ῐ
J. Jpn. Soc. Soil Phys.
῏῍ῌῐῑ῎
No. 3+, p. ,/ῌ-2 ῍,**,῎Sediment Yield from Various Land Use Practices
in a Hilly Tropical Area of Lampung Region,
South Sumatra, Indonesia
AFANDI*, Bustomi ROSADI*, MARYANTO**, NURARIFANI**, Muhajir UTOMO*,
Masateru SENGE*** and Tadashi ADACHI***** Faculty of Agriculture and ** Faculty of Engineering, University of Lampung,
Jl. Sumantri Brojonegoro +, Bandar Lampung -/+./, Indonesia*** Faculty of Agriculture, Gifu University, +ῌ+ Yanagido Gifu /*+ῌ++3-, Japan**** Faculty of Environmental Science and Technology, Okayama University,-ῌ+ῌ+ Tsushimanaka Okayama 1**ῌ2/-*, Japan
Abstract
Sediments transported from various land uses and entrapped by natural vegetative ﬁlter were
measured from January to November +333 in a hilly humid tropical area of Lampung, South
Sumatra, Indonesia. A very simple sediment trap made from a PVC pipe with diameter of +*.3 cm
was designed for measuring the sediment yield. Five types of land uses were chosen as follows :(a) co#ee garden in multistrata system followed by rain-fed agriculture and grass ﬁlter, (b)mixed-co#ee garden followed by short shrub ﬁlter, (c) clean-weeded co#ee garden followed bylong shrub ﬁlter, (d) clean-weeded co#ee garden, and (e) secondary forest followed by new forest
remnant. The measurement during eleven months showed that the mixed-co#ee garden produced the highest sediment yield (1+3.1g/m,), and the lowest sediment yield was derived fromsecondary forest area (*.*2g/m,).

The sediment yield from clean-weeded co#ee system wasaround 3-..ῌ,13.1 g/m,, and multistrata system indicated a low sediment yield (,.- g/m,). Although mixed-co#ee garden showed a very high yield of sediment, natural vegetative strips
entrapped 33.1ῌ of the sediment. The vegetative ﬁlter zone covered with grass (+./ m long) andshort shrubs (- m in length) could entrap 3-./ῌ and 33.1ῌ of sediment respectively, and the longshrub ﬁlter (+, m in length) could entrap only /,./ῌ of the sediment due to the concentrated ﬂow
in the longer slope. The surface cover condition of the land use system and farming activities(weeding, tillage, fertilizer application) indicated a high contribution on sediment yield than theother erosion factor.
Key words : sediment yield, co#ee, vegetative ﬁlter, Indonesia+.

Introduction

Forest scattering has been a major problem
in Lampung, Indonesia. The study conductedby Syam et al. (+331) at the upper part of Way
Besai catchment, West Lampung, showed thatin +31* the forest occupied /1..ῌ of that areas,
which became ,+..ῌ in +33*, on the other hand
the monoculture plantations (co#ee tree) in-

creased from *ῌ in +31* to .+.2ῌ in +33*.
During +332ῌ+333, the forest scattering in West
Lampung was very intensive due to the changeof government which caused the weakness oflaw enforcement as well as the increasing of
co#ee price in +333 ; the co#ee price increased
more than three times in +333. Most of protected forest areas in West Lampung have beenchanged into co#ee garden in a very short῏  3+

26time. Although the above land use change has
caused the deterioration of soil fertility asreported by Lumbanraja et al. (+332), the overall negative e#ects of this phenomenon on soil
erosion process, especially o#-site e#ect of soil
erosion, is still unclear. The abundance of natural ﬁeld border in this area, such as riparian,hedgerows, shrubs areas, as well litter which
covered the soil surface, could a#ect the transfer of erosion materials (sediment). The extent
of soil erosion material that will be transported
is highly depended on whether the sediment
meets something that can block its ﬂow, so theposition of vegetation in landscape is more
important than the percentage of coverage. Although soil erosion rate from various land uses
types can be easily measured using erosion
plot studies, however, in a landscape scale, theexistence of border strip has made the extrapolation of the results from erosion plot studies
di$cult.
This research emphasizes the sedimenttransfer across various types of land uses onco#ee culture based and natural ﬁeld border inWest Lampung, Indonesia. In this experiment,“point measurement” is used, and can bechanged into “spatial measurement” by multiplying with width and length of the areas
under consideration. The objective of this research is to know the extent of sediment transfer from various land use types and naturalvegetative ﬁlter.
,.

