||The major focus of current research on production of biomass for use as an energy feedstock involves selection of species and genotypes best suited for specific regions of the United States and development of crop management techniques that maximize biomass productivity while minimizing environmental impacts and economic costs. These efforts usually involve establishment and maintenance of monocultural systems. A major cost in these systems is the expense of establishing and maintaining monocultures. When activities to maintain monocultures are abandoned, vegetation previously excluded by cultivation and the use of herbicides becomes established. The naturally occurring vegetation is self-sustaining and requires minimal inputs to produce significant quantities of biomass
composed primarily of llgnocellulosic materials suitable for use as energy feedstocks by the same processes being developed for conventionally produced lignocellulosic crops. Therefore, successional
vegetation may offer the potential for production of cost-competltive lignocellulosic materials useful as energy feedstocks. The productivity and chemical composition responses of vegetation from two old-fleld plant communities to harvesting frequency, fertilizer, and llme were measured over a 3-year interval. The two experimental sites, an abandoned soybean field (AS) and an abandoned pasture (AP) were studied. At the AS site, the effects of two harvest
frequencies (I or 2 harvests annually), two nitrogen fertilizer treatments (0 or 87 kg ha-1.yr-1), and two phosphorous fertilizer treatments (0 or 111 kg ha-1,yr-I) were determined. At the AP site, the effects of two harvest treatments (1 or 2 harvests annually), two fertilizer treatments (56:56:135 kg of N:P:K.ha-1 yr’1), and two lime treatments (0 or 4600 kg ha-1.yr -1) were determined. At both sites, treatments were arranged in a randomized complete block 2 X 2 X 2 factorial experiment.