Fighting to keep forages in the green

Jul 8, 2011
by DTN

It isn’t easy being a warmseason forage. It’s hot. Probably dry. There are pests and weeds around every turn. And the last thing anyone is thinking about this time of the year is soil testing. Right? Big mistake.

Gary Hill found out the importance of soil testing the hard way. The University of Georgia animal scientist works with Tifton 85 bermudagrass at the Coastal Plain Experiment Station in Tifton, as well as on his own cattle operation. He started noticing stand losses in the highly productive forage.

Hill wasn’t worried about pH because Tifton 85 is highly tolerant of acidic soils. He discovered, however, the plants were low in potassium because it isn’t taken up as efficiently by forages in acidic soils.

“Potassium is what keeps the plants healthy and growing and keeps a good stand of grass,” he explains.

So even when you think pH doesn’t matter, it really does. Hill says it’s important to test pH in the fall and winter because it takes time to get things back in line.

“Lime is not like ammo nium nitrate. It takes time— four to six months—after lime is spread to do the plants any good. And it costs $35 to $40 an acre, so it isn’t going to break the bank. It’s sure cheaper than pasture renovation.”

Hill remedied his problem with lime and a fertilizer high in potassium. He says “24-6-12 is the standard fertilizer, along with ammonium nitrate for bermudagrass.

“In our case, we added lime and then applied 20-4-18—which is higher in potassium—trying to feed the plants more potassium to stop stand loss and build better, healthier plants. If pH is 6.0 or higher, we usually apply 24-6-12 in the spring, then add two or more applications of ammonium nitrate.”

Weed worries

Most good producers know a good fertilization program is two-sided. It feeds the grass, but it also can feed the weeds if precautions aren’t taken.

Hill says “judicious use of the mower can take out some of the weeds but where needed, spray with herbicides.”

Opelika, AL, cattle producer Banks Herndon agrees. “I keep our Bahia pastures clipped with the mower and I pray for rain. I usually only have to spray once a year.”

If pastures have a light infestation of horsenettles and thistles, Herndon uses an ounce of 2,4-D and an ounce of Remedy (active ingredient triclopyr) in a boom sprayer. “I spray when horsenettles are in the flowering stage,” he adds.

For heavier infestations, including coffee weed and pigweed, he uses a half pint of Remedy and a quart of 2,4-D per acre, spraying the whole pasture.

The owner of Homestead Farms, Herndon allows cattle to lightly graze his Max Q fescue pastures in the summer if he’s had enough rain to keep them green and growing.

“There isn’t much spraying for weeds with the Max Q because the sod is so thick. That is one of the beauties of it,” he says.

Keeping cool

In Illinois, Natural Resources Conservation Service grassland specialist Roger Staff says most producers end up using tall fescue—a cool-season forage—for their summer grazing needs. Unfortunately, most of it is the original Kentucky 31 fescue, complete with the toxic endophyte that wrecks animal performance and makes them more susceptible to heat stress. To help, Staff recommends planting and managing pastures so they contain about 30 percent legumes.

“The legumes help improve the nutritional quali ties of the pastures and add nitrogen,” he says.

While some producers in his area use summer annuals like pearl millet, Staff urges them to include 10 to 20 percent of their grazing acres in native warm-season grasses like big bluestem or eastern gama grass.

“These perennials are there year to year and can really help with the summer slump,” Staff says.

Rotation advantages

A good rotation plan can mean the world when it comes to keeping summer pastures productive as long as possible. A 30-day rotation is often best, although it will vary with climate and forage.

1. Bermudagrass. Longterm studies with bermudagrass in Georgia have shown it’s best to keep the grass about 4 inches in height, says animal scientist Hill.

“Bermudagrass grows short on the ground and four inches is the most efficient height for the grass and animals,” he adds.

If you notice patchy grazing on bermuda, where livestock are only grazing new growth, try increasing stocking rates by moving more animals into that pasture.

2. Cool-season mix. If you’re using a cool-season mix like fescue and clover, Staff recommends turning livestock in when pastures are 6 to 8 inches in height. Remove them when forages get down to 3 or 4 inches.

3. Warm-season grasses.

For native warm-season grasses, turn livestock in eastern gama grass when the forage is about 18 to 20 inches high. Remove them when it is grazed down to 8 to 10 inches.

4. Bluestem and switchgrass. For big bluestem and switchgrass, Staff recommends turning livestock in at 16 to 18 inches and then moving them when the forages are about 8 inches tall.

5. Novel endophytes. If, like Herndon, you use a novel endophyte variety of fescue like Max Q, Auburn University Extension forage specialist Don Ball says to manage it carefully.

Although the novel endophyte varieties of fescue still have the hardiness associated with the older, toxic endophyte fescue, they are cool-season grasses.

“You have to be very careful in the summer not to overdo it,” says Ball. “Defoliation of the top growth is a stress on the plant, particularly a cool-season grass in the summer. There is a limit to the stress any plant can take.”

He recommends not grazing Max Q fescue below 4 inches in height. And, he adds, “rotational grazing is the way to do that.” — DTN