of 18
8/10/2019 1-s2.0-S0167880996010651-main
1/18
ELSEVIER
Agr icu ltu re , Ecosys tems and Env i ronm en t 60 (1996) 29 -46
A g r i c u l t u r e
E c o s y s t e m s &
E n w r o n m e n t
So il erosion and environm ental impact o f vegetable production in
the C am eron H ighlands, M alaysia
D av i d J . M i d m o re a,1, H an s G .P . J an s en a ,* , Ro b e r t (3 . D u m s d ay b
a Asian Vegetable Research and Development Center AVRDC), P.O. Box 42, Shanhua, Tainan, Taiwan
b School of Agriculture, La Trobe University, Bundoora, Vic. 3083, Australia
Accep ted 3 May 1996
A b s t r a c t
Vegetable production in the Cameron Highlands of Malaysia has expanded over the past 25 years and has been
implicated in the increase in sedimentation in reservoirs in the region. The present study was executed to evaluate current
methods, patterns and profitabi lity of vegetable production; study the causes, environmental impact and externality cost of
soil erosion; assess the effectiveness and adoption of soil conservation and management practices; determine the extent o f
adoption of integrated pest management methods; and elicit farmers' perceptions regarding the main constraints in vegetable
cultivation. Recent changes in land use within the area are quantif ied by a geographical information system, Landsat
imagery, a digital elevat ion model and a 1992 farm survey of 10% of the farmers. Farmers modify the natural envi ronment
by mechanical excavations and other earthworks, and compensate for the negative effects of soil erosion on productivity by
extensive use of irrigation, chicken manure, lime, and inorganic fertilizers. The preparation of broad platform terraces, cut
out of the natural slope, is a major source of soil erosion which is estimated at 24 t ha- ~ year - l on average. However, on a
per event basis, soil loss may be as high as 155 t ha - l per event. Terraces are resurfaced periodically because of
impoveri shed soil and reducing yields. Bench terraces, while reducing erosion, are rare owing to labor shortages. With the
exception of polyethylene rain shelters, other agronomic practices do not substantially reduce soil erosion. Recommendations
are made regarding the timing of land clear ing and resurfacing of terraces, and suggestions for interventions that may
improve catchment management are offered. The value of the negative external ities imposed on the Electricity Board as a
resul t of sedimentation in waterways and reservoirs is estimated at M 2 106 per year, or less than 4% of the total annual
gross value of vegetable production in the CH. However, soil erosion resulting from vegetable cult ivation in the CH is likely
to cause other negative off-site effects that cannot easily be quantified, including adverse effects on public health as a resul t
of run-off of chemicals, loss of wildlife habitat, and potential loss of tourism.
Keywords: Env ironm ent; IPM; M alaysia; Profi tabil ity ; Soil erosion; Sustainab il i ty ; Veg etables
* Cor re spond ing au tho r a t: R esea rch P rog ram on Sus ta inab i l i ty
in Agr icu l tu re (REPOSA, CATIE/UAW/MAG), Apdo. 224,
7210 Gufipiles , Costa Rica . Tel . : 506-710-6595; fax: 506-710-
2327; e-mail: [email protected].
P re sen t add ress: Depa r tm en t o f Bio logy , Cen t ra l Queen s land
Univ ersi ty , Ro ckham pton, Qld. 4702, Austral ia .
1 . I n t r o d u c t i o n
1.1. Background
The relative economic importance of agriculture
in Malaysia has declined as a result of diversification
and industrialization of the economy. Demographic
016 7-8 809 /96 /$1 5 .0 0 Copyr igh t 1996 Elsev ie r Sc ience B.V. Al l r igh ts re se rved .
PII S 0 1 6 7 - 8 8 0 9 ( 9 6 ) 0 1 0 6 5 - 1
8/10/2019 1-s2.0-S0167880996010651-main
2/18
30
D.J. Midmore et al. / Agriculture, Ecosystems and Environment 60 1996) 29 -4 6
pr e s s u r e on t he l a nd ha s i nc r e a s e d a s w i t ne s s e d by
a v e r a g e p o p u l a t i o n d e n s it y w h i c h h a s i n c r e a se d f r o m
25 . 5 pe r s ons km - 2 i n 1961 t o 59 . 7 pe r s ons k r n - 2 i n
1994 ( W or l d B a nk , 1995 ) . S t r a t e g i e s t o e nha nc e
a g r ic u l tu r a l d e v e l o p m e n t n e e d t o t a k e a c c o u n t o f t h e
s h r i nka ge i n l a nd a va i l a b l e f o r a g r i c u l t u r e due t o
u r ba n i z a t i on a nd i ndus t r i a l i z a t i on . O n t he ba s i s o f
da t a i n W or l d B a nk ( 1995) i t c a n be c a l c u l a t e d t ha t
w he r e a s r u r a l popu l a t i ons ha ve i nc r e a s e d a t a n a ve r -
a ge a nnua l r a t e o f 1 . 3% be t w e e n 1961 a nd 1994 , t he
c o r r e s pond i ng r a t e f o r u r ba n popu l a t i ons i s 4 . 7% .
T he s a me s ou r c e r e ve a l s t ha t , b e t w e e n 1980 a nd
1990 , a g r i c u l t u r a l ou t pu t g r e w a t a n a ve r a ge r a t e o f
3 . 8 % y e a r - j , w h e r e a s i n d u s tr y a n d m a n u f a c t u r in g
g r e w a t a ve r a ge a nnua l r a t e s o f 7 . 1% a nd 8 . 8% ,
r e s p e c t iv e l y . T h e s e d e v e l o p m e n t s h a v e l e d t o g r e a t e r
c ompe t i t i on a c r os s s e c t o r s f o r r e s ou r c e s i nc l ud i ng
l a bo r a nd c a p i t a l , a s w e l l a s a n i nc r e a s i ng c onc e r n
f o r p r e s e r v i ng t he e nv i r onme n t . A gr i c u l t u r e i n t he
h i gh l a nds e nc ompa s s e s t he s e i s s ue s a nd , w i t h a pp r o -
p r i a t e t e c hno l og i e s , c ou l d he l p t o i mpr ov e t he ove r a l l
pe r f o r ma nc e o f t he a g r i c u l t u r a l s e c t o r .
A l a r ge pa r t o f the m oun t a i no us s t e e p l a nds i n
M a l a y s i a i s k e p t u n d e r f o r e s t. H o w e v e r , i n p e n i n s u -
l a r M a l a y s ia , n e a r l y l 0 4 h a o f s te e p m o u n t a i n o u s
l a n d i n t h e C a m e r o n H i g h l a n d s ( C H ) h a v e b e e n
d e v e l o p e d f o r ( l a r g e ly ) t e m p e r a t e v e g e t a b l e s ( m a i n l y
c a bba ge , t oma t o , a nd l e a f y ve ge t a b l e s ) , a s w e l l a s
f o r t e a , f l o r i c u l t u r e , a nd f r u i t s . A dd i t i ona l l a nd ha s
b e e n o p e n e d f o r n o n - a g r i c u lt u r a l u se s ( i n c lu d i n g g o l f
c ou r s e s ) . O t he r h i gh l a nd a r e a s i n M a l a ys i a w h i c h
h a v e b e e n d e v e l o p e d f o r a g r i cu l tu r a l p u r p o s e s c a n b e
f o u n d i n e a st M a l a y s i a , w h e r e c o c o a a n d p e p p e r a r e
p l a n t e d on s t e e p l a nds . A no t he r l a nd u s e t ype i n
s t e e p a r e a s i s s h i f t i ng c u l t i va t i on , a l s o ma i n l y f ound
i n e a s t M a l a y s i a ( S a r a w a k ) a n d a m o u n t i n g t o a b o u t
2 .7 106 ha , of wh ich 0 .1 10 6 ha a r e c l e a r e d
a nnua l l y f o r t he c u l t i va t ion o f h i l l r ic e a nd o t he r
f ood c r ops . T he o t he r e a s t M a l a ys i a n s t a t e , S a ba h , i s
dom i na t e d by a l a nds c a pe o f h i l l y a nd s t e e p l a nd
w hi c h a c c oun t s f o r ove r 60% o f i t s t o t a l a r e a . I n
K u n d a s a n g , p r i m a r y j u n g l e i s b e i n g r e p la c e d t h r o u g h
c l e a r i ng ope r a t i ons a nd ve ge t a b l e p r oduc t i on on s t e e p
l a nd i s ga i n i ng popu l a r i t y .
