Growing food crops for biofuel on productive agricultural lands may become less viable as requirements to feed a growing human population increase. This has increased interest in growing cellulosic biofuel feedstocks on marginal lands. Switchgrass (Panicum virgatum L.), a warm-season perennial, is a viable bioenergy crop candidate because it produces high yields on marginal lands under low fertility conditions. In other studies, switchgrass dry matter (DM) yields on marginal croplands varied from 5.0 to 10.0 Mg ha −1 annually. West Virginia contains immense areas of reclaimed surface mined lands that could support a switchgrass-based biofuel industry, but yield data on these lands are lacking. Field experiments were established in 2008 to determine yields of three switchgrass cultivars on two West Virginia mine sites. One site reclaimed with topsoil and municipal sludge produced biomass yields of 19.0 Mg DM ha −1 for Cave-inRock switchgrass after the sixth year, almost double the varieties Shawnee and Carthage, at 10.0 and 5.7 Mg ha −1 , respectively. Switchgrass yields on another site with no topsoil were 1.0 Mg ha −1 after the sixth year, with little variation among cultivars. A second experiment was conducted at two other mine sites with a layer of topsoil over gray overburden. Cavein-Rock was seeded with fertilizer applications of 0, 34, and 68 kg N-P 2 O 5 -K 2 O ha −1 . After the third year, the no fertilizer treatment averaged biomass yields of 0.3 Mg ha −1 , while responses to the other two rates averaged 1.1 and 2.0 Mg ha −1 , respectively. Fertilization significantly increased yields on reclaimed mine soils. Where mine soil fertility was good, yields were similar to those reported on agricultural soils in the Northeastern USA.
Biomass crops are being grown on agricultural and marginal lands to provide feedstock for co-firing in power plants and conversion to transportation fuels. Switchgrass (Panicum virgatum L.), Miscanthus (Miscanthus x giganteus), and giant cane (Arundo donax L.) are three biofuel feedstocks that have been planted on reclaimed surface-mined land to determine their establishment and potential for biomass production. This study documents the establishment and dry matter (DM) yield of these biomass crops on several mined sites in West Virginia. The Alton site has all three species planted, and DM yield after the fourth growing season averaged 5,200 kg ha -1 for switchgrass (Kanlow and Bomaster varieties) and 9,000 kg ha -1 for two varieties of Miscanthus. Giant cane had less than 1,000 kg ha -1 . Cave-In-Rock switchgrass was planted on 8 ha at the MeadWestvaco (MWV), WV, site and at The Wilds, OH, site in 2013. After the first growing season, switchgrass production was 752 kg ha -1 at MWV and 1,045 kg ha -1 at The Wilds site. Miscanthus was also planted on these two latter sites, and biomass production after one year was 200 and 600 kg ha -1 , respectively. These biomass averages at The Wilds and MWV were lower than averages produced at Alton after the first growing season. At the Coal Mac site, an average of 10,000 kg ha -1 of Arundo was produced after the third growing season. As demonstrated in these and other studies, two to three years are required for these bioenergy plants to establish and expand to produce suitable amounts of biomass.
Switchgrass (Panicum virgatum L.), a warmseason perennial grass, is an important bioenergy crop candidate because it produces high biomass yields on marginal lands and on reclaimed surface mined sites. In companion studies, dry matter (DM) yields for Cave-inRock, Shawnee, and Carthage cultivars varied from 4.2 to 13.0 Mg ha −1 averaged over 6 years at the reclaimed Hampshire site, and fertilization increased yields of Cave-in-Rock at Black Castle and Coal Mac sites from 0.3 to 2 Mg ha −1 during the first 3 years. The objective of these experiments was to compare the impacts of cultivar and soil amendments on biomass quality and theoretical ethanol production of switchgrass grown on surface mines with differing soil characteristics. Biomass quality was determined for fiber, ash, lignin, digestibility, and carbohydrate contents via near-infrared reflectance spectroscopy, and carbohydrates were used to calculate theoretical ethanol yield (TEY; L Mg −1 ) and multiplied by biomass yield to calculate theoretical ethanol production (TEP; L ha −1 ). Cultivars at the Hampshire site did not differ in TEY and ranged from 426 to 457 L Mg −1 . Theoretical ethanol production from Cave-in-Rock at Hampshire was 7350 L ha −1 , which was higher than other cultivars because of its greater biomass production. This TEP was higher than in other studies which predicted 4000 to 5000 L ha −1 . At the Black Castle and Coal Mac sites, fertilizer applications slightly affected biomass quality of switchgrass and TEY, but provided greater TEP as a function of increased yield. Similar to other findings, total switchgrass biomass production has more impact than compositional differences on TEP, so maximizing biomass production is critical for maximizing potential biofuel production. With appropriate soil substrates, fertilization, planning, and management, large areas of reclaimed surface mines can be converted to switchgrass stands to produce high biomass quality and yields to support a bioethanol industry.
Abstract:The invasion of Tree-of-Heaven (Ailanthus altissima) has been documented in disturbed landscapes leading to biodiversity loss and degradation of ecosystem function. Ailanthus interferes with the restoration of native species by its aggressive growth habit, alteration of nutrient cycles, and allelopathic chemical production. Recent studies suggest that allelopathy has a negative effect on the growth of red oak (Quercus rubra), possibly by interfering with the symbiosis of beneficial ectomycorrhizal fungi (ECM). This fungal symbiont is essential for healthy tree growth and the unavailability of these fungi may impede the success of seedling regeneration. This study investigated the effects of Ailanthus on biomass production and ectomycorrhizal fungal (ECM) colonization of red oak (Q. rubra) seedlings on a reclaimed coal mine site in eastern Ohio. Six plots were designated in an existing riparian buffer zone in a wetland at The Wilds Conservation Center in Muskingum County. Three of the plots were in an area where mature Ailanthus was present. The other three plots were located in the same riparian zone that was without Ailanthus. Naturally regenerating two-year-old red oak seedlings were selected for study (10 seedlings per plot, 60 seedlings total). The oak seedlings were sampled for biomass (g) and ECM root colonization. Twoyear-old oak seedlings growing among mature Tree-of-Heaven produced significantly less biomass, specifically in root production, than the oaks growing without the invasive tree (P = 0.02). There was a decrease in ECM colonization (P = 0.001) and a shift in ECM community composition in plots where the Tree-ofHeaven was present (P = 0.0004). The increase in root biomass and ECM colonization may aid in the plant's competitive ability for belowground resources, important for reestablishment. These data suggest that areas impacted by the invasion of Tree-of-Heaven may require restoration with plant species less reliant on ECM colonization when planting in soils immediately following invasive species removal.
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