Consider frost-seeding pasture
Farmers wanting to add to the stand or improve forage in their existing pastures should consider using either the frost-seeding method in February and early March, or interseeding later in the spring months. Brian Lang, Iowa State University Extension field agronomist at Decorah, says you can use either method to thicken up or improve pasture depending on which practice best fits your situation.
Frost seeding involves spreading forage seed on existing pastures during late winter or early spring while the ground is still frozen. Freeze-thaw cycles then provide shallow coverage of seed, with help from early-spring rains. Frost seeding is the easiest method farmers have to add new forage grasses or legumes to their pasture, and is likely the least-expensive method. To increase its chances of success, you should spread the seed on the thinnest pasture sod areas and where bare soil has been exposed due to heavy grazing or disturbance.
Never frost-seed on top of snow. “The goal of frost seeding is to get seed on bare soil,” explains Lang. What if you do the seeding and then it snows? “It is perfectly OK if snowfall occurs after frost seeding. In fact, it may be a benefit,” he says.
Red clover has been the forage species of choice in Iowa for frost seeding. Other legumes, such as white clover and birdsfoot trefoil, also can be frost-seeded but with less success than red clover. In general, frost seeding doesn’t work as well with grasses, notes Lang.
Research has determined that following a few important steps will improve the success of frost seeding. Refer to the ISU Extension publication PM-856, “Improving Pasture by Frost Seeding,” for suggested seeding rates and other guidelines.
• You can thicken or improve pasture sod using frost seeding or interseeding.
• Late winter and early spring are target planting dates for grasses and legumes.
• Select compatible, competitive forage species; reduce existing competition.
Interseeding is an option
Interseeding is another method that can be used to thicken and improve pasture productivity. Interseeding involves using a no-till drill to aid in the incorporation of a legume, or a more productive grass into an existing pasture sod. Interseeding is normally done from mid-March through early May in Iowa, when soil moisture and temperature are more suitable for rapid seedling establishment.
Interseeding can be done with relatively few field operations, notes Lang. Opening of the grass sod, shallow seed placement and seed coverage are required. A number of drills can be used in sod seeding. Some drills may have improved features related to better sod penetration, depth control, seed metering or coverage. Equipment limitations for sod seeding implements sometimes are overcome by operator experience and shop modifications.
“Legumes interseeded into grass sod should increase pasture yield, improve forage quality, and eliminate or minimize the need for nitrogen fertilizer,” he says. “The goal is to achieve about a 40% legume stand for the legume to supply all of the nitrogen fertility needs for the grasses in the forage mixture. Both legumes and grasses have been successfully established by interseeding, and with a higher probability of success than for frost seeding.”
Delaying your seeding into late spring to improve growing conditions often leads to greater competition from existing grass sod. Close grazing in the fall or spring, ahead of interseeding, will reduce sod competition. Labeled, contact herbicides are sometimes used to temporarily reduce competition from plants in the stand. When using any pesticide, read and follow label instructions. Interseeding success depends a lot on attention to details, timeliness, careful management of sod competition, control of seeding depth and a little bit of luck with weather.
Source: Iowa State University
This article published in the February, 2015 edition of WALLACES FARMER.
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