Foliar Nitrogen Uptake Following Urea Application to Putting Green Turfgrass Species

摘要

Foliar fertilization often comprises a significant portion of the total annual N applied to putting greens. This study was initiated to evaluate the efficiency of this practice under field conditions. N-15-labeled urea was used to quantify seasonal uptake of foliar-applied N by creeping bentgrass (Agrostis stolonifera var. L. palustris (Huds.) Farw. 'Penn A1') and hybrid bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt Davy 'Tifeagle') managed as putting greens. Urea was spray-applied monthly, May through September, at rates of 0.5 and 1.25 g N m(-2). Both species absorbed urea rapidly, with 24 to 67% of the fertilizer N entering the foliage within 1 h following treatment; peak foliar absorption was generally observed at 4 h after treatment. Percentage of foliar uptake was significantly reduced at higher application rates for both species. In addition, absorption of urea-N by foliage of both species was affected by month of application and year. When averaged across all sampling times and N rates, foliar absorption percentages were similar between the two species, ranging from 36 to 69% for creeping bentgrass and 38 to 62% for bermudagrass. Overall, foliar absorption efficiency was variable and there were no consistent seasonal trends associated with these differences.