Keys to successful establishment of grass-legume conventional seedings: Part II
Careful seeding practices and close monitoring of the new seeding improves chances for success.
In Keys to successful establishment of grass-legume conventional seedings: Part I, preliminary factors were addressed, including controlling perennial weeds before seeding, soil testing to correct nutrient and pH deficiencies, nurse crops and strategies for weed control. Now, we’ll think about the process of seedbed preparation, seeding and monitoring the emerging crop.
The two basic goals of seedbed preparation are to:
- Minimize competition from existing vegetation or weeds for sunlight and moisture.
- Provide a firm seedbed to allow precise seed placement and good seed/soil contact.
If the planting site has been a well-established sod or a clay-type soil, fall plowing may be desirable to loosen compacted soil and get a head-start on breakdown of dead vegetation. This will also allow for lime application and incorporation. Phosphorus and potassium fertilizers, if needed, can also be applied in fall. If the seeding follows a small grain or row crop, less tillage may be needed and can be accomplished in spring on better-drained soils.
Before seeding, plow, chisel, disk or harrow as needed to eliminate clods and prepare a firm seedbed. Firming the soil will allow for good seed placement and coverage and prevent the seedbed from drying out quickly. Avoid overworking the soil, which can damage soil structure, resulting in formation of a crust on the surface and inhibiting seedling emergence.
When ready, the seedbed should be firm enough that your footprints are no deeper than the sole of your boot (Alberta Agriculture and Rural Development staff recommend 0.65 centimeters, or about 0.25 inches).
Select crop species well-adapted to climate and soil conditions. A combination of grass and legume that will mature together as closely as possible is desirable for mixed plantings. Timothy, orchardgrass, Kentucky bluegrass and smooth brome are common cool-season forage grasses used in combination with legumes. Be sure to consider some of the newer grasses as well, including meadow bromegrass and tall fescue. Alfalfa, red clover, ladino, alsike and white clovers, and birdsfoot trefoil are the forage legumes commonly included in mixed seedings in Michigan. Be aware that alsike clover is not recommended for horse pastures. Alfalfa is the best-yielding forage legume when grown under the right conditions.
Variety selection should be matched to intended use (hay, grazing), climate and soil conditions. Red clover varieties do not generally persist more than two years, although improved varieties like Marathon and Arlington may last a bit longer. Birdsfoot trefoil and clovers are better suited for lower pH and less well-drained soils than alfalfa. Birdsfoot trefoil is well-suited for grazing and is persistent due to its semi-prostrate growth habit, allowing low-lying seed pods to mature and drop seed. Some farmers seeding pasture in soils not suitable for alfalfa include both red clover and birdsfoot trefoil in their seed mixture. The trefoil tends to become better established as the red clover fades away over the first few years following seeding.
The websites Forage Varieties for Michigan in 2011 and University of Wisconsin Forage Research and Extension have good tools to describe the various species available to farmers and where they fit.
Legume seed inoculation. Check your seed package to determine if your legume seed has been properly inoculated. If it has, store the seed in a cool site before seeding. If it hasn’t, be sure to purchase and apply the proper inoculant for your legume species.
Planting date. Mixed hay seedings should be completed either in spring or late summer. Legumes should not be planted to allow at least six to eight weeks before killing frost. That’s about August 1 in upper Michigan and mid-August in Lower Michigan. Spring seedings are preferable because they are generally planted into moist soil and allow plenty of time for good establishment before winter. Summer seedings generally have less weed competition, but run the risk of more insect damage and hot, dry weather.
Seeding rate and depth. Generally, forage seedings should be made at 0.5- to 0.75-inch depth. Small seeding species, like timothy, should be at the shallower end of this range. In sandier soils, seeding at the deeper end of the range will help seedlings find adequate moisture. Seeding too deep in clay soils or loose soils can result in very poor emergence. Seed depth should be checked after press wheels pass over the seed.
Monitoring the emerging crop
Keep a close eye on emerging grass/legume stands. Annual weeds are very likely to out-grow the emerging seedlings and must be clipped off before they become so large that the cut weed plants will smother the smaller seedlings. Plan to mow off weeds when there is adequate height difference so most of the weed plant can be removed with minimal damage to forage seedlings. If only the top of the weed plant is removed, it will quickly regrow from undamaged buds.
If the field was adequately fertilized before seeding, no additional fertilizers will be needed for the establishment year. An exception could be in situations where the legume component fails, leaving primarily grass forage in place. Nitrogen fertilization on grass seedlings can be counterproductive, stimulating weed growth more than grass seedlings, which have immature root systems. After the grasses reach 6 to 8 inches in height, 40 to 60 lbs of nitrogen per acre could be applied if soil moisture is adequate and enough of the growing season remains for the grass to take it up. If legume development is successful, nitrogen fertilizer will not be necessary. Annual topdressing should be made based on soil test information and production goals.
For those interested in no-till establishment of forages, check out MSU Extension bulletin E-2880, Steps to Successful No-till Establishment of Forages.
For other viewpoints on establishing mixed grass/legume hayfields and pastures:
- Perennial Forage Establishment in Alberta, Alberta Agriculture and Rural Development
- Establishing Improved Pastures, Rhonda Gildersleeve, UWEX