J. Jpn. Soc. Soil Phys. No. 22, p.++ +2,**+ * ** Janya SANG ARUN*** * E#ect of Grass Strips on Reduction of Sediment Loss from Upland Field Takashi UENO*,Machito MIHARA**,Janya SANG ARUN*** and Yukiko DOKIYA* * Tokyo University of Agriculture and Technology, - / 2 Saiwaiocho Fuchuoshi Tokyo,Japan ** Tokyo University of Agriculture, + + + Sakuragaoka Setagayaoku Tokyo,Japan *** Mae Fah Luang University, --- Moo. +. Tasud subodistrict,muang district, Chiang Rai,Thailand Abstract The e#ect of grass strips on the reduction of sediment and eutrophic salt loads is been widely recognized. However,there is very little knowledge of the e#ect of grass strips on the reduction of sediment and eutrophic salt losses. Attention was hence focused on the investigation of what grass strips should be managed. Soil suspension was supplied to the experimental plots under simulated rainfall. During the experiment,surface discharge and sediment concentration were measured. In order to observe the e#ect of grass strips on the reduction of sediment loss,the di#erence between the amounts of sediment supplied and sediment loss was investigated in each plot. While the sediment concentration and load from the bare upland field exceeded the concentration and load of the soil suspension supplied,the sediment concentration and load from all the grass strips were lower than the concentration and load of the supplied soil suspension. The di#erence between the sediment supplied and the sediment loss from the cutting weeds plot for pest control was approximately equivalent to that of the plot with the natural weeds. Therefore, it was concluded that cutting weeds for pest control can be applied to the grass strip for reduction of the sediment loss. There was little di#erence between the reduction of the sediment loss from the plot with 2** stems/m, and that from the plot with +,.2* stems/m, of Tall Fescue (F. arundinacea). However the plot with,,--* stems/m, of Tall Fescue was e#ective for the reduction of sediment loss comparing with 2** stems/m, and +,.2* stems/m,. It suggests that stem density for grass strips should be maintain,,--* stems/m, to control soil loss from upland field. Key words : Grass strips,sediment loss,surface runo#,upland + Pennisetum alopecuroides Vetiveria zizanioides +33/ Dalton +330 0* m +* m * +2-2/*3 - / 2 ** +/0 2/*, + + + *** :
12 22,**+,-.1 0 Uusi Kamppa and Ylaranta, +33, -1 m..- m 2./ m /* Parsons +33. Ghadiri,***,* cm.* cm +333 +33. F. arundinacea +*** stems/m, +33*, + Plot Plot *./ m, m +0 *., m LiC +..* + Plot Plot Plot - Plot - Plot +* + Photo. + Simulated rainfall system and experimental plots. + Table + Physical properties of soil Specific gravity Particle size distribution* ( ) Gravel Coarse sand Fine sand Silt Clay Dispersion ratio ( ) Ignition loss ( ) Soil texture,40* *4* 241 -*40,/40 -/4+ 14* +.4* LiC * International methods.
: 13, Table, Vegetation and management in plots Plot Vegetation (scientific name) rd (g/cm - ) Density of stems ( + ) (stems/m, ) Management Plot I Plot II Plot III Plot IV Plot V Plot VI Weed (10 with Setaria viridis) Weed (2- with Setaria viridis) Tall Fescue (F. arundinacea) Tall Fescue (F. arundinacea) Tall Fescue (F. arundinacea) *42- *421 *42- *42, *42. *42-,5.2*,5//*,5-2*,52.* 2** +5.2*,5--* Bare Cutting + :, weeks after the cutting weed of plot II. + Fig. + Plot (before the cutting weed in plot II)., Fig., Plot (just after the cutting weed in plot II). cm Plot Plot Plot r d), Plot *.2, *.21 g/cm - Plot +** cm, +* 3/
14 22,**+ - Fig. - Plot, (, weeks after the cutting weed in plot II). Plots / Plot Plot Setaria viridis 10 2- Plots,.2* stems/m,,-2* stems/m,, Plot,//* stems/m, Plot,2.* stems/m, Plot Plots 2** stems / m, +.2* stems / m,,--* stems/m, +*** stems/m, Plot Plots. Fig.. Plot with additional suspended water supply (just after the cutting weed in plot II). Plot,..2 mm/h -* + ms/cm.2 mm/h +/ +/ Plot *.*- dm - /s Plot USLE +331 0 Mihara,**+
: 15 / Fig. / Plot, with additional suspended water supply (, weeks after the cutting weed in plot II). +1,0**,+,-** g/m - - + Plot Plots + - Plot Plots Plot Plots Plot, 3/ -/- g/m - Plot,*0 g/m - Plot /,.+ g/m - 0 Fig. 0 (Tall Fescue). Plot,. / Plot Plots Plot Plots Plot, Plots Plot
16 22,**+ 1 Fig. 1 with additional suspended water supply (Tall Fescue). +* cm, 0 1 Plots 2** stems/m, +.2* stems/m,,--* stems/m, 3/ 0,/ g/m - 0.. g/ m - +/- g/m - / Plot Plot,--* stems/m, Plot Plot 2 Plot II Fig. 2 Comparison between amount of soil supplied and of soil loss under simulated rainfall with additional suspended water supply (just after the cutting weed in plot II). Plot / Plot Plot 0 +2 Plots / Plot Plots 2** stems/m,,--* stems/ m, Plots +*** stems/m,,--* stems/m,
: 17 3 Plot II, Fig. 3 Comparison between amount of soil supplied and of soil loss under simulated rainfall with additional suspended water supply (, weeks after the cutting weed in plot II). - Plot L, L+ L, L+ Plot 2 +* 2 Plot 1+3 g/m, Plot Plot /02 g/m, /3* g/m, Plots 2** stems/m, +.2* stems/m, 0,, g/m, Plot +* Fig. +* Comparison between amount of soil supplied and of soil loss under simulated rainfall with additional suspended water supply (Tall Fescue).,--* stems/m, 00. g/m, Plots +*** stems/m,,--* stems/m,. Plot +* cm Plot Plot
18 22,**+ Plot 2**,--* stems/m, Plot 2** stems/m, +.1* stems/m, Plot,--* stems/m, 2** stems/m, +.2* stems/m, +*** stems/m,,--* stems/m, Dalton, P.A., Smith, R. J. and Truong, P.N.V. (+330) : Vetiver grass hedges for erosion control on a cropped flood plain : hedge hydraulics, Agricultural Water Management, -+ : 3+ +*.. Ghadiri, H., Hogarth, B. and Rose, C. (,***) :Thee#ectiveness of grass strips for the control of sediment and associated pollutant transport in runo#, The Role of Erosion and Sediment Transport in Nutrient and Contaminant Transfer, pp. 2-3+, International Association of Hydrological Science Press, U.K.. Mihara, M. (,**+) : Nitrogen and phosphorus losses due to soil erosion during a typhoon, Japan, Journal of Agricultural Engineering Research, 12 (,) :,*3,+0. Uusi Kamppa, J. and Ylaranta, T. (+33,) : Reduction of sediment, phosphorus and nitrogen transport on vegetated bu#er strips, Agric.Sci.Finl. + : /03 /1/. Parsons, J.E., Gilliam, J.W., Mun oz Carpena, R., Daniels, R.B. and Dillaha, T.A. (+33.) : Nutrient and sediment removal by grass and riparian bu#ers, Environmentally sound agriculture proceedings of the second conference : +.1 +/.. +33. : pp. +/,3 +33/ : 1+ : -1.*. +33* : pp. +30 +32 +333 :,** : 1 +.. :,*** 3 +- :,**+ -,-