Items to consider when preparing pastures for 2013

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By Gary Carter

As we approach another year with our cattle operations it is important that we consider our pastures and the maintenance that will be needed. The following is a few items we need to consider as we prepare for 2013.
Seeding Forages or Renovations – Sometimes pasture and hayfields must be re-seeded or renovated to maintain proper stands. The time of year forage seeding occurs can determine weed species that will be most troublesome during the establishment phase. Seeding in late summer or early fall will enable the crop to become established and cmmplete with weeds such as large crabgrass and yellow foxtail that emerge the following spring; however, a spring seeding is vulnerable to these weeds. Common chickweed and other cool-season weeds that begin to emerge too late fall and early winter can compete with forages seeded in the fall.
When establishing grass-legume forage mixtures, it may be desirable to seed the grass component to late summer or fall and interseed the legume species the following spring. This would allow flexibility for use of a broadleaf herbicide, if needed, prior to seeding a legume.
Weed-Free Seed – It is also important to use weed-free seed to prevent the introduction of weedy plants. The seed tag should be examined to determine the purity of the seed and the potential presence of weed seed contaminants. The state regulations of the Kentucky Seed Law classify certain plants such as Canada thistle, johnsongrass, and quackgrass as noxious weeds and prohibit their presence in commercial seed sold in Kentucky.
Fertility – Adjusting the soil pH and nutrient levels according to soil test recommendations helps increase the stand density for desirable forage species. However, such practices as the addition of lime and/or proper fertilization alone are usually not effective in eliminating established weeds. In fact, some weeds such as common chickweed, crabgrass, and curly dock can respond favorably to fertilization and grow well in fertile soils.
Grazing Practices – Grazing can be effective and economical weed management tool. The greatest benefits are obtained when weeds are small. IN the early vegetative stage of growth, many weeds can provide a good source of animal nutrition that would be comparable to desired forages. However, the forage quality of weeds declines rapidly as the plan matures.
Animals tend to selectively graze certain plant species because of differences in the plant’s palatability; therefore, weeds such as horse nettle or tall ironweed become more prominent over time in grazed pastures because they are less palatable to the animal.
As grazing pressure increases, animal selectivity decreases; thus, more weeds are consumed by animals regardless of forage quality. Flash grazing (putting a lot of cattle, goats, or other livestock on a small area for a short time period) is one method whereby weedy-type plants could be consumed by the animal. Animals should be rotated off these areas to allow desirable plants to recover. A potential drawback of flash grazing is that the forage stand density may be reduced, allowing the germination and growth of other undesirable plants.
Mowing – Timely mowing or clipping of pastures can be beneficial for control of suppressing growth of erect weedy grasses and many broadleaf weeds. A primary benefit of mowing is to prevent or reduce seed production and spread of undesirable plants; therefore, moving should begin when weeds are in the stem elongation stage but before flowers or grass seedheads are produced. Fields mowed after weed seed become mature offer little benefit to minimize future weed problems.
Some weeds such as common cocklebur that are mowed when they are small or when clipped high may develop new growth from lateral buds. Ideally, mowing should be done when most weeds reach 12 to 18 inches in height. Although some plants when mowed will produce new shoots and seedheads, the number of flowers and amount of seed produced will be notably less than if the field had not been mowed. Best results are obtained if the vegetation is clipped as close to the soil as possible.
Frequent mowing, repeated over a three to five year time span, can deplete root reserves of some perennial weeds such as horse nettle or johnsongrass. This practice will help suppress their growth and reproduction.
Not all weeds are inhibited by mowing. Low-growing plants such as dandelions, crabgrass, and nimblewill tend to be more prevalent in pastures that are frequently moved.
It is important to mow or clip pastures that have been selectively grazed by animals. This helps to prevent or reduce seed production of weedy plants left by the animals. Timely mowing can also promote regrowth of desirable forage species; in fact, mowing can stimulate the production of tender new forage grasses for livestock to graze.
The benefits of clipping pastures may not be evident if mowing is not part of a complete pasture management system, particularly if mowing has been delayed until after new weed seed are produced or perennial weeds have been able to build up their root reserves.