1 . 2. V e g e t a b l e s t a t is t i c s i n M a l a y s i a
A n y a na l ys i s o f the s t a t u s o f the ve ge t a b l e s e c t o r
i n M a l a ys i a a t t he na t i ona l l e ve l i s ha mpe r e d by t he
un r e l i a b i l i t y o f o f f i c i a l da t a on ve ge t a b l e a r e a a nd
p r o d u c t i o n . F o r e x a m p l e , w h i l e d a t a a d a p t e d f r o m
t he gove r nme n t a l F i f t h M a l a ys i a P l a n s ugge s t t ha t
t he a r e a unde r ve ge t a b l e s ha s f l uc t ua t e d a r ound 104
ha t h r oughou t t he pa s t de c a de ( A na ng , 1989 ) , da t a
f r o m t h e M i n i s t r y o f A g r i c u l t u r e ( M O A ) s u g g e s t
f l uc t ua t i ons i n t he a r e a unde r ve ge t a b l e s be t w e e n
8 103 a nd 2 . 8 104 ha d u r i ng t he pe r i od 19 70 -
1989 ( M O A , va r i ous ye a r s ) . S i mi l a r l y , f i gu r e s s up -
p l i ed b y A n a n g ( 1 9 8 9 ) a n d F A O ( 1 9 9 0 ) s e e m t o
a g r e e on a n a nnu a l p r odu c t i on o f s ome 5 105 t
ye a r - ~ i n t he l a t e 1980s , a s o ppos e d t o o f f i c i a l
es t imates of l es s th an 3 X 105 t (A hm ad e t a l . ,
1992) .
E s t i m a t e s o f v e g e t a b l e c o n s u m p t i o n b a s e d o n
c o n s u m p t i o n s u r v e y s c a r r i e d o u t b y t h e F e d e r a l
A g r i c u l t u r a l M a r k e t i n g A u t h o r i t y ( F A M A ) p a i n t a
p i c t u r e in w h i c h t he c ons um pt i on o f ve ge t a b l e s i n -
c r e a s e d f r o m l l 8 g p e r c a p i ta d a y - l i n 1 9 8 2 to 1 53
g per capi t a day - I in 1985 (A hm ad e t a l. , 1992) .
H o w e v e r , t h e m o s t r e c e n t F A O f i g u r e s ( w h i c h d o n o t
i n c l u d e h o m e g a r d e n p r o d u c t i o n ) f o r a v a i l a b i l i t y o f
ve ge t a b l e s i nd i c a t e a pe r c a p i t a da i l y s up p l y o f j u s t
ove r 100 g ( F A O , 1991) , c ons i s t e n t w i t h f i gu r e s f o r
d o m e s t i c p r o d u c t io n a n d t ra d e f o r 1 9 8 5 - 1 9 9 0
( A na n g , 1989; F A O , 1990) w h i c h i nd i c a t e tha t ve g -
e t a b l e a va i l a b i l i t y f a ll s s i gn i f i c a n t l y s ho r t o f t he 200
g p e r c a p i t a d a y - 1 c o n s i d e r e d n e c e s s a r y t o m e e t
da i l y mi c r o - nu t r i e n t r e q u i r e me n t s ( A l i e t a l . , 1996 ) .
M o r e s e r io u s l y , a c o m p a r i s o n o f a h y p o t h e t i ca l c o n -
t i nua t i on o f h i s t o r i c a l g r ow t h pa t t e r n s o f ve ge t a b l e
s upp l y ove r t he pa s t t w o de c a de s i n t o t he f u t u r e w i t h
p r o j e c t e d i n c r e a s e s i n v e g e t a b l e d e m a n d ( b a s e d o n
e xpe c t e d g r ow t h i n popu l a t i on a nd pe r c a p i t a i n -
c om e ) s ugge s t s a c ons i de r a b l e w i de n i ng o f the ga p
b e t w e e n d o m e s t ic d e m a n d a n d s u p p l y , m a i n l y f u e l ed
b y s t ro n g g r o w t h i n p e r c a p it a i n c o m e e x c e e d i n g 6 %
y e a r - ~ a n d u r b a n iz a t io n o f a b o u t 5 % y e a r - l ( J an -
sen , 1992; Ah m ad e t a l ., 19 92) .
E v e n t h o u g h a s i z a b l e p r o p o r t i o n o f M a l a y s i a ' s
t o t a l ve ge t a b l e p r oduc t i on i s e xpo r t e d ( ma i n l y
t o m a t o , c h i l i e s a n d c a b b a g e p r o d u c e d i n t h e C H f o r
t he S i nga por e ma r ke t , w or t h a bou t M S z 5 107
2 M$ stands for M alaysian dollar (or Ringg it) for which the
1992 exchange rate is ab out 2.6 to the US d ollar.
8/10/2019 1-s2.0-S0167880996010651-main
3/18
8/10/2019 1-s2.0-S0167880996010651-main
4/18
32 D~I. Midmore et al. / Agriculture, Ecosystems and Environment 60 1996) 29-4 6
m a n a g e m e n t ( I P M ) p r a c t i c e s a m o n g s u r v e y f a r m e r s
t o a s c e r t a i n t he ne e d f o r f u r t he r r e s e a r c h a nd p r omo-
t i on ; a nd s ug ge s t i n t e r ve n t i on me a s u r e s t ha t m a y
i m p r o v e c a t c h m e n t m a n a g e m e n t . A f t e r d i s c u s s i n g
s o m e m e t h o d o l o g i c a l a sp e c t s o f th e s t u d y a n d d e -
s c r i b i ng t he ma j o r s ou r c e s o f da t a i n t he ne x t s e c t ion ,
e a c h o f t he s e ob j e c t i ve s w i l l be a dd r e s s e d i n s e pa r a t e
s ub - s e c t i ons o f S e c t i on 3 . T he l a t t e r i s f o l l ow e d by a
d i s c us s i on , w h i l e t he l a s t s e c t i on i s r e s e r ve d f o r
c onc l us i ons .
2 . M a t e r i a l s a n d m e t h o d s
2 . 1 . S t u d y a r e a
m o n t h l y m e a n t e m p e r a t u r e r a n g in g f r o m 2 1 t o 2 4 C
a nd mi n i mum f r om 11 t o 14 C . A ve r a ge r a i n f a l l da t a
f o r 1 9 8 1 - 1 9 9 1 s h o w s a b i m o d a l a n n u a l p a tt e rn , w it h
p e a k s i n A p r i l / M a y a n d O c t o b e r / N o v e m b e r t h at
a r e c l o s e l y r e l a t e d t o e r o s i on r a t e s ( D ums da y a nd
H ua ng , 1992 ; M i dmor e e t a l . , 1996 ) . N o mon t h i s
w i t hou t r a i n f a l l , a nd t he d r i e s t mon t hs a r e D e c e mbe r
a nd J une . A nnua l r a i n f a l l f o r t he pa s t 35 ye a r s
a v e r a g e d 2 2 0 5 m m y e a r - ~ . L o c a l p e r c e p t io n i s t h a t
a i r t e mpe r a t u r e ha s r i s e n a nd r a i n f a l l d i mi n i s he d
o v e r t h e p a s t f o u r d e c a d e s , t o s o m e e x t e n t c o n f ir m e d
b y d a t a f r o m t h e M a l a y s i a n M e t e o r o l o g i c a l S e r v i c e
( M i dmor e e t a l . , 1996 ) . F o r e s t c l e a r i ng ha s be e n
c o m m o n l y s u g g e s t e d a s a c a u s e o f c l im a t e c h a n g e i n
the a rea .
E x t e n d i n g o v e r a n a r e a o f 7 1 2 5 5 h a , t h e C H i s
l o c a t e d in t h e s t a te o f P a h a n g , 2 5 0 k m f r o m t h e
c a p i t a l K u a l a L u m p u r . A f t e r J o h o r s t a t e , P a h a n g ,
w i t h s o m e 2 5 0 0 h a u n d e r v e g e t a b l e s , i s t h e s e c o n d
mos t i mpor t a n t ve ge t a b l e g r ow i ng s t a t e i n M a l a ys i a .
T h e t o t a l a r e a u n d e r v e g e t a b l e c u l t i v a t i o n i n C H
a c c o u n t s f o r a b o u t h a l f o f t h e t o t a l h i g h l a n d v e g -
e t a b l e a r e a i n M a l a ys i a . S ou r c e s at t h e M a l a y s i a n
A g r i c u l t u r a l R e s e a r c h a n d D e v e l o p m e n t I n s t i t u t e
( M A R D I ) e s t i m a t e v e g e t a b l e p r o d u c t i o n in t h e C H a t
180 t da y - I w i t h a va l ue o f M $ 0 . 15 10 6 ( D u m s -
day e t a l . , 1991) .
