Abstract
Nitrogen balance was measured in lysimeter experiments to clarify nitrate leaching in turfgrass fields. The results are summarized as follows. 1) On the cultivation of turfgrass, 33 gm^<-2> of nitrogen was applied in the plot using standard application, procedures by split dressing 11 times from April to September. During the early stage of growth, the nitrate concentration in the soil solution became higher in the upper soil layer, and during the active stage of growth, became lower due to the plant uptake. 2) Nitrate concentration in leaching water increased in July, with the highest value indicated during the summer (July to September), a gradual decrease in November and the lowest value indicated during the winter (February to March). 3) The annual amount of leached nitrogen was 11.6 gm^<-2>. It was analyzed that 4.3 gm^<-2> of nitrogen was derived from fertilizer by the ^<15>N tracer technique. 4) The total amount of nitrogen absorbed by turfgrass was 29.0 gm^<-2>, and 17.0 gm^<-2> of the nitrogen was derived from fertilizer. After harvesting, the amount of fertilizer nitrogen accumulated in the soil layer (0-90 cm) was 9.4 gm^<-2>. 5) When 330 kg ha^<-1> of nitrogen was applied as fertilizer to a turfgrass field, the nitrogen balance estimated that 51.5% of the fertilizer nitrogen was absorbed by turfgrass, 28.6% of the nitrogen was accumulated, and 13.2% of the nitrogen was leached.
