Switchgrass for forage and bioenergy: harvest and nitrogen rate effects on biomass yields and nutrient composition

• Published in: Plant and soil Vol. 339; no. 1-2; pp. 69 - 81
• Main Authors: Guretzky, John A, Biermacher, Jon T, Cook, Billy J, Kering, Maru K, Mosali, Jagadeesh
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.02.2011; Springer; Springer Netherlands; Springer Nature B.V
• Subjects: Agricultural production; Biodiesel fuels; Biofuels; Biomass; Biomass energy; Biomass energy production; Biomass production; Biomass quality; Biomedical and Life Sciences; Cellulosic feedstock production; Crop harvesting; Crop science; Ecology; Energy crops; ethanol; Fertilizers; Forage; forage quality; Frost; Grasses; Life Sciences; Nitrogen; Panicum virgatum; Plant Physiology; Plant Sciences; Rain and rainfall; Regular Article; Seed set; Soil nutrients; Soil Science & Conservation; Soil sciences; Oklahoma; USA, Great Plains; USA; Ethanol; Biofuels; Cellulosic feedstock production; Biomass quality; Forage quality
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-010-0376-4

Switchgrass (Panicum virgatum L.) may have value as forage and a bioenergy feedstock. Our objective was to evaluate how harvest system and N fertilizer rates affected biomass yield and nutrient composition of young stands of switchgrass (cv. Alamo) in the southern Great Plains, USA. Nitrogen fertilization increased biomass yields from 10.4, 10.8, and 12.2 Mg ha⁻¹ at 0 kg N ha⁻¹ to 13.7, 14.6, and 21.0 Mg ha⁻¹ at 225 kg N ha⁻¹ when harvested after seed set (October), after frost (December), and twice per year after boot stage (July) and frost, respectively. Nutrient concentrations and removal were generally twice as great when biomass was harvested twice versus once per year. Precipitation strongly affected biomass yields across the two years of these experiments. When late-summer precipitation is available to support regrowth in this environment, harvesting switchgrass twice per year will result in greater biomass yields. Harvesting twice per year, however, will increase fertilization requirements and reduce feedstock biomass quality. Switchgrass harvested during mid-summer after boot stage was of poor forage quality. To have value as a dual-purpose forage and bioenergy feedstock, switchgrass would need to be utilized during spring to early summer while in a vegetative stage.