M os t ve ge t a b l e c u l t i va t i on i n t he C H t a ke s p l a c e
be t w e e n 900 a nd 1400 m a bove s e a l e ve l . S o i l s a r e
m a i n l y d e r i v e d f r o m g r a n i t e , w i t h s a n d y t o s a n d y
c l a y l oa m t e x t u r e s , a nd a r e c l a s s i f i e d a s pa l e udu l t s
( P a r a m a n a t h a n , 1 9 7 7 ) . T h e u n d i s t u r b e d so i l 0 - 1 0 c m
b e n e a t h t h e o r g a n i c o r h u m u s l a y e r c o m p r i s e s 4 0 %
s a nd , 16% s i l t , 44% c l a y , e l e c t r i c a l c onduc t i v i t y
( E C ) 0 .1 3 m S c m - I a n d p H 4 . 2 (M A R D I , u n p u b -
l i s he d da t a , 1983 ) . F o r mos t o f t he s t udy a r e a ,
na t u r a l o r d i ve r t e d d r a i na ge i s t o a r e s e r vo i r c on -
s t r uc t e d i n 1965 f o r t he pu r pos e o f ge ne r a t i on o f
h y d r o e l e c t r i c p o w e r . W i t h t h e e x c e p t i o n o f v a l l e y
f l oo r s , ve ge t a b l e p r oduc t i on i s r a r e l y p r a c t i c e d on
na t u r a l s l ope s bu t r a t he r on ( mos t l y p l a t f o r m) t e r -
r a c e s c u t ou t o f t he na t u r a l s l ope w i t hou t c onc e r n f o r
r e pos i t i on i ng o f t op s o i l o r humu s . F a r m e r s , t he r e -
f o r e , re q u i re h e a v y i n p u t s o f n u t r ie n t s e v e n o n n e w l y
ope ne d l a nd i n o r de r t o s u s t a i n c r op g r ow t h .
T he c oo l t e mpe r a t e c l i ma t e o f t he C H i de a l l y s u i t s
p r o d u c t i o n o f t e m p e r a t e v e g e t a b l e s , w i t h m a x i m u m
2 . 2 . S a m p l i n g m e t h o d o l o g y
A s t r a t i f i e d r a ndom s a mpl e c ons i s t i ng o f 206
f a r me r s i n 13 d i f f e r e n t l oc a t i ons ( be t w e e n 9 a nd 28
f a r me r s pe r l oc a t i on ) i n t he C H w a s i n t e r v i e w e d 3
du r i ng J a nua r y 1992 , w i t h t he s u r ve y da t a r e f e r ri ng
t o t he 1991 c a l e nda r ye a r . I nd i v i dua l f a r ms w e r e
c hos e n on t he ba s i s o f i nd i v i dua l f a r m l oc a t i on , s i z e ,
ve ge t a b l e t ype a nd a r e a a nd hous e ho l d s i z e , w i t h t he
h e l p o f d e t a i l e d m a p s o b t a i n e d f r o m F A M A . R e p r e -
s e n t a t i ve s o i l s a mp l e s w e r e c o l l e c t e d a t e a c h f a r m ,
a nd a na l yz e d f o r t e x t u r e , pH a nd E C . S i mi l a r l y ,
na t u r a l l a nd s l ope s a nd s l ope s o f t e r r a c e s a nd be ds
w e r e a s s e s s e d on e a c h f a r m . O bs e r va t i ons on t he
d e g r e e o f s o i l e r o s i o n o n e a c h f a r m w e r e a l s o
r e c o r d e d . F r o m t h e s a m p l e , 1 9 3 f a r m s f o r w h i c h
c ompl e t e da t a s e t s w e r e a va i l a b l e w e r e r e t a i ne d f o r
a na l y s i s , r e p r e s e n t i ng a pp r ox i ma t e l y 10% o f a l l ve g -
e t a b l e f a r ms i n t he C H .
2 . 3 . L a n d u s e a n d s a t e l l i t e d a t a
T o a s s e s s c ha nge s i n l a nd u s e be t w e e n 1986 a nd
1990 , D i g i t a l L a nds a t M a ppe r ( T M ) da t a f o r 1990 , a
1 : 5 0 0 0 0 t o p o g r a p h i c m a p , a n d a l a n d u s e m a p f o r
1 9 8 6 p r o d u c e d b y D O A w e r e u t i l i z e d . T o p r o d u c e a
l a nd u s e ma p f o r 1990 , a s t a nda r d f a l s e c o l o r c om-
p o s i te T M i m a g e a t a s c al e o f 1 : 5 0 0 0 0 w a s d e v e l -
ope d f o r v i s ua l i n t e r p r e t a t i on a i de d by g r ound
3 The surv ey sample and questionnaire are described in Dums-
day et al. (1992).
8/10/2019 1-s2.0-S0167880996010651-main
5/18
D.I. Midmore et al ./ Agriculture, Ecosystems and Environment 60 1996) 29-46
33
t r u t h i ng . A d i g i t a l e l e va t i on mode l ( D E M ) o f t he
s t udy a r e a w a s a l s o de ve l ope d , t a k i ng 100 m c on t ou r
l i ne s a nd pe a ks f r om t he t opog r a ph i c ma p a t a s c a l e
o f 1 : 5 0 0 0 0 . S e p a r a t e l a n d u s e m a p s f o r 1 9 8 6 a n d
1 9 9 0 w e r e o v e r l a y e d o n t h e m o d e l , u s in g 1 0 0 m
100 m ( 1 ha ) g r i d s i z e ( w h i c h l i ne a r l y i n t e r po l a t e d
a l t i t ude o f g r i d c e l l s w he n t he y l a y be t w e e n c on -
t ou r s ) , a nd a s l ope ma p w a s p r e pa r e d w i t h t he f o l -
l o w i n g s lo p e c la s se s : le s s t h a n 2 , 2 - 5 , 5 - 1 0 , 1 0 - 2 0 ,
2 0 - 3 0 , 3 0 - 4 0 , a n d o v e r 4 0
2.4. Rainfall and erosivity
P l u v i o g r a p h i c c h a r t s f o r t h e p e r i o d 1 9 8 1 - 1 9 9 1
w e r e s u r ve ye d , a nd t he k i ne t i c e ne r gy o f r a i n s t o r ms
o f o v e r 1 0 m m ( o v e r t h e w o r s t 3 0 m i n p e r i o d ) w a s
c a l c u l a t e d a s f o l l ow s ( W i s c hme i e r a nd S mi t h , 1978 ;
D u m s d a y a n d H u a n g , 1 9 9 2 )
KE = 21 0 + 891og~0 I
w h e r e KE is k i n et ic en e r g y ( m - t h a - l c m - l ) a n d I
i s i n t e n s i t y ( c m h - l ) .
T h u s ,
KE
r e p r e s e n t s t he un i t s o f w or k done ( i . e .
m o v i n g 1 t b y 1 m ) p e r u n i t v o l u m e (1 h a - c m ) .
3 . R e s u l t s a n d d i s c u s s i o n
3.1. Changes in land use between 1986 and 1990
T he l a nd u s e ma p f o r 1990 s ugge s t s t ha t mor e
t h a n 3 0 0 0 h a w e r e u s e d f o r v e g e t a b l e a n d f l o w e r
Table I
Land use stati stics for 1986 a and 1990 b for the CH
Land use types 1986 1990
ha % of total ha % of total
Vegeta bles and flowe rs 1453 23,1 3237 c 33.2
Tea estat es 2942 46.8 2821 28.9
Cleared tea area ND - 210 2.2
Newl y opened forests ND - 1453 a 14.9
Scrub and sca tter ed farms 1702 27.1 1860 e 19.1
Tow n 194 3.1 179 1.8
Tota l 6291 100.0 9759 100.0
a Land use map of DOA.
b Satellite imagery.
c Includes farm roads, farm houses, rain shelters, and farm yards.
a Includes dead ferns, cleared forest, barren land, and land slides.
e Includes fruit orchards.
ND, no data included.
Table 2
Distribution of vegetable area (%) according to DEM and survey
Slope class ()
0-2 2-5 5-10 10-20 20-30 30-40 > 40
Sur vey 2.1 12 29.3 46.1 11.5 0 0
DEM 30.2 9.3 18.4 28.0 11.1 2.7 0.3
pr oduc t i on i n t ha t ye a r ( T a b l e 1 ) , e xc e e d i ng p r e v i ous
e s t i ma t e s by s ome 50% ( K o e t a l . , 1987 ) . A na l ys i s
o f l a nd d i s t r i bu t i on i n t he de s i gna t e d s l ope c l a s s e s
w i t h t h e D E M i n d ic a t es t h a t 4 0 % o f v e g e t a b l e p r o -
duc t i on i n 1990 w a s on l a nd w i t h na t u r a l s l ope s ove r
5 ( M i dm or e e t a l . , 1996 ) . T he c o r r e s p ond e nc e be -
t w e e n n a t u r a l s l o p e s m e a s u r e d f r o m t h e D E M a n d
t hos e c o l l e c t e d on s a mpl e f a r ms i s r e a s ona b l e w i t h
t he e xc e p t i on o f l a nd i n t he 0 - 2 c la s s ( T a b l e 2 ) .
