Potential of several native and introduced warm season grasses as components of Silvopastures in the Southeastern United States

The goal of this study was to evaluate growth and nutritional characteristics of seven warm season grasses, including several natives, produced under simulated partial shading (50%) typical of loblolly pine silvopastoral systems in the southeastern United States. Forages included ‘Tifton 9’ bahiagrass (Paspalum notatum), ‘Tifton 85’ bermudagrass (Cynodon dactylon), ‘Alamo’ switchgrass (Panicum virgatum), ‘Kaw’ Big Bluestem (Andropogon gerardii), ‘Americus’ Indiangrass (Sorghastrum nutans), ‘Harrison’ Florida paspalum (Paspalum floridanum), and Nacogdoches Eastern gamagrass (Tripsacum dactyloides). Shade affected several quality parameters, including crude protein (CP) (p?<?0.0001), acid detergent fiber (ADF) (p?=?0.0413), in vitro true digestibility (IVTD) (p?<?0.0001), and total digestible nutrients (TDN) (p?=?0.0132). Shade affected the parameters differently depending on forage type, but generally improved quality by increasing CP, IVTD, and TDN; however, shade significantly increased ADF (p?=?0.0413), though the magnitude was small (344.2 vs. 351.1 g kg^?1), and increases were isolated to big bluestem and bahiagrass. Shade reduced dry matter yield (DMY) (p?<?0.0001), and there were differences among forage species (p?<?0.0001). Bahiagrass and Florida paspalum showed the highest yields, regardless of shade treatment. Gamagrass and Florida paspalum would likely have performed better if harvested by days of rest, instead of by height. These could be viable forage species to a silvopasture system, but further studies should be conducted. Based on overall quality and yield, potential beef cattle gains, and persistence under intensive defoliation, the best forage was bahiagrass (introduced), and the best selections for native grasses were switchgrass and Indiangrass. These results indicate that there is potential for several warm season forages, including native grasses, to maintain productivity and quality under shade, which would increase the site-specific options for forage selections in this system.

     

Nutrient Composition in Litter Fall in Northern Louisiana Hardwood Deciduous Forests

Minor stream bottoms (alluvial floodplains) in the southeastern United States contain large areas of hardwood forests which are a potential sink for upstream nutrients. As a sink, they serve an important role in reducing the loss of nutrients from the sites via the watershed. However, little is known about nutrients stored in forest litter that have the potential to be cycled back to the forest or lost through removal from the site. Three hardwood stands of varying management regimens that span common scenarios found in north Louisiana were sampled for nutrient concentration and quantity in falling litter including leaf, woody, and other debris. Across sites, the well-drained site constitutively contributed more nutrients in litter than the poorly drained sites. Also, the sampling time spanning from March to October had the most litter fall and subsequent nutrient discharge from the trees. Of the five nutrients measured, nitrogen was the largest component followed by potassium. These features in nutrient quantity have broad implications for nutrient management based on site and timing of timber removal. This study provides novel nutrient levels in litter fall of hardwood forests typical along minor stream bottoms.