Methodology,. + Land Use Systems
The experimental ﬁelds were located at
Sumberjaya District, West Lampung, Sumatra
Island, Indonesia (Fig. +) with elevation between 1**2,* m above the sea level. Five
representative land use systems were chosen :(A) Co#ee garden in multistrata systemfollowed by rain-fed agricultural ﬁeldof horticultural crop with a grass ﬁlter,(B) Mixed-co#ee garden followed by shortshrub ﬁlter,(C) Clean-weeded co#ee garden followed by,**,

Fig. +

Location of experimental site.

long shrub ﬁlter,(D) Clean-weeded co#ee garden without
ﬁlter,(E) Secondary forest followed by new forest
remnant
Mixed-co#ee gardens consisted of various
trees with di#erent height in which co#ee was
the main vegetation (-*ῌ1/ῌ). Two mixedco#ee gardens were selected ; the ﬁrst had
nearly -*ῌ of co#ee trees with more diverse
trees, and the other was dominated by co#eetree (1/ῌ) with less various trees (A+ and B+
respectively in Table +). We designated A+ as“multistrata system” because the trees distribution is diverse, with di#erent height than B+.
The rain-fed agricultural ﬁeld (A,) was locateddirectly below the mixed-co#ee garden (A+),
and a narrow grass ﬁlter (A-) was situated at
the edge of rain-fed agricultural ﬁled.
Two types of co#ee garden with cleanweeded ground surface were chosen. One typehad a short slope of steep gradient (C+) with along shrub ﬁlter (C,) at the edge of this slope,and the other was consisted of two long slopes(D+ and D,) without vegetative ﬁlter.
The forest area was a secondary forest withvarious types of trees (E+). Below this forest
area, there was a new cleared land of forest
with ground surface covered by cutting trees(E,). We designated E, as “new forest remnant”

ΐῒ : Sediment Yield from Various Land Use Practices in a Hilly Tropical Area of Lampung Region, South Sumatra, Indonesia 27

The annual rainfall was around ,0** mm/year ; the rainy season is usually from November to May of the following year. The rainyseason was followed by weak dry season because usually rainfall still occurs more than +**mm every month. The daily average temperature was ,,ῑ and relative humidity was 21.,ῌ.
The period of experiment lasted from January+333 to November +333.
,. , Sediment Trap Equipment
The designed simple sediment trap (Fig. ,)consisted of four components as follows :(a) Sediment collector made of PVC-tube
with +*.3 cm diameter.
(b) Plastic funnel inside the L-tube.
(c) PVC tube with diameter 1./ cm ; the tube
was drilled with nine holes at the wallside, and one hole was connected tosmall plastic bucket ; a ﬁlter paper wasplaced at the bottom of tube and supported by a cloth.
(d) Small plastic bucket, consisted of ﬁlter
paper and cloth
Samples of sediment were collected at least
once in a week ; the frequency of sampling
depended on the amount of the rainfall. The
sample was collected by changing the ﬁlter
paper with a new one (known weight) andpacked into plastic bag. The sediment was
taken to laboratory, dried and weighed. Whenthe samples were too large, a sub sample wastaken.
Total sediment was calculated as follows :SaῐSe῎3῏SbῌSe : dry weight of sediment in the PVC tube(g)Sb : dry weight of sediment in small plastic
bucket (g)Sa : total sediment weight (g),. - Location of Sediment Traps
Three to ﬁve sediment traps were set up
respectively at the lower boundaries of theland use as follows :(A) ῎Multistrata systems with co#ee trees
and surface mulch (A+)῎Rain-fed agricultural ﬁeld in the valleys

Fig. ,

Structure of Sediment Trap.

grown with horticultural crops (A,)῎Grass ﬁlter zone (A-)(B) ῎Mixed-co#ee garden with short slope(B+)
῎Short shrub strip (B,)(C) ῎Clean-weeded co#ee garden before
shrub strip (C+)῎Long shrub strip (C,)(D) ῎Clean-weeded co#ee garden at upper
part of slope (D+)῎Clean-weeded co#ee garden at lower
part of slope (D,)(E) ῎Secondary forest areas (E+)῎New forest remnant (E,)
The description of each site is tabulated inTable + and those photos are shown in Fig. -.
,. . Analysis
The sediment yield was calculated by dividing the sediment caught in sediment trap withareas, i.e. the slope length times the width of
the sediment trap as follows :SyῐSaῌῌL῏W῍῍Sy : sediment yield per unit area (g/m,)
Sa : total sediment weight (g)L : slope length (m)W : width of sediment trap (ῐ*.+*3 m)
Because no exact boundaries were made, theaccuracy of soil erosion (sediment) entrappedby the sediment trap is more or less inﬂuenced