D a ta f ro m G O M / A D B ( 1 98 8 ) a n d M a c k en a n d O n g
( 1979) a r e c ons i s t e n t w i t h t he f i e l d s u r ve y r a t he r
t ha n t he D E M . O w i ng t o t he l a r ge ve r t i c a l i n t e r va l
u s e d ( 100 m) , i t i s l i ke l y t ha t t he D E M i nc o r r e c t l y
i n t e r p r e t e d l a nd i n t he l ow s l ope c a t e go r y . I n l oc a -
t ions wh ere the re i s l i tt l e land in the c l as s 0 -5 the
r e l a t i ons h i p be t w e e n s l ope s on s a mpl e f a r ms a nd t he
D E M i s ve r y c l o s e . S u r ve y da t a i nd i c a t e tha t , a l-
t hough mos t f a r me r s a r e c u l t i va t i ng ve ge t a b l e s on
l a nd w i t h a n a t u r a l s l ope o f 10 - 2 0 , mor e t ha n
one - ha l f u s e s be ds w i t h a s l ope o f l e s s t ha n 2 and
o n l y 1 0 % h a d b e d s w i th a s l o p e o f o v e r 5 . O n l y
1 6 % o f a ll n e w l y o p e n e d a r e a s h a v e s l op e s o v e r 2 0 ,
w h i c h i s no t e xc e s s i ve c ons i de r i ng t ha t mos t ne w
l a nds a r e ups l ope o f t hos e a l r e a dy ope ne d w i t h i n
e a c h va l l e y i n t he C H .
3.2. Structure and patterns of vegetable production
A t j u s t ove r 0 .8 ha ( T a b l e 3 ) , a ve r a ge f a r m s i z e
a m o n g s a m p l e f a r m e r s i s a b o u t d o u b l e t h e n a t i o n a l
a ve r a ge f o r ve ge t a b l e f a r me r s ( A na ng , 1989) . I t e x -
c e e ds t he a ve r a ge f a r m s i z e o f 0 . 55 h a i n t he C H
r e por t e d by D ums da y e t a l . ( 1991 ) bu t i s i n l i ne w i t h
t h e a v e r a g e f a r m s i z e o f 0 . 8 5 h a r e p o r t e d b y T a y l o r
e t a l. ( 1 9 9 3 ). I f f a r m n u m b e r s h a v e n o t m a r k e d l y
i nc r e a s e d i n t he r e c e n t pa s t , t he r e c o r de d i nc r e a s e i n
i nd i v i dua l f a r m s i z e i s i n l i ne w i t h t he obs e r ve d
i nc r e a s e i n t o t a l a r e a unde r ve ge t a b l e s i n t he C H .
M o s t f a r m e r s ' t e n u re a r r a n g e m e n t c o n s i s ts o f a T e m -
p o r a r y O w n e r s h i p L i c e n c e ( T O L ) . T O L s a r e a c o r n -
8/10/2019 1-s2.0-S0167880996010651-main
6/18
34 DJ . Midmore et al. Agriculture, Ecosystems and Environment 60 1996) 29 -46
Table 3
Land statistics (ha) for individual sample farms
N M e a n M i n . M a x . CV
Total farm size 193 0 .8 2 0.1 6 4.0 0.57
Cultivated land 193 0.7 5 0.16 4.0 0.58
Owned land 32 0.75 0.28 2.0 0.48
Temporarilyoccupied and 130 0. 8 9 0.16 4.0 0.57
Rented-in land 32 0 .5 6 0.2 0 1.6 0.60
Irrigated land
Sprinkler 175 0 .7 4 0.1 6 4.0 0.60
Other irrigation 26 0 .5 3 0. 10 1.2 0.68
Plastic shelter area 50 0 .4 0 0.0 4 1.8 0.78
Area un der terraces
Platform terrace 157 0 .6 7 0.0 2 4.0 0.62
Bench terrace 47 0 .2 7 0.0 2 1.2 1.04
m o n f o r m o f la n d t e n u r e w h e r e l a n d i s h e l d f o r 5 - 1 5
y e a r s , c a r r y i n g n o m i n a l f e e s ( a b o u t M $ 2 5 0 - 3 5 0
h a - t y e a r - l ) , a c c o m p a n i e d b y r e v ie w s o f l a nd u s e
a n d m a n a g e m e n t p r a c t i c e s . T h e r e h a v e b e e n f e w
c a s e s o f T O L s b e i n g r e v o k e d . O n l y 1 6 % o f a ll
s a m p l e f a r m e r s r e n t s o m e o f t h e i r la n d f r o m o t h e r s,
w i t h a n a ve r a ge r e n t e d - i n a r e a o f l e s s t ha n 0 . 6 ha a t
a n a v e r a g e r e n t a l c o s t o f a b o u t M $ 7 0 0 0 h a - ~ . A l l
f a r m s h a v e s o m e f o r m o f i r r i g a t i o n f a c i l i t y , 9 0 %
w i t h s p r i nk l e r i r r i ga t i on . W a t e r i s d i r e c t e d f r om
s t re a m f l o w h i g h e r i n t h e w a t e r sh e d , b y w a y o f s m a l l
w e i r s a nd p l a s t i c p i pe s t o p r ov i de a s u f f i c i e n t he a d t o
ope r a t e s p r i nk l e r s . F a r me r s ge ne r a l l y ha ve s u f f i c i e n t
f a c i l i t i e s t o i r r i ga t e t he i r w ho l e f a r m a r e a . A bou t
one - q u a r t e r o f a l l s a mp l e f a r m e r s ma ke u s e o f p la s t i c
s h e lt e rs , o n a v e r a g e c o v e r i n g a b o u t 0 . 4 h a o f l a n d .
W h i l e m o s t s a m p l e f a r m e r s g r o w e x c l u s i v e l y v e g -
e t a b l e s , 14 ( 7% o f t he s a mpl e ) a l s o p r oduc e c u t
f l o w e r s. T h e a n n u a l v a l u e o f f l o w e r p r o d u c t io n i n
t h e C H h a s b e e n e s t i m a t e d a t s o m e M $ 2 X 1 07
( D u m s d a y e t a l ., 1 9 9 1 ), o r a b o u t 4 0 % o f t h e v a lu e o f
v e g e t a b l e p r o d u c t i o n . E v e n t h o u g h f l o w e r c u l t iv a t i o n
i s ge ne r a l l y c ons i de r e d a n i nc r e a s i ng l y i mpor t a n t a nd
p r o f i t a b l e e n t e r p r i s e , da t a c o l l e c t e d t o c a l c u l a t e t he
( a bs o l u t e a nd r e l a t i ve ) p r o f i t a b i l it y o f f l ow e r c u l t iva -
t i on t u r ne d ou t un r e l i a b l e .
M o s t f a r m e r s g r o w b e t w e e n t w o a n d f i v e d i f f e r en t
ve ge t a b l e s pe c i e s , o f w h i c h t he mos t popu l a r i nc l ude
c a b b a g e ( E n g l i s h
Brass ica o leracea var cap i ta ta ,
C h i n e s e
Brass ica pek inens is ) ,
t o m a t o ( L y c o p e r s i c o n
escu len tum) , l e t t uc e ( I nd i a n Lactuca ind ica a n d h e a d
Lactuca sa t ivum) ,
o n i o n
All ium cepa) ,
s n o w p e a s
Pisum sa t ivum var . macrocarpon) ,
c e l e r y ( E ng l i s h
Apium graveo lans var . du lce
a n d C h i n e s e
A p i u m
graveo lans var . seca l inum) , s p i na c h Spinacia oler-
acea) ,
ga r l a nd c h r ys a n t h
Chrysan themum coronar -
ium) ,
b e a n s ( b u t t e r
Phaseo lus luna tus ,
g r e e n
Phase-
olus vulgaris, F r e n c h Phaseo lus vu lgar is ) , mus t a r d
( C h i n e s e B r a ss i c a j u n c e a ka ve s , l e a ve s ) , Ca p s ic u m
sp . , and radi sh
R a p h a n u s sa t i v u s ) .
F a r m e r s ' c r o p -
p i ng pa t t e r n s a r e de t e r mi ne d by a va r i e t y o f f a c t o r s .
F o r e x a m p l e , c a b b a g e i s r e l a t i v e l y e a s y t o g r o w ,
w i t hou t t he ne e d f o r p l a s t i c s he l t e r s . H ow e ve r , c r ops
s uc h a s s p i na c h , t ong - ho a nd l e t t uc e ne e d r a i n s he l -
t e rs f o r o p t i m a l y i e l d p e r f o r m a n c e . T o m a t o i s a c r o p
w i t h a r e l a t i ve l y h i gh l a bo r r e q u i r e me n t .
