Keys to successful establishment of grass-legume conventional seedings: Part I

Plan ahead and pay attention to details for good results when it comes to grass-legume conventional seedings.

Many producers, large and small, make mixed hay and pasture seedings using conventional tillage practices every year. Whether a few acres for grazing horses or larger areas for hay and grazing, a successful outcome depends on acceptable weather during crop establishment and good management practices. Since you can’t control the first, better make your best effort on the others.

Here are some factors to consider.

Control perennial weeds ahead of time

Two realistic options exist. You can cultivate your soil repeatedly, killing germinating weeds and disturbing the reestablishment of perennial weed root systems frequently. This gradually kills the perennials as they dry up, or use up all their reserve energy in a losing struggle for survival. This technique, called fallowing, takes considerable time, fuel and equipment. Quackgrass is a common problem weed and can take up to six cultivations to kill. Quackgrass Management on Organic Farms from the University Of Maine Sustainable Agriculture Program provides good information on controlling quack with fallow and other methods.

Perennial weeds may also be successfully controlled with application of a non-selective herbicide containing glyphosate. These products should be applied at rates specified on the label. Spray-grade ammonium sulfate should be added to the spray water at a rate of 17 pounds per 100 gallons. Refer to the Michigan State University Extension article Select and handle ammonium sulfate products properly when preparing glyphosate spray mixes. Glyphosate can provide a very thorough “kill” of perennial weeds, especially when applied later in the fall on a sunny day over 50 degrees Fahrenheit. It will not, however, provide any control of annual weed seed germination and growth.

Evaluate and correct plant nutrient deficiencies

Collect a good, representative soil sample from the areas to be seeded. Fall is a good time for this. Soil samples can be submitted to several dependable labs for analysis, but naturally, I recommend the MSU Soil and Plant Nutrient Laboratory. MSU recommends a maximum area of 20 acres per soil test. Considering the expense of a new seeding, the cost of soil testing is tiny and well worth-while. The depth of sampling is important and should be the same as your depth of tillage. This will influence the amount of lime recommended per acre, if any. Include your depth of sampling on theSoil Test Information Sheet provided along with the sample box . If you don’t, MSU will recommend lime for a depth of 9 inches.

The cost of a soil sample box at your local MSU Extension office is $12 for commercial farms and you are responsible for mailing the sample to MSU. Visit the lab website for complete information on how to collect samples, the various analyses offered and how to interpret results. Samples can be brought in directly to the MSU Soil and Plant Nutrient Lab, room A81 (basement), in MSU’s Plant and Soil Science Building (view map).

You can also mail samples directly to:
Soil and Plant Nutrient Laboratory
Department of Crop and Soil Sciences
Plant and Soil Sciences Building
1066 Bogue Street, Room A81
East Lansing, MI 48824-1325

Get a clear understanding of the results of your soil test after you receive it. If phosphorus and potassium levels are very low, MSU will recommend a “build-up” fertilizer rate to meet crop nutrient removal and increase nutrient levels in the soil for following crops. You may prefer to fertilize for crop removal only if money is too tight. Your local MSU Extension office can direct you to an MSU educator who can help you adjust the fertilizer recommendations. Apply lime in the fall if possible. Lime takes time to react in the soil and raise soil pH.

Nurse crop: yes or no?

If you need feed from the newly seeding field during the first year, then a “nurse” crop of oats or barley can be planted. The seeding rate of the small grain should be reduced to one-half to two-thirds rate to reduce competition. The grain crop can be grazed, taken as silage, cut for hay or harvested as grain. If the growing season is dry, it may be best to remove the grain crop early to conserve moisture for the seeding. If forage or grain from a nurse crop is not important, then the seeding has a better chance for good establishment without the nurse crop.

Develop your strategy for weed control during the establishment period

Be sure to prepare a good seedbed with all perennial weeds removed and germinating weeds destroyed. Weed control chemical options are very limited when establishing mixed grass-legume seedings. 2,4-DB (Butyrac) and bormoxynil (Buctril) are labeled only for post-emergent CRP grass-legume mixtures. Areas treated with either of these cannot be grazed or harvested for hay during the year of treatment. If a broadleaf weed problem is bad enough to justify the sacrifice of the legume component in a pasture or hayfield area, then spot-spraying with an herbicide labeled for broadleaf control in grass pasture can salvage at least the grass component. Forage legumes will be killed.

Inevitably, annual weeds will emerge along with the seeding. Plan to mow your new seeding when they reach a height of 6 to 8 inches or whenever there is a large difference in height between the desired grass and legume seedlings and the developing weeds. Mowing only the tops of weeds will leave behind enough of the plant to allow quick regrowth from buds. Keep a close watch on these fields. Don’t let the weeds get too tall or they will create a thick mat when cut and can smother the small forage plants.

Part II of this article will cover more factors, including:

  • Seedbed preparation
  • Planting practices
  • Evaluating the seeding
  • Scouting for problems

Additional information:

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