Run-off Performance of Drained Water and Herbicides in Zoysia turf through Under-drain sheet

Abstract

Experiments were conducted to obtain same informations on the effect of under-drain materials on surface-drained water and herbicide run-off losses under rainfall simulations using test-yard ofZoysia japonica turf during 1993 to 1994. Treated plots were; conventional underdrain with drainpipe and masa soil (A), underdrain with drainsheet and masa soil (B), and underdrain with drainsheet and sand (C) . The herbicides used were; simazine, isoxaben, mecoprop, and asulam. The results were as follows;
1. Irrigation was simulated with 40-47mm/h. At plots C, surface water appeared slowly with less amount and disappeared faster as compared to other two plots
2. At the plots, B and C, underdrained water ranoff quickly in larger amount after irrigation, followed by quick decrease, while at plot A, water drained slowly with less amount of underdrained water.
3. The groundwater disappeared quickly in plot C, while in plot A the water disappeared very slowly, taking four times as long as the former. The groundwater of surface layer in plot A disappeared very slowly.
4. There were not much differences between the three plots in relation to the distribution of root weight at successive soil strata in 1994. But less amount of rhizomes were measured at surface layer in plot C as compared to the other.
5. Herbicide run-offs was examined in plots, A and C. Concentrations of simazine and isoxaben decreased more quickly in early under-drained water than surface-drained water in both plots. This tendency was clearer in plot C. The concentrations of mecoprop and asulam in underdrained water did not change much as compared to that of surface-drained water in both plots.