A reader from the West Coast writes: “Uneven summer grazing has left one of our fields with grass 18 inches high in some parts, and chewed to the nubbins in others. What can I do to prevent this from happening next year?”
My smart-aleck answer (and the first one that came to mind) is to open a golf course. This shepherd already has a good mix of putting greens and rough.
But when it comes to uneven grazing, our correspondent is far from the only victim. “It’s a very common scenario that I see on many farms,” says Jack Kyle, pasture specialist with Ontario’s Ministry of Agriculture, Food and Rural Affairs. On the plus side, fixing the pasture is probably cheaper than taking up golf. A modest investment in fencing, understanding livestock behaviour and paddock planning can produce a field that’s less like a golf course and more like a productive pasture.
The details
Last July our correspondent turned 23 ewes into a six-acre, irrigated field of orchard grass. The sheep grazed the field for two months. Things went well at first, but “after about five weeks the sheep started re-grazing some areas and leaving other areas utterly alone,” the farmer says. “Some grass was grazed into the ground,” he adds. “The rest grew rank.”
It’s tempting to see the ewes as spoiled kids who won’t eat their veggies. Maybe if they were left out on the pasture they’d learn to clean their plates?
Don’t count on it, says Kyle. On this relatively large pasture, the sheep, “ate what they liked and left the rest . . . then what is left gets mature, coarse and is refused for the rest of the season.” Like school kids let loose in an all-you-can eat restaurant, they gobbled their favourites — the ovine equivalent of ice cream, chicken wings and onion rings — and ignored the Brussels sprouts, beets, and kale.
After they finish the yummy stuff, the grazers discover the rest of the salad bar has gone off. The neglected grass is mature and tough, smeared by dung, or flattened for use as a bed. It’s gross. The ewes would rather nip off the tender green shoots from the areas they’ve already grazed than eat that overgrown stuff.
Reworking the buffet
Rather than lose a test of wills with your livestock, consider altering the dining room rules. Instead of laying out too much grass and allowing animals to pick and choose, opt for a smaller smorgasbord, in a more confined area. When the stock cleans their plates — eating about half the available grass — shift them to a new paddock.
Here’s how:
1. Subdivide pastures
Use temporary electric fencing and a flexible watering system to restrict animals to smaller areas for limited times. Increasing “stock density” on the pasture (see sidebar: Management tool) puts animals in a competitive grazing situation. They no longer have the luxury of seeking out the Nanaimo bars from the dessert tray, but instead must grab what they can before someone else does. The result is more even grazing pressure and more uniform grazing.
2. Limit grazing
Getting grazed once isn’t hard on grass, but it’s tremendously damaging if the plant is re-eaten a few days later as it’s starting to grow again. This second bite saps root reserves, weakens the grass and leads to an unproductive, erosion-prone pasture.
Keep grass healthy by limiting the time stock graze individual paddocks, especially when grass is actively growing. As a rule of thumb, it’s best to change paddocks every three days or less.
3. Give the grass a break
Ensure pastures get sufficient rest for healthy regrowth. Once stock has moved on, give your pasture enough time to fully recover, typically 25-60 days, sometimes more, depending on weather, climate and region.
4. Be flexible and deal with the surplus
Managed grazing is a dynamic process, one that cannot operate on a pre-set schedule. Be prepared to adjust your plans, tweak paddock size and alter timing. Grass grows most rapidly in the spring, so prepare to cope with a surplus by moving stock through paddocks more quickly, harvesting hay or silage or clipping the mature growth. Many regions in Canada also face a mid-summer slump in grass output, so have a plan to deal with that too. Good options include grazing annual forages (green corn, oats, ryegrass etc.), and bringing hay aftermath into the rotation.
5. Relax. It’s not going to be perfect
Despite your best efforts, some grass will go to seed. Some paddocks may be overgrazed. But if you aim to get things mostly right, most days, the benefits of good management will accrue over the months, years and decades. The long-term payoff is stronger soil, healthier livestock and a more resilient, profitable farm operation. (And one that doesn’t look like a cut-rate golf course.)
Uneven grazing is harder to control on pastures with mixed terrains—livestock would rather regraze grass in sunny areas rather than graze longer, lush-looking grasses in shaded and damp areas.
Management tool: Stock density
“Stock density” describes short-term grazing pressure on a particular area. In the example provided by the B.C. farmer, placing 23 ewes (averaging 150 pounds each) on six acres for two months produced a stock density of 3.8 ewes, or 570 pounds per acre. As density goes, it’s relatively low. The long, two-month grazing period also makes management difficult, because it takes weeks to see the impact of the grazing.
Now let’s increase the density by dividing the pasture into 24 quarter-acre paddocks, and rotating the sheep through them. Right away, density rises to almost 14,000 pounds per acre, a pressure that’s high enough to allow a farmer to assess grazing impact within a day (sometimes an afternoon), and make plans to move to the next paddock.
Appropriate stock density “results in uniform grazing, consumption of otherwise unpalatable plants, uniform manure distribution and the pulsing of nutrients into the system,” writes U.S. pasture researcher Jim Gerrish. The key, he adds, “is knowing when to turn the (grazing) pressure on, and when to turn it off.”
Paddock planning
While many graziers are trial-and-error types, a few minutes with a pencil and calculator will provide a rough idea of available forage, and help plan the number and size of paddocks for intensive grazing. Here’s an example from Jack Kyle, once again using 23 ewes on six acres. (Forage weights and intakes are provided on a dry matter basis.)
• Available forage: Productive grass yields 250-300 pounds per acre per inch of height. If the sheep graze the pasture from ten inches in height down to about four, they’ll use about 1,500 pounds of forage per acre.
• Stock requirements: Sheep need to eat 2.5 per cent of their body weight per day, but let’s round that up to 3.5 per cent to cover wastage, pasture that’s refused, etc. If each 150-pound ewe needs five or six pounds of forage a day, the whole flock of 23 will eat 120-150 pounds, more or less.
• Paddock planning: Since each acre offers about 1,500 pounds of forage, or roughly ten days of grazing per acre, the entire six-acre field — grazed evenly — provides about 60 days of feed. In a system where sheep get fresh pasture every day, each paddock should cover a tenth of an acre, or about 4,500 square feet. To move every three days, you’ll need about 15,000 square feet and so forth. As Kyle says, “Using this method of grazing the livestock will consume most if not all of the plants, and we leave a good residual to start the next cycle of growth.”
- Ray Ford