Grazing practices employed this fall greatly affect the grass growth next spring. The hot temperatures will soon be over and fall weather will be here. It’s time to be thinking about fall grass utilization and how it will affect next year’s spring growth. Those of us who have irrigated and improved pastures may be tempted to harvest more forage this fall than is good for the plants’ well-being.
Fall is the season in which our region’s cool season grasses develop the embryonic tissue, the apical meristems in the plant’s crown, that become next spring’s growth. If the grasses are grazed down too close to the crown, the meristems will not be developed to full potential and the plant will not produce as well as it could next spring. So, this is one of the most critical periods in the grass plant’s growth cycle and care must be taken to manage accordingly.
What is too close? How much grass tissue should we leave? Steve Fransen, Washington State University forage agronomist, suggests 3 inches, for most grasses, is a reasonable amount to leave. He points out that the base of the stem, in the crown area, is where the grass plant stores plant sugars.
These sugars, known as fructans, are needed to provide energy for plant regrowth. When grasses are grazed too close, this energy source is reduced, making the plants less able to respond next spring, which reduces the potential for survival of the plant.
Leaving an adequate amount of residual plant tissue is particularly important in the fall, but is a generally good practice all during the growing season. This is because root growth and root survival are closely related to the amount of leaf tissue remaining after grazing. Research shows that the more leaf area removed in grazing, the greater is the loss of root tissue and root function.
The recovery period, after grazing, allows plant leaves to grow. This enhances the plant’s ability to produce carbohydrates for storage and aids in root growth. All this promotes overall plant vigor.
A key factor for the manager is to determine the most appropriate recovery period. The season, amount of moisture and other growing conditions influence what the recovery period should be for a particular time during the growing season. In the spring, when the growth rate is fast, the recovery period can be shorter than in the summer, when the growth rate is slower.
The most appropriate recovery period for a specific pasture or paddock depends on the season and conditions prevalent. It varies with the type of plants, the available moisture, the amount of residual forage, the season and other factors.
With irrigated pastures, it may be as short as 15 days in the early growing season to as long as 35 days in the hot weather. In the arid rangelands, it may mean having only a few days of grazing each year with most of the year for recovery. The appropriate recovery period is best determined through the observations and experience of the grazing manager.
For the forage plants to stay healthy and productive, grazing animals should be removed in time to leave an appropriate amount of residual plant tissue and there must be adequate time for plant recovery before being grazed again.
A grazing plan should be based on the best information available regarding the plant growing patterns in the specific area and the outcome desired. As the plan is put into action, the manager needs to keep close watch on what is happening and to adjust according to what is observed. It is only in this way that the target results can be achieved.