Planning Ahead For The Next Grazing Season

Winter is a great time to assess the previous years grazing season, and plan to make improvements in the grazing system for the next year. It is tempting to read about the latest pasture fertilizers or pasture seed mixes advertised in the farm magazines, but there are less expensive ways to increase pasture quality and quantity.

So before spending the money on re-seeding, first lets make sure the problem isn’t being caused by the grazing management system. In perennial pastures, overgrazing damage is one of the most common causes of poor pasture quality & productivity. If a pasture is tilled and reseeded, but the grazing management system is not changed to stop the ongoing damage from poor grazing, then reseeding will only provide a temporary solution to poor pasture quality.

The way that livestock graze changes the pasture plant species to either include more productive and palatable species, or towards less desirable plants. Under good grazing management, productive grazing adapted plants will thrive, while poor quality pasture plants will die out. Grazing adapted legumes such as white clover will naturally spread naturally, grasses will spread by tillering (side shoots), while weed species that do not like to be grazed frequently will grow less vigorously and die out.

The basis of good grazing management is allowing pasture plants enough time to rest after each grazing in order to photosynthesize and replenish the energy stored in the base & roots of the plant. Repeated grazing, without adequate time for plants to re-grow, results in plants that weaken, may stop growing and die. These weakened plants will not be able to compete with weed species, and won’t be able to hold the soil as well, resulting in bare soil and erosion. Some grasses and clovers will survive continuous grazing by staying very short, never growing tall enough for livestock to easily graze. Other areas in the same pasture will be rejected by livestock, soon growing up into weeds, brush or small trees. So an overgrazed pasture will often have areas which do not appear to grow much forage at all, while other areas may be overgrown and weedy.

Overgrazing damage happens whenever a plant that is still growing from carbohydrate reserves rather than from active photosynthesis is grazed. This will rob pastures of future production, and when repeated, results in desirable forages dying, and being replaced by undesirable weeds or unproductive, slow growing plants.

Some of the common situations that result in overgrazing damage include:

Removing interior fences at the end of the grazing season to let cows “clean up” pastures.
Having a “rotational” system of 6 or 7 paddocks, with each grazed for 1-2 days over the entire grazing season.
Leaving animals in the same pasture for a week or more.
Returning animals to the pasture before all of the plants have re-grown.
Not adding additional acres into the grazing rotation when plant growth rates slow.

Grazing management: Poor grazing management and overgrazing damage can happen even in a well-designed system, so a good understanding of how pasture plants grow and how they respond to different types of grazing management is important.

In a continuous grazing or set-stocked system, plants are continuously grazed as they grow and don’t get a complete regrowth period. In a rotational system with a non-variable recovery period, plants get a regrowth period, but it is not long enough during some of the grazing season. So both these systems result in overgrazing damage.

In contrast, Managed Intensive Grazing (MIG), and Holistic Planned Grazing are grazing systems where a paddock is grazed by a group of animals and then rested for as long as the plants need before it is grazed again. Both systems have regrowth or rest periods which are varied to allow plants to recover before the next grazing cycle. So in this system, when pasture plant growth rates slow, the speed of the rotation through the paddocks is also slowed. Some of the strategies to get through the times of year when pastures grow more slowly (mid summer slump) include:

Additional land is added into the grazing rotation, often by grazing hay fields or other cropland.
Irrigation can be used to keep plants growing rapidly.
Annual crops such as sorghum Sudan grass, millet or other warm season grasses or grain crops may be used as part of the grazing rotation.

A well-designed MIG or Holistic Planned Grazing system can significantly increase forage production and quality and improve weed management. In a good MIG system, tillage and reseeding of the pastures every few years is generally not necessary since the cattle grazing will actually improve the pasture over time.

Winter access to pasture—another source of damage Another cause of damage to pastures is allowing livestock access during the non-grazing season when soils are wet, or during freeze/thaw conditions. Soil compaction and damage to plant roots from winter access will sometimes be obvious, while in other situations it will result in slower spring growth rates and overall decreased pasture productivity.

Grazing system design One way to prevent overgrazing damage is to make sure the grazing system is correctly designed. Many farms have a grazing system that may be outdated, or may have been designed for a different herd size and management system. Often the grazing system infrastructure does not meet the farm’s current grazing management goals and needs to be updated.

Take the time to re-assess the paddock size, number of acres of permanent pasture and number of acres available to graze after crop harvest. If the paddocks are too small or there is not enough total acreage, this will usually result in overgrazing damage and low DMI (dry matter intake).

Paddock sizing: The paddock sizes will depend on how many animals are in the group, how much pasture dry matter (DM) they need, how long they will be in the paddock, and how much feed is in the pasture.

The simple formula for calculating the number of acres needed per day is to divide the number of pounds of pasture DM required for the whole group by the number of pounds of pasture DM available per acre. This will give you the number of acres needed per 24 hours. It will be necessary to adjust the actual paddock size based on several factors including:

How much feed is being fed in addition to pasture? This will affect how much DMI they actually need from the pasture.
Pasture height—the plants must be tall enough. Plants too short will not allow cows to get enough DMI even if you make larger paddocks.
Plant density may be lower or higher than estimated. If density is low, there will be less DM available per acre.
Weeds, rocks, swamps, and other things in the pasture will need to be factored in.

Once the number of acres needed per day is known, multiply this by the number of days the pastures need to re-grow after each grazing. This will tell us the total number of acres needed.

If the decision is made to expand or update the grazing system, some grazing system resources & ideas to consider include:

Mapping & satellite imagery using freeware such as Google Earth, can provide the bird’s eye view of their farm as well as linear measurements for effective planning and design.
Cost effective electric fence technology, lane building techniques and portable water troughs
NRCS programs to assist with design, management and cost of improvements.
If adding additional land to the grazing system, use high quality cropland for dairy cow pastures instead of marginal land.
Test the pasture soils every few years to see if there is a deficiency or imbalance of nutrients.

Once the farms grazing infrastructure and management system has been re-assessed and a plan to prevent problems such as overgrazing damage is in place, then it may be worth taking a closer look investing in some of the new improved pasture plant seed mixtures, soil fertility inputs.