V e g e t a b l e s a r e g r o w n y e a r - r o u n d , a l t h o u g h s o m e
s e a s ona l i t y is e nc ou n t e r e d a m ong s pe c i e s . C ons ide r a -
t i on o f ha r ve s t t i me i s i mpor t a n t i n r e l a t i on t o s o i l
e xpos u r e a nd e r os i on du r i ng p r e - s ow i ng c u l t i va t i on ,
a n d b e f o r e c o m p l e t e g r o u n d c o v e r b y t h e s u c c e e d i n g
c r op ( M i dmor e e t a l . , 1996 ) . A l t hough t he popu l a r i t y
o f i n t e r c r opp i ng de pe nds on t he s pe c i e s g r ow n , a
l a r ge p r opo r t i on o f r e s ponde n t s i nd i c a t e d t ha t i n t e r -
c r o p p i n g w a s o f t e n n o t p r a c t i c e d o w i n g t o l a b o r
s ho r t a ge s , bu t i s be l i e ve d t o r e duc e p r i c e r i s k s a nd
p r o v i d e s o m e d e g r e e o f c o n t r o l o f p e s t s a n d d i se a s es
( T a y l o r e t a l ., 1993 ) .
3 .3 . Vo lumes and pro f i tabi l i ty o f vege table produc-
tion
T he t o t a l g r os s a r e a c u l t i va t e d w i t h ve ge t a b l e s
( i .e . t a k i ng a c c o un t o f mu l t i p l e c r opp i ng a nd i n t e r -
c r o p p i n g ) b y s a m p l e f a r m e r s i s 3 1 8 h a w i t h c a b b a g e
( C h i ne s e a nd E ng l i s h ) , t oma t o , a nd l e t t uc e a c c oun t -
i n g f o r r e s p e c t iv e l y 4 7 % , 1 5 % , a n d 7 % . T h e a v e r a g e
c r o p p i n g i n t en s i ty (a r e a c ro p p e d y e a r - l p e r a re a )
e q ua l s 2 . 2 , w h i c h i s c ons i de r a b l y l e s s t ha n t he va l ue
o f 3 . 2 c a l c u l a t e d on t he ba s i s o f 1988 da t a
( G O M / A D B , 1 9 88 ). A r ea , p ro d u c t io n a nd y i el d s o f
i nd i v i dua l ve ge t a b l e s pe c i e s s how w i de va r i a t i on
b e t w e e n s a m p l e f a r m e r s ( T a b l e 4 ) . G i v e n t h a t t h e
s a mpl e r e p r e s e n t s 10% o f a l l ve ge t a b l e f a r me r s i n
t he C H , t he f i gu r e s i n T a b l e 4 r e s u l t i n a t o t a l da i l y
ve ge t a b l e p r oduc t i on o f 179 t , c on f i r mi ng t he e a r l i e r
M A R D I e s t i m a t e . T h e v a l u e o f a n n u a l v e g e t a b l e
p r od uc t i on by t he s a mpl e f a r m e r s a t a ve r a ge p r i c e s i s
M $ 5 . 642 X 106 ( T a b l e 5 ) , g i v i ng a n e s t i ma t e d t o t a l
a n n u a l p r o d u c t i o n v a l u e f o r th e C H o f M $ 5 . 6 4 2 x
10 7 . T hi s l a t t e r f i gu r e a ga i n i s i n a g r e e me n t w i t h
8/10/2019 1-s2.0-S0167880996010651-main
7/18
D . I . M i d m o r e e t a l . / A g r ic u l tu r e , E c o s y st e m s a n d E n v i r o n m e n t 6 0 1 9 9 6 ) 2 9 - 4 6 3 5
T a b l e 4
A r e a a n d y i e l d o f v e g e t a b l e cr o p s f o r s a m p l e f a r m s , p e r a n n u m
N G r o s s a r e a ( h a ) Y i e l d ( t h a - t )
M e a n M i n . M a x . C V M e a n M i n . M a x . C V
E ng l i sh 13 5 0 . 73 0 . 12 4 . 8 0 . 87 27 . 1
c a b b a g e
C h i n e s e 8 8 0 . 5 4 0 . 1 2 2 . 0 0 . 6 4 2 6 . 4
c a b b a g e
M us t a rd 17 0 . 57 0 . 12 2 . 4 1 . 06 12 . 9
Spi na c h 23 0 . 62 0 . 12 2 . 2 0 . 86 14 .5
Ga r l a nd 18 0 . 47 0 . 12 1 .2 0 . 82 14 .8
c h r y s a n t h
Le t t uc e 53 0 . 42 0 . 10 2 . 0 0 . 77 12 . 8
C e l e ry 23 0 . 40 0 . 08 2 . 2 1 . 10 13 . 9
O n i o n 3 4 0 . 5 6 0 . 1 2 2 . 8 0 . 9 3 1 3 . 0
B e a n s 17 0 . 3 0 0 . 08 1 . 2 0 . 89 10 .1
P e a s 2 7 0 . 4 4 0 . 1 0 2 . 0 0 . 7 9 5 . 7
T o m a t o 1 01 0 . 4 6 0 . 0 8 2 . 0 0 . 7 2 2 6 . 0
C a ps i c um 13 0 . 3 3 0 . 13 0 . 7 0 . 55 27 ,1
R a di sh 10 0 . 43 0 . 10 1 .2 0 . 77 16 ,1
Ot he r 3 0 0 . 56 0 . 10 1 .7 0 . 84 18 . 7
ve ge t a b l e s b
6 . 3 84 . 4 0 . 59
5 . 0 72 . 5 0 . 55
4 . 5 27 . 5 0 . 57
1.3 56.3 0.95
1 .3 45 . 0 0 . 77
3 . 4 26 . 3 0 . 48
0 . 8 45 . 0 0 . 88
1 . 0 60 . 0 0 . 87
2 . 0 23 . 8 0 . 64
0 . 2 22 . 5 0 . 78
0 a 75 . 0 0 . 60
3 . 3 68 . 8 0 . 90
7 . 0 3 0 . 0 0 . 43
1 . 4 65 . 5 0 . 95
a O n e f a r m e r e x p e r i e n c e d c r o p f a i lu r e .
b I n c l u d e s a w i d e r a n g e o f v e g e t a b l e s , e a c h g r o w n b y s i x s a m p l e
fa rme rs o r l e s s .
estimates made by MARDI, though s ignif icantly be-
low the es timate o f M 108 provided by the DO A
(Du msd ay et al. , 1991) . Ow ing to i ts large area and
h igh y i e ld s , Eng l i sh c a bb a ge i s r e spons ib l e f o r ne a r ly
one - th i r d o f t he t o t a l va lue o f ve ge t a b l e p r oduc t ion
in the CH, despi te i t s low pr ice re la t ive to most o ther
vege tables .
The a ve r a ge d i f f e r e nc e be tw e e n the h ighe s t a nd
low e s t p r i c e s r e c e ive d r a nge s f r om a f a c to r o f 1 . 4
( for beans) to 2 .7 ( for caps icum) . Da ta presented in
D in g e t a l . (1981) c om bine d w i th 1991 p ri c e da t a
f r o m F A M A , a l l o w a c o m p a r is o n b e t w e e n 1 9 9 1 a n d
1981 ve ge t a b l e p r i c e s ( i n nom ina l t e r m s) . A l though
pr i c e s f o r sp ina c h ha ve ne a r ly doub le d a nd those o f
be a ns i nc r e a se d by 50% ove r t he l a s t de c a de , p ri c es
o f Eng l i sh c a bba ge , c a ps i c um a nd r a d i sh ha ve se e n
s ign i f i c a n t de c r e a se s o f t he o r de r o f 40% . N om ina l
p r i c es o f l e tt uc e , m us t a r d a nd tom a to ha ve r e m a ine d
a bou t t he s a m e , im p ly ing s ign i f i c a n t de c r e a se s i n
r e a l p r i c e s. W i th in - ye a r p r ic e f l uc tua t ions ( m e a su r e d
by the r a t i o o f t he h ighe s t a nd low e s t a ve r a ge p r i c e
r e c e ive d by f a r m e r s du r ing a pa r t i c u l a r ye a r ) de -
c r e a se d be tw e e n 1981 a nd 1991 f o r m os t ve ge t a b l e s.
Th i s r a t i o ha d subs t a n t i a l l y e xc e e de d 2 . 0 f o r a lm os t
a l l ve ge t a b l e s i n 1981 , bu t ha d d r oppe d be low 2 . 0
f o r m os t ve ge t a b l e s by 1991 .
