ῐ
J. Jpn. Soc. Soil Phys.
῏῍ῌῐῑ῎
No. 3/, p. //ῌ0, ῍,**-῎

The Change of Morphology in Red Acid Soil after FourYears Treatment of Co#ee Plantation with Di#erent
Weeds Management in a Hilly Area of Lampung,South Sumatra, Indonesia
AFANDI*, Didin WIHARSO*, Masateru SENGE**, Adomako John TAWIAH***,
Yoko OKI**** and Tadashi ADACHI***** Faculty of Agriculture, University of Lampung, J+. Sumantri Brojonegoro +,Bandar Lumpung -/+./, Indonesia** Faculty of Agriculture, Gifu University, +ῌ+ Yanagido Gifu /*+ῌ++32, Japan*** Soil Research Institute of Ghana Kwadaso, Kumasi, Ghana**** Faculty of Environmental Science and Technology, Okayama University, -ῌ+ῌ+Tsushimanaka Okayama 1**ῌ2/-*, Japan
Abstract
Research was conducted on the red soils formed from young intermediary to maﬁc volcanic
materials that occupy the hilly areas of South Sumatra, Indonesia within the humid tropicalclimate. This research was aimed at investigating the inﬂuences of di#erent soil cover crops on
soil morphology and soil properties after four years treatment as well as examining the probablechanges in the soil taxonomy. Three soil proﬁles were made in the middle of erosion plots after. years treatment with di#erent soil cover crops under co#ee trees. The treatment plots were ;T-+, keeping the ground bare by hand weeding at two weeks interval (co#ee without cover crop) ;T-,, Co#ee with Paspalum conjugatum as cover crop and T--, co#ee with natural weeds as covercrops. The soil proﬁles were described and sampled according to Soil Survey Manual (+33-) andSoil Taxonomy Classiﬁcation System (+332). It was observed that after . years, soil surface layer
had become thicker and darker than before. Almost all the soil chemical properties in soil surface
layer increased, particularly soil pH, organic carbon content, total nitrogen, available P, exchangeable bases, and base saturation. On the other hand, exchangeable Al and Al saturation of soil
surface layer decreased. Although several soil characteristics changed during the study period, it
was evident that . years treatment was too short to change soil taxonomy of the three pedons in
sub-group category.

In the sub-group category, all pedons were still classiﬁed as Vertic

Dystrudepts. Covering soil surface by natural weeds was able to increase exchangeable bases andbase saturation in the sub- surface layer, therefore over a long period of time there will be apossibility of the changing the soil taxonomy from Vertic Dystrudepts to Eutrudepts in the greatsoil group category.
Key words : Red Soil, co#ee, cover crop, weeds, Vertic Dystrudepts, Sumatra+.

Introduction

The term of Red Soil is used to describe soils
that have hue of +* YR until / YR, with value

and chroma ranging between , and 2 (Wiharso,+330). This type of soil is widely distributed in
the tropical regions of the world, includingIndonesia. They are formed from many kinds

῏56  3/of rocks, both felsic and maﬁc, spread over low
and high altitudes of undulating mountainous
regions with perhumid to semiarid climates(Buurman, +32*). Red soil is associated withacid soils, marginal soils, and infertile soils.
According to Soil Classiﬁcation System in thepast, these soils were called Latosol or Lateritic
soils (Uehara and Gillman, +32+). Since +30+,
red soils in Indonesia had been classiﬁed into
four, namely ; Red-Yellow Mediterranean,
Latosol, Red-Yellow Podzolic, and Lateritic(Buurman, +32*).
Soils that are formed from recent volcanic
materials, ﬂuvial, or in the young landscape are
generally rich in nutrients and capable ofsupporting plant growth and animal community, if the availability of water, sunshine, andtemperature are not limiting factors. The soils
formed by these volcanic materials usually
have enough nutrients that can support various plants. However, under humid tropicalclimate, the soils will be subjected to soil erosion and the soil degradation become fast. Materials left on the landscape are subsurface
layer, which are abundant with insoluble materials, hence showed the inability of soils to
support sustainable agriculture.
Within the research area, drastic changes inland use from primary forests to cultivatedlands without proper soil conservation practices had led to severe land deterioration causing signiﬁcant soil fertility decline between+31* and +33* (Lumbanraja et al., +332).
Improving soil ability to support various
plants and sustain agriculture, soils should bemanaged and maintained through conservation practices such as covering soil by covercrops or weeds. Afandi et al. (,**,) reported
that covering soil by grass (Paspalum conjugatum) and natural weeds could decrease
runo# and erosion signiﬁcantly.
This research was aimed to characterize thesoil morphology and soil properties of threepedons of red soil in a hilly area under co#ee
plantation in South Sumatra, Indonesia, after
four years of cover cropping management,**-

