Comparing cultivars of three cool-season turfgrasses for nitrogen recovery in clippings

Abstract

Economic and environmental concerns over nitrogen (N) fertilization of turf-grasses are prompting serious considerations of how to best use various N pools in turf-soil ecosystems. Nitrogen in clippings is receiving special consideration but Information on how large and variable this N source might be for different turfgrasses is limited. Therefore, a field study investigated growth of and N recovery in clippings from 10 cultivars each of kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue (Festuca arundinacea Schreb.) turf at the University of Rhode Island Turfgrass Research Station, Kingston, daring 1990 and 1991 growing seasons. All turf had been established in 1985,1986 or 1987 on an Enfield silt loam (Coarse loamy over sandy skeletal, mixed, mesic, iypic Dystroclirepts) and maintained under N fertilization rate of 147 kg N ha/year. Daily clipping growth rate (DCG), leaf blade N concentration (NC), and daily N recovery rate (DNR) in clippings were compared across species and cultivars. Seasonal clipping yieicls ranged from 5152 kg dry weight/ha for tall fescue to 3680 kg·ha -1 for pe-rennial ryegrass. Significant species differences in the amount and seasonal pattern of N recovery were identified. Cultivar differences in N recovery were greatest for kentucky blnegrass but much less for perennial ryegrass and tall fescue. Total N recovery in clippings ranged from 260 to 111 kg N/ha/year generally exceeded N supplied as fertilizer, thus emphasizing potential importance of clipping N in turf management.