J. Jpn. Soc. Soil Phys.
/No. 22, p. +++2 ,**+

*ῌ **ῌJanya SANGῌARUN***ῌ*E#ect of Grass Strips on Reduction of Sediment Loss from Upland Field
Takashi UENO*, Machito MIHARA**, Janya SANGῌARUN*** and Yukiko DOKIYA** Tokyo University of Agriculture and Technology, -ῌ/ῌ2 Saiwaiocho Fuchuoshi Tokyo, Japan** Tokyo University of Agriculture, +ῌ+ῌ+ Sakuragaoka Setagayaoku Tokyo, Japan*** Mae Fah Luang University, --- Moo. +. Tasud subodistrict, Muang district,Chiang Rai, ThailandAbstract
The e#ect of grass strips on the reduction of sediment and eutrophic salt loads is been widelyrecognized.

However, there is very little knowledge of the e#ect of grass strips on the reductionof 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 theexperiment, 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 ofsediment 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 thegrass 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 forpest 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 reductionof the sediment loss.

There was little di#erence between the reduction of the sediment loss fromthe 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 reduc-tion 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JU56V%0WX34'56 =YZ( +33/(+    Dalton ( +330>7 [\&( ]^5)*+_`+a_  !"#$%&'( )*+,-./01234'567
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12

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Simulated rainfall system and experimental plots.

<<$@

Physical properties of soil

Particle size distribution* (ῌ)

Speciﬁcgravity

GravelCoarse sandFine sand

SiltClay

Dispersion
ratio (ῌ)

Ignitionloss (ῌ)

Soiltexture,40**4*241-*40,/40-/4+

14*+.4*LiC* International methods.

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῍ῌ,
Table ,

13

PQR,23'5STUV

Vegetation and management in plots

PlotVegetation (scientiﬁc name)rd(g/cm-)

Density of stems (W+)(stems/m,)

Management

Plot I
Plot II
Plot IIIPlot IV
Plot V
Plot VI

None
Weed (10ῌ with Setaria viridis)
Weed (2-ῌ with Setaria viridis)
Tall Fescue (F. arundinacea)
Tall Fescue (F. arundinacea)
Tall Fescue (F. arundinacea)*42*421*42*42,*42.
*42-X,5.2* 1,5//*:,5-2* 1,52.*:
2**+5.2*,5--*

BareCutting
None
None
None
None

W+: , weeks after the cutting weed of plot II.

ῌῌ+

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Changes in cumulative surface runo#
and soil loss under simulated rainfall(before the cutting weed in plot II).

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and soil loss under simulated rainfall(just after the cutting weed in plot II).

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14

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Changes in cumulative surface runo#
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Fig. .

Changes in cumulative surface runo#
and soil loss under simulated rainfallwith additional suspended water supply(just after the cutting weed in plot II).

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Changes in cumulative surface runo#and soil loss under simulated rainfallwith additional suspended water supply(Tall Fescue).

ῌῌ2 Plot II er
h;< U:a*Fig. 2Comparison 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).

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Fig. 3Comparison 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).

Fig. +*

Comparison between amount of soil
supplied and of soil loss under simulated rainfall with additional suspended
water supply (Tall Fescue).

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18      Plot 

tiveness of grass strips for the control of sediment and associated pollutant transport in !"# $" %&'() runo#, The Role of Erosion and Sediment Trans-  *+ ,- .

port in Nutrient and Contaminant Transfer, pp.

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m +.2* stems/m BCD)&p , 

E!F.)&:*A"#:+;<)& qrsEc & tQR
KScience Press, U.K..
Mihara, M. (,**+) : Nitrogen and phosphorus losses
due to soil erosion during a typhoon, Japan,

N O "BCD>C P !F2-ῌ3+, International Association of Hydrological+*** stems/m, uP>CPBCD

NJK& + ,--* stems/m, uP>C Pvwg :Nxyz+ :*A"#

Journal of Agricultural Engineering Research,12 (,) : ,*3ῌ,+0.
UusiῌKamppa, J. and Ylaranta, T. (+33,) : Reductionof sediment, phosphorus and nitrogen transport
on vegetated bu#er strips, Agric.Sci.Finl. + : /03ῌ/1/.
`Parsons, J.E., Gilliam, J.W., MunozῌCarpena, R.,
Daniels, R.B. and Dillaha, T.A. (+33.) : Nutrientand sediment removal by grass and riparianbu#ers, Environmentally sound agriculture proceedings of the second conference : +.1ῌ+/..

>{|}ῌ~ῌ +33. : =>?] pp. +/ῌ,3   +33/ : "U>r E)m 1+ : -1ῌ.*.

ῌ ῏ ῎ ῍
Dalton, P.A., Smith, R. J. and Truong, P.N.V. (+330) :  ¡¢ +33* : & ts a£ῌ¤s¥ pp. +30ῌ+32 ¦§¨©¡¢ ª«¬­®ῌy¯° +333 : EcVetiver grass hedges for erosion control on a±²E)m³´    µ¢

cropped ﬂood plain : hedge hydraulics, Agricul-¨¶ ,** : 1ῌ+..

tural Water Management, -+ : 3+ῌ+*..
Ghadiri, H., Hogarth, B. and Rose, C. (,***) : The e#ec-·¸¹º» : ,*** ¹ 3 º +- »·¹º» : ,**+ ¹ - º ,- »