Costs and re turns of vege table cul t iva t ion a re
ca lcula ted a t two leve ls . F i r s t , ne t re turns ha-J
ye a r - 1 w e r e c a l c u l a t e d f o r e a c h ind iv idua l ve ge t a b l e
spec ies ( i . e . to ta ls for the year for a l l c rops of each
spec ies) , de f ined as the d i f fe rence be tween sa les
T a b l e 5
P r i c e s a n d a n n u a l p r o d u c t i o n v a l u e o f v e g e t a b l e c r o p s o f s a m p l e f a r m e r s i n t h e C H
Pr i c e
( M S k g - ~
T ot a l p roduc t i on va l ue
( 1 0 3 M S ) b a s e d o n
A v e r a g e H i g h L o w A v g . p r i c e
H i g h p r i c e L o w p r i ce
E n g l i s h c a b b a g e 0 . 6 4 0 . 8 4 0 . 4 6 1 7 9 9 2 4 2 4 1 0 8 6
C h i n e s e c a b b a g e 0 . 5 3 0 . 6 7 0 . 3 8 6 6 9 8 5 4 4 7 7
M ustard 0.83 1.07 0.61 85 111 60
Spi na c h 1 . 19 1 . 64 0 . 73 202 279 118
Ga r l a nd c hry sa n t h 1 . 3 9 1 .85 0 . 9 131 174 81
Le t t uc e 1 . 04 1 . 3 0 0 . 77 291 3 68 207
C e l e ry 1 . 06 1 .42 0 . 67 96 126 57
Oni on 0 . 82 1 .13 0 . 48 23 2 3 59 102
Bean s 1.54 1.81 1.29 112 135 89
P e a s 4 . 6 6 5 . 8 6 3 . 4 7 3 3 9 4 3 5 2 4 2
T o m a t o 0 . 9 2 1 .2 3 0 . 6 4 9 7 6 1 3 3 0 6 4 4
C a ps i c um 1 . 97 3 . 00 1 . 13 193 289 117
R a di sh 0 . 45 0 . 61 0 . 28 26 3 5 16
Ot he r ve ge t a b l e s 1 .73 2 . 05 1 . 20 491 63 4 3 13
T o t a l 5 6 4 2 7 5 5 3 3 6 0 9
8/10/2019 1-s2.0-S0167880996010651-main
8/18
3 6
D.J. Midmore et al . / Agriculture, Ecosystems and Environment 60 1996) 29-46
r e v e n u e s a n d t h e s u m o f e x p e n d i t u r e s o n s e e d , m a -
nu r e , c he mi c a l f e r t i l i z e r s , pe s t i c i de s a nd t r a c t o r u s e .
N e t r e t u r ns c a l c u l a t e d i n t h i s w a y c a n be i n t e r p r e t e d
a s r e t u r ns t o l a bo r ( i nc l ud i ng ma na ge me n t ) p l u s
m o n e y l e f t o v e r t o p a y f o r w h a t m o s t l y a r e f i x e d
c os t s , i nc l ud i ng i r r i ga t i on i nve s t me n t c os t s , p l a s t i c
s he l t e r c os t s , c o s t s t o ma ke be ds a nd t e r r a c e s , l a nd
r e n t a nd t a xe s , e l e c t r i c i t y c os ts , a nd ma r k e t i ng c os t s .
S e c o n d , n e t i n c o m e ( N I ) p e r f a r m y e a r - t i s c a l c u -
l a t e d a s t he s um ( ove r ve ge t a b l e s pe c i e s ) o f ne t
r e tu r n s h a - ~ y e a r - l , m u l t i p l ie d b y t h e a c tu a l a r e a
f o r e a c h i nd i v i dua l s pe c i e s , m i nus t he s um o f the
c os t i te ms w h i c h c o u l d no t be a t t r ibu t e d t o i nd i v i dua l
ve ge t a b l e s pe c i e s . T he l a t t e r inc l ude h i r e d l a bo r c os t s
( i n c l u d i n g p e r m a n e n t l a b o r , b u t e x c l u d i n g f a m i l y
l a bo r ) ; a nnua l i z e d c os t s o f i r r i ga ti on , p l a s t i c s he l t e r s
a nd t e r r a c e c ons t r uc t i on ; r e c u r r e n t c os t o f be ds ( r e -
ma k i ng ) a nd t e r r a c e s ( r e - s u r f a c i ng ) ; o t he r ma t e r i a l
c os t s ; la nd r e n t a nd t a xe s ; e l e c t r i c i t y c os t s ; ma r ke t -
i ng c os t s ; a nd a ny o t he r c os t s no t i nc l ude d e l s e -
w h e r e . N I p e r f a r m y e a r - 1 c a lc u l a te d i n t h is w a y c a n
be i n t e r p r e t e d a s ne t p r o f i t s , o r r e t u r ns t o ow n l a nd ,
f a m i l y l a b o r a n d m a n a g e m e n t .
N e t r e t u rn s h a - ~ y e a r - l a t a v e r a g e p r i ce s v a r y
b e t w e e n M $ 9 l 0 3 a nd 1 . 4 10 4 f o r m os t v e g -
e t a b l e s pe c i e s ( T a b l e 6 ) . W hi l e on i on a nd r a d i s h
s e e m t o ge ne r a t e r e l a t i ve l y l ow r e t u r ns ( pa r t i c u l a r l y
a t the l ow e r e nd o f t he p r i c e r a nge ) , pe a s , t oma t o a nd
( pa r t i c u l a r l y ) c a ps i c um ha ve a bove - a ve r a ge r e t u r ns .
W i t h t h e e x c e p t i o n o f c a p s i c u m f o r w h i c h t h e s u r v e y
f i n d s e x c e p t io n a l l y h i g h r e t u r n s (w h i c h m a y h o w e v e r
be o f f s e t by t he h i gh c os t s o f c ons t r uc t i ng r a i n
s he l te r s ) , the s e r e s u l t s a r e c o ns i s t e n t w i th t hos e f r o m
a n e a r l ie r s u r v e y c a r r ie d o u t b y M A R D I ( D i n g e t a l .,
1981) .
E x p e n d i t u r e s f o r m a n u r e ( m o s t l y c h ic k e n d u n g t o
i mpr ove s o i l f e r t i l i t y ) a c c oun t f o r t he l a r ge s t pa r t o f
t o t a l ma t e r i a l c os t s f o r mos t ve ge t a b l e s ( M i dmor e e t
a l . , 1996 ) . M a ny f a r me r s a r e r e l uc t a n t t o g i ve i n f o r -
ma t i on a b ou t pe s t i c i de s , a nd q ua n t it ie s , u s e d a r e c e r -
t a i n l y unde r - r e po r t e d , r e s u l t i ng i n a n ove r - e s t i ma t i on
o f ne t r e t u r ns . T he s ha r e o f s e e d c os t s d i f f e r s w i de l y
a m o n g d i f f e re n t v e g e ta b l e s , o n a v e r a g e v a r y i n g f r o m
on l y 1% f o r t om a t o ( i nd i c a t i ve o f the f a c t t ha t ne a r ly
a ll t o m a t o f a r m e r s u s e t h e i r o w n s e e d ) t o n e a r l y 5 0 %
f or s e e d ma t e r i a l f o r on i on .
