COCHRANE, Alta. – There are many ways to rejuvenate a tired pasture, but it usually depends on the producer’s goals.
Rebuilding plans should include an assessment of costs, methods, available forage types and fertility tests, Mike Preston of Crop Protection Services told a recent hay meeting in Cochrane.
“Annual fertilizer applications on these forage stands is something we need to take a look at as to whether you are spending your money efficiently,” he said. “You may want to spend your money in a different place.”
Newly seeded hay is an efficient user of nitrogen because the plants are young and growing, whereas a 25-year-old native pasture does not take it up as well.
“There are probably better ways to make those pastures efficient rather than fertilizing,” he said.
Cattle manure may be the best way to deliver nitrogen to an older stand.
Soil tests indicate what nutrients are available in the soil and measure pH and organic matter.
For example, a five tonne legume hay crop in central Alberta will need 220 pounds of nitrogen, 50 lb. of phosphorus, 200 lb. of potassium and some sulfur, said Rebecca Weber, also of Crop Protection Services.
“Your crop is going to grow to its first limiting nutrient, and that nutrient might be nitrogen or it might be phosphorus,” she said.
“The only way you will really know is to pull a representative soil sample.”
Soil test depths are important because many nutrients are mobile, depending on water flow. Many tests suggest six inches down, but plant roots go deeper than that and the results could show a richer soil than really exists.
“Soil test to make sure that stand has all the groceries it needs to grow,” said Kevin Dunse of Pickseed.
Another approach is to simply leave a tired pasture alone, but forage value is likely minimal if weeds have overtaken the stand.
“It is probably best to control the weeds and then do a fertility program to try and rejuvenate that pasture,” he said.
Producers can also introduce new and better species of grass along with fertility.
“That will also require the suppression of weeds or other undesirable plants because they offer competition to the plants you want,” Dunse said. “If you introduce new species, you don’t want it to be stressed by trying to compete with grasses that are already there.”
A cheaper approach may be to mow the field to remove weeds, brush and tree suckers but still allow the forages to come back. This is best done before weeds set seeds.
Controlled burns are an extreme option.
Some producers desiccate the field with chemicals in the fall and burn off the trash, but it is important to acquire a burning permit and make sure to control the fire.
Producers could later work the land with harrows to return carbon to the soil. Plowing the field down and replanting it is sometimes the only option.
“The variety you choose for your field is extremely important,” Dunse said.
No amount of management will help if the wrong variety is selected for a region.
Perennials are a better choice than annuals that do not survive the winter. They have deep roots to improve soil structure, reduce erosion, control fertilizer and chemical runoff and are more tolerant to extreme grazing.
Adding alfalfa to the mix improves palatability, digestibility and feed quality and allows animals to gain better and stay healthy.
Alfalfa, clover and cicer milkvetch can poke holes in the soil with their roots for better water penetration and fix nitrogen so that there is more protein in subsequent crops.
A stand should be seeded as early as possible to take advantage of moisture and cool days, which also reduces stress on young plants with less than 10 leaves.
Fertilizer should be limited in the first year of seeding because it may benefit only weeds.
Dormant seeding in the fall works in some areas, but it can be dicey in southern Alberta because chinook winds can fool the plants into sprouting too early.
Broadcast seeding is the easiest option but is best done before a rain because it helps seeds stick to the ground. Rolling a field will also help seeds stick and can thicken up a pasture. However, broadcast seeding is also unpredictable. Birds may eat the seeds and wind can blow them away.
Direct seeding, zero till and sod seeding is more successful because seeds are protected from birds, wind and frost.
Forages shouldn’t be seeded any deeper than one-quarter to one-half an inch. Seeds that are planted too deep don’t have the vigour to emerge.
Animal assisted seeding is another way to thicken a stand. The seeds are added in loose mineral or feed and then spread on the field through the manure.
Inoculated seed shouldn’t affect livestock, but don’t use pesticide treated seed. This method is best suited for legumes because the seeds have a hard outer coat that is softened in the digestive tract.
Producers should check the fields to make sure the seeds germinated and to assess weed populations compared to the plant count.
Rotational grazing can keep a new pasture in better shape and increases the amount of forage that livestock eat because fresh forage is always available.
Don’t graze new pastures until fall so that the new plants sustain less damage.