Predicting runoff and associated nitrogen losses from turfgrass using the Root Zone Water Quality Model (RZWQM).
Nitrogen fertilizers are used to maintain optimum turfgrass quality, but off-site movement of this primary nutrient can affect water quality. We conducted a 4-yr study (1998-2001) designed to measure nitrate N runoff from turfgrass, gathering data to be used in the model. The process-based Root Zone Water Quality Model (RZWQM) was used to predict nitrate associated with runoff from turfgrass. The measurements were made on 12 sloped (5%), 25-m2 plots of 'Tifway' bermudagrass [Cynodon dactylon (L.) Pers.], managed as golf course fair-ways and exposed to natural and simulated rainfall. Surface runoff volume and nitrate N loads were monitored after applying simulated rainfall at an average intensity of 27.4 mm h(-1). The irrigation occurred (25 or 50 mm) 4 through 168 h after treatment with various rates of N fertilizers for 1998-2001. RZWQM adequately simulated water runoff volumes (<19%; nonsignificant, paired t test) in the first three (normal or wet) years, but overpredicted (70%) in the fourth, dry year. RZWQM overpredicted nitrate N loads by a factor of 1.3 for the first three years (nonsignificant), and by a factor of almost 6 for the fourth year (highly significant). These overpredictions occurred when the runoff volumes and N loads were very small. The research has shown that refinements to RZWQM are needed for turfgrass management applications.
Schwartz
Liliana
L
Department of Crop and Soil Sciences, University of Georgia, 1109 Experiment Street, Griffin, GA 30223, USA. schwartz@griffin.uga.edu
Shuman
Larry M
LM
D005308:Fertilizers; D005544:Forecasting; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis*; D018517:Plant Roots / Q000737:chemistry*; D006109:Poaceae / Q000254:growth & development; D012989:Soil Pollutants / Q000032:analysis*; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis*
D005308:Fertilizers; D012989:Soil Pollutants; D014873:Water Pollutants; D009584:Nitrogen