using grass (Paspalum conjugatum) and naturalweeds. The probable changes in the soil taxonomy with reference to the Soil Taxonomy Classiﬁcation System (Soil Survey Sta#, +332) werealso examined.
,.

Materials and Method

The research was conducted in co#ee plantation which had been under three di#erent
cover cropping management systems since+33/ to +333 in a hilly area of Sumber Jaya
District, Lampung Province, South Sumatra at
an altitude of about 2** meters above sea leveland +/ gradient.
The detailed treatments were discussed byAfandi et al. (,**,) and could be summarized asfollows :(+) Treatment + (T-+) : Clean-weeded co#ee.
Ground surface was always keeping bare byhand weeding at two weeks interval. This
management is a general practice in this co#ee
plantation area so that this treatment isregarded as a control.
(,) Treatment , (T-,) : Co#ee with Paspalum
conjugatum as cover crop. Young Paspalum
conjugatum was transplanted to the experiment plot in November +33/ and February+330.
(-) Treatment - (T--) : Co#ee with naturalweeds as cover crop.
In each plot, seedlings of Arabica co#ee wereplanted with planting distance +./ m by , m on
November +33/. Weed management was done
every two weeks by clearing all the weeds inclean-weeded plot (T-+), and cutting the weeds
around the co#ee tree with diameter + m forthe weedy plots (T-, and T--). Before and after
rainy season, the Paspalum mats (T-,) and natural weeds (T--) were mowed at +/-cm height.
Application of fertilizer and pesticides had
been adopted according to the standard usual
practice.
The natural weeds were dominated by
Clibadium surinamense, Ageratum conyzoides,
Chromolaena odorata, Melastoma malabatricum,
Clidemia hirta, Dicranopteris linearis, Imperata῎῍ : The Change of Morphology in Red Acid Soil after Four Years Treatment of Co#ee Plantation with Di#erent Weeds Management in a Hilly Area of Lampung, South Sumatra, Indonesia 57

cylindrica, Paspalum conjugatum, and Borreria
leaves (Salam et al., ,**+).
The treatments were located side by side.
Each treatment had two plots with an area of+** m, of / m width and ,* m length. One plot
was used for soil erosion measurement (undisturbed during four years), and the other plot
was used for soil sampling. So each erosion
plot was separated by sampling plot. After
four years of treatments, a representative soil
proﬁle was dug in the middle of soil erosion
plot in each treatment plot.
Chemical fertilizers including ,** kg haῌ+ of
urea, ./ kg haῌ+ of P, O/ in the form of Ca(H, PO.),, and +** kg haῌ+ of potassium chloride,
were applied just after transplanting and thentwice a year in April and October.
Soil samples were taken from each horizon
for chemical and physical analyses. Soil pH
was determined in H, O and + N-KCl at soil toliquid ratio of + : ,./, Organic Carbon (Walkley
and Black), total Nitrogen (Kjeldahl), available
P (Bray-I), CEC, exchangeable bases extractedby NH. OAc. at pH 1.*, and exchangeable Aluminum extracted by + N-KCl. The soil proﬁleswere described and sampled according to Soil
Survey Manual (+33-) and Soil Taxonomy Classiﬁcation System (+332) to determine themorphological processes that occurred in the
red soil.
The soil strength in each horizon was measured using hand penetrometer, and repeated +*times, and the results was the average of themeasurements.
-.

