Perspectives on farmer adoption of alley cropping in semiarid areas of
B.A. Jama* and P.E. Hildebrand
This paper presents evidence, collected through farm surveys in Machakos
district of Kenya, that the potentials for adoption of alley cropping are limited.
If any, the potentials for farmers adoption of alley cropping are more for fodder
and less for soil fertility improvement. Although the farm holdings were small,
with 76% of the farmers sampled having less than three hectares, farm size
appeared not likely to constrain the adoption of the technology. The principal
constraint was fears of decreased crop yields due to competition from the tree
hedgerows. Other constraints identified were the relatively high capital
investments required to plant and raise the large number of trees required by
alley cropping in an environment where termites are a problem.
Key words. Alley cropping, farmer adoption, fodder, mulch, semiarid tropics,
B.A. Jama: International Centre for Research in
Agroforestry, P.O. Box 30677, Nairobi, Kenya. Corresponding
P.E. Hildebrand: Professor, Food Resource and Economics
Department, Institute of Food and Agricultural Sciences,
University of Florida, Gainesville, Fl. 32611, U.S.A.
Several studies have reported the beneficial effect of alley cropping
(synonymous with hedgerow intercropping) on soil fertility and crop productivity
in humid and sub-humid tropics (Kang et al., 1990). Consequently, there has
been an increasing interest to study the potential of alley cropping in semiarid
tropics (Singh et al., 1986; Nair, 1987; Rao et al., 1991). However, these
studies have shown several constraints to the success of alley cropping in
semiarid tropics: 1) the quantity of biomass produced by hedgerows may be
inadequate to improve soil fertility, 2) hedgerow prunings are too valuable as
livestock fodder to be used for soil fertility, and, 3) competition for water
between hedgerows and crops may outweigh soil fertility improvement (Singh
et al., 1989; Ong et al., 1991). Based on this, it could be argued that the
potentials for adoption of alley cropping by farmers are low. However, given
the novelty of the alley cropping and its limited presence on farms in general,
there are few and sometimes contrasting reports about its potential for adoption
by farmers (Dvorak, 1993; Fujisaka et al., 1994; Swinkels et al., in preparation).
So far, most of the research efforts on alley cropping in both the humid and
the semiarid tropics has been on the biophysical aspects of the technology such
as improvement of soil fertility (Kang et al., 1990). There are relatively few
studies on the socio-economics aspects of the technology, in particular, on
factors that may influence the potentials for adoption by farmers (Hoekstra and
Darnhoffer, 1992). Such studies are important as they may help generate and
prioritize the research issues required, particularly in the semiarid tropics where
the potentials for competition are high between the trees and crops for limited
With the above considerations in view, a survey was conducted in 1991 on
small farms in the semiarid Machakos District of Kenya (a) to determine current
practices used by farmers to maintain and/or improve soil fertility in the context
of a farming system and (b) to assess the potentials and constraints to the
adoption of alley cropping multipurpose trees and shrubs for purposes of soil
fertility improvement. The results of the survey are reported in this paper.
2.0 Study Area and Methodolovg
The study was conducted on farms scattered on the hill slopes immediately
south of Machakos, Kenya (latitude 10 N 33' S, longitude of 370 14' E). The
ecology of the area is semiarid with a mean annual rainfall of about 600 to 700
mm, falling in two seasons: long-rains (March to July) and short-rains (October
to February). Besides meeting the criteria of semiarid, the site was selected
because earlier studies (Hoekstra et al., 1984; Rocheleau et al., 1988)
suggested that crop yields were low, perhaps as a result of low soil fertility, and
that agroforestry technologies such as alley cropping multipurpose trees and
shrubs could be tried.
The study site was close to the Research Station of ICRAF where alley
cropping research was going on since 1982. Thus, as one might either expect
or assume, farmers in this area would be better informed about and potentially
more adoptive of the technology than distant farmers.
