From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335

Summer 2001, No. 8


Forage crops are a major source of nutrition for animals. In a similar manner, for many plants the nutrients in fertilizer are their major source of feed. Both groups require nitrogen, phosphorus and potassium in a balanced ration if they are to grow and develop into the desired finished product. There are no short cuts.

The primary purpose for growing forage is to produce feed for a specific type and size of livestock operation. Thus, minimum requirements for forage quality and management become site-specific. When properly managed, forages become the lowest cost source of quality feed. In addition, they can contribute to off-farm sale of hay, protect land subject to erosion, provide wildlife habitat, or even add aesthetic beauty to the rural landscape.

Decades of research have revealed many of the secrets to forage crop establishment and maintenance for high yield, high quality, and long life of the stand. Crop harvest frequency and full-feed fertilization are two very critical management practices essential for success. They help to insure feed quantity, quality, and long-term availability.

Legume or legume/grass stand establishment is a critical first step. Incorporate lime and build up phosphorus and potassium levels into the high range prior to seeding. High soil fertility levels are essential for seedling development and later for rapid regrowth after each harvest.

Frequency of harvest is key to quality, yield, stand longevity, and fertilizer needs. The best harvest interval is crop dependent and designed to deliver quality feed (high protein, total digestible nutrients, digestibility, palatability, etc.). By combining a 28 to 30 day harvest interval with a sound fertility maintenance program, many forage crops deliver livestock feed quality needs while maintaining long-term stand survival. Fertilizing after the first harvest in the spring and the last harvest in the fall has proven effective in meeting seasonal crop needs and in preparing the plants for winter stress and earliest spring regrowth.

Frequency of fertilization is key to forage quality and long-term productivity. Forages remove large quantities of nutrients from the field. Each ton of quality forage, for example, can remove about 60 pounds per acre of nitrogen, 12 to 15 pounds of P2O5, and 50 to 60 pounds of K2O. If the total forage yield was 6 tons per acre, then about 360 pounds of nitrogen, 72 to 90 pounds of P2O5, and 300 to 360 pounds of K2O would be removed from the field and would need to be returned in the maintenance fertilization program. Crop requirements for sulfur, boron and magnesium continue to increase and are also key ingredients in the maintenance fertilization program.

Proper forage crop fertilization pays in other ways. A well-nourished plant can better withstand stress generated by extremes in temperature, moisture shortages, diseases, and frequent harvesting. Both phosphorus and potassium promote quality root systems that best capture available soil water and that allow rapid re-growth of roots and shoots following harvest. When soil phosphorus and potassium fertility levels are allowed to decline, certain undesirable changes take place. Forage composition changes, yield and quality decline, more competitive weeds and undesirable species take over, and the need for high cost reestablishment occurs earlier than need be.

Fertilization is a management practice that should never become a limiting factor in forage crop production. A well-nourished crop is best able to deliver the quantity of low-cost, quality feed needed by the livestock enterprise. Since each crop responds best to site-specific management, contact your area forage specialist for more detailed information.

— NRU —

For more information, contact Dr. Noble R. Usherwood, Southeast Director, PPI, 233 Kenilworth Circle, Stone Mountain, GA 30083. Phone: (404) 294-0137. E-mail:
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