28

Table +
Code Land Use

NumberMultiStrata

co#eebananasjack fruit
guava
durianbeans
chilliA,

Rain-fed
agriculture

A-

Grass
(ﬁlter)small grass

B+

Co#ee
(mixed)co#eebananastrees

B,

Shrubs(ﬁlter)weeds(woodyweeds,
ferns)

C+
C,

Co#ee
Shrubsco#ee
weeds(woodyweeds,
ferns)

D+

Co#ee

co#ee

D,

Co#ee

co#ee

E+

ForestE,

Forest(open)

mixed(trees,bamboo,
rattan,etc.)
surfacecoveredwith falling
trees

,**,

Description of each representative land use

Name

A+

3+

main
+*
,
+
+* furrows

Vegetation
Height Distance
(m)
(m)
,
,
.
.
/

-,4/

Slope
(ῌ)

Length
(m)

Note

-1

3ῌ+*4/

surface covered by litter (,/ῌ) below thisland use is rain-fed
agriculture./+/ῌ,,4/Jan.-March (beans)
Apr.-June (cowpea/chili)
Jul.-Dec. (fallow)
A, was below A+*4*/ῌ*4+

dense

/ῌ3

+4/

A- was below A,
Sawah/paddy ﬁeld isbelow this ﬁlter

,
,
0

-,4/

,/

34/

dense

2,

-

Clean-weeded.
co#ee tree /*ῌ withother trees alternate between the co#ee tree
B, was below B+.
Sawah is below thisﬁlter.
The weeds were dominated by Clibadia surinamenses.

+40/

,,
dense

0/
3*

+24/
+,

Clean-weeded co#ee garden.
C, follows C+.
Creek is below this ﬁlter.
Clibadia sp. is dominated.

main

+40/

,,

.,

--4/

main

+40/

,,

.,

+-4/

Clean-weeded co#ee ﬁeld.
Clean-weeded co#ee ﬁeld.
D, was below D+.
Intermittent creek isbelow this ﬁeld

dense

3*

main
/
-

1*

-** Below E+ was E,
to the top.*
New at theJanuary, +333.

end

of

῍ῌ : Sediment Yield from Various Land Use Practices in a Hilly Tropical Area of Lampung Region, South Sumatra, Indonesia 29

Fig. -

Land use types.

by the place of location of sediment trap. Fivesediment traps were set up randomly in eachland use, one or two in rill and runo# pathways. That is why the data between replications is varied, with high standard deviation. It
was assumed that the sediment entrapped bythis equipment was representative of the soil
loss from the area with the width of sedimentcollector and slope length. In these methods,“point measurement” can be changed into “spatial measurement” by multiplying with theareas under consideration.
Since there were two or three types of land
use in one land use system, the sediment yieldof the second or third land use was calculatedusing the total length of upper slopes. The
following example shows the calculation of
sediment yield for A-land use system that consisted of multistrata (MS), rain-fed agriculture(RA) and grass ﬁlter (GF).
Figure . shows that the sediment yields
which deposited in grass ﬁlter (SaGF) was the  3+  ,**,

30

Fig. .

Multistrata system followed by rain-fed agriculture and grass ﬁlter.

result of soil loss from the whole areas (multistrata, rain-fed agriculture, and grass ﬁlter).
The calculation of the sediment yield in eachland use is as follows :SyMSSaMSῌLMSW
ῌ
SyMSῐRASaRAῌLMSLRAW῍
SyMSῐRAῐGFSaGFῌLMSLRALGFW῎
Where :SyMS : sediment yield from multistrata system (g/m,)
SaMS : sediment caught by sediment trap at
multistrata system (g)LMS : slope length of mulstistrata system (m)W : width of sediment trap (*.+*3 m)
SyMS-RA : sediment yield from multistrata andrain-fed agricultural system (g/m,)
Sa RA : sediment caught by sediment trap at
rain-fed agriculture (g)LRA : slope length of rain-fed agricultural
system (m)SyMS-RA-GF : sediment yield from the wholeland use system (multistratarain-fed
agricultural systemgrass ﬁlter) (g/m,)
SaGF : sediment caught by sediment trap at
grass ﬁlter (g)LGF : slope length grass ﬁlter (m)To test the e#ectiveness of the ﬁlter, a simple
comparison was made between the amounts ofFig. /

Distribution of rainfall
experimental period.

duringthethe sediment entering the ﬁlter (Se) and thesediment leaving the ﬁlter (So) as follows :Filter effectivenessSeSoῌSe
+** ῌ῏
Se : sediment yield entering from upper slope
to the ﬁlter (g/m,)
So : sediment yield leaving the ﬁlter for the
next land use system (g/m,)-.

