March 16, 2007

Applying manure before seeding alfalfa may seem counter productive since alfalfa is not likely to benefit from the nitrogen in manure; however, manure is also rich in phosphorus, potassium, sulfur and many micronutrients that alfalfa needs in large quantities.

Research studies show that applying as much as 12,000 gallons or 50 tons of dry manure per acre before planting alfalfa can boost alfalfa yield more than commercial fertilizers at the same nutrient levels. And, yield increases occur on both low and high fertility soils with manure while only low fertility soils responded to commercial fertilizer. The increases may be due to other factors such as improved soil tilth, increased soil microbial activity, micronutrients and early nitrogen availability.

If you also plant a companion crop like oats that you plan to harvest for grain, don't apply a heavy level of manure prior to alfalfa seeding. It is likely to lodge and smother much alfalfa. If you cut the companion crop early for hay, though, it will be fine.

Use soil and manure tests to determine how much manure to apply. Then mix manure well into the soil using tillage, making sure to prepare a firm seedbed so new alfalfa seedlings will emerge rapidly and vigorously.

Plan your weed control program carefully since manure can stimulate weed seedlings. Proper timing of seeding, firm seedbeds and herbicides or clipping can control weed pressure.

Bruce Anderson
Extension Forage Specialist