I n c a l c u l a t i ng N I pe r f a r m ye a r - 1 ( T a b l e 7 ) , c o s ts
f o r s e mi - pe r ma ne n t s t r uc t u r e s s uc h a s i r r i ga t i on f a -
c i l i t i e s , p l as t i c she l t e rs and t e r races a re annua l i zed
us i ng t he f o r mu l a : A = P [ r / 1 - ( 1 + r ) - t ) ] , w h e r e
A i s t he a nnua l i z e d c a p i t a l c os t o f t he s t r uc tu r e ; P i s
t he c u r r e n t c os t o f t he s t r uc t u r e ; t i s t he a s s ume d
l i f e s pa n o f t he s t ruc t u r e ; a nd r i s t he bo r r ow i n g r a te
f o r f a r me r s ( 8% i n 1992) . O n t he ba s i s o f the s u r ve y
da t a , t he l i f e s pa n o f i r r iga t i on s t r uc t u r e s a nd p l a s ti c
she l t e r s t ruc tures i s s e t to 10 years , w i th the l i fe span
T a b l e 6
M e a n c o s t s a n d r e t u r n s o f v e g e t a b l e c r o p s i n t h e C H ( M S h a - i )
N A v e r a g e g r o s s
r e v e n u e s a t
M e a n p r i ce H i g h p r i c e L o w p r i ce
Ma t e r i a l N e t r e t u rns a t
c os t s a
M e a n p r i ce H i g h p r i c e L o w p r i ce
E n g l i s h c a b b a g e 1 35 1 7 1 6 6 2 2 6 2 5 1 2 1 1 4 3 5 9 8 1 3 5 6 7 1 9 0 2 7 8 5 1 6
C h i n e s e c a b b a g e 8 8 1 3 4 7 2 1 6 9 1 5 9 9 7 4 3 6 4 9 9 8 2 4 1 3 2 6 6 6 3 2 5
M u s t a r d 1 7 1 1 4 4 6 1 4 4 1 0 8 6 6 5 2 1 2 9 9 3 1 6 1 2 2 8 0 6 5 3 6
S p i n a c h 2 3 1 5 5 5 3 2 1 5 6 9 9 4 2 3 2 4 4 8 1 3 1 0 5 1 9 12 1 6 9 7 6
G a r l a n d c h r y s a n t h 1 8 1 5 5 8 3 2 1 4 2 7 9 4 5 5 2 0 0 0 1 3 5 8 4 1 9 4 2 7 7 4 5 5
Le t t uc e 53 12884 163 01 9480 2711 10172 13 590 6769
C e l e ry 23 13 484 19217 7 558 2013 11471 1720 4 55 45
O n i o n 3 4 9 7 9 4 1 3 4 4 0 5 7 9 8 2 9 7 6 6 8 1 8 1 0 4 6 4 2 8 2 2
B e a n s 17 15708 18 744 12577 2262 13 446 16482 103 15
P e a s 2 7 2 4 5 7 5 3 0 7 9 2 1 8 0 7 2 4 2 1 6 2 0 3 5 9 2 6 5 7 5 1 3 8 5 5
T o m a t o 1 01 2 2 9 9 7 3 1 6 7 5 1 5 2 4 0 4 1 1 1 1 8 8 8 7 2 7 5 6 4 1 1 1 2 9
C a p s i c u m 1 3 5 0 2 5 1 7 6 9 9 6 3 0 5 0 8 6 6 9 7 4 3 5 5 4 7 0 2 9 9 2 3 8 1 1
R a d i s h 1 0 7 7 5 9 1 0 6 1 0 4 7 6 6 2 5 0 3 5 2 5 6 8 1 0 7 2 2 6 3
O t h e r v e g e t a b l e s 3 0 2 3 9 2 3 2 9 1 8 2 1 6 10 1 2 7 6 9 2 1 1 5 4 2 6 4 1 3 1 3 3 3 2
a Inc l ude s c os t s fo r s e e d , m a nure , f e r t i li z e r , pe s t i c i de s a nd t r a c t o r use .
8/10/2019 1-s2.0-S0167880996010651-main
9/18
D.J. Midmore et aL / Agriculture, Ecosystems and Environment 60 1996) 29-46
3 7
T a b l e 7
M e a n a n n u a l c o s t s a n d r e t u r n s ( M S p e r f a r m ) f o r v e g e t a b l e
p r o d u c t i o n
N M e a n S D
T o t a l a n n u a l g r o s s r e v e n u e s 1 93 2 7 7 0 2 2 6 9 1 9
f r o m v e g e t a b l e c r o p s
A n n u a l m a t e r i al c o s t s
(ve ge t a b l e c rop-spe c i f i c )
Se e d 190 519 591
M a n u r e 1 88 2 5 1 0 2 5 1 9
Fe r t i l iz e r 189 1486 183 5
Pe s t i c i de s 164 748 729
T ra c t o r use 166 92 185
A n n u a l c o s t s ( n o n - v e g e t a b l e
c rop spe c i f i c )
H i re d l a b or c os t s 91 5771 8 447
A n n u a l i z e d c o s ts o f
Spr i nk l e r i r r i ga t ion 172 1682 243 2
Ot he r i r r i ga ti on 17 1045 1268
Pl a s t i c she l t e r s 3 9 5095 4559
B e n c h t e rr a c e s 4 8 3 7 4 3 9 5
Pl a t fo rm t e r ra c e s 158 213 1 13 3 0
B e d c o s t s 5 7 9 1 0 1 2 3 3
C o s t o f l i m i n g 1 17 3 0 6 3 6 0
C o s t s o f o t h e r 1 88 2 3 5 7 1 6 0 8
ma t e r i a l s
L a n d r e n t 3 2 3 9 4 6 3 3 6 1
L a n d t a x e s 1 58 2 8 6 2 7 7
E l e c t r i c it y c os t s 80 3 3 7 218
Ma rke t i ng c os t s 13 1 883 724
O t h e r c o s t s 2 4 5 0 0 7 0 7
T ot a l i npu t c os t s 193 16729 12925
N e t a n n u a l i n c o m e 1 9 3 1 0 9 7 4 2 1 8 7 6
p e r f a r m
of t he p l a s t i c i t s e l f s e t t o 2 ye a r s . T e r r a c e s a r e
a s s ume d t o l a s t f o r 15 ye a r s . T he s u r ve y da t a i nd i -
c a t e t ha t t he c os t s o f t e r r a c e c ons t r uc t i on a nd pe r i -
o d i c r e - s u rf a c i n g a m o u n t t o a b o u t M $ 1 1 7 0 0 h a - l
a n d M $ 2 7 2 0 0 h a - l f o r b e n c h a n d w i d e te r ra c e s ,
r e s pe c t i ve l y , w h i c h t r a ns l a t e i n t o c o r r e s pond i ng a n -
n u a l c o st s o f M $ 1 3 6 5 a n d M $ 3 1 7 7 ( a s s u m i n g a n
i n t e r e s t r a t e o f 8% w h i c h r e f l e c t s t he p r e va i l ing ba nk
r a t e i n 1992). N I pe r f a r m ye a r - f r om ve ge t a b l e s
a ve r a ge s M $ 1 .1
1 0 4 ,
t hough w i t h c ons i de r a b l e
va r i a t i on a mong f a r ms .
3.4. Soil erosion
3.4.1. Erosivity
A l t hough a c l o s e l i ne a r f i t i s obs e r ve d be t w e e n
mon t h l y r a i n f a l l e r o s i v i t y a nd r a i n f a l l ( F i g . 1 ) , t he r e
i s a n i mpor t a n t ou t l i e r , na me l y M a y 1991 , w he n
e r o s i v i ty w a s m u c h g r e a t e r t h a n e x p e c t e d b a s e d u p o n
da t a f o r t he mon t h l y r a i n f a l l . I t i s pos s i b l e t ha t a
l a r ge p r opo r t i on o f the e r o s i on f o r t he 11 ye a r pe r i od
( 1 9 8 1 - 1 9 9 1 ) i s a c c o u n t e d f o r b y t h a t m o n t h ' s KE.
A v i s it to t h e a r e a i n S e p t e m b e r 1 9 9 1 p r o v i d e d
v i s ua l e v i de nc e o f s e ve r e gu l l y e r o s i on a nd l a nd
s l ip s , a nd s ugge s t s t ha t t o be e f f e c t i ve , e r o s i on c on -
t r o l p r a c t i c e s s hou l d be i mp l e me n t e d i n a n t i c i pa t i on
o f e x t r a o r d i na r y r a i n f a ll e ve n t s . T he l ow l i ke l i hood
of s uc h r a r e e ve n t s doe s no t e nc ou r a ge f a r me r s t o
a dop t p r e ve n t i ve me a s u r e s .
3.4.2. Sources of soil erosion
I n t h e C H , s o il b e c o m e s e x p o s e d f o l l o w i n g f o r e s t
c l e a ri n g (a p p r o x i m a t e l y 8 8 0 h a y e a r - 1 b e t w e e n 1 9 86
a nd 1990 ; T a b l e 1 ), c l e a r i ng a nd p r un i ng o f te a , a nd
c r op ha r ve s t ( i n a dd i t i on t o l e ve l i ng f o r r oa ds a nd
bu i l d i ngs , w h i c h i s no t c ons i de r e d he r e ) . R a p i d s he e t
e r os i on t a ke s p l a c e i mme d i a t e l y a f t e r l a nd c l e a r i ng
be f o r e ve ge t a b l e s a r e p l a n t e d . B a s e d on s a t e l l i t e
i ma ge r y , a bou t 7 . 5% o f t e a l a nd i s s ub j e c t t o r e j uve -
na t i on , a nd t he r e f o r e l ia b l e t o e r o s i on ( i .e . i s e xpos e d
a t a ny pa r t i c u l a r t i me ) . S e a s ona l i t y i n t he ha r ve s t o f
c a b b a g e ( t h e m o s t w i d e l y g r o w n v e g e t a b l e c r o p i n
t he C H ) ha s t he g r e a t e s t i n f l ue nc e on e xpos e d c u l t i -
va t e d l a nd a r e a , pa r t i c u l a rl y s i nc e f a r m e r s a r e a c c us -
t o m e d t o c o l l e c t a n d r e m o v e c r o p r e s i d u e s f r o m t h e i r
f i e l d s . M a j o r ha r ve s t a c t i v i t y i s i n A pr i l a nd A ugus t ,
a nd t he s e a r e t he mon t hs w i t h s ome o f t he h i ghe s t
r a i n f a l l e r o s i v i t i e s r e c o r d e d ( D u m s d a y a n d H u a n g ,
1992) .
