Be Careful of Early Spring Fertilization

By Gary Bates, Professor Plant Sciences and published by University of Tennessee in Beef Cattle Time, Volume 25, Number 1, Winter 2007 - During winter, hay is the primary source of feed for most Tennessee cattle. Cattle producers usually anxiously await the warmer temperatures of spring and the grass growth in pastures that accompanies them.
calendar icon 1 March 2007
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Warm temperatures and a little nitrogen fertilizer will cut the hay feeding season short. The question is exactly when to apply the fertilizer.

This is important because the nitrogen in fertilizer will only be available for grass growth for about a 45 – 60 day period. By that time, it has either been used by a weed growing in the field, leached out with rainfall or removed by some other method. If the fertilizer is applied too early in the spring, some of the nitrogen will not be available for grass growth, and production will be reduced.

A classic scenario occurs in February nearly every year. We have cold conditions during January. About the middle of February, the weather warms, and it looks like winter is over. But during the first week of March, the worst of the snow and cold conditions hit, and pastures don’t begin to grow until mid- to late-March. If you were to apply the fertilizer in mid-February when we had the initial warm conditions, some, if not most, of the nitrogen applied would not be utilized by the grass plants in the pasture. The most efficient use of fertilizer would occur after the worst of the cold conditions had passed and the tall fescue and orchardgrass had begun to grow. If plants are not actively growing, they will not be able to utilize the nitrogen.

Is there ever a place to fertilize early with nitrogen? If you want to promote early forage growth to decrease hay feeding and are willing to risk the potential for latefreezes and the loss of the nitrogen value, your success will depend mostly on the weather you encounter.

Treat a limited number of acres, which will reduce the risk. Also, apply the nitrogen to fields that do not have a stand of clover. Nitrogen applications to grass/ clover fields can result in the stimulation of the grass stand and the loss of the clover component.

In general, it is better to fertilize a couple of weeks late rather than a couple of weeks early. Environmental conditions have such a large impact on early season forage production that it is important to consider the potential for late freezes when planning pasture and hay fertilization.

February 2007

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