Average population densities in 1983 were around 250/km2, rising to
300/km2 in the wetter areas, much higher than the 72 persons/km2 for the
district (Warner, 1993). Most of the people living in the area are the Akamba
who owned the land, officially or by de facto.
Sixty farms from three administrative sub-locations (Kiima-Kimwe, Muvuti
and Kivandini) were included in the study. Based on the outcome of a three day
rapid appraisal exercise, stratification of the farms relative to their location on
the hills (low, middle and top slopes) was felt necessary. Interviews were
conducted on single-day visits in the months of July and August, 1991. A one-
page check-list was used as a guide during the interviews. The interview team
was made up of the first author and a local who helped with the interpretation
of the Akamba language. Interpretation was not always necessary because a
large number of the farmers spoke either Swahili and/or English which the first
author also speaks. On average, five farmers were interviewed in a day.
After analyzing the data from the 60 farmers, a second stratification or
regrouping of the farms was carried out. The farmers were grouped according
to their identified interests in the use of the pruning from the alley cropped
hedges. Basically, two distinct use-interests were identified: fodder or mulch
(soil fertility). The purpose of the second stratification was two-fold: (a) to get
more in-depth information of the farming practices and, (b) to obtain a more
informed evaluation of alley cropping from the farmers. On the basis of the
two major use-interests of the alley cropping technology, three farmers from
each interest group were randomly selected from the low, middle and upper
slopes of each of the three sub-locations. Thus, a subsample of 18 farmers out
of the initial 60 was generated. This sub-group of farmers were taken to ICRAF
Research Station over a three day duration. At the station, the farmers were
given a tour of the trials where prunings from alley cropped species were being
used either as mulch or as fodder. During the tour, questions and concerns
raised by the farmers about the technology were recorded.
3.0 Statistical analyses
SAS statistical package (SAS, 1992) was used to generate descriptive
statistics of the farming system and frequency tables of the potential uses of
alley cropping by farmers. Chi-square was used to test the significance of
association of the preferred use of alley cropping with various farm or
4.1 Household characteristics of the farmers interviewed.
Table 1 summarizes the major household characteristics of the farms
surveyed. Farm size varied widely from 0.4 17.4 ha with nearly 50% of the
farms being under two hectares. In general, there were larger land holdings in
the more semiarid areas at the foothills and smaller, more intensively managed
land holdings in the more subhumid slopes and hill tops. In spite of their small
size, the farms supported a large number of dependents. On average, there
were 14 members in a household, with 50% of these members being children
(under 18 years). Hence, the dependency factor on the farms and on the adult
members of the household was high.
Most farmers relied on family labour to do farm activities. Hiring of labour
for weeding was, however, common (n = 36). Also, farmers with coffee (n =
34) hired labour for picking. Additionally, 68% of the farmers interviewed
exchanged labour, particularly for weeding.
Although there was limited scope for off-farm employment, 44% of the
farmers interviewed had at least one member of the family engaged in regular
off-farm employment. Most were men, often in distant urban centres. This off-
farm employment created patterns of out-migration that results in a
disproportionate number of female-headed or represented households. Indeed,
60% of the farmers interviewed were women.
4.2 Farming system.
4.2.1 Crop Component
The farming system is based on food crops as the dominant and livestock
as a subsidiary. The predominant crops are maize, beans and pigeon pea.
Various vegetable crops such as tomatoes and kale were also grown by nearly
all farmers during the wet season and during the dry season by those close to
river beds. Bananas, sweet potato and cassava are also grown. Typically,
farmers attempt to grow two crops a year.
In spite of all their efforts to grow sufficient food for the needs of the
family, nearly all farmers interviewed expressed insufficiency of food supply.
Indeed, 67% of the farmers interviewed bought their staple food (maize) in the
previous year. The insufficiency of food was probably due to low crop yields
(Table 2) and less to shortage of land. Crop yields were low because of both
low rainfall (only 214 mm at ICRAF Research Station during the season of the
study) and poor soil fertility. Renting of land for crop production was rare.
