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              By Dunstan S. C. Spencer,1 Peter J. Matlon,2 and Huub Löffler3

Background Paper No. 1 was commissioned by the InterAcademy Council
(IAC) Study Panel on Science and Technology Strategies for Improving
Agricultural Productivity and Food Security in Africa. The Panel has made use
of the paper in its deliberations but its publication does not necessarily imply
endorsement by the Panel or the IAC, nor does the author necessarily endorse
the IAC Panel report.

  Managing Director, Dunstan Spencer and Associates, Freetown, Sierra Leone
  Deputy Director, Food Security, Rockefeller Foundation, New York, N.Y., USA
  Team Leader, Food and Health, BU Genetics and Breeding, Wagenigen Agricultural University and Research
Centre, The Netherlands
                                             Page 1 of 25


African farmers pursue a wide range of crop and livestock enterprises that vary not only
within but across the major agro-ecological zones. Even at the level of the individual farm
unit, farmers typically cultivate 10 or more crops in diverse mixtures, depending on soil type,
topographical position, and distance from the household compound. Research has verified
that such mixed-cropping systems diminish risk, reduce crop losses from pests and diseases,
and make for more efficient use of farm labor.

Dixon et al (2001) provide the most comprehensive description of the numerous farming
systems currently in use throughout the world. They identify and broadly delimit these
systems based on criteria that include:

   the natural-resource base
   dominant livelihoods (main staple and cash income sources as well as the balance
    between crops, livestock, fishing, forestry, and off-farm activities)
   the degree of crop-livestock integration
   the scale of operation.

Definitions of each of these systems derive from the most typical farm-households’ traits,
including natural resources and climate, altitude, main crops, importance of livestock, and
access to supplementary or full irrigation. Because of the gradual transition from one farming
system to the next, and the intimate linkages between them, the geographic boundaries
between these systems, shown for Africa in Figure 1, are approximate.

Table 1 lists the major farming systems in Sub-Saharan Africa and North Africa/Middle East
in accordance with percentage of land area in the region, percentage of agricultural
population, principal crops, prevalence of poverty, and potential for agricultural growth (and
hence, poverty reduction). Factors determining a system’s apparent growth potential include:
 favorable resource endowments, including underlying agro-climatic and soil conditions, a
    relatively high ratio of land and other resources (water, forest) to human population, and a
    currently low intensity of exploitation
 favorable access to infrastructure and services, including markets
 the potential for removing or reducing developmental constraints.

Figure 1: Farming systems in Africa

                                         Page 2 of 25
Table 1: Farming Systems of Sub-Saharan Africa (SSA) and North Africa and the Middle
           East (NA/ME), according to Dixon et al (2001)

Farming System       Land Area   Agric.        Principal                      Prevalenc   Agric.
                     (% of       Popln (% of   Crops                          e of        Growth
                     region)     region)                                      Poverty     Potential
Sub-Saharan Africa
Maize Mixed          10          15            Maize, tobacco, cotton,        Moderate    Medium-
                                               cattle, goats, poultry, off-               High
                                               farm work
Cereal-Root Crop     13          15            Maize, sorghum, millet,        Limited     High
Mixed                                          cassava, yams, legumes,
Root Crop            11          11            Yams, cassava, legumes,        Limited -   Medium
                                               off-farm income                Moderate
Agro-Pastoral        8           9             Sorghum, pearl millet,         Extensiv    Low-Medium
Millet/Sorghum                                 pulses, sesame, cattle,        e
                                               sheep, goats, poultry, off-
                                               farm work
Highland Perennial   1           8             Banana, plantain, enset,       Extensiv    Low
                                               coffee, cassava, sweet         e
                                               potato, beans, cereals,
                                               livestock, poultry, off-
                                               farm work
Forest Based         11          7             Cassava, maize. beans,         Extensiv    Low-Medium
                                               cocoyams                       e
Highland             2           7             Wheat barley, tef, peas,       Moderate    Medium
Temperate Mixed                                lentils, broadbeans, rape,     -
                                               potatoes, sheep, goats,        extensive
                                               cattle, poultry, off-farm
Pastoral             14          7             Cattle, camels, sheep,         Extensiv    Low-Medium
                                               goats, remittances             e
Tree-Crop            3           6             Cocoa, coffee, oil palm,       Limited-    Medium-
                                               rubber, yams, maize, off-      moderate    High
                                               farm work
Commercial—          5           4             Maize, pulses, sunflower,      Moderate    Medium
Large and                                      cattle, sheep, goats,
Smallholder                                    remittances
Coastal Artisanal    2           3             Marine fish, coconuts,         Moderate    Low-Medium
Fishing                                        cashew, banana, yams,
                                               fruit, goats, poultry, off-
                                               farm work
Irrigated            1           2             Rice, cotton, vegetables,      Limited     High
                                               rainfed crops, cattle,
Rice-Tree Crop       1           2             Rice, banana, coffee,          Moderate    Low
                                               maize, cassava, legumes,
                                               livestock, off-farm work
Sparse Agriculture   18          1             Irrigated maize,               Extensive   Low
(arid)                                         vegetables, date palms,
                                               cattle, off-farm work
Urban Based          little      3             Fruit, vegetables, dairy,      Moderate    Medium
                                               cattle, goats, poultry, off-
                                               farm work
North Africa/Middle East