Results and Discussions

Morphology and Physico-chemical
Properties of Soil
The morphology and physico-chemical properties of the three pedons are relatively similar in terms of their structure, texture, consistence, color and thickness (Table +). These are,clay texture, blocky to sub-angular blocky
shape structure in the surface horizon, crumb
structure in the sub-surface and friable in all
horizons. However, when soils were observed-. +critically, di#erences in color, internal drainage, and the thickness of surface horizon were
noticed. The soil surface horizon of pedons
treated with Paspalum grass and natural weeds
were found to be thicker than the control. Thisobservation can be attributed to the fact thatcover crops are able to decrease run o# anderosion (Afandi et al., ,**,), therefore useful forsoil conservation measures.
Soil color is closely related to parent material, organic carbon content, the intensity of Fe/
Al oxidation, age of parent material, and soil
moisture condition. The color of soil in surface
horizon of pedons (A horizon) that were covered by either Paspalum grass or natural weeds
was darker than control, due to their organic
materials released to the soil. Soil color in thesubsoil of Paspalum grass and natural weeds
plots had red color brighter than clean-weededco#ee plot (control), with that of grass superior
to natural weeds plot. Reduction and oxidation (Redox) process in soils a#ect the stabilityof iron (Fe) and manganese (Mn) compounds.
Soil color can indicate certain moisture condition due to the mobilization of Fe and Mn
caused by Redox processes. Generally, the subsoil of three pedons showed enough oxidationand good internal drainage conditions. Thesephenomena were proved by the high chroma(ῌ.). But, soil colors in the lowest horizon ofpedon T-+ (at 2+ῌ+*- cm depth) and pedon T-(at +*2ῌ+-, cm depth) that reached ,./ Y showed
less oxidative condition and the internal drainage worse than T-, (at +,*ῌ+-/ cm depth).
Among the three pedons, T-+ was the least
oxidative compared to others, even though thelowest layer had ever experienced redox reaction in the past as shown by the red mottles (+*YR //2).
Although there are di#erent colors (matrix
or mottles) in subsoil among the three pedons,
it is too early to conclude that those di#erenceswere caused during four years of study. Conceptually, a biological process or vegetation
plays an important role in soil formation over along-term period. In a more detailed analysis,

58

Table +,**-Morphology and Soil Physical Properties of Three Pedons under Di#erent Cover CropManagement Systems

Soil
Plot Depth(cm)

Soil Separates
Horiz
on

Matrix Color

Dark Brown +* YR -/-

+*ῌ-,

AB

-,ῌ2+

Bw+

2+ῌ+*- Bw,

T-+

Soil

Text

(kg/kg)Structure

ure
Sand

A

*ῌ+*

T-,

3/

Sab, f, +

Silt

Clay

Soil
StrengthkPa

Consist Mottles /
ence

Crack

Roots

md-few,f-m*4,/- *4,0, *4.2/

C

,./4,

fr

Crack

Yellowish Brown +* YR //0

Sab, f-m, + *4,/. *4+-, *40+.

C

,-*4/

fr

Crack

f-cm

Strong Brown 14/ YR //0

Cr, vf, +*4,11 *4+-+ *4/3,

C

+1+40

fr

Crack

f-few

Light Yellowish Brown,4/ Y 0/.

Cr, vf, +*4,/. *4+,+ *40,/

C

+.14+

fr

+* R
f-very//2, sdk few

b, vf, +*4-30 *4+2+ *4.,-

C

,-*4/

fr

Crack

md-few,
f-m
f-cm

*ῌ+/

A

Dark Greyish
Brown +* YR -/,

+/ῌ.*

AB

Yellowish Dark Brown+* YR ./0ῌ//0ab, f-m, + *4-+2 *4+,* *4/0,

C

,0.42

fr

Crack

.*ῌ2/

Bw+

Strong Brown 14/ YR //0

Cr, vf, +

C

,,*40

fr

Crack

f-few

Crack

f-veryfew*4,3- *4+-0 *4/1+

2/ῌ+,* Bw,

Yellowish Red / YR //0

Cr, vf, +*4,+, *4+,- *400/

C

,*/43

fr

+,*ῌ+-/ Bw-

Yellowish Red / YR //0 &Brownish Yellow +* YR 0/0b, vf, +*4+1/ *4+-. *403+

C

,.*4-

fr

b, f, +

*4--- *4,,+ *4..0

C

+2+4.