Coffee was a major cash crop for farmers on the cooler upper slopes and/or
those on the windward valleys of the hills. Fifty seven of the farmers
interviewed had coffee on their farms. Besides coffee, other cash crops were
mangoes, guava, citrus, avocado and various vegetables. Sale of sisal baskets,
particularly by women, was also another source of cash.
4.2.2 Livestock component
Livestock statistics on an average farm of two hectares are shown in Table
3. The absence of livestock on some farms (n = 21) was attributed to drought,
diseases and/or sale. However, most farmers without livestock (n = 17) had
intentions of buying them soon. In addition to providing manure, livestock
acted as capital stocks that could be converted to cash when needed.
Moreover cattle, particularly bulls, provided drought power. Sixty seven percent
of the farmers interviewed ploughed their fields by ox-plough. Those without
ox-plough rented them. At times, those who did not own the oxen owned only
the plough, and vice versa. This often necessitated an exchange of the ox-
plough parts. Possession of both the oxen and the plough was expensive for
individual farmers. Most farmers ploughed at the onset of the rains and planting
was done at the same time as ploughing. Besides cattle, farmers kept sheep
and goats mainly for sale and home consumption.
All the farmers with livestock (n = 39) responded positively to shortage of
fodder, particularly during the dry periods. Many farmers (n =30) did not have
designated grazing areas although in some, it was at least twice as big as the
area under crops. Where grazing lands existed (n = 9), the vegetation cover
was generally poor, overgrazed and the soil often eroded. Additionally, the
amount of land under grazing was declining on many farms because of
expansion of cropland. In an attempt to increase the supply of livestock feed,
farmers rented additional grazing lands and/or crop fields after the harvest. The
renting of crop fields once the grain was removed was practised by 45% of the
farmers interviewed. Typically, the expenses for hiring additional grazing lands
were met by selling animals and\or off-farm employment although some
obtained it from relatives.
4.2.3 Farmers practices to improve soil fertility
and crop yields.
All farmers interviewed used livestock manure on their crop fields. However,
amounts of farmyard manure available from ones livestock was not sufficient
for all the land cropped. To enhance the use-efficiency of the little manure
available, it was applied on the crop rows and not broadcast. Additionally,
farmers bought manure, mainly from a few with large poultry houses and/or
from cattle ranches 40 50 km away from the study area.
Between the fodder and mulch-interest groups, the percentages of each
group that bought manure were similar, approximately 39%. The purchase of
inorganic fertilizers by farmers was negligible; only 3% of the farmers
interviewed mentioned inorganic fertilizers as their most expensive farm input.
However, for farmers with coffee, use of fertilizers was substantial and it was
obtained at a subsidized price from coffee factories in the area.
The use of tree mulch as an organic manure was rare. Where it was
reportedly used (n = 12), it was typically mixed with manure in the livestock
yard. However, the use of grass mulch placed under coffee or fruit trees was
common (n = 22).
Intercropping maize and beans (Phaseolus vulgaris), pigeon pea (Cajanus
cajan) was a practice mentioned by many farmers (n = 27) to improve soil
fertility. Intercropping was more common on the smaller farms than on larger
ones, suggesting that it was preconditioned by farm size. For instance, of
those farmers that intercropped, 60% had farms two or less hectares. On other
hand, 85% of the farmers that did not intercrop had farms greater than two
hectares. Besides intercropping, rotation of legume crops with cereals was
another measure mentioned by farmers (n = 15) to improve soil fertility.
However, there was little evidence of land fallowing (n = 11).
Soil erosion was not seen as a problem contributing to low crop yields. This
is because most farms (n = 42) were terraced well. "Fanya juu" or soil bands
placed on the upper slopes of cut-off drains was the common method of
terracing. In addition to soil conservation, the "Fanya Juu" ditches acted as
microcatchments for water; hence crops planted in the "Fanya-Juu" ditches
often grew and yielded more than those outside. Also, various species of
grasses (the predominant one being Panicum coloratum) were planted on the
"Fanya-Juu" soil bands. In addition to reinforcing the soil bands against erosion,
grasses were periodically cut for fodder and house thatching.
