Initial establishment success of five forages in an east Texas loblolly pine (Pinus taeda) silvopasture

The establishment at the end of 1 year of five forages was evaluated in a loblolly pine (Pinus taeda L.) silvopasture system. The five forages were: ‘Pensacola” bahiagrass (Paspalum notatum Fluegge), “Texas Tough” bermudagrass (Cynodon dactylon L. Pers.), “Alamo” switchgrass (Panicum virgatum L.), “San Marcos” Eastern gamagrass (Tripsacum dactyloides L.), and a native mix containing 45% “Texas” little bluestem (Schizachyrium scoparium Michx Nash), 15% sand lovegrass (Eragrostis trichodes Nutt. L. Alph. Wood), 15% “Blackwell” switchgrass (Panicum virgatum L.), 10% “Lometa” indiangrass (Sorgastrum nutans L. Nash), 10% “Haskell” Sideoats grama (Bouteloua curtipendula Michx Torr) and 5% “Earl” big bluestem (Andropgon gerardii Vitman) by weight. The silvopasture was in a 22 year old stand of loblolly pine in the Fairchild State Forest near Rusk, Texas. Five plots for each forage were sown in March 2008 and the density of each forage after one year calculated. Soil samples were taken to a depth of 10 cm from each corner of each plot using a push probe sampler and a composite sample created for chemical analyses Soil depth to B horizon or restrictive layer was determined using an 8 cm diameter hand bucket auger. In addition, light quality under the canopy was evaluated in August, October and January using a hand-held spectroradiometer: for light quality analysis, light was divided into blue, green, red, and far red bands. Irradiance (μmol photons m-2 s-1) for each band was divided by the total for all bands to create a proportion. Soil depth was positively correlated to plant density in the silvopasture. Bahiagrass and Eastern gamagrass were well established after one growing season. Compared to full sun, light intensity in the silvopasture was reduced by 29% in August, 51% in October, and 56% in January. Proportion and light intensity of the far red band decreased from August to January. Light quality was not affected by the canopy; but the intensity of light reflected or absorbed by the canopy decreased between August and January. Light readings may have been influenced by the decrease in solar angle from August to January. Light intensity was higher than the light compensation point, but lower than the light saturation point for several of the grasses; light in the silvopasture was lowest in January when warm season forages are generally dormant.