With the wet spring weather much of Iowa has experienced the past couple of years many farmers have had problems getting spring seeded forages established. Some of the resulting stands of alfalfa, for example, haven't been very good. Ground was worked wet, creating a cloddy seedbed which resulted in poor seed-to-soil contact. In some cases, seedling diseases took their tool thanks to the cool, wet weather. Also, the weather was so wet in some areas that planting of forages, whether alfalfa or grass or a legume-grass mixture, occurred so late that the stands were disappointing for that reason, too.
"Forage seedings can be made in the spring as soon as a suitable seedbed can be prepared," says Steve Barnhart, Iowa State University Extension forage agronomist. "Spring seedings made after mid-May may not be as successful, due to rapid drying of surface soils." Barnhart points out that as much as you have to pay for seed and the cost of getting the seed into the ground, you should try to do the seeding job the right way. He offers the following recommendations.
Start by preparing a good seedbed for your forage planting
Site preparation. If you are seeding a pasture, clear the brush, fill in the gullies and take soil samples. Lime and fertilize according to needs shown by soil testing. For most efficient lime use, it is best to have needed lime applied and incorporated six months to a year before planting.
Seedbed preparation. Destroy sod by shallow plowing or disking, followed by necessary secondary seedbed preparation operations. Seedbed firmness is very important. Using a cultipacker or roller on tilled seedbeds before planting is recommended. Another alternative is to use a non-selective herbicide to kill the old sod. Incorporate needed fertilizer before seedbed preparation, or surface topdress on killed sod sites.
Species and variety selection. Select species based on the desired use, persistence and tolerance to site conditions. Iowa State University Extension publication Selecting Forage Species, PM 1792 covers characteristics of many forage legumes and grasses used in Iowa, and provides suggested seeding mixtures and seeding rates for various situations.
Seeding. Seed in one of the following ways on a well prepared seedbed:
• Use a grassland drill with depth-control and press wheels or a cultipacker-roller type seeder designed for small seeded forage legumes and grasses. Plant at a ¼ to ¾ inch depth.
• Use a grain drill, equipped with small seeded forage boxes, as a broadcast seeder for small seeded legumes and grasses to prevent small forage seed from being planted too deeply. Cultipack or roll after seeding.
• Broadcast seed onto a firm, tilled seedbed and cultipack or roll for shallow seed coverage and seed-to-soil contact.
Or, if planting into a killed sod, or untilled crop residue field, use a no-till drill, control seeding depth to no deeper than ½ inch, and adjust press wheels to provide good seed-to-soil contact.
On sloping sites consider the need for soil erosion protection
Where there is a risk for erosion on tilled seedbeds, 1 to 2 bushels of oats per acre or a reduced seeding rate of another spring cereal grain may be seeded with forage mixtures as a companion crop or cover crop. The cereal grain will serve first as soil erosion protection, but will increasingly become competition for the newly planted forages. The sooner the cereal competition can be removed, the quicker the new forage seeding will establish.
Cereal companion crops may be grazed, cut for silage or hay, or harvested later as grain and straw with associated longer completion. Particularly in dry springs, removing companion crops as early as possible can conserve moisture for the new forage seeding.
Management to use after establishment of forage seedings
For weed control and for companion crop competition control, graze new seedings rotationally or mow (clip) sequentially, during the first few months of the establishment to limit unneeded competition for light, moisture and plant nutrients. Developing seedlings will establish more quickly. Also avoid any cutting or grazing new seedings after early September to improve winter hardening.
For some mixtures or pure stands, selective preplant or postemergence herbicides may be used in place of a companion crop. This option may only be appropriate on sites where soil erosion is not a risk. Seek help from your ag professionals when selecting and using herbicide for weed management in new forage seedings. Be sure to read and follow labels when using any ag chemical. Also take into account any harvest or grazing withdrawal periods called for. You can apply fertilizer in later years according to soil test recommendations.
Graze rotationally and avoid overgrazing to maintain ground cover and animal grains. Remove grazing livestock and limit grazing for the last four to six weeks of the growing season to allow plants to adequately harden for winter. Use management practices that retain adequate plant cover if cutting or grazing after fall dormancy.
For more information, see the following Iowa State University Extension publications Selecting Forage Species, PM 1792 and Steps to Establish and Maintain Legume-Grass Pastures, PM 1008.