Fertilizing Cool-Season Grasses In May
Fertilizing cool season pastures can help you take full advantage of recent spring rains.
Grass growth is stimulated by nitrogen fertilizer just like other crops. One key to profitable fertilizing of pastures, though, is to time fertilization to stimulate grass growth when you need it. We often fertilize cool-season grass pastures in early April to get a good boost in early growth. By June or July, though, these pastures run out of both moisture and fertilizer. Add in hot temperatures and their growth nearly stops.
This spring many pastures received abundant rain. With just a little more moisture, pastures should be able to continue to grow longer into summer if soil fertility is adequate. To take advantage of this extra soil moisture, fertilize cool-season pastures with 30-60 lb of nitrogen per acre between now and Memorial Day to gain extra summer forage.
To make May fertilizing work best, I have found that it helps to graze pastures moderately before adding nitrogen fertilizer. This seems to encourage more thickening of the grass stand and slightly reduces the number of seed stalks produced. Don't graze too short, though, or plants will be stunned and regrow more slowly.
Would it be smart to fertilize again in May if you applied nitrogen earlier this spring? Normally I say no, especially with nitrogen so expensive, but if you applied just a light amount earlier and already have grazed off most of the grass, a second application might be beneficial, similar to the multiple nitrogen applications used on irrigated pastures.
Extension Forage Specialist