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Bioenergy grasses such as giant miscanthus ( Miscanthus × giganteus) and switchgrass ( Panicum virgatum L.) are promising alternatives to the traditional coastal bermudagrass [ Cynodon dactylon (L.) Pers.] at spray fields in Eastern North Carolina. The objective of this study was to determine the impact of different harvest practices on yield and nutrient removal of miscanthus and switchgrass in a swine ( Sus scrofa domesticus) lagoon effluent spray field environment. Field trials of grasses under six single-cut and double-cut harvest practices (May/October, June/October, July/October, Aug/October, October only, and December only) were established at three commercial swine farms in Eastern North Carolina in either 2011 or 2012. Throughout the 4-year experimental period (2012-2015), both miscanthus and switchgrass produced significantly higher biomass yield than coastal bermudagrass. Two-cut harvest systems significantly improved the yields of miscanthus and switchgrass relative to a single harvest in December at spray fields. The maximum yields were 24 Mg ha year for miscanthus and 18 Mg ha year for switchgrass. Bioenergy grasses removed more nutrients under two-cut systems than under a single harvest. The significantly greater nutrient removals under two-cut harvest systems would result in lower requirements for receiver crop acreage and are more desirable from a spray field nutrient management perspective. [ABSTRACT FROM AUTHOR]