Fall Management for Pastures: Renovate or Restore?
Posted: July 2, 2012
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 bring pastures back to productivity.
Soil testing is a tool that is underutilized by many pasture managers. If fertility and pH is low and the need for pasture production is high due to high stocking rates, take a soil test. If pastures are under-stocked and there is a grass surplus, take a soil test. Testing can help us understand how the soil resource is performing and where to make the next soil management decision. For example, if feed supplies become tight, then the use of lime is justified to increase the utilization of manures by plants. A basic soil test kit from the Ag Analytical Services Lab at Penn State is available through county extension offices across the state for $9.00 and covers about 10 acres.
I also recommend that organic matter content should be tested, along with fertility. Pasture managers can monitor the change in organic matter over time. Organic matter influences biological activity, porosity and the soil’s ability to hold more nutrients. If you take a Penn State soil test, add another $5.00 to the kit and check the box on the form.
Weed management is directly tied to soil fertility. Weed problems are often present in pastures due to an overabundance or insufficient amount of soil fertility or improper pH. If grass cannot grow due to inadequate nutrients, then weeds will be more competitive than the grass. If there is an overabundance of fertility, weeds can 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.
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, then plants lose vigor and die out of the pastures, replaced by weeds.
Farms that are overstocked need to use a rotational or a managed grazing system. A grazing system requires more subdivisions or “paddocks.” Animals are removed from the paddocks at grass heights at no shorter than 3 to 4 inches. A “sacrifice lot” is usually needed. A sacrifice lot is a paddock devoted to the animals when the grass can no longer grow. Animals are kept off the pastures until the grass regrows. Stored feeds will have to be used. This 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 existing pasture and reestablishment of the 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). The types of weeds are usually aggressively growing and not considered palatable by animals. An evaluation tool that can be used by managers to access the need for renovation is a Pasture Condition Score, developed by the USDA-NRCS to help assess the quality of the pasture. (See Resources)
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, crowding out weed growth.
Soil fertility 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 gotten more diverse and can include grasses and legumes. Managers are better off researching 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 than relying on a single monoculture.
Once your pasture is germinated and growing, newly planted pasture 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.
|Soil testing to identify fertility, pH and inputs applied as recommended. Build organic matter over time.||Soil testing taken in advance to adequately address fertility BEFORE seeding.|
|Use of rotational or managed grazing to maintain grass height. Grass height no shorter than 3-4 inches. Use of sacrifice lot if overstocked.||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.”|
|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 with seed. Overseeding is difficult in competitive pastures.||More emphasis on new seeds. Match specie 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 de seeding and will do a superior job than do-it-yourself.|
|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.||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.|
- Guide to Pasture Conditioning Scoring Website, USDA-NRCS
- Ten Questions about Pastures and Biodiversity Fact Sheet, USDA ARS Pasture Systems and Watershed Management and Research Unit
- Agronomy Fact Sheets (various topics)
- Diversity: A Graziers Best Friend: Part II