Effect of tillage on soil water and alfalfa establishment in corn stubble

The effect of soil water on alfalfa (Medicago sativa L.) seedling growth during no-till establishment into corn stubble has not been documented. Our objective was to determine the effects of differences in soil water levels resulting from different tillage methods and seeding dates on alfalfa emergence and seedling growth. The experiment was located at the Rock Spring Agricultural Research Center in Centre County, PA (40 degrees 42'N Lat., 77 degrees 57'W Long., elev. 365 m (1200 ft)), on a Hublersburg silt loam soil (clayey, mixed, mesic typic Hapludult) in 1986 and 1987 and a Hagerstown silt loam soil (fine, mixed, mesic Typic Hapludalf) in 1988. Alfalfa (cv. 'WL316') was drilled no-till into stubbles from corn harvested for grain (NT-G), silage (NT-S), or silage plus a rye (Secale cereale L. cv. common) cover crop (NT-SR), and seeded into a conventionally prepared seedbed resulting from corn harvested for grain (CT). Seeding dates were early April (EA), late April (LA), and mid-May (MM). Soil water content was not adversely affected by the inclusion of the rye cover crop in the NT-SR treatment. Good stands of over 70% seedling frequency were obtained with all treatments, but the NT-S treatment had significantly higher seedling yields, yields at one-tenth bloom, and total seedling year yields than the others. Seedling yields were significantly lower in the NT-SR treatment, however rye silage yields made this treatment one of the most productive in the seedling year. In addition the rye cover crop of the NT-SR treatment provides a conservation cover during the winter and a means of capturing nitrate left over from the corn crop or mineralized during the early spring. In the first production year, there was no significant effect of tillage or seeding date on first harvest yields.