Irrigation Level and Nitrogen Rate Affect Evapotranspiration and Quality of Perennial Ryegrass (Lolium perenne)

This study examined the effects of different irrigation levels and nitrogen rates on perennial ryegrass (Lolium perenne L.) evapotranspiration and quality in a sub-humid climate over a two-year period (2007-2008). Nitrogen treatment (25 kg N ha(-1); N-1 and 50 kg N ha(-1); N-2) varied among main plots and irrigation levels (25%; I-1, 50%; I-2, 75%; I-3, 100%; I-4 and 125%; I-5 of the Class A pan evaporation) by subplot. Irrigation was performed at 3-day intervals during May-September using a pop-up sprinkler irrigation system, and N applied as a monthly rate during the irrigation period. Seasonal turfgrass evapotranspiration was found to vary by treatment from 309-1178 mm in 2007 and from 379-1097 mm in 2008. Turfgrass visual color, quality and clipping yield were shown to decrease significantly with decreases in irrigation water and N fertilizer. The study findings demonstrated that under a non-limiting water supply, irrigation could be decreased by adjusting N fertilizer rates according to turfgrass visual color and quality and that N1I4 or N2I3 treatments can maintain acceptable turfgrass visual color and quality under sub-humid climatic conditions. (C) 2015 Friends Science Publishers