Effect of Native Warm-Season Grass Canopy Development and Characteristics On the Establishment and Production of Forage Legumes.

Currently in Kentucky, livestock production relies almost exclusively on cool-season forages.  Although these species are productive during the early spring and fall, they are also often susceptible to limited production during the summer months.  Native warm-season grass (NWSG), however, are more adapted to warmer and drier conditions and produce most of their growth during the summer.  While this may fill the gap in forage production left by the “summer slump” with cool-season species, NWSG are lower in forage nutritive value and may reduce animal performance.  The incorporation of legumes into grass mixtures may increase animal production due to their inherently higher nutritive value and their ability to convert atmospheric nitrogen into organic forms.  There have been limited studies examining the production of legumes in NWSG stands.  Of these studies, red clover [Trifolium pretense L.] has shown the greatest potential, but because of their earlier initiation of growth, cool-season legumes may have a competitive advantage over warm-season species within the stand.  Similarly, the removal of cool-season legumes before appreciable growth of the NWSG forage may also remove photosynthetic tissue needed for development of the grass and may compromise summer forage yields.  Perennial warm-season legumes may be more compatible with NWSG and, in central Kentucky, species selection from these types of forage legumes is frequently limited to sericea lespedeza [Lespedeza cuneata (Dum. Cours) G. Don].  The establishment and persistence of legumes within mixtures with grass, regardless of growth habit, is often constrained by the legume species’ ability to exploit environmental niches, such as openings within the canopy.  As the canopy architecture of NWSG varies between and within species, closer examination of the variability of this factor in relation to legume production may provide further insight into their maintenance within sustainable agriculture systems.