Early Competition for Soil Resources Beneath Dual-Cropped Loblolly Pine and Switchgrass Plantations.

Growing desire for domestic energy reliance and environmental concern has prompted recent interest in utilizing lignocellulosic materials for bioenergy production. Switchgrass (Panicum virgatum) has been recognized as a highly productive and sustainable bioenergy feedstock. Loblolly pine (Pinus taeda) is one of the most widely planted tree species throughout the southern U.S. due to its rapid growth and high sawtimber value. Growing pine and switchgrass in co-culture may have positive economic and environmental impacts compared to monoculture production systems. However, few studies have examined the effectiveness of growing pine and switchgrass in close proximity, and intense competition prior to canopy closure could affect growth of both species, especially on the marginal soils often utilized for cultivating bioenergy crops. The goal of this study is to gain an understanding of the benefits/trade-offs of combining the long-term productivity of pine with the short-term yield potential of switchgrass. Recognizing the potential for strong interspecies competition, our objective is to examine differences in soil moisture, soil nutrient content, and aboveground growth across varying competitive intensities and in comparison to pine and switchgrass monocultures. We will present study design and early indications of resource usage for two pine/switchgrass co-cultures established on the Upper-East Gulf Coastal Plain in 2010.