                                         Page 3 of 25
Highland Mixed       7             30            Cereals, legumes, sheep,      Extensive    High
                                                 off-farm work
Rainfed Mixed        2             18            Tree crops, cereals,          Moderate     High
                                                 legumes, off-farm work        (for small
Irrigated            2             17            Fruits, vegetables, cash      Moderate     High
Dryland Mixed        4             14            Cereals, sheep, off-farm      Extensive    Moderate
                                                 work                          (for small
Pastoral             23            9             Sheep, goats, barley, off-    Extensive    Low
                                                 farm work                     (for small
Urban-based          <1            6             Horticulture, poultry, off-   Limited      Low
                                                 farm work
Sparse (Arid)        62            5                                                        Low
                                                 Camels, sheep, off-farm       Limited
Coastal Artisanal    1             1             Fishing, off-farm work        Moderate     Low
Source: Dixon et. al. (2001)
Note: Poverty is defined by the international poverty-line of average daily consumption equivalent to
US$1 per day per capita. Prevalence of poverty refers to number in poverty, not depth of poverty, and
is assessed relative to the region.

The above data are not permanent; over time, one system can in fact transform into another.
As noted by Dixon et al (2001), the evolution of individual farms and, in aggregate, the
overall farming system, depend on factors—household goals, the technologies in use, and the
resource base—that are internal and closely related to population pressure. Meanwhile,
external and more diverse factors also drive system transitions. These include market
development and shifts in demand, agricultural services and policies, and the availability of
market and policy information. Moreover, relationships are reciprocal; the farming system
co-evolves with its external environment.

Often, the evolution of farming systems follows a recognizable pathway. For example, a
system originally based on hand hoes may face new pressures as market-driven
diversification occurs. This could lead to the increasing use of cattle for draught power,
replacement of some manual operations and, if land is available, an expansion of the
cultivated area. Later, intensification of crop production may be impelled by population
growth and shortage of land. Market-driven evolution tends to result in production
specialization, a higher degree of mechanization, increased use of external inputs, and greater
orientation to exports.

But even at any one location within a farming system, different farms are likely to be at
different stages because their respective resource base, family goals, capacity to bear risk, or
degree of market access will vary. Individual farm systems may also be shifted out of its
evolution pathway altogether because of internal or external shocks such as family sickness,
natural disasters, or policy interventions (structural adjustment, for example). Meanwhile,
apart from evolution there is always the possibility of “revolution”: completely new
alternatives may arise in the future, perhaps related to technology or markets, that cannot
easily be foreseen.

                                            Page 4 of 25
The 17 most important farming/production systems in Africa at present are briefly described

Irrigated. Large-scale irrigation schemes have mostly been linked in the past to perennial
surface-water resources, notably in Egypt, Nigeria, Mali, Senegal, and Mauritania. Since the
1960s, however, the advancement of drilling and pumping technology has permitted the
development of large groundwater-dependent schemes, which are now found across all zones
and include high-value cash and export cropping as well as intensive vegetable and fruit
cropping. Although patterns of water-resource utilization vary greatly, water is often used
inefficiently, with the result that significant economic and environmental externalities are
produced through too-rapid drawdown of aquifers and excessive irrigation (which causes
rising groundwater tables and soil-salinization problems).

