By all measures the early spring of 2018 in many areas of the U.S. was uncharacteristically wet, and significant damage occurred in many horse pastures. This damage will heal in time, but prevention is best accomplished by growing healthy pastures supported by strong roots.

How Grasses Grow

Grass growth isn’t overly complicated, but it’s a concept that’s important to understand when you’re managing horse pastures. So, here’s a very basic refresher course from the experts.

Grasses absorb sunlight in their leaves and produce energy from photosynthesis. This energy is then used for growth or stored in the roots as carbohydrates. When grass is grazed (or mowed), leaves are removed, reducing the amount of light the plant can absorb and energy it can produce. To recover, grasses use carbohydrates from the roots to regrow their leaves. But this comes at a price: Roots will physically shrink as these carbohydrate reserves are used up. Once the leaves are able to absorb adequate sunlight for photosynthesis, the root reserves are replenished. This is a normal process and allows grasses to recover from grazing and thrive.

How Horses and People Affect Grass Growth

In ancient times, wild horses and other grazing wildlife roamed over large areas, meaning they didn’t graze the same plant over and over. This gave each grassland area a chance to recover before being grazed again.

However, most horses today are confined to much smaller pastures and, thus, graze the same areas repeatedly. In fact, horses do this more than cattle or other livestock, as they prefer the short, tender leaves associated with new growth rather than the long, stemmy forage found in established plants. Repeated grazing eventually depletes root reserves. With no energy left to grow new leaves, the plant will die. And when wet conditions are present, such as those we experienced this spring, hoofs and tractor tires can also sink down into the soil, damaging roots and reducing carbohydrate reserves.

The bottom line is that healthy pastures need healthy roots. Think of the soil surface as a mirror: whatever you see above the ground is also what’s below. Pastures with tall, thick grasses will also have thick, healthy roots. These will hold the soil down during heavy rainfall, withstand hoof and tractor traffic better, and survive longer in droughts. Conversely, thin, short, overgrazed pastures will have shallow, sparse roots and will be more vulnerable to traffic, drought, and grazing.

Improving Pastures by Encouraging Root Development

Pasture managers can take simple steps to develop a healthy root system and, in turn, a more resilient and productive pasture.

The orchardgrass plant on the left was clipped to one inch each week for 4 weeks to simulate continuous grazing. The plant on the right was clipped at three and a half inches monthly to simulate rotational grazing. Both were then allowed five days to regrow. The rotationally grazed plant had more root reserves and was able to recover, while the other was depleted of nutrients and struggled to produce any regrowth. Watch a video of the experiment here. | Photo: Courtesy Krista Lea

• Use rotational grazing. Rotating horses between pastures gives grass time to recover from grazing. This can be as simple as moving horses to new paddocks every few weeks or even dividing a larger pasture in half. In time, increase the number of paddocks to give each one a longer rest period. Learn more about rotational grazing here.
• Mow less and cut grass high. In rotationally grazed pastures, mow only after removing horses from a pasture to even out the grass heights, usually around 4 inches. Allow pastures to grow up to 6 to 8 inches before grazing again. In continuously grazed systems, mow no lower than 6 inches and only when grass or weed seedheads are emerging.
• Fertilize pastures. Pasture growth can be limited by the availability of nutrients. Soil test pastures every 2 to 3 years and apply any needed fertilizers per recommendations. Submit soil samples to your local county extension office or work with the local farm store where you buy fertilizer to determine what your pasture needs to thrive. Learn more about soil sampling and fertilizing here.
• Install high-traffic area pads. Some areas where traffic is frequent, such as around gates, waterers and feeding areas will never maintain grass cover. Consider installing geotextile fabric under dense rock pads to reduce soil erosion and provide solid footing year around. Learn more about high traffic area pads here.
• Designate a sacrifice area. Sacrifice areas are just what the sound like: a small area that is sacrificed to protect larger pastures. Remove horses from pastures during periods of heavy rainfall or low growth (such as winter) to prevent damage and confine them horses to the sacrifice area, knowing that it will have little or no cover. This could be a dry lot covered in horse-safe gravel or simply a turnout paddock that’s allowed to be abused.

Good pasture management starts below the soil and results in strong, more resilient pastures. Highly productive pastures can feed horses and provide safe footing, reduce the cost of horse ownership, and protect natural resources.

Krista Lea, MS, UK Horse Pasture Evaluation Coordinator from UK’s Department of Plant and Soil Sciences, provided this information.