NITROGEN AND PHOSPHORUS LEACHING FROM FERTILIZER APPLIED ON GOLF COURSE - LYSIMETER STUDY

Fertilizers applied to turfgrass may pose a threat to surface and grou ndwater quality, and hence, a study was carried out to evaluate the fa te of fertilizer applied to turfgrass of the Clearwater Bay Golf and C ountry Club in Hong Kong. Lysimeters with reconstituted soils collecte d from fairways and greens with Bermudagrass (Cynodon dactylon) growin g in the surface were used to evaluate the leaching loss of nitrate (N O3-) ammonium (NH4+), and phosphate (PO43-) for 22 weeks under greenho use condition. Both soils received a slow release fertilizer at an app lication rate of 25 (low) or 50 (high) kg N ha(-1), and an application frequency of monthly and fortnightly for fairways and greens, respect ively simulating the fertilizer application strategy of the golf cours e. Both low and high fertilizer application rate supported the same am ount of biomass production for each soil type. Breakthrough of NO3- oc curred only in greens after 11 weeks of leaching, but the total amount of NO3- leached did not differ significantly for the two different fe rtilizer application rates. The continued addition of fertilizer to gr eens resulted in a final leachate NO3- concentration exceeding 45 mg L -1, while fairways maintained a concentration below 5 mg L-1. Also PO4 3- concentration in leachate of,greens exceeded the surface water stan dard of 0.3 mg L-1. The results of the lysimeter study showed that the current application rate on greens would create adverse environmental impacts on the surface water and groundwater due to leaching loss of PO43- and NO3-.