Overseeding Legumes Into Permanent Cool-Season Pastures.

The benefits of adding clover to cool-season permanent pastures are well known.  Successful establishment of clover into permanent pasture can be difficult, however.  A better understanding of the variables that determine successful clover establishment would be useful to help producers.  Grazing and manipulative small-plot experiments were conducted in Blacksburg, Va.  to  address this issue.  In the grazing experiment, two seeding methods, frost seeding and no-till drilling were compared and data collected over the 2009 and 2010 growing seasons.  Frost seeding resulted in more clover seedlings than no-till drill (P = 0.10), but no difference in clover biomass and population density were found subsequently.   Residual biomass at sowing was negatively related to clover seedling density in 2009 (P < 0.05).  Clover seedling density was positively related to on clover biomass in fall of 2009 and in 2010 ( P < 0.05).   The small plot experiment evaluated three factors: fertilization, defoliation frequency, and residual biomass at sowing on clover establishment.   Our results suggest that achieving maximum clover biomass is dependent on several interacting factors:  1) reducing vegetation cover before overseeding, 2) suppressing grass competition in spring with frequent defoliations, 3) providing adequate P and K during establishment and 4) plentiful rainfall during the establishment year.  This combination of conditions allows for many clover seedlings to emerge and then establish later in the growing season.  Our results also suggest that these variables may act synergistically such that if one of these condition is not met (e.g., frequent defoliation in spring), successful clover establishment may not occur.