There aren’t very many freebies in farming. In this respect, bale grazing and bale unrolling offer a unique opportunity. The nitrogen from the manure and urine the cattle leave behind as they graze are gratis compared with feeding in a corral and hauling the manure to the field.
Research from the Western Beef Development Centre (WBDC) has shown that only one per cent of the original nitrogen from the feed is recaptured in a corral-feeding/manure-spreading scenario versus 34 per cent when winter bale feeding out on perennial forage. A 1,300-pound bale with 50 per cent alfalfa and 50 per cent grass has about 25 to 30 pounds of nitrogen.
Four years ago, Lorne Klein, forage development specialist with the Saskatchewan Ministry of Agriculture at Weyburn, set up a project to monitor how long the benefit of nutrients from the manure lasts in terms of increasing yields on perennial forages that have been used for bale grazing and bale unrolling.
His documentation supports previous trials at the WBDC indicating that unrolling bales appears to have a slight advantage over bale grazing in optimizing fertility. This is because the manure is spread more evenly across the field.
On average over the four-year period, one treatment of bale unrolling at 25 bales per acre boosted for-
age production by about 44 per cent. Bale grazing at the same rate bumped it up by 35 per cent. The benefit would be greater at higher bale densities and less at lower bale densities, Klein explains.
In this test, the cows were fed on a pasture containing a mix of alfalfa, smooth brome and Kentucky bluegrass during the winter of 2005. The yield benefit was greatest in the second year following bale feeding and dwindled away by the fourth season. The chart below shows the yields in grams per metre square on a dry matter basis for bale grazing (BG), bale unrolling (BU) and the check.
“Bale grazing and bale unrolling work better with rhizomatous grasses than it does for bunch grasses and alfalfa. The rhizomatous grasses, such as smooth brome, have more ability to grow through a thick trash layer than bunch grasses, such as meadow brome, Russian wild ryegrass and crested wheat grass,” Klein explains. “There is significantly less advantage to bale grazing or bale unrolling on alfalfa fields because alfalfa fixes its own nitrogen.”
The general rule of thumb when bale grazing is to place the bales about 40 feet apart from centre to centre, which equates to 25 bales per acre. “Ideally then, you would bale graze, wait one or maybe two years, then bale graze again on the spots between where you placed the bales the previous time,” he suggests. At the 25-bales-per-acre density, wait four years if you will be placing the bales on the same spots to avoid overfertilizing.