Weather is unpredictable, so developing a grazing strategy for the rest of the season is an important tool. Beef, forage, and livestock specialists at Alberta Agriculture and Forestry (AF) recently offered some thoughts on the factors that producers should keep in mind when formulating a plan.
“May and June are typically Alberta’s wetter months, so it is easy to forget about weather issues we could face later in the summer,” says Karin Lindquist, a forage and beef specialist. “With July and August usually the drier months in the province, plant growth can be affected by lack of moisture and higher daytime temperatures. The risk of a dry summer can be a very real concern.”
Lindquist says that a formal plan is ideal, but just formulating a simple plan for addressing grazing shortfalls is a start.
“A grazing strategy needs to take into account various factors, from plant responses to different conditions, to soil fertility, and the potential need for seeding annual forages as a backup. Finally, what grazing system to use will provide a basis to better manage pastures for greater longevity of those pasture stands and to reduce overgrazing.”
Take into consideration the types of plants in the pasture stands. Perennial plants have the ability to change their physiological growth rates with response to the change in conditions. When soil moisture decreases, plants begin to slow down their metabolic rates, and as a direct consequence of dehydration, the cellular contents of the plant cells become concentrated and the plant’s osmotic potential decreases. “In other words,” explains Lindquist, “when conditions are unfavourable, plant growth slows down to the point where it goes into dormancy. That is how a plant preserves itself until conditions are more favourable, and it can grow again.”
The beginning of the growing season is a good time to soil test and to address any soil fertility issues. “The main goal for soil fertility is to provide what nutrients are needed to ensure the plants are able to establish and maintain a healthy root system,” says Grant Lastiwka, livestock and forage business specialist. “A diverse pasture stand can be tricky as providing more nitrogen to a grass/legume stand will favour the grasses, but legumes will be reduced. To ensure the legumes and broad-leafed grasses remain in the stand, phosphorus is an important ingredient to add to a fertilizer pasture mix.”
Having a diverse mixture of forage species in a pasture provides more options for grazing, especially if there are different plant species that will grow better than others in more extreme conditions that may be experienced over a single growing season.
“Your forage should include legumes, the group of nitrogen-fixing forages with tap roots that can drill deep down into the soil to access moisture that other plants may not be able to access,” explains Andrea Hanson, beef extension specialist. “During dry conditions, sometimes the only green plants in the ditch are alfalfa or legume plants. To ensure that some species aren’t grazed out of a pasture, be sure to monitor what the plant percentages are, and to fertilize accordingly.”
Keep in mind that the root system is the foundation of plant productivity. Typically, what is seen above ground equates to what is below ground. The grass root system will remain strong when plants are grazed after the 3.5-leaf stage of growth in spring with only about 30 per cent removal most preferred. But when defoliated before the 3.5-leaf stage in spring with 50 per cent or more of a plant eaten, the plant’s roots will stop growing or will even slough off.
“Time is needed for the plant to not only grow back its leaves, but also its roots,” says Hanson. “In Alberta’s short growing season, early defoliation causes a huge loss in pasture production for the whole grazing year. As well, if a plant is later defoliated and grazed before it has recovered, the root system and the next year’s yield will be greatly compromised.”
Reducing the volume of a root system reduces the above-ground yield. “Grazing heavily in the spring when the plants are developing their root system will affect their ability to regrow and survive any drier conditions later in the growing season,” adds Hanson. “The more frequently plants are grazed without full recovery even later on in the season, the greater this impact will be seen in pastures this year or in future years.”
Litter, or old plant residue, is important for moisture retention and offers protection to new seedlings from being grazed down too far. However, too much litter can also hinder plant regrowth in the spring by not allowing enough sunlight to penetrate to the soil surface and slowing down the rate of soil warming. Says Hanson, “Selecting a pasture that contains the most plant litter would be a wise move if you need to put your animals out to pasture now and may encourage more regrowth in the coming year. The litter also contains some nutrients so it helps to supplement the animal’s diet and provide fill.”
A grazing plan can also include annual crops. Seeding fall rye, winter wheat, triticale, or a cocktail of annuals early in the year will provide vegetative pastures at various times throughout the growing season, depending on growing conditions. Add any fertility requirements necessary for better yields.
“Another option is to add any of these crops in with a silage or greenfeed mix to provide late-season grazing after the crop has been harvested,” says Lastiwka. “These annual crops take pressure off the perennial pastures in adverse conditions. Plus if they are overgrazed, it won’t affect the plants’ future next year since they are annuals.”
There are a number of grazing systems to consider when making a plan so a producer needs to find the one that works for that operation and its management. “Rotational grazing principles of monitoring plant growth/regrowth stages are important to employ to get the greatest and most stable pasture yield,” explains Lastiwka. “It ensures plant health both above and below ground. Preventing the herd from continually coming back to the same plants allows for recovery of both foliage and root system. Allowing the plants in a pasture to recover is critical to the pasture’s longevity and production.
“However,” adds Lastiwka, “if a pasture has to be sacrificed one year, providing a longer rest period the next year would allow the plants that survived to set seed and help rejuvenate the pasture for future use. For many of us who were short of moisture last year, that is the case this year. If grazing is about one-half to two-thirds the cost of hay or silage systems, you will be well rewarded by planning your grazing for a longer growing season.”
For more information visit the Alberta Agriculture website for its factsheet Calculating Grazing and Forage Needs.