Frequently measuring and recording the amount of standing forage in your pastures is a smart practice for graziers when conditions are ideal. It's also the first step in preparing to deal with drought, says grazing guru Jim Gerrish.
A regularly updated forage inventory “is going to give you information you can use to make better decisions,” he says. “In a drought, it's going to let you know in advance that you have a problem coming.”
Gerrish, former director of the University of Missouri Forage Systems Research Center, now owns American Grazinglands Services, May, ID. He urges graziers to maintain detailed livestock-use records for each pasture, along with number and class of livestock on the farm.
“By looking at those records, you can project your animals' forage requirements up to a year in advance,” he says. “Spreadsheets, as long as they're tailored to fit your needs, are the easiest way to track those requirements.”
He recommends that available forage inventories be updated bi-weekly during the growing season using cow days/acre (or ewe or stocker days/acre, depending on the animals grazed).
Cow days/acre (CDA) is the amount of forage a cow can eat in a day, and each inch of forage on your farm has a certain number of CDAs. Generally, a thin stand has 5 CDAs per inch, an average stand has 9 or 10 and a thick stand (90% ground cover) has about 15. But every farm is different.
While CDAs can be calculated with tools such as quadrant clippings, pasture plates and yardsticks, Gerrish prefers to do it visually. Visual evaluation will be just as accurate as other methods once graziers gain experience, he says.
Every two weeks, estimate and record the CDA for every pasture and the total number for your farm, Gerrish advises. Write down your CDA estimate for each paddock before and after it's grazed, and calculate the amount of forage utilized. For example, if an average pasture (about 10 CDAs/inch) is 10" tall and cattle graze it down to 5", they have consumed 50 CDAs of forage.
“If you do this for a little while, you can look at a pasture and know how much you have,” he says. “That's the point you want to get to; it's so easy.”
He suggests that two people on each farm make separate evaluations because “each person's going to see different things.” Initially, the two estimates may differ, but with practice, “they'll start coming together and pretty soon everybody's going to make consistent estimates.”
Over time, biweekly evaluations will give you a better understanding of pasture growth at different times of year and after different amounts of precipitation so you can predict forage availability. It'll help you anticipate dry periods. You can adjust stocking rates, increase rest periods or perhaps buy hay early, before prices go up.
Other ways he suggests to prepare for drought:
Diversify pastures. “Diversified pastures are more stable over time,” says Gerrish, who recommends mixtures of cool- and warm-season grasses plus legumes.
Diversify livestock. A diversified operation “gives you a lot more flexibility in what you can do to adjust the stocking rate,” he says. “It's very difficult to manage through a drought … if you have only one class of livestock.”
Use good overall pasture management. “Good management is the best drought insurance you can buy,” Gerrish concludes.