The concern that sheep inherently destroy grass is understandable, as visible damage often appears when they graze a pasture. Sheep are an effective tool for managing forage, but their unique grazing style means poor oversight can lead to significant degradation of the sward. They possess a natural ability to select and consume forage efficiently, yet this requires careful oversight to maintain the health and productivity of the land. The true threat to a pasture is not the animal itself, but how its grazing behavior is managed over time.
How Sheep Graze
Sheep are anatomically equipped to graze grass much shorter than larger livestock like cattle. Unlike cattle, which use a long, rough tongue to wrap around forage and tear it off, sheep utilize their highly flexible, cleft upper lip to manipulate the plant material. They then press the grass against a hard upper dental pad with their sharp lower incisor teeth, allowing them to bite off blades with precision. This specialized mouth structure enables sheep to crop the grass extremely close to the soil surface, reaching the lower leaves and stems that other grazers cannot easily access.
This close-cropping ability makes grass plants vulnerable. The crown, or growing point of the grass plant, is where new leaves and tillers originate. When sheep consistently graze below the functional leaf area, they remove the photosynthetic machinery needed for regrowth. If sheep remain in one area for too long, they can repeatedly nip the grass down to a height that compromises its survival.
The Real Causes of Grass Death
The death of pasture plants is a direct result of two management failures: overgrazing and soil compaction. Overgrazing is defined not by the number of animals, but by the duration of time they remain in a single location. Allowing continuous close cropping starves the root system because the plant cannot perform the necessary photosynthesis to sustain itself.
When the leaf area is repeatedly reduced below the two-leaf stage, the plant’s energy reserves stored in the roots are depleted, and root growth slows significantly. This prolongs the plant’s recovery time, eventually leading to plant death and pasture degradation. A dense concentration of animals in a small area can also cause significant mechanical damage to the soil structure.
This physical damage is known as soil compaction or pugging, especially when the ground is wet. Sheep hooves, which are relatively small and sharp, exert substantial downward pressure, reducing the spaces between soil particles. This limits the movement of air and water into the soil, which is necessary for healthy root function and nutrient uptake. Compaction smothers the grass by restricting root growth and limiting the soil’s ability to cycle nutrients, leading to a decline in productivity and eventual loss of the sward.
Maintaining Healthy Pastures
Preventing pasture damage relies on prioritizing the grass plant’s need for recovery time. The most effective measure is rotational grazing, which involves moving sheep frequently to new paddocks. This system ensures the animals graze hard and fast, utilizing the forage efficiently, and then move on to allow the grazed area to rest for an extended period.
During the rest period, the grass regenerates its leaf area and restores energy reserves in its roots. This process can take 15 to 21 days during peak growing season or 90 days or more in the winter. Management focuses on leaving behind a specific residual height, typically 4 to 5 centimeters, which holds the plant’s sugar reserves and allows for rapid regrowth. Calculating the appropriate stocking density—the number of sheep per acre—is also necessary, ensuring the available forage matches the animals’ needs.
Protecting the soil from compaction is important, especially during adverse weather conditions. When the ground is saturated from heavy rain or snowmelt, the risk of pugging increases dramatically as the soil structure is more vulnerable. During these times, it is advisable to move the flock to a designated sacrifice area, such as a dry lot or feed pad, which absorbs the hoof traffic damage. This measure prevents the long-term degradation of the permanent pasture, allowing it to remain healthy and productive when the growing season returns.