4.3 Interests of farmers in alley cropping
As expected, most of the farmers (62% of those surveyed) were
interested in the fodder aspects of alley cropping, 33% in mulch or soil fertility
and 5% were not interested at all in alley cropping. Notable among the many
factors that were associated significantly with the interests of farmers in alley
cropping was the presence or absence of coffee on the farm. Among the
coffee farmers, 76% were interested in the fodder aspects of alley cropping.
Although precise determination of the area under coffee on all the farms was
not done, estimates from 10 farms ranged from 0.1 to 0.4 ha. Because of the
prevailing low prices of coffee at the time of the study, many farmers with
coffee (n = 18) were converting their coffee fields into other crops or uses (in
spite of not being allowed to do so by the government).
In addition to the presence or absence of coffee, four other factors (Table 4)
were associated significantly (p > 0.10) with the interests of farmers in alley
cropping. The number of farmers interested in the fodder aspects of alley
cropping was significantly higher (p > 0.10) for all factors (excepting prior
knowledge about alley cropping) than those with mulch interests. Contrary to
expectation, the interests of farmers in alley cropping were not associated
significantly (p > 0.20) with farm size.
The use of chemical fertilizers, hired labour, ox-plough, purchased manure,
purchase of animal feed, frequency of weeding and, purchase of food were all
observed to be significantly higher for farmers with coffee than those without.
All the other factors considered (e.g., farm size, number and type of livestock
kept, number of household members engaged in off-farm work, etc) were not
significantly associated ( p > 0.20) with the possession of coffee on the farm.
Although the use or purchase of fertilizers was significantly higher for farmers
with coffee on their farms than those without, the yield of maize of those with
or without coffee were not significantly different (p > 0.20). This suggests
that fertilizer was either not applied to maize on farms with coffee or the effect
of fertilizer applied was not significant.
When asked where the tree hedgerows would be planted if they adopted
alley cropping (regardless of whether the interest was in fodder or mulch),
nearly all farmers demonstrated some confusion. Ninety percent of the farmers
interviewed were concerned about competition between the hedges and crops if
the hedges were planted inside the crop fields. Even those farmers who earlier
responded positively to planting the trees inside the crop fields expressed
serious doubts when they saw alley cropping trials with Leucaena leucocephala
(Mimosoideae) and Cassia siamea (Caesalpinioideae) at the research station.
The trials demonstrated poor growth of maize close to the hedges. The soil
conservation bands could be an alternative site for planting the hedges.
However, this site was generally planted to grass. The question asked by many
farmers was "is planting the hedges on the soil bands better than grass for soil
5.1) Biophysical and economic potentials of alley cropping
The significantly higher interest of farmers in alley cropping for fodder rather
than for mulch was expected from farmers in an arid area and is consistent with
the observations of others (Singh et al., 1986). Livestock feed was scarce not
only because the area is semiarid but also because the cropping area was
expanding into the grazing lands, an observation made also by Vonk (1983)
from an area adjacent to that of the present study. The expansion of the crop
area into the grazing land is due to the increased demand for food from the
In addition to the loss of land that could be cropped due to the physical
presence of the hedgerows, competition between the hedgerows and the crops
(and the accompanying risks of crop loss) was a major concern of the farmers
about alley cropping. This concern becomes acceptable when one considers
that most of the studies on alley cropping in the semiarid tropics have reported
reduced crop yields (Singh et al, 1986; Sang and Hoekstra, 1986; Nair, 1987;
Ong et al; Jama, 1993). In most of these studies, reduction in crop yields under
alley cropping has been attributed to competition for the limited available water
between the tree hedgerows and crops.
