Evaluating the agronomic effect of warm‐season annual grasses interseeded into orchardgrass

Abstract Pasture systems in the northeastern United States are primarily comprised of cool‐season perennial grasses. However, these systems are subject to a lag in forage production during the hot summer months. Incorporating warm‐season annual grasses (WSA) into these forage systems may improve overall forage productivity, especially for producers with a limited land base. Therefore, the objective of this study was to compare the agronomic effect of WSA interseeded into orchardgrass ( Dactylus glomerata L.; OG) and harvested at two different intervals. This study compared monocultures of OG to OG interseeded with sorghum‐sudangrass ( Sorghum bicolor × S. bicolor var. sudanense; SSG), pearl millet ( Pennisetum glaucum L.; PM) or teff grass ( Eragrostis tef L.; TEFF), harvested on either a 6‐ or 12‐week interval. Results indicated that inclusion of WSA into OG did not improve total herbage accumulation or nutritive value beyond the OG monoculture at either harvest interval ( p > 0.42). However, inclusion of WSA into OG did affect the proportion of OG in the stand at both harvest intervals ( p < 0.01). The greatest effect was observed in plots interseeded with SSG, in which there was a ∼14% and ∼25% decrease in OG compared to OG monoculture plots when harvested on a 6‐ and 12‐week interval, respectively. This study concluded that interseeding WSA into OG did not improve agronomic parameters of the stand compared to OG despite implementing different harvest frequencies. Future research is warranted evaluating the effect of warm‐season annual legumes under similar conditions on the forage production of cool‐season perennial grass pastures.