Results and Discussion-. + Rainfall
The amount of rainfall during the experiments was +31/./ mm. The distribution of rainfall is shown in Fig. / and is not well distributed. A very low rainfall was found in
April although it was rainy season. A dry
season developed from July to September. The

ῒῑ : Sediment Yield from Various Land Use Practices in a Hilly Tropical Area of Lampung Region, South Sumatra, Indonesia 31

Table ,

Composition of soil fraction at the experiment site (*῍,* cm)*

No

Land use

Clay
ῌ

Silt
ῌ

Sand
ῌ

Texture
Class

+
,
.
/
0
1

Multistrata system
Rainfed agriculture (horticultural crop)
Mixed co#ee garden
Clean-weeded co#ee with ﬁlter
Clean-weeded co#ee-upper slope
Clean-weeded co#ee-lower slope
Forest (Mount Rigis)

//4.
.240
/24,
.24/
0*4/*4,
-24*

+,4/
+24.
+/4.
,*4+
+.4.
+24.
,.4*

-,4+
--4*
,04.
-+4.
,/4--4.
-24*

Clay
Clay
Clay
Clay
Clay
Clay
Clay loam*ῌ analyzed using hydrometer method

Table - Selected soil physical properties
No

+
,
.
/
0
1

Land use

Multistrata
Rainfed agriculture
Mixed co#ee garden
Clean weeded co#ee-long shrub
Clean weeded co#ee-upper slope
Clean weeded co#ee-lower slope
ForestBulk
Density(g/cm-)

Particledensity(g/cm-)

*431
+4++
*432
+4*+4*,
*432
*430

,4.2
,4/+
,4.0
,4.0
,4.2
,4.0
,4.-

Organic-C Dispersion
ratio*ῌ(g/kg)
.-41
,+43
-*4/
,142
,240
-/40
//4.

01
23
12
2/
2,
20
0*

*ῌ Dispersion ratio (ῌ)ῐ(clay῍silt) undispersed/(clay῍silt) dipersed῏+**amount of rainfall in May and June (starting
dry season) was ,// and +-, mm respectively, alittle higher than that of March and April (,.and 2, mm respectively) still in rainy season.
The rainfall erosivity index (R) in this area
could be approached by using equation proposed by Utomo and Supriyadi (+323) as
follows :Rῐ῎2.13῍1.*+ CHb
ῌ
R : monthly rain erosivity (t · m,/ha/h), CHb :Monthly rainfall (cm)Using this equation, the total erosivity index
during eleven months of experiment was estimated at +,23(t · m,/ha/h).
-. , Soil Properties
Based on the soil taxonomy by Soil Survey
Sta# (+332), the soil was classiﬁed as Dystrudepts, dominated by clay fraction whose
ranges are from -2.* to 0*.-ῌ (Table ,).
Due to the fact that the soil is still relatively

young (Inceptisols), the bulk density and particle density are relatively low, and the dispersion ratio is very high although the organiccarbon is high enough (Table -). The researcharea is located in the mountainous areas which
elevation between 12*῍2/* m, so the low temperature is enough to maintain the high organic matter in this area. The soil permeability is
di$cult to measure because the soil has swelland shrink properties, so many cracks arealways found in the soil proﬁle. From this fact,
it could be estimated that the permeability ofthe soil is very high or the internal drainage isvery excessive. The strong red color of the soil
proﬁle supports this fact. As consequence, theleaching process which carried soil particles
from upper layer is very intensive, and although the dispersion ratio is very high andthe soil could be classiﬁed as erodible, the soil
erosion by runo# water could be low.

