Biofuel Grass Species Effect on Nutrient Management for Swine Lagoon Effluent Sprayfields.

Potential grass alternatives to the commonly planted bermudagrass [Cynodon dactylon) on swine lagoon effluent sprayfields were evaluated in large-scale replicated plot experiments at three commercial farms in Duplin, Sampson, and Wayne counties. Related nitrogen response experiments were conducted in small experimental plots at the Williamsdale Biofuels Field Laboratory in Duplin Co. Results varied among sites and input levels, and highlight interactions between perennial species and cutting schedules in productivity and nutrient removal during the first five years after establishment. All perennial species, but not the annual sorghums, responded to nitrogen inputs after depleting initially present residual soil N. While higher productivity and nutrient removal levels can occur with Giant Miscanthus (Miscanthus x giganteus), Switchgrass (Panicum virgatum), and both forage and sweet sorghum (Sorghum vulgare) than with bermudagrass, results also suggest the importance of defining the business management plan. Management simplicity and marketability of species varies substantially, and multi-cut systems maximize nutrient removal while a single late-season cut system may maximize dry carbon-rich biomass. The choice of receiver crop and management intensity effects on productivity and nutrient removal are likely to influence farm nutrient management plans and acreage requirements for lagoon effluent management.