Inclusion of cool- and warm-season species in tall fescue swards for increased productivity

Pasture systems that include cool- and warm-season species have the potential to enhance tall fescue (TF) [Schedonorus arundinaceus (Schreb.) Dumort.] forage systems beyond their typical season. The objectives of this study were to incorporate crabgrass (Digitaria ciliaris Retz.) into TF swards and compare the production of monoculture TF to a binary mixture of crabgrass and TF as well as its effect with different sources of nitrogen (such as red clover [Trifolium pratense L.] or sunn hemp [Crotalaria juncea L.]). The experiment was conducted in Crossville, TN, in 2020 and 2021. The treatments were as follows: (1) TF + 0 N (T), (2) TF + ammonium nitrate (TA), (3) TF + red clover (TR), (4) TF + sunn hemp (TS), (5) TF + crabgrass + 0 N (TFC), (6) TF + crabgrass + ammonium nitrate (TCA), (7) TF + crabgrass + red clover (TCR), and (8) TF + crabgrass + sunn hemp (TCS). The plots containing red clover indicated a greater herbage mass (HM) and crude protein (CP) along with lesser neutral detergent fiber compared to the other treatments. Sunn hemp performed best during the mid-summer, contributing to the increase of HM. Tall fescue swards that were mixed with crabgrass and a source of N (legumes or N fertilizer) had greater HM during the warm season, having the potential to decrease the stationarity of production. Thus, including crabgrass, red clover, and sunn hemp (grass and legumes, respectively) in TF pasture can be a great strategy to increase HM and improve nutritive value.