The financial potential and environmental impact of agroforestry practices are being evaluated on approximately 300 acres of land at the Hill Farm Research Station, Homer, LA. Currently, the land base is comprised of loblolly pine silvopastures, loblolly pine plantations, and open-pastures.
Long-term objectives are to determine the potential for annual timber harvests and for maintaining livestock ownership through a timber production cycle. Intermediate objectives are to determine the impact of the interactive competition between the tree and forage crops on timber and livestock productivity.
Tree crop growth plays a pivotal role is the success of a silvopasture because tree to tree competition influences both timber and forage production. Reducing the number of trees, altering the spatial arrangement of the trees, and manipulating canopy size can control the competitive impact of the tree crop. Since the study area contains six different tree-age classes, five types of spatial arrangement and an array of pruning options, the impact of timber management practices can be evaluated in a chronosequential manner. Tree crop establishment practices include planting density rates from 680 to 220 trees per acre and spatial arrangements of one, two, and three row sets planted on 8, 12, 16, 24, and 32 foot-centers.
Intermediate harvests will reduce tree density to 50, 75, 100, or 150 trees per acre at ages 10 and 15, and final harvest are planned for ages 25, 35, and 45. Mechanical and chemical pruning methods are being used manipulate canopy size at ages 4, 7, and 10. Tree growth rate and quality characteristics will be evaluated in response to annual N fertilization, reduced tree densities, and damage from hail and ice.
The influence of timber management practices on the performance of perennial warm-season (bahiagrass, common bermudagrass, and Coastal bermudagrass) and annual cool-season forage crops (ryegrass and subterranean clover) will be evaluated at tree canopy densities of 0, 50, 75, 100, and 150 trees per acre for varying tree ages. Fertilization applications will include either N at 100 or 200 lbs. per acre combined with a basic pasture mix of P, K, and S, or broiler litter at 2 and 4 tons per acre. Potential for alley crop hay production will be investigated in tree spatial arrangements of one, two, and three row sets planted on 16, 24, and 32 foot-centers. Electric fencing and portable watering systems are being used to develop rotational grazing systems and to provide remedial riparian zones along streams and existing ponds.
Beef cattle production under a tree canopy is being evaluated by comparing cow/calf productivity on open pasture with silvopastoral productivity. Both open pastures and silvopastures are being managed to sustain 9 months of grazing by overseeding a warm-season perennial forage with ryegrass and/or subterranean clover. Both pasture types are being rotationally grazed at a stocking of 1 animal unit per acre and pasture productivity is being measured by cow weight changes, body condition scores, cow pregnancy rates, and calf weaning weights. Although weather conditions in 1998 limited stocking to 0.5 animals per acre, animal performance was similar on both pasture types. Cow weight changes, cow body condition scores, cow pregnancy rates, and 205-day calf weaning weights averaged +60 lbs, 5.7, 100%, and 540 lbs, respectively. In addition to beef cattle production, the study area will be used to evaluate the potential to background dairy heifers in a silvopastoral situation.