Late-summer pasture interseeding and no-till forage seeding is an excellent way to conserve moisture, provided weeds are controlled prior to seeding. Remove all straw after small grain harvest. Any remaining stubble should either be left standing, or clipped and removed. Do not leave clipped stubble in fields as it forms a dense mat that prevents good emergence.
Don't plant alfalfa immediately after older established alfalfa, Barnhart advises. Autotoxic compounds are released by old alfalfa plants that inhibit growth and productivity of new alfalfa seedlings. It is best to rotate to another crop for a year or more before going back to alfalfa; however, thickening up seedings within 12 to 15 months of the original planting date is considered to be a low-risk practice because autotoxicity concerns are greatest with older alfalfa fields.
Seed when soil moisture is adequate or a good rain system is in the forecast, he suggests. There is a higher risk of seedling failure when planting seeds into dry soil, as there may be just enough moisture to germinate the seed but not enough for seedling establishment.
Plant seed shallow and in firm contact with the soil. Carefully check seeding depth, especially when no-tilling. Drills with press wheels usually provide the greatest success in the summer. Broadcasting seed on the surface without good soil coverage and without firm packing is usually a recipe for failure in the summer.
Use high-quality seed of known varieties. Cheap seed often results in big disappointments and shorter stand life, Barnhart says. Make sure legume seed has fresh inoculum of the proper rhizobium.
Finally, don’t harvest new summer seedings this fall. Allow them to establish well and develop winter hardiness.
Source: Iowa State University