fr

Crack

md-cm,
f-m



*ῌ+-

A

Dark Greyish Brown+* YR -/,

+-ῌ.2

AB

Yellowish Brown +* YR //0

Sab, f-m, + *4,3. *4+-+ *4/1/

C

,.*4-

fr

Crack

md-few,
f-cm

T-- .2ῌ 3, Bw+

Yellowish Strong Brown
14/ YR //0ῌ+* YR //0

Cr, vf, +*4-+, *4+.- *4/./

C

,0.42

fr

Crack

f-few

3,ῌ+*2 Bw,

Strong Brown to Yellowish Red
14/ YR //0ῌ/ YR //0

Cr, vf, +*4,-1 *4+,+ *40.,

C

,/*4+

fr

f-veryfew+*2ῌ+-, Bw-

Strong Brown and Olive Yellow
14/ YR //0 & ,4/ Y 0/0b, f, +

*4,,+ *4+-+ *40.2

C

,+*42

fr

f-veryfew

Ex : bblocky, abangular blocky, sabsub angular blocky, Crcrumb, CClay, frfriable, Crack, fﬁne, mdmedium, cmcommon, mmany.

the concept of biosequence needs thorough discussion in order to understand the uniformityof parent material in a land unit. Inﬂuences ofsoil cover crop on morphology and soil properties are more signiﬁcantly shown in soil
surface layer, particularly, color, thickness ofsoil surface layer, soil chemical properties, suchas pH, organic carbon content, total nitrogen,available P, exchangeable bases, exchangeable
Al, base saturation and Al saturation (Table ,).
Generally, cover crops have the capability to
improve chemical properties of soil surface
layers (Wiharso, Afandi and Senge, ,**+). The
content of organic carbon, total nitrogen, available P, exchangeable bases, and pH of soil surface layer in both grass and natural weed plots,
were higher than control plot, while exchange-

able Al and Al saturation decreased.
Accumulation of organic matters and exchangeable bases in soil surface horizon ofco#ee plantation treated with grass (T-,) or
natural weed (T--) show that bases in the formof nutrients had been translocated from subsoil
to various tissues of cover crops through roots,
and these bases and organic matter were later
returned into the soil surface after decomposition. Bases returned to the soil surface in thismanner retarded the loss of exchangeablebases by leaching and retarded the development of soil acidity, hence the pH values werehigher in T-, and T-- compared to T-+.
Paspalum grass and natural weeds in this research had total biomass larger than control(Sriyani et al., +333), hence its ability to de-ΐῒ : The Change of Morphology in Red Acid Soil after Four Years Treatment of Co#ee Plantation with Di#erent Weeds Management in a Hilly Area of Lampung, South Sumatra, Indonesia 59

Table ,

Soil Chemical Properties of Three Pedons under Di#erent Cover Crop Management Systems

Soil

pH

Plot depth Hor
(cm)

T-+

T-,

T--

C-

T-

Org

N

(mg/ (mg/
H, O KClkg)

kg)

Exchangeable Bases

Avail4 P
Bray I

cmol (῍) kg῎+

CEC 1

(mg/kg)

Ca

Mg

K

ῑ
Exch4

Na

Bases

BS 1
(ῌ)

ECEC

Exch4 Al sat
Al

(ῌ)

*ῌ+*

A

.4,3 -41. ,,41

+43

-4*3

+14-

-41* +432 *4,0 *4*/

/433

-.40

2433

-4**

--4.

+*ῌ-,

AB

.4,/ -403

34*

*43

+4*-

+04+

-4.. +432 *4,+ *4*.

/401

-/4,

143,

,4,/

,24.

-,ῌ2+ Bw+ -43, -40/

,43

*4/

ῌ

+24+

,42+ +4-/ *4+, *4*,

.4-*

,-42

142/

-4//

./4,

2+ῌ+*- Bw, -430 -40-

,43

*4.

ῌ

,04.

