This past week I received a call about how to improve a poor alfalfa stand.
This situation brings up many questions that must be answered before making any decisions about what to do.
The first is, “Can over-seeding (planting alfalfa into existing stands) be done?
Maybe, but it’s a high-risk practice for several reasons.
• First, alfalfa is a slow growing perennial and has a hard time competing with existing plants (1,000 x its size) and weeds for light, nutrients, and water. Additionally, soils in established fields are not conducive to germination.
• Second, if the cause of the stand loss is not corrected, the original cause of plant loss is likely to repeat itself.
• Third, alfalfa produces autotoxins that reduce development of seedling plants, and so suppress growth of young alfalfa seedlings in existing stands.
Species Can Be Used to Thicken a Thin Alfalfa Stand?
Several other forage species have been utilized for thickening existing alfalfa stands, including cereal grains (oats, beardless barley, wheat, triticale); annual and perennial ryegrasses; sorghum-sudangrass; orchardgrass; and red, berseem and ladino clovers (1).
Choice of species to over-seed into alfalfa depends on the desired forage quality, yield, and length of stand extension needed.
Over-seeding with legumes such as red clover will result in a high-quality product suitable for lactating dairy cattle when harvested at the appropriate stage (bud – <20% bloom). Unless harvested early (boot stage), over-seeded cereals and grasses may result in a slightly lower quality forage, but will provide adequate tonnage and nutrients for dry cows, bred heifers and other livestock.
Grasses over-seeded into alfalfa stands generally produce higher yields of forage than over-seeded legumes, so should be considered if higher yields are important.
Adding a perennial species such as orchardgrass is useful if extending the stand life beyond the current growing season is desired. Annual grasses and cereal grains provide tonnage early in the growing season, but decline by mid-summer.
They would be an appropriate choice for a stand that will be taken
out for a late summer seeding after one or two cuttings.
What can I
expect for forage quality and yields?
According to WI research conducted at the UW Lancaster Agriculture Research Station (Tables 1), orchardgrass, diploid/tetraploid Italian ryegrasses, or oats followed by sorghum-sudangrass all produce yields and forage quality comparable to that of a thinned alfalfa stand (less than 3 -5 plants/ft2).
In this study, all forages were cut 3 times by Sept. 1st in each year, except sorghum-sudangrass, which was cut twice in 1997 and 3 times in 1998/1999. Cuttings were timed to optimize forage quality and quantity.
Research from other states also suggests that over-seeding other forages into alfalfa has potential to extend stand life one or more growing seasons, and can be considered as an alternative when economics or conservation planning require maintenance of the current thin alfalfa stand.
What establishment practices are recommended for over-seeding alfalfa?
Establishment Methods Research suggests that the benefits of over-seeding on yield are not seen unless the alfalfa stand is less than 5 plants/ft2 or 40 stems/ft2.
Older alfalfa stands that carry a heavy weed load of species such as dandelion or quackgrass may be better candidates for rotation to another crop rather than for over-seeding to extend the stand life.
Ideally, cool season grasses, legumes, and cereals should be over-seeded in April as soon as the soil is dry enough to plant into and the extent of winter injury damage is evident.
Warm season annuals such as sudangrass should be planted later, when the soil has warmed to approximately 60°F.
While a no-till drill is desirable, seeding with a conventional drill or broadcasting seed will also work. Tillage is usually unnecessary if seeding is done early enough and the soil is moist.
Fertilizer needs and other management considerations
Legumes added to a thin alfalfa stand should be inoculated prior to seeding to ensure adequate nodulation and nitrogen fixation.
Cereals and grasses may need additional nitrogen at rates to support yield and forage quality. If manure has been applied to the alfalfa stand during the previous fall or winter, additional nitrogen may not be necessary.
Forage from over-seeded fields should be harvested at the appropriate stage for desired tonnage and quality and may be put up as greenchop, haylage, baleage or dry hay, depending on harvest conditions.
Early harvest of cereals and annual grasses (prior to boot stage) will maximize quality and encourage a second cutting. Perennial grasses are usually harvested slightly later as they will need a longer initial establishment period.
Red clover can be harvested at the same times that one would harvest alfalfa to obtain highest quality. One disadvantage of red clover is that it cures to a dark brown/black color, which some producers find visually undesirable.
However, if harvested and stored properly, red clover’s quality is very comparable to that of alfalfa despite the darker color.
Warm season annual grasses such as sudangrass should be cut at 24 – 30 inches tall and harvested on a 30 – 40-day schedule for dairy quality forage to be fed to lactating animals. For higher tonnage or silage, harvest at a later maturity (36 inches tall for heifers or 48 inches tall for dry cows or beef cattle).
Leave at least 6 –8 inches of stubble for regrowth.
Seeding into an Existing Alfalfa Stand, by Rhonda Gildersleeve, Dan Undersander, and Tim Wood, University of Wisconsin Extension.
Overseeding Alfalfa into Alfalfa – When it works and when it doesn’t, by Rachael Long, Daniel H Putnam, News and information from UC Cooperative Extension .