Even in the absence of competition, mulch from the alley cropped hedgerows
may not realize significant gains in crop yields and/or the opportunity costs
foregone in terms of milk production may be great. Generally, the use of
hedgerow prunings as mulch has been observed in both humid and semiarid
conditions to have significant impacts on soil fertility and crop yields mainly
when applied at high rates, e.g., 8 10 t ha1- yr-1 (Kang et al., 1990; Mugendi,
1991). Under the conditions of the present study, biomass yield of alley
cropped species may not exceed 4 t ha-' yr-1 (Jama, 1993). Even if the use of
such amounts of mulch were to realise improvements in crop yields, economic
analyses (Hoekstra and Darnhoffer, 1992) suggest that, given the price
structure of milk and maize in Kenya in 1991-92, the use of the foliage of alley
cropped hedges as fodder for milk production is three to four times more
profitable than as green manuring for crop (maize) production.
From the foregoing, it appears that the potentials for adoption of alley
cropping by farmers for soil fertility improvement is limited. The exception to
this generalization may be contour hedgerow intercropping which has been
reported to control soil and water runoff under both humid and semiarid
conditions (Young, 1989; Lal, 1989; Bannister and Nair, 1991; Kiepe and Rao,
1994). With contour hedgerows, the use of the rather expensive "Fanya Juu"
structures could be minimized. However, even for purposes of soil and water
conservation, a number of factors need to be taken into consideration. It is
important, for example, to establish whether (a) the hedges alone or their
mixture with grass are more effective in the control of soil and water loss than
grass alone, (b) the hedges or their mixture with grass are less competitive with
adjacent crops than grass alone and, (c) it is cost effective and technically
feasible to establish the hedgerows inside or close to the grass strips.
The higher interests of farmers with coffee in alley cropping compared to
those without raises some speculations. It would, for instance, suggest that
the farmers with coffee on their farms are likely to adopt alley cropping
(primarily for fodder) more than other farmers. This could be true because a
considerable amount of the farmland of coffee farmers was under coffee and
food crops and little or none under fodder production. As a consequence,
coffee farmers purchased livestock feed significantly more frequently than those
5.2 Constraints to establishing and managing alley cropping
Whatever purpose alley cropping may serve, its large scale adoption in
the study area is likely to be limited by the lack of cash among farmers to meet
the basic inputs required for establishing and managing the system. For
instance, the labour demands of alley cropping are high (Dvorak, 1993), yet
both family labour and cash to hire additional labour were scarce. Besides
labour, alley cropping does require a large number of seedlings. Cash is required
to procure seedlings especially when a large number is required. For instance,
to plant 20% of a hectare of land under hedges spaced at 5 meters between
rows and 0.5 m between plants in a row would require 800 plants. Assuming a
highly optimistic 50% survival after six months, one would require at least
1600 potted seedlings. If all the 60 farmers interviewed were to plant 20% of
their land to hedgerows, this would require 96,000 potted seedlings. One
seedling would in 1992 cost at least one Kenya shillings ($0.05); 96,000 potted
seedlings would require $4,800 or $80 per farm. By local standards, this is a
lot of money that may not be readily available to many resource-poor farmers.
It could, however, be argued that the use of seeds as opposed to potted
seedlings may be a less costly route to establish the hedges. For cash limited
farmers, it is observed that it is the number of trees established at the least cost
that provides a better criterion for evaluating the cost of tree-based technologies
than the number established or surviving from given number of seedlings
planted (Bradley, 1993). Because the area is semiarid, potted seedlings and not
seeds or bare root seedlings, would perhaps be the more preferred means of
establishing trees. This needs to be confirmed by on-farm trials.
On small farms such as those surveyed, it could be hypothesized that land
shortage would constrain the planting of many trees required by alley cropping
system. However, this did not appear to be true for farms within the study
area. This observation was unexpected but yet consistent with that of others
elsewhere (Scherr and Alitsi, 1991). This is because trees were grown on sites
not generally suitable for cropping (e.g., rocky areas) and farm boundaries.
