Want to rejuvenate your tame pasture? Graze it.
Pasture management experts report that a well-executed grazing plan may be more effective than other methods designed to increase the plant population.
Studies show that mechanical disturbance within the top 10 centimetres of the soil has little effect on yields and may create problems.
Allan Foster of Saskatchewan Agriculture in Tisdale said the technique may allow invasive species to gain a foothold in the forage stand.
“At Melfort they found that mechanical aeration can actually cause plant injury in the first year reducing yields that year and then had little or no effect on yields in the second year of that study,” he said.
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Studies in Alberta showed similar results with some improvement shown at one site.
But overall improvements were limited in the long term and when averaged over multiple sites and growing conditions.
In wet years, the over-seeding of plants such as alfalfa, sweet clover and red clover with mechanical incorporation showed some plant establishment, but overall pasture yields were not improved.
Bart Lardner of the Western Beef Development Centre in Humboldt, Sask., said producers tend to carefully watch newly established pastures. But over time, they may manage less closely and as a result see a significant loss in quality.
“They manage them well when they are new and the cost and effort establishing them is still fresh in their minds,” he said.
Foster told cattle producers and pasture managers attending a Saskatchewan Forage Council and WBDC organized pasture school in Saskatoon on June 15 that often their cattle could better improve pastures than other techniques.
“Even resting a tame pasture isn’t the solution. In areas where trees were dominant plant species, prior to clearing for agriculture, they will return given the opportunity. So unlike southern grazing lands, where grass was historically dominant, rest is not a technique that works unless a pasture was heavily over grazed,” he said.
Foster said defining pasture condition is a good start. When 76 to 100 percent of production comes from desirable species, a pasture is considered excellent. When that range is 51-75 percent it is considered in good condition, 26 to 50 percent fair and when it is less than 25 percent it is considered poor.
“Don’t go out and look to tear out a fair-to-good pasture and expect it to pay off economically,” he said.
Shortening grazing periods on plants when they are in their critical early production stage will add to root growth and is critical for alfalfa’s winter survivability.
“You may need to move cattle twice as often, leaving plenty of material in the field for a couple of seasons to get out invasive species and clean up a pasture,” he said.
Foster also recommended moving salt and water where possible, to encourage better cattle and manure distribution.
Fertilizer applied in early spring can be a year-by-year aid to pastures that have lost their carrying capacity.
A well-managed pasture with good nutrient distribution by the animals will need only occasional fertilizing. Applications of no more than 50 pounds per acre of nitrogen will produce the biggest gains, but soil tests will indicate other nutrient shortfalls.
Phosphorus and sulfur are necessary for alfalfa to flourish.
However high nitrogen prices and regulations limiting the use of ammonium nitrate have raised doubts about the economics of fertilizing pastures.
Expected returns in all three soil zones across Saskatchewan show that for 2006, based on 45 cent per lb.
nitrogen, 26 cent phosphorus and a $4 application cost, a balanced fertilizer application yielded a positive economic return only in the heavy black soils near Indian Head or the grey land in the Pathlow area near Melfort. Returns from those areas varied from break even to $1.23 per acre.
“If you know you have to carry 40 more heifers this season then you need to cost a fertilizer application and consider that it may or may not have any effect beyond a single year,” he said.
“If it’s a pasture of poor condition, it makes the most sense to rip it up and start again,” he said.
When starting a new pasture stand, agrologists recommend producers allow cattle to graze the existing pasture heavily until late July.
As soon as it shows signs of regrowth, spray it with gylphosate. Then work the soil or sod seed an annual crop the following spring and spray with gylphosate before or immediately after harvest.
Foster said in the second year, plant another annual grain or forage crop and repeat the spraying, or plant an annual crop with a companion perennial forage.