32ΐῐ῎῔῕ῑ ῒ 3+ ῏ ῌ,**,῍Sediment Yield from each Land Use
system(+) Sediment yield from multistrata systemfollowed by rain-fed agricultural ﬁeld with horticultural crops and grass ﬁlter (A-system)
The sediment yield measured at lower
boundary of multistrata system, rain-fed agricultural ﬁeld with horticultural crops andgrass ﬁlter are shown in Fig. 0.
As shown in Fig. 0, the sediment yield frommultistrata system was very low.
Totalamount of sediment yield from multistratasystem was only ,.- g/m, in ++-months measurement, compared to the sediments caught by
the traps of rain-fed agricultural ﬁeld and grassﬁlter which were .,-., g/m, and ,0./ g/m, respectively. The sediment yield caught at rainfed agriculture increased +2. times than in
multistrata system, however, most of this sediment was deposited in grass ﬁlter. This experiment showed that although the grass ﬁlter
was very short (, m length), it could entrap the
sediments up to 3-ῌ (in Table .) of inﬂow, andonly small portion of sediment was transferredto the next system (rice ﬁeld).
It is interesting to note that the sedimentyield during the dry season was still very high.
As shown in Fig. 0, the sediment yield in May,
June, and July were higher than that of therainy season (January-April). Even for grassﬁlter, the major contribution of sediment yieldoccurred on July (about /+ῌ of all sedimentation for ++ months), although the monthly rainfall was low.
Tillage activity and time lag of sedimenttransportation may induce the above results.
During heavy rainfall event on rainy season,
the weeds and beans covered the portion ofground surface at rain-fed agricultural ﬁeld, so
this vegetation would reduce soil erosion process. Following the beans harvest in April, thefarmer began preparing the land for growing
chili and cowpea, and this land preparation
would have strongly a#ected the soil conditionand surface cover ; soil surface was clear andsoil structure was loose. This condition would-. -Fig. 0

Accumulation of sediment yield frommultistrata system followed by rain-fed
agriculture and grass ﬁlter (A-system).

Fig. 1

Accumulation of sediment yield frommixed-co#ee garden followed by shortshrub ﬁlter (B-system).

Fig. 2

Accumulation of sediment yield form
clean-weeded co#ee before entering
long shrub ﬁlter (C-system).

stimulate soil erosion process. Time lag of
sediment transportation will also inﬂuence sediment transfer, especially in the ﬁlter area. The
accumulation of sediment yield, which was
produced during rainy season, was transported
in the following dry season.
(,) Sediment yield from mixed-co#ee garden followed by shrubs ﬁlter (B-system)
As shown in Fig. 1, the sediment yield frommixed-co#ee garden and entrapped by shrubs῍ῌ : Sediment Yield from Various Land Use Practices in a Hilly Tropical Area of Lampung Region, South Sumatra, Indonesia 33

Fig. 3

Accumulation of sediment yield fromclean-weeded co#ee without ﬁlter(D-system).

Fig. +*

Accumulation of sediment yield fromsecondaryforestwithoutﬁlter(E-system).

Fig. ++

Cumulative sediment yield from various land use system.

ﬁlter were 1+3.1 g/m, and ,.- g/m, respectively.
The vegetative ﬁlter was dominated by woody
weed species, identiﬁed as Clibadia surinamenses. Ferns comprised the other species. Although the shrub ﬁlter was very steep (slope
gradient was 2,ῌ) and short (only - m), it wasvery e#ective to entrap the sediment from theabove system. Most sediment from mixedco#ee garden was entrapped in the ﬁlter (33.1ῌ
in Table .), and only small portion (*.-ῌ)
passed and transferred to the next land use(rice ﬁeld).
The biggest contribution of sediment fromthe mixed-co#ee garden occurred in October.
Due to abundance of water during rainyseason, weeds under the co#ee tree grew very
fast, so farmer began clearing weeds at the endof rainy season (May or June). Farmers cut theweeds using hoe. The hoe is struck into the soil
surface, so the weed roots will be truncatedfrom the soil. This activity would also be doneat the beginning of rainy season (early October), due to some reasons such as weeding activity and fertilizer application. Those tillage
activities could break and loose the soil surface, and enhance soil erosion due to detachment process by farmer hoe.
(-) Sediment yield from clean-weededco#ee followed by shrub ﬁlter (C-system)
Sediment yield from clean-weeded co#ee andentrapped by shrubs ﬁlter were ,13., g/m, and+-,.03 g/m, respectively as shown in Fig. 2.
The biggest contribution of sediment yieldfrom the ﬁlter occurred on October and November +333, about 01ῌ of total sediment yieldfor ++-months observation. It is fairly di$cult
to decide which process was responsible forhigh sediment transfer. Although ﬁeld evaluation showed that a rill has developed at theupper part of this sediment trap, an evidence of
sediment accumulation indicated that a smalllandslide might also be responsible.
The other possibility is the side e#ect of
weeding activity by the farmer. As commented above, the farmer usually has a lot of
activities at the end of rainy season and at the
beginning of rainy season, including weeding,fertilizer application, and soil tillage. As shownin Fig. 2, the results of these activities wereshown in the form of sediment yield, whichstill occurred in the co#ee garden during thedry season (July). During the next rainy

