Restoration: Soil Building and Grass Height Management
Many pastures are just in need of some "restoration." Examples of restoration include fertilization, liming, weed control and improving the movement of animals through the pasture to control grass height. Often, "restoration" can be applied and to bring pastures back to productivity.
Soil testing is a tool that is underutilized by many pasture managers. Testing can help us understand how the soil resource is performing and where to make the next soil management decision. For example, a soil test may reveal acidic conditions that are preventing plants from adequately accessing the nutrients being supplied by manure. In this case, the use of lime is justified to increase the utilization of manures by plants. A basic soil test kit from the Ag Analytical Lab at Penn State University is available through county extension offices across the state for $9.00 and covers about 10 acres.
In addition to the fertility measures included in a basic soil test, pasture managers also may want to test for organic matter content, which influences a soil's biological activity, porosity and ability to hold nutrients. Pasture managers can monitor the change in organic matter over time by regularly measuring it as part of their soil-testing routine. Penn State offers an organic matter content test as a $5.00 add-on to its basic soil test kit.
Weed management is directly tied to soil fertility. Weed problems in pastures are often the result of overabundant or insufficient soil nutrients or improper pH that affects nutrient availability. If grass cannot grow due to inadequate nutrients, then weeds will be more competitive than the grass. Overabundant nutrients can cause weeds to grow very vigorously. Using herbicides in pastures is mostly justified where we need spot treatment and they should be part of an integrated approach--not the sole answer to weed control.
Movement of animals
Animal movement through pastures has a tremendous effect on pasture growth and weeds. In southeast Pennsylvania, the largest barrier to pasture productivity is animal overstocking. Farms tend to overstock due to the high land values and cost of farming. Other regions of the state have a tremendous opportunity to utilize more grass acres. Overgrazing or "continuous grazing" prevents abundant grass growth. If individual grass plants cannot regenerate leaves, they lose vigor and die out of the pastures, and are replaced by weeds.
Farms that are overstocked need to use a rotational or managed grazing system. A grazing system requires more subdivisions or "paddocks" which animals are moved through in order to prevent overgrazing. Animals are removed from a paddock when grass heights are no shorter than 3 to 4 inches. Often, a "sacrifice lot" is needed. A sacrifice lot is a paddock where animals are moved to when pastures can no longer grow. The sacrifice lot allows animals to be kept off the pastures until the grass regrows. Although this measure requires stored feeds to be used, it will result in greater grass production (more tons of dry matter).
Farms that are understocked have more options. Usually those farms can use rotational/managed grazing and make stored feed (hay, baleage or stockpile) with the excess growth.
Renovation Comes with Risks and Rewards
Renovation is defined as the complete destruction of and subsequent reestablishment of a pasture. This is best done when the pasture has been severely overgrazed and most of the grass has been lost. Usually, weed growth is dominant (i.e., 40% or less of grass in the pasture), and the weeds present are aggressive and not considered by animals to be palatable. An evaluation tool that can be used by managers to evaluate the need for renovation is a Pasture Condition Score, developed by the USDA-NRCS to help assess the quality of the pasture.
Renovation should not be taken lightly. It is costly in terms of inputs, labor and time (including the time loss of those acres for production). The overall goal should be to rapidly establish a seeding with minimal weed competition. The following suggestions are all techniques to arrive at this goal:
- Seed in the early fall months. Soils will be warmer than in the spring, which results in rapid germination and crowding out of weed growth.
- Soil fertility testing is best done several months in advance in order to make decisions and gather inputs. If the pH is adequate, a producer could consider using no-till to establish the grass, assuming they have access to a no-till seeder. If the pH is very low (below pH 6), consider using tillage. Tillage will mix the lime throughout the soil.
- Make the decision regarding tillage or no-tillage based on access to equipment or a custom applicator. Modern no-till seeders do an excellent job and are becoming more commonly available.
- If no-till is being used, kill the existing pasture with glyphosate ahead of the seeding date. Check seeding depth required by your seed mixture. Make sure the seed is being dropped into the soil, not the killed thatch layer.
- If using conventional tillage, make sure the seedbed is properly established. Prepare the seed bed so that it is firm. Your foot should leave an imprint on the soil surface.
- The pasture plants to be seeded need to be matched to the soil type to ensure plant survival over time. Seed mixtures have become more diverse and can include grasses and legumes. Managers should research what seed mixtures or combinations would work best for their site. New research indicates that a diverse pasture mixture (i.e. 6 species) can help with reducing weed competition more than a single monoculture can.
- Once your pasture is germinated and growing, the new plants need time to develop strong roots. Grow the pasture to flowering height, mow and bale, cutting as high as possible. Allow the pasture to regrow and then allow animals to graze.
- After establishment comes ongoing pasture maintenance.
Restoration and renovation are two approaches to maintaining a dynamic ecosystem that is constantly changing based on factors such as weather, grass height management, and fertility. Your goal should be to maintain a robust grass ecosystem that supports healthy productive animals with quality feed.
Summary of a Comparison Between Pasture Restoration and Renovation
Soil testing to identify fertility and pH; inputs applied as recommended. Build organic matter over time.
Use of rotational or managed grazing to maintain grass height. Grass height no shorter than 3-4 inches. Use of sacrifice lot if overstocked.
Work with existing plant diversity present in the pasture. Emphasize pasture management to keep grass and legumes competitive. Use of frost seeding to introduce legumes into pasture. May seed bare spots. Overseeding is difficult in competitive pastures.
Weed control is integrated. Spot treatments with herbicides for aggressive weeds such as horse nettle or Canadian thistle. Keep up fertility. Periodic mowing if lots of seed set by weeds.
Soil testing taken in advance to adequately address fertility BEFORE seeding.
New grass just established needs to grow to a height where it can be taken for hay and then can be grazed. Maintain grass height as in "renovation."
More emphasis on new seeds. Match species to site. Complex seed mixtures help with preventing weed establishment. Use of no-till or tillage to establish pastures is based on availability of equipment. Custom operators can be hired to do seeding and will do a superior job than do-it-yourself.
Weeds are best managed by controlling aggressive weeds before seeding, planting in fall, good grass stand establishment to crowd out weeds. Mowing and herbicides are not used until after plants are established.