Biomass production by fescue and switchgrass alone and in mixed swards with legumes. Final project report

In assessing the role of biomass in alleviating potential global warming, the absence of information on the sustainability of biomass production on soils of limited agricultural potential is cited as a major constraint to the assessment of the role of biomass. Research on the sustainability of yields, recycling of nutrients, and emphasis on reduced inputs of agricultural chemicals in the production of biomass are among the critical research needs to clarify optimum cropping practice in biomass production. Two field experiments were conducted between 1989 and 1993. One study evaluated biomass production and composition of switchgrass (Panicum virgatum L.) grown alone and with bigflower vetch (Vicia grandiflora L.) and the other assessed biomass productivity and composition of tall fescue (Festuca arundinacea Schreb.) grown alone and with perennial legumes. Switchgrass received 0, 75 or 150 kg ha{sup {minus}1} of N annually as NH{sub 4}NO{sub 3} or was interseeded with vetch. Tall fescue received 0, 75, 150 or 225 kg ha{sup {minus}1} of N annually or was interseeded with alfalfa (Medicago L.) or birdsfoot trefoil (Lotus corniculatus L.). It is hoped that production systems can be designed to produce high yields of biomass with minimal inputs of fertilizer N. Achievement of this goal would reduce the potential for movement of NO{sub 3} and other undesirable N forms outside the biomass production system into the environment. In addition, management systems involving legumes could reduce the cost of biomass production