34ΐῐ῎῔῕ῑ ῒ 3+ ῏ ῌ,**,῍season, the sediment will be transferred to thelower slope.
(.) Sediment yield from clean-weededco#ee (D-system)
The sediment yield from upper and lower
slope of clean-weeded co#ee garden without
any conservation measure or vegetative ﬁlter
was 3-.0 g/m, and +/3.3 g/m, respectively as
shown in Fig. 3. Total sediment yield at lower
slope was greater than upper slope which suggests that sediment from upper slope made ahigher contribution to the sediment at thelower slope. Also of note is the ﬁnding that
before October, the sediment yield of upper
slope was always greater than that caught inthe trap of lower slope. As shown in Fig. 3,
major portion of sediment yield (.-.,ῌ) caught
in clean-weeded co#ee at lower slope occurredon November. Instead of farmer activities thathave been discussed above, the litter of co#ee
leaves also a#ected the sediment transfer
before November. As shown in Fig. -, the litter
had blocked the sediment trap, thus reducing
the transportation of sediment. After the
farmer removed litter because it was afraidthat the litters were used as insect nest, thesediment yield increased remarkably.
As
shown in Fig. 3, there is increasing sedimentyield in November +333, from -- g/m, in October to +/3.3 g/m, in November.
(/) Sediment yield from secondary forest
and new forest remnant (E-system)
Total sediment yield from forest areas andentrapped by new forest remnant were *.*2 g/
m, and *.0, g/m, respectively as shown in Fig.
+*. Although the slope is very steep (3*ῌ),sediment yield from secondary forest was very
low. The reduction of rainfall energy bycanopy of trees and the dense of vegetation at
ground surface that served as barrier were responsible of low sediment yield. However,about 0.3 times of sediment yield occurred
when forest was opened, but the value was still
lower than the other land use system measured
in this experiment. As shown in Fig. -, thesurface condition of new forest remnant was

still fully covered by litter,wood debris as well
as falling tress, which are still very e#ective inpreventing sediment transfer.
(0) Total sediment yield from various land
uses (F-system)
Total sediment yield from various land uses
during ++ months measurement are shown in
Fig. ++. The amount of sediment yield entrapped by each land use system was asfollows : the mixed-co#ee garden (1+3.1 g/m,) ;multistrata system followed by rain-fed agri
culture (.,-., g/m,) ; clean-weeded co#ee garden (,13.1 g/m,) ; clean-weeded co#ee garden
at upper and lower slope (+/3.3 g/m,) ; cleanweeded co#ee garden and long shrub ﬁlter
system (+-,.1 g / m,) ; clean-weeded co#ee
garden at upper slope (3..* g/m,). On the other
hand, the sediment yield from the forest areas
was almost zero (*.*2 g/m,) and which was entrapped by new remnant system was *.0 g/m,.
The multistrata system also produced a very
low sediment yield (,.- g/m,) and sediment entrapped by grass ﬁlter (which composed ofmultistrata and agriculture system above) was,0./ g/m,.
If the above unit changes into t/ha or mm(assumed soil bulk density + g/cm-), the valuesof sediment yield range from *.***2 to 1., t/ha
or *.****2 to *.1 mm. These values are lower
than sedimentation in some critical watersheds
in Indonesia reported by Utomo (+323). For
example, sediment yields in Way Sekampung
watershed, Cilutung, and Brantas were 2.1, 3.*,and *.,/ mm/year respectively.
In the current study, three co#ee garden systems produced di#erent amounts of sediment,
i.e. co#ee in multistrata indicated *.*,- t/ha,
clean-weeded co#ee indicated ,.2 t/ha and +.0
t/ha (at lower slope) and mixed-co#ee garden
indicated 1., t/ha. The highest value of sediment yield in mixed-co#ee garden was due tothe more intensive farmer activity in this land
use compared to the other co#ee land use
system.
The high value of sediment yield in mixedco#ee garden will not reach the stream since῎῍ : Sediment Yield from Various Land Use Practices in a Hilly Tropical Area of Lampung Region, South Sumatra, Indonesia 35

Table .

E#ectiveness of various natural vegetative strips in the
study area (*ῌ.* cm)

No

Description of ﬁlter+

Grass ﬁlter : consists of small grass and sparsebananas ; located at bottom of the slope (/ῌ3ῌ) ; +ῌm length. The sediment source is rain-fed agriculture
with horticultural crops.
Shrubs ﬁlter : consists of woody species (Clibadia sp.
and various ferns) ; located near at foot slope withlength - m and gradient of 2,ῌ. The sediment sourceis mixed-co#ee garden.
Shrubs ﬁlter : consists of woody species (Clibadia sp.
and various ferns are dominant) and small grass atbottom of this ﬁlter ; located at mid-slope with +, min length and gradient 3*ῌ. The sediment source isclean-weeded co#ee.