C ons t r uc t i on o f be ds a nd ( pa r t i c u l a r l y p l a t f o r m)
t e r r a c e s i s a no t he r s ou r c e o f s o i l e r o s i on . G r ow i ng
v e g e t a b l e s o n b e d s i s c o m m o n i n t h e C H f o r a l l
ve ge t a b l e c r ops . S u r ve y da t a i nd i c a t e t ha t , on a ve r -
a g e , b e d s n e e d t o b e r e - m a d e e v e r y 2 2 w e e k s , m o s t l y
b e c a u s e o f p o o r s o i l a n d l o w v e g e t a b l e y ie l d s . A b o u t
7 5 % o f a ll s a m p l e f a r m e r s m a k e b e d s a c r o s s th e
s l ope , w i t h mos t o f t he r e ma i n i ng f a r me r s c ons t r uc t -
i ng t he m up a nd dow n t he s l ope . F a r me r s r a r e l y
o r i e n t a t e t he i r be ds i n l i ne w i t h t he c on t ou r .
F i f t y - f o u r ( i .e . l e s s t ha n one - t h i r d o f s a mp l e f a r m-
e r s , in a g r e e me n t w i th T a y l o r e t a l. ( 1993 ) ) a n d 187
f a r m e r s h a v e c o n s t r u c t e d b e n c h a n d p l a t f o r m t e r -
r a c e s , r e s p e c t i v e l y . T h e p e r c e n t a g e o f l a n d u n d e r
w i de t e r r a c e s g r e a t l y e xc e e ds t ha t unde r be nc h t e r -
r a c e s , w i t h on a ve r a ge 36% o f t he l a nd o f t he 54
8/10/2019 1-s2.0-S0167880996010651-main
10/18
3 8
D.J. Midmore et a l. / Agriculture, Ecosystems and Enuironment 60 1996) 29-46
, i
>
o
1 , -
n i l
8 0 0
6 0 0
4 0 0
2 0 0
y = - 1 9 . 5 9 + 0 . 8 7 x R . 2 = 0 . 7 9
0 '
0
:
I
i
" : " " " i
.
*e : I i
1 0 0 2 0 0 30 0 4 0 0 5 0 0 6 0 0
Rainfa l l (mm)
Fi g . I . R e l a t i onsh i p b e t w e e n mo nt h l y e ros i v i t y a nd ra i n fa l l fo r t he C a me ron h i gh l a nds , 1981 - 1991 .
f a r me r s unde r be nc h t e r r a c e s , w h i l e p l a t f o r m t e r r a c e s
o n a v e r a g e o c c u p y 9 2 % o f f a r m l a n d . B e n c h t e r r ac e s
h a v e a n u m b e r o f d i s a d v a n t a g e s c o m p a r e d w i t h p l a t-
f o r m t e r r a c e s . T he i r c ons t r uc t i on i s done e n t i r e l y by
h a n d ( a s o p p o s e d t o p l a t f o r m t e r r a c e s w h i c h a r e
c o n s t r u c t e d l a r g e l y b y m a c h i n e , l e a d i n g t o a h i g h
de g r e e o f s o i l e r o s i on ) , c u l t i va t i on i s mor e l a bo r - i n -
t e ns i ve , t he y a r e r e l a t i ve l y d i f f i c u l t t o i r r iga t e , a nd i t
i s i mpr a c t i c a l t o p r o t e c t t he m w i t h p l a s t i c s he l t e r s .
R e - s u r f a c i n g o f t e r r a c e s 4 - 1 0 y e a r s a f t e r c o n s t r u c -
t i on i s ne c e s s a r y t o a vo i d de c l i n i ng y i e l d s a nd i s
m o s t l y d o n e ( 7 1 % o f r e s p o n d e n t s ) b y c o v e r i n g t h e
t e r r a c e w i t h f r e s h s o i l t a ke n f r om a f a c e ne w l y c u t
f r om t he ba t t e r o f t he na t u r a l s l ope . T he o t he r one -
t h ir d o f f a r m e r s s c r a p e d o f f p o o r t o p s o i l t o e x p o s e
s o i l be ne a t h . S o i l e r o s i on a l s o oc c u r s f r om t he ba c k -
s l ope s a nd r i s e s o f t e r r a c e s , e s pe c i a l l y i f no t p r o -
t e c t e d w i t h mu l c he s o r c ove r c r ops . I n s p i t e o f t he
g r e a t e r d i f f i c u l t y a s s oc i a t e d w i t h t he c ons t r uc t i on
a n d m a n a g e m e n t o f b e n c h t e r r a c e s , t h e r e d o e s n o t
s e e m t o be a be ne f i t i n t e r ms o f r e t a i ne d s i lt a nd l e s s
s a nd a s t he p r opo r t i on o f be nc h t e r r a c e pe r f a r m
i nc r e a s e d ( M i dm or e e t a l ., 1996 ) . S o i l e r o s i on ma y
i n t e n s if y w h e n a c o m b i n a t i o n o f c o n d i t io n s o c c u r s
s uc h t ha t t he s o i l i s he a v i l y c ha r ge d w i t h w a t e r a nd
i s f o l l o w e d b y l o n g c o n t i n u o u s h e a v y r a i n c a u s i n g
land s l ips .
3.4 .3 . Phy s ica l ex ten t a nd ex ternal i ty cos t s o f so i l
eros ion
T h e e x t e n t o f s o i l e r o s i o n w a s d e t e r m i n e d t h r o u g h
a na l ys i s o f s o i l s a mp l e s a s w e l l a s by v i s ua l a s s e s s -
m e n t m a d e b y s u r v e y e n u m e r a t o r s o n e a c h i n d i v i d -
ua l f a r m . B a s e d on t he s o i l s a mp l e s t a ke n a t e a c h
f a r m, t he t e x t u r e o f t ops o i l i s q ua n t i f i e d on t he
a s s u m p t i o n t h a t m o r e e r o d e d s o i ls w o u l d h a v e l o w e r
c l a y f r a c t i ons a nd h i ghe r s a nd f r a c t i ons . D a t a on t he
pe r c e n t a ge o f c l a y i n s o i l f r om f a r ms w i t h p l a s t i c
s he l t e r s , a s s ume d t o ha ve l e a s t s o i l e r o s i on , s how a
s i gn i f i c a n t pos i t ive i nc r e a s e a s t he p r o po r t i on o f la nd
unde r p l a s t i c i nc r e a s e s ( F i g . 2 ) . T he c l a y f r a c t i on i n
s o i l f r om f a r m s w i t h a l l l a nd c ove r e d by p l a s t ic
8/10/2019 1-s2.0-S0167880996010651-main
11/18
D . J . M i d m o r e e t a l ./ A g r i c u l t u r e , E c o s y s te m s a n d E n v i r o n m e n t 6 0 1 9 9 6 ) 2 9 - 4 6
39
s h e l t e r s i s a l s o g r e a t e r t h a n t h a t f r o m f a r m s w i t h o u t
p l a s t i c s h e l t e r s ( M i d m o r e e t a l . , 1 9 9 6 ) . E v e n t h o u g h
d a t a ( n o t g i v e n h e r e ) f o r c u l t i v a t e d s o i l s s h o w t h a t
m u c h s i l t a n d c l a y h a s b e e n w a s h e d a w a y c o m p a r e d
w i t h u n d i s t u r b e d s o i l, t h e e x t e n t o f a l t e r at i o n o f
c o m p o s i t i o n w a s n o t g r e a t l y a f f e c t e d b y a g r o n o m i c
m a n a g e m e n t p r a c t i c e s , o t h e r t h a n b y t h e u s e o f
p l a s t i c r a inshe i t e r s (18 .0 vs . 15 .6%, t = 2 .32 , d . f . =
4 - 1 5 3 ) . A l t h o u g h p l a s t i c s h e l t e r s r e s u l t i n l e s s p e s t i -
c i d e u s a g e ( T a y l o r e t a l . , 1 9 9 3 ) , b e t t e r q u a l i t y p r o -
d u c e ( C h a n g a n d L i a o , 1 9 8 9 ) a n d r e d u c e d e r o s i o n
( F i g . 2 ) , t h e i r l o n g - t e r m u s e m a y c r e a t e n e w p r o b -
l e m s r e l a t e d t o a n i n c r e a s e i n s o i l E C . T h e s o i l
s a m p l e a n a l y s i s i n d i c a t e s t h a t a l l f i v e f a r m s w i t h E C
o v e r 1 .5 m S c m - 1 h a v e a p r o p o r t i o n o f t h e ir p r o d u c -
t i o n u n d e r p l a s t i c . O n a v e r a g e , f a r m s w i t h p l a s t i c
s h e lt e rs h a v e a n E C o f 0. 4 7 m S c m - l c o m p a r e d
w i t h 0 . 2 7 f o r f a r m s w i t h o u t s h e l t e rs ( t = 2 . 4 9 , P
