The 2012 ASHS Annual Conference

In order to predict the best management practices for the turf industry in Colorado, the DAYCENT ecosystem model was parameterized and applied on turf ecosystem. In this study, the daily time step DAYCENT model was validated using field measured data of clipping yields, evapotranspiration (ET), deep percolation, nitrate leaching, and soil temperature from a three-year lysimeter study. The prediction of ET and deep percolation was acceptable for the three years (r > 0.6). The simulation result of clipping yield was improved compared to the monthly time step CENTURY ecosystem model, with r value increased from –0.32 to 0.74. The long-term irrigation effect on Kentucky bluegrass biomass and soil carbon and nitrogen was examined. The annual net production is predicted to drop by 50% as irrigation decreases from 100% potential evapotranspiration (PET) to 60% PET in this semi-arid region. Irrigation replacing 100% PET poses much more risk than 80% PET on nitrate leaching in the long-term. Reducing mowing heights from 7 cm to 3 cm with clipping fully returned were predicted to have little influence on carbon sequestration rate and nitrate leaching rate. The simulation result suggests that the annual fertilization rates should be gradually reduced to approximately half of the initial rate after 10 years for both moderately and highly managed turf, and the rates could be further reduced with the increasing age of turf stand.