,-

33.1ῌ will be trapped by shrubs ﬁlter, and even
if it passed through the ﬁlter, the sediment will
be deposited in the next land use system,
paddy ﬁeld. This situation demonstrated theimportance of natural vegetative ﬁlter as wellas the arrangement or structure of land use
system in a landscape for soil conservation inco#ee areas in Lampung, Indonesia. Thisﬁnding was conﬁrmed by the experiment of
Sinukaban et al. (,***). Using a catchment’s
approach, Sinukaban et al. (,***) had shownthat the water ﬂow from that area relatively
remained constants although sharp land usechanges occurred in this area from forest toco#ee plantation during the years +31* to +33*.
In case of clean-weeded co#ee garden without ﬁlter (at lower slope), the sediment will
directly ﬂow into the creek and carried byrunning water. So from the viewpoint of soil
erosion process, the clean-weeded co#ee atlower slope has contributed the highest sediment yield. On the other hand, the multistratasystem produced a very low sediment yield,
indicating this is an optimal system to protect
soil against water erosion. Multistrata system
is very e#ective to reduce the rainfall energy
by intercepting raindrops before they strike to

Sediment
entrapped
(ῌ)

3-.1

33.1

/,./

the soil. Litter leaves that covered groundsurface also reduced surface runoff.
It appears that surface cover condition ofland use system provided a high contribution
on sediment yield other than the soil erosion
factors. Although forest area has steeper slope(3*ῌ) than clean-weeded co#ee garden (,/ῌ0/ῌ), they o#er better performance in modifying the erosion process. The e#ect of farming
activities (weeding, tillage) showed a high contribution in promoting sediment yield. These
activities had a#ected the soil surface condition, such as vegetation coverage and soil condition. If erosive agent could deﬁne soil erosion
process as detachment and transportation ofsoil particles, then the soil detachment process
has been done by the farmer activities.
(1) Filter e#ectiveness
Filter in general sense can include a range oflandscapes elements : depression, cut-o# drains,ditches, embankment, vegetated strips, hedgerows, and riparian vegetation (van Noordwijk
et al., +332). We recognized one natural vegetative strip which is abundant in the study area,
i.e. shrubs ﬁlter which consisted of various
weed species, mainly Clibadia surinamense andvarious type of ferns. Clibadia sp. is a woodyΐῐ῎῔῕ῑ ῒ 3+ ῏ ῌ,**,῍

36Table /

No

+
,
.
/
0
1
2
3
+*
++

Average of standard deviation (SD) and coe$cient of variation (CV)among the replications
Land use

Multistrata
Rain-fed agriculture
Grass ﬁlter
Mixed-co#ee garden
Shrub ﬁlter
Clean-weeded co#ee
Long shrub ﬁlter
Clean-weeded co#ee upper slope
Clean-weeded co#ee lower slope
Secondary forest
New forest remnant

Mean*
(g)

Standard
deviation**(g)

Coe$cientof Variation(ῌ),4/+.*24+
3-43
1//4+-4//-42
.-+
-.-4+
2+34,
,4,
,-4+

+421
-,043
3042
1/14-4,...4/
3*34+324,
/1042
,4/
.,4/

1/
,+*+**
32
2*
,++
/2
1*
+++2.

*῍ mean monthly during total experiment time (++ months)**῍ among replications for ++ months measurement

species that could reach +./ m in height. The
description of each ﬁlter strips is presented inTable .. All the vegetative ﬁlter strips fully
covered the ground surface. However, there
are several di#erences among the canopy typesof each ﬁlter. Grass ﬁlter could cover the entire
soil surface, however due to short height of thegrass, runo# water and sediment could still
ﬂow above the grass. Shrubs ﬁlter which was
mainly consisted of “woody species”, haveleaves and branches which could cover theentire ground surface cover, so it will be e#ective in protecting against raindrop. However,under the canopy of shrubs, the coverage on
the ground surface is not so dense, and runo#
water and sediment still could run between the“individual species”.
The e#ectiveness of natural vegetative ﬁlterin entrapping sediment was as follows : grassﬁlter 3-./ῌ, short shrubs ﬁlter 33.1ῌ and longshrubs ﬁlter /,./ῌ.
Instead of vegetation type inside the ﬁlter,the e#ectiveness of natural ﬁlter strip in entrapping or transferring sediment also depends
on slope length. This study showed that shortﬁlter cover with small grass or shrubs was very
e#ective to entrap the sediment than a very
long one. Runo# will have a chance to accu-

