A good rotational grazing system for a grass-based dairy or beef herd continually keeps livestock on the best pasture available. Cows graze one paddock to the proper stubble height, then are moved to another that has just come into prime shape.
A grazing-wedge system that maintains pastures or paddocks in a staggered or “stair-step” growth pattern can help achieve that, says Rob Kallenbach, forage agronomist with the University of Missouri.
But it takes some work. To help, Kallenbach and university extension have an online grazing-wedge tool that calculates the quality and quantity of forage dry matter available for grazing — from one grazing period to another. It can be found at plantsci.missouri.edu/grazingwedge.
But to create a grazing wedge, graziers must monitor and measure their pastures.
“We go out weekly and look at pastures and sometimes measure them with rising plate meters or even a yardstick to get some idea as to where the pastures are (in growth),” Kallenbach says.
“Sometimes, like in spring, pasture may be growing so rapidly that, no matter what stocking rate of livestock, you can't graze all the grass you've got. But if you see where you are in that wedge, you may find out that half of this farm could be hayed right now. Or you need graze only half of the paddocks.”
When summer slows cool-season grass growth, some hayed paddocks may need to be pulled back into the grazing system, he says.
“If you're short on forage, you may want to fertilize a portion of your paddocks with nitrogen for a little more rapid growth. Or maybe you want to use supplements to be able to extend the length of how long you can graze.
“You can make those decisions if you know what you've got,” says Kallenbach.
The online grazing-wedge tool can do its calculations after a grazier has set up his or her farm in the system. Growers must specify their grazing operation, name each pasture and forage type (warm- or cool-season) and how much each paddock holds.
“We use pounds/acre, but if you're using a rising plate meter, just write in whatever the plate meter says for each paddock,” Kallenbach says. If you use a grazing yardstick, use the equation that's printed on it. Include the dates you measured crop.
The tool spits out a chart. “It shows the paddock that has the most forage and the next one down and the next one down. You can see what's going on on your farm, and it puts a blue line across. Anything that goes above that line shows you have more forage than you need — and you need to think about making hay, taking paddocks out or adding livestock.”
Anything below that line shows that, at some point, you'll run out of forage and need to strategize, he says. From then on, graziers can enter new data weekly, and the tool will keep track of it.
“If you do this on a week-by-week basis and look at the previous time you entered data, it calculates your growth rate for you. The data will give you clues as to how fast forage is growing on your farm at this time.”
Those who use the wedge tool have the option of sharing data online with the general public or keeping it where only they can access it.
“We have about 100 people enter in weekly or every 10 days. I would say 75% of those are private, but you can look at the public side and see what people are doing and what growth rates they're getting. They'll have some comments at the bottom sometimes of what management steps they think they should take.”
Missourians aren't the only ones making use of the tool, he says. “We have some from Indiana, Ohio, Arkansas and Texas.
“People who use it seem to be pretty excited about it,” Kallenbach says. One participant told him he'd saved $13,000 on fertilizer a few years ago because the tool helped him realize his pastures didn't need the amount of fertilization he thought was needed.