Whether planted in an alley cropping setting or otherwise, tree establishment
and production in the semiarid tropics is likely to be limited by drought
conditions and related problems of termites. Indeed, 86% of the farmers
interviewed complained of termite damage to trees. There were a number of
commercial termite-control chemicals in the markets of the study area but many
farmers did not use them because of limitations of cash. As an alternative,
wood ash was used by many farmers although its effectiveness appeared to
vary a lot from farm to farm. The reasons for this are unclear and requires
5.3 Measures to improve yields
With or without alley cropping, the low yields of maize (the staple food crop)
on farms that support large families is, indeed, an issue of concern. It is
doubtful whether the low yields of maize, an observation made also by others
(Ockwell et al., 1991; Nadar and Faught, 1984) could be improved without the
use of inorganic fertilizers. While the low crop yields (Table 2) could be just a
reflection of the aridity of the area, it could also be due to low soil fertility. The
latter is exemplified by the reportedly large responses of maize to fertilizers, in
particular nitrogen (Ikombo, 1984). However, fertilizers are rarely used by
farmers because they require seasonal expenditures of cash that is often not
available. Also, the probability of returns of cash spent on fertilizers in terms of
improved yields is low in a high-risk production environment such as the study
area (Ockwell et al., 1991).
Generally, farmers used farm manure as the main source of nutrients to
crops although the amounts available were not sufficient for all the land
cropped. Moreover, the quality of manure available is reportedly poor (Probert
et al., 1991). Measures to improve the quality and use-efficiency of livestock
manure that farmers use would be desirable. It is perhaps in this regard that
alley cropping multipurpose trees and shrubs could help improve soil fertility and
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This study was funded by the Ford Foundation and ICRAF. We are very
grateful. We would also like to thank the extension staff of the Ministry of
Agriculture, Machakos District who helped in various ways. Additionally, our
thanks goes to Mr. Willy Nzuki of the Catholic Diocese of Machakos for his
tremendous help in locating farms and providing interpretation of the Akamba
language. Our appreciation also goes to all farmers who graciously accepted to
take in the study.
LEGENDS TO TABLES
Table 1. Farm and household characteristics of the 60 farmers interviewed.
Table 2. Estimates of maize yield with or without inputs (manure or fertilizer) of
farmers with interests in fodder or mulch aspects of alley cropping.
Table 3. Livestock statistics on an average farm of two hectares.
Table 4. Factors associated significantly with the interests of farmers in alley
cropping for fodder or for mulch.
Table 1. Farm and household characteristics of the 60 farmers interviewed.
Cumu- number of Average members
Farm lative members number of that were
size distri- in a children children
range bution house- in a (<18 yrs)
(ha) (%) hold household (%)
0-4 77 13(4) 7 (4) 54
5-8 17 16(3) 8 (3) 50
9-17.4 6 14(6) 7 (5) 50
Figures in parentheses are the standard deviations of the mean.
Table 2. Estimates of maize yield with or without inputs (manure or fertilizer) of
farmers with interests in fodder or mulch aspects of alley cropping.
Interests Maize yield (t ha1')
in alley With Without
cropping inputs inputs Mean
Fodder 0.4 (0.2) 0.2 (0.1) 0.3 (0.2)
Mulch 0.3 (0.2) 0.1 (0.1) 0.2 (0.2)
Figures in parentheses are the standard deviation of the mean.
Table 3. Livestock statistics on an average farm of two hectares.
Livestock type Average Range % of farmers
( sd) without livestock
Cattle 2(4) 0- 12 35
Goats 9 (8) 0 30 25
Sheep 4(4) 0-13 83
Chicken 21 (21) 0 2000 7
Excluding a single farmer with 2000 heads of chicken.
Table 4. Factors associated significantly with the interests of farmers in alley cropping for
fodder or for mulch.
Use of Posses- Prior
crop/trees sion of know-
mulch at coffee ledge
Interests Use present Use of trees about
in alley of ox or in the fertil- on the alley
cropping plough past izer farm cropping
Fodder 27 22 21 37 13
Mulch 7 12 5 20 9
p-value 0.10 0.06 0.14 0.12 0.09