mulate in the longer slope, and a rill will becreated if there is a concentrated ﬂow.
(2) Variability
The sediment trap was very simple and very
easy to maintain. The data could be collected
on rainfall event basis or daily basis. However,
because the measurement has been done in thenatural condition, some weakness related tostatistical aspect is appeared. The variability
among the replications could be expressed by
calculating the standard deviation (SD) and the
coe$cient of variation (CV). The SD and CV
during the experimental period are shown in
Table /. The CV was very high, between ,-ῌuntil ,++ῌ.
The lowest variability was found in rain-fed
agriculture with horticultural crop (,-ῌ) due
to the fact that the farmer have cultivated thesoil as uniform as possible for growing a highvalue crops that need the same distance andgood soil management. A very high coe$cientof variation was found in long shrubs ﬁlter(,++ῌ), new forest remnant (+2.ῌ), and secondary forest (++-ῌ). At least there are threereasons why high coe$cient of variation
among the replications appeared : (a) the development of a concentrated ﬂow of runo# (or rill
erosion) above a sediment trap, (b) the farmer῎῍ : Sediment Yield from Various Land Use Practices in a Hilly Tropical Area of Lampung Region, South Sumatra, Indonesia 37

activity for cultivating the soil, and (c) and theexistence of litter at the ground surface, as
shown in Fig. -.
..

Conclusion

The existence of natural vegetative strips
was very e#ective in entrapping sedimenttransfer, and the e#ectiveness ranged between/,.,ῌ33.1ῌ. Although mixed-co#ee garden indicated the highest yield of sediment (1+3.1 g/m,), the sediment that left the whole mixed
co#ee garden system was very low (,.- g/m,)
due to ﬁlter entrapping. The lowest sedimentyield was found in secondary forest (*.*2 g/m,),and the highest values of sediment yield which
discharged into the river was found in cleanweeded co#ee garden as much as +/3.3 g/m,.
Co#ee in multistrata system also produced avery low sediment yield (,.- g/m,). The sediment yield values in this area were still lower
than the other place in Indonesia. The soil
covered condition of land use system andfarmer activities (weeding, tillage, and fertilizer application) gave a high contribution on
sediment transfer other than soil erosion
factors such as slope gradient and rainfall.
Since the measurement was made under natural condition, the coe$cient of variation
among the replications was very high. The
minimum value of coe$cient of variation was
found on rain-fed agriculture (,-ῌ) and the
maximum value was found on long shrubs
ﬁlter (,++ῌ).
Acknowledgments
We wish to convey our gratitude to the Inter-national Center for Research in Agroforestry(ICRAF) South East Asia, especially to ICRAF
sta# Dr. Meine van Noordwijk and Dr. Thomas
P. Tomich, and the Asian Development Bank(RETA /1++) for ﬁnancial support.
Reference
Lumbanraja, J., Syam, T., Nishide, H., Mahi, A. K.,
Utomo, M., Sarno and Kimura, M. (+332) :Deterioration of soil fertility by land usechanges in South Sumatra, Indonesia (from+31* to +33*) Hydrological Processes, +, : ,**ῌ,*+-.
van Noordwijk, M., van Roode, M., McCallie, E.L.
and Lusiana, B. (+332) : Soil erosion and sedimentation as multiscale, fractal process : Implication for models and experiments and thereal world. Soil Erosion at Multiple Scales :principles and methods for assessing causes
and impacts, ed. de Vries, P.W.T. Penning,
Agus, F. and Kerr, J. IBSRAM. CABI Publishing : ,,-ῌ,/-.
Sinukaban, N., Tarigan, S.D, Purwakusuma, W.,
Baskoro, T. and Wahyuni, E.D. (,***) : Analysis of watershed function : sediment transfer
across various types of ﬁeld boundaries. Final
Report. Bogor Agriculture UniversityῌICRAFSouth East Asia. Bogor.
Soil Survey Sta# (+332) : Keys to Soil Taxonomy,
2th ed. United States Department of Agriculture. Washington D.C.
Syam, T., Nishide, H., Salam, A.D., Utomo, M., Mahi,
A.K., Lumbanraja, J., Nugroho, S.G. andKimura, M. (+331) : Land use and cover changes in a hilly area of South Sumatra, Indonesia(from +31* to +33*). Soil Sci. Plant Nutr., .- : /21
ῌ/33.
Utomo, W.H. (+323) : Soil and Water Conservationin Indonesia, A Record and Analysis. Rajawali
Press, Jakarta.

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