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Fall tips for productive pastures

Craig Sheaffer, Extension forage agronomist, Roger Becker, Extension weed scientist, Nathan Drewitz, and Troy Salzer, Extension educators

Pastures are important forage resources for many farms. The intensity of pasture use can range from continuous grazing to intensive rotational grazing and species composition of the pasture. The following general tips focus on  increasing pasture productivity this fall and next spring. Improved pasture management is even more essential now considering the stress imposed on grazing systems due to the wide-spread drought conditions these past two growing seasons. These tips may not apply to all pasture situations because of difference in producer goals. Overall pasture management schemes are provided at the web sites at the end of the article.

Assess pasture potential

Assess pasture yield potential as well as species composition and vigor. Also, note the amount of open space and annual and perennial weed composition of the pasture. Knowing its yield potential will help plan stocking rates and whether supplemental hay is needed. Differences in the stature and growth habit of grasses and legumes may require different grazing strategies to avoid overgrazing. Use scissor clippings or a pasture stick to better estimate yields for planning.

Avoid overgrazing

Although fall is a peak time for cool season grass and legume forage production, pasture plants are often recovering from hot and dry summer conditions. Stocking rates and grazing duration should be controlled to allow plants to store energy to improve overwintering and to develop resilient root systems. 

Consequently, begin rotational grazing with 2-7 day grazing periods when tall grasses and legumes have 10 inches of growth and stop at a height of about 4 inches. When short grasses and legumes are grazed, 2-3 inches of stubble should remain. Alfalfa is often a component of pasture mixtures and fall grazing from early September to November poses a special risk to its persistence. It is best to graze alfalfa only after a freeze of 26 F or below has occurred when regrowth potential from crown buds is minimal.

Minimize hoof traffic damage

Congregating livestock in certain areas of the pasture (e.g., around water or feed bunks) can destroy vegetation. During wet periods, livestock should be removed from pastures or moved to sacrifice paddocks where hay is fed. Temporary fencing can be installed to create sacrifice paddocks that exclude damaged areas and allow the pasture to rejuvenate. Moving livestock daily to new pasture can also spread hoof traffic over a wider area in a rotational system. 

A more aggressive approach to intensive rotational grazing allows for shorter durations and more control of the grazing residue.  Increasing the density also increases grazing efficiency from 40-50% up to 85-90%. This can be especially important during low forage production years.

Control weeds

There is no substitute for good pasture management to control weeds by preventing their establishment in the first place. Management that improves forage productivity, such as controlled grazing, forage species selection, liming, and fertilization, etc., also increases competition with weeds and reduces open space available for weeds to establish. With overgrazing and loss of forage cover, annual, biennial, and perennial weeds can be a problem. 

Improved total season grazing and fertility management will aid in reducing annual weed issues, but perennials may need to be controlled using herbicides. Fall is an excellent time to control perennial weeds such as Canada thistle, as plants increase carbohydrate flow to crowns, roots and rhizomes. This results in improved translocation of systemic herbicides resulting in more consistent and complete kill of crowns and lateral roots and rhizomes, often with lower labeled rates of herbicide. Fall and early spring herbicide applications also provide improved control of biennial rosettes from musk, plumeless and bull thistles. Always read the herbicide label prior to use.

Ensure the product is labeled for use on pastures, follow all grazing and haying restrictions, and comply with site and environment use restrictions.  A summary article of currently available herbicides from Iowa State University states, “The majority of herbicides used in pastures are growth regulator herbicides (Group 4). While products containing picloram (Tordon, Grazon P+D, etc.) and aminopyralid (Milestone, Forefront, Grazon Next HL, etc.) typically cost more than the ‘traditional’ pasture treatment of 2,4-D and dicamba, they generally provide better long-term control of perennials like Canada thistle. Products containing metsulfuron-methyl (Group 2; Escort XP) provide an alternative to the growth regulators.”

Adjust soil fertility

To determine soil pH, P and K levels, soils should be sampled and tested. Randomly take small soil samples to a 6-inch depth from 10 to 20 locations throughout the pasture and submit a composited sample to a soil testing laboratory. Synthetic fertilizers and manures applied by early September can stimulate plant growth and yield in the fall and following spring. Nitrogen is often the most limiting nutrient for perennial grass growth and should be considered for pastures with less than 30% legume cover. N rates for late summer-fall application are dependent on yield goals but can range from 30 to 50 lb/acre. Both commercial synthetic fertilizers and manures can be a source of nutrients for pastures.

Fertilizer guidelines for hay and pasture grasses

Consider mowing and dragging

If the pastures contain spots of annual weeds or mature residue from the summer, mowing can be beneficial. Mowing to a 4-inch height will stimulate pasture plants to regrow and have high quality, especially if seed heads have formed. Dragging areas with accumulated manures is a strategy to distribute nutrients and organic matter and to reduce livestock pests.

Pasture improvement

If pastures have a significant amount of exposed soil, reseeding with perennials has potential to increase forage yields the following spring. No-till seeding of appropriate pasture forages will provide seed at optimum planting depths but may require suppression of any existing vegetation. No-till seeding into pastures should occur in early September to allow forage plants adequate time before the frost to establish. 

Another option is to attempt frost seeding during the winter. For successful frost seeding, forage seed is deposited on the soil surface and is covered by freezing and thawing of the soil. Seeds then germinate and seedlings grow in the spring when air temperatures are favorable. For reseeding to be successful, livestock will need to be excluded for 40 to 60 days to allow seedlings to establish. 

Reseeding pastures can introduce new grasses and legumes that can improve pasture productivity. For example, meadow fescue, a relatively new, tall grass, has excellent yield, forage quality and persistence. Tall fescue and orchardgrass are other persistent grasses that tolerate frequent grazing during the year. Both meadow fescue and tall fescue are excellent stockpiled grasses that can be grazed later in the season. Perennial ryegrass is often used in pasture renovation because of its high seedling vigor, but it often does not persist more than two years after seeding.. 

Introducing legumes, like white clover, red clover and alfalfa, can enhance forage quality and also add nitrogen to the system that can replace N fertilizers. When frost seeding, white clover and red clover have the best chance to establish. Any renovation via interseeding or frost will have a higher rate of success if weed control is considered in advance.  

If a herbicide has been applied for weed control before seeding or interseeding, be sure to follow the labeled replant restrictions (if any) for the forage species being seeded before planting. Conversely, before applying a herbicide after new seedings or interseedings, follow the herbicide label guidelines and restrictions (if any) for minimum time interval following seeding, and that any labeled minimum crop stage or height have been attained.

Consider stockpiling of forage

If you determine that you have adequate forage, save or “stockpile” some of the pasture for late fall grazing by fencing-off an area. This will allow more efficient use of all pasture while extending the grazing season.

Consider supplemental pasture

While the focus of this discussion is on existing perennial grass or legume based pastures, sometimes their productivity may be inadequate to meet late-fall livestock herd needs. Other options include seeding and grazing spring planted small grains, annual ryegrass, turnips and warm season grasses like sorghum sudangrass. These forages can be available to graze as early as 40 days after seeding in late summer.  If winter rye is included, you may also be able to start grazing two to three weeks earlier the following spring. Using supplemental pastures allow your perennial pastures to regrow and maintain stand health when they're not overgrazed. 

Plan for the new year

By the fall of the year, we should have a good idea about good and bad aspects of the pasture system. If the pasture was inadequate for the livestock numbers, options are to increase the pasture productivity by renovation, fertilization or rotational grazing, increasing the pasture acreage, or reducing livestock numbers.

References

Grazing

Weed control


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