-430 +4/0 *4+* *4*+

/40-

,+4-

34/,

-42/

.*43

*ῌ+/

A

.4/1 -422 ,04+

,4,

+3432

+04,

14*, 04.0 *4.1 *4+*

+.4*/

2041

+/4/*

+4./

34.

+/ῌ.*

AB

.4++ -402

340

+4*

+423

+040

-41* +4*. *4+- *4*,

.423

,34/

1423

-4**

-24*

.*ῌ2/ Bw+ -410 -4.,

-41

*40

ῌ

+042

,4// +4*, *4+, *4*,

-41+

,,4+

042+

-4+*

./4/

2/ῌ+,* Bw, -43, -40*

.4*

*4.

ῌ

+14-

,4+1 +4*. *4+* *4*,

-4--

+34,

14-2

.4*/

/.43

+,*ῌ+-/ Bw- -43* -4/1

,41

*4-

ῌ

,.42

+43+ +4*. *4*3 *4*+

-4*/

+,4-

24*/

/4**

0,4+

*ῌ+-

A

.42* -42- ,34*

,4.

24+.

+342

14/- .4*2 *4,1 *4*1

++43/

0*4.

+,40*

*40/

/4,

+-ῌ.2

AB

.4-2 -41-

34,

*43

,4*+

+.41

.4.1 ,41+ *4+1 *4*.

14-3

/*4-

+*4/3

-4,*

-*4,

.2ῌ3, Bw+ .4*, -41.

,41

*4.

ῌ

+-4-

,402 +4-/ *4+. *4*-

.4,*

-+40

14.*

-4,*

.-4,

3,ῌ+*2 Bw, .4*+ -41/

,4-

*4.

ῌ

+.4+

+400 +4-/ *4*3 *4*+

-4++

,,4+

0410

-40/

/.4*

+*2ῌ+-, Bw- .4** -41.

+4/

*4-

ῌ

-24*

+40/ +4-- *4*3 *4*+

-4*2

24+

14+-

.4*/

/042

῎+

CEC 1ῐCEC by + N NH.OAc at pH 1.*. cmol (῍) kg ; BS 1ῐῑExch. Bases/CEC 1῏+**ῌ ; ECEC (E#ectiveCEC)ῐῑExch. Bases῍Exch. Al, cmol (῍) kg῎+ ; Al Sat. (Al Saturation)ῐExch. Al/ECEC῏+**ῌ.

crease soil erosion signiﬁcantly (Afandi et al.,,**,). This is also supported by the thicker soil
surface layer of both grasses and natural weeds
plots compared to the control.
Soil surface horizon of both grass and natural weed plots contain organic carbon higher
than control, with natural weeds plot having
the highest value. But the highest percentage
of organic carbon from natural weed plot did
not have corresponding values of exchangeable bases and available P. Exchangeable bases
and available P in the surface layer of natural
weed plot was lower than that of grass.
Table , showed that the use of Paspalum
grass and natural weeds can increase exchangeable bases and base saturation, especially in the surface layer (A horizon). The increasing exchangeable bases and base saturation by
Paspalum grass were more concentrated in soil
surface layer, while that of natural weeds increased those properties down to the sub-layer.
Although the natural weeds plot contains exchangeable bases less than grasses in soil surface horizon, its exchangeable calcium washigher than the rest.

This phenomenon showed that in Paspalum
plot as well as in natural weeds plot, Al saturation was decreased and the pH was increased in
the surface horizon. Yearly observation which
was made from +330 to +333 also showed thatthe soil pH and organic matter in Paspalum
plot and natural weeds plot were higher thanin control plot up to .* cm depth (Salam et al.,,**+). Probably the main reason of this phenomenon arised from the abundant of organic
matter in Paspalum as well as natural weeds
plot. The average content of soil organiccarbon from +330 to +333 in Paspalum plot andnatural weeds plot was -,.+ g/kg and ,0./ kg
respectively where in control plot it was ,*., g/
kg (Afandi et al., ,**-).
-. , Soil Classiﬁcation
Morphology of the observed soils was almost
similar to the soil morphology in lowland areasin Lampung, Indonesia, in which the observed
soils are dominated by halloysite (Lumbanraja,
Syam, Sarno and Wada, +333).
The three pedons have deep solum and thinsoil surface layers with weak structure, therefore belong to ochric epipedon. Due to the60

