom stage. Rotational grazing with at least 20 to 35 days of rest is recommended. Alfalfa becomes dormant during the summer time and is at least 4 weeks of growth are recommended to replenish carbohydrate reserves.

Forage Quality: This is a high quality forage for horses and dairy cattle. Protein content ranges from 12 to 18%, ADF 30 to 40%, NDF 40 to 50%, IVDMD 55 to 67%, and RFV 100 to 140%.

Varieties/Cultivars: New round-up ready varieties provided a better management for weed control and establishment.

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Portrait of Dr. Rocky Lemus
Extension/Research Professor