absence of clay ﬁlm in the sub surface horizon
as well as soils having CEC of more than +0
cmol () kg+, it indicates that the three pedons
belong to the cambic horizon as their diagnostic horizon. According to Soil Survey Sta#(+332), those pedons are classiﬁed as Inceptisolin the order category. Those pedons do nothave aquic conditions within /* cm of the mineral soil surface, but they have udic moistureregime, therefore soils are classiﬁed as udepts inthe sub-order category. In the great soil groupcategory, the three pedons are classiﬁed as
Dystrudepts, because they do not have sulfuric
horizon, duripan, fragipan, free carbonate, anda base saturation of 0*῍ or more in one ormore horizons at a depth between ,/ and 1/ cm
from the mineral soil surface.
The natural weeds plot (T--) had a base saturation of /*.+1῍ between ,/ and 1/ cm depththat satisﬁes the approximate requirement by
Eutrudepts (ῌ0*῍). It can therefore be deduced
that when co#ee plantation is properly
managed with natural weeds, base saturation
is likely to increase within ,/ῌ1/ cm depth of
the sub surface horizon. So, there is a possibility of the changing soil class in great groupcategory from Dystrudepts to Eutrudepts.
Although clay minerals near this researcharea (Rigis Hill) are dominated by halloysite, + :+ type of clay mineral, but soils still haveenough amount of chlorite, vermicullite andsmectite (Lumbanraja, Syam, Sarno and Wada,+333), therefore soils have ability to swell andshrink. This phenomenon is shown by crack of/ mm or more width and -* cm or more length
in a depth of less than +,/ cm from soil surface
in each soil proﬁle. Beside, soils do not havelithic contact within /* cm from soil surface
and mollic or umbric epipedon. Based on thediscussions above, the three pedons are classiﬁed as vertic dystrudepts in sub group category,
although the slickensides or wedge-shape aggregates were not found.
-. - The Co#ee Growth
Although the existence of weeds could bepositive e#ect on the soil, however, in short

3/

,**-

term, it could suppress the co#ee growth performance. The control plot where the conventional weed management applied gave the best
performance of co#ee growth as shown inplant height, canopy diameter and coverage.
As reported by Afandi et al. (,**,), the weeds
had suppressed the co#ee height at Paspalum
plot about .*῍ and at natural weed plot about-*῍. The canopy diameter was also suppressed as much as /1῍ at Paspalum plot and/.῍ at natural weeds plot.
Sriyani et al. (,***) also reported that theyield reduction of co#ee beans in weedy plots
in +333 was .*῍ at Paspalum plot and 1/῍ atnatural weed plot compared to clean-weededplot.
-. . Conclusion
Covering soil surface by crops or weeds forfour years was able to conserve soils in hilly
area of South Sumatra and improved soil morphology as well as soil chemical properties.
Surface layer of soils treated with grasses andnatural weeds became thicker and darker than
before. Almost all soil chemical properties insoil surface layer increased depending on thetype of treatment. Thus, grasses plot had
thicker soil surface as well as higher available
P, exchangeable bases, Mg, K, Na, and basesaturation than natural weeds. On the other
hand, natural weeds increased organic carbon
content, total nitrogen, soil pH, CEC, exchangeable calcium, as well as decreased exchangeable Al and Al saturation in soil surface horizon.
It can be deduced from the study that, sincenatural weeds were able to increase exchangeable bases and base down to the sub-surface
layer, the soil class could possibly change from
Dystrudepts to Eutrudepts in the great soil
group category.
Even though several soil characteristics
changed, they were not enough to distinguishsoil nomenclature of three pedons in sub groupcategory. All pedons had vertic property in
sub group category, hence classiﬁed as Vertic
Dystrudepts.

῍ῌ : The Change of Morphology in Red Acid Soil after Four Years Treatment of Co#ee Plantation with Di#erent Weeds Management in a Hilly Area of Lampung, South Sumatra, Indonesia 61

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