Small-scale irrigated systems occur in many places across the region as well. But although
they may not be significant individually in terms of percentage of the population involved or
the amount of crops produced, they are a significant element in people’s survival in dry areas,
where the major crops are mixed cereals and vegetables. Such systems develop along small
perennial streams and at oases, in places where flood and spate irrigation is feasible, or
around boreholes. These locations often provide focal points for socioeconomic activity,
though intense local competition between livestock owners and farmers for limited water
resources is becoming increasingly evident.

In many cases, irrigated cropping is combined with rainfed cropping or animal husbandry. It
is also possible to distinguish between full and partial water control. Crop failure is generally
not a problem, but livelihoods are vulnerable to water shortages, scheme breakdowns, and
deteriorating input/output price ratios. Major constraints include iron-toxicity problems,
scarcity and quality of water resources in dry regions, and excessive water in humid zones.

Highland mixed. There are two subsystems in this category, and they sometimes interlock.
The first is dominated by rainfed cereal and legume cropping, complemented by tree crops
like fruits, coffee, qat, and olives as well as vegetable crops planted on terraces, sometimes
with supplementary irrigation in the summer months for crops such as melons or high-value
fruits. The second system is based on livestock (mostly sheep) on communally managed
lands. In some cases, livestock, and the people who control them, are involved in a
transhumance system, migrating seasonally between lowland steppe in the more humid
winter season and upland in the dry season. Such systems still exist in Morocco. Wheat and
barley dominate these systems, which are generally monoculture-based with occasional
fallows. Surrounding the cropped areas are common grazing lands, which may be used by
owners from the same region or by pastoralists migrating to the plains for the winter season.

The major constraint on these systems is the decline in quality of the natural-resource base
(caused by reduced maintenance of terraces and increasing water erosion), which leads in
turn to productivity losses. In addition, degraded soil fertility caused by continuous cropping,
overuse of groundwater, and low nutrient return is an issue in some plateau areas. Where
livestock are present, overgrazing close to settlements and water points has also contributed
to soil degradation.

Rainfed mixed. The crops in this system are primarily rainfed, although supplementary
irrigation for wheat, and full irrigation for summer cash crops, are developing rapidly in some
areas. Main enterprises in the steppe areas include tree crops (olives and fruits), melons, and

                                          Page 5 of 25
grapes. There is also some protected cropping with supplementary irrigation for potatoes,
sugar beet, other vegetables, and specialist crops and flowers. In the more humid areas, there
are fewer trees apart from the more drought-resistant varieties. Common crops are wheat,
barley, chickpeas, lentils, and the fodder crops—vetches and medics. Here too, some
supplementary irrigation may be used for vegetable and flower production. Many farms are
intensively capitalized with a high level of inputs, and farmers are very sensitive to market
opportunities. In particular, there are a number of specialized dairy and poultry systems
within this ecological zone, which may also include summer crops grown following winter
fallow or with some supplementary irrigation.

Major production constraints on these systems are poor access to quality land by an
increasing number of small farmers; soil erosion on slopes during rainstorms; and erosion by
wind on light, over-cultivated, and exposed soils.

Dryland mixed. This system is common in the dry sub-humid areas where the main rainfed
cereals are barley and some wheat with annual or two-year fallow. Occasionally, and in
higher-rainfall areas, legumes (lentils and chickpeas) may be grown. Interactions with
pastoral systems are strong, as sheep may graze whole-crop barley in a dry year and the
stubble of the harvested crop in average or wetter years. Small areas of irrigated vegetables
may be cultivated in association with these systems.

The reliability of cropping is highly dependent on rainfall, and the whole system is vulnerable
to its inter-annual and seasonal variations (both temporal and spatial). In the recent past, there
has been a decline in wheat-growing areas and renewed use of indigenous barley varieties.
The most critical issues appear to be limited access to new crops and varieties; wind-erosion
problems during the dry season in some of the more arid areas with lighter soils; and

Pastoral. Pastoral systems, mainly involving sheep and goats, are found across large areas of
the arid and semi-arid zones of Africa4. They have strong linkages to other farming systems,
both in the more humid areas and in urban areas with large feedlots. The animals are involved
in seasonal migration, which is dependent on the availability of grass, water, and crop
residues. For example, during the driest period of the year, Sahelian pastoralists move south
to the “cereal-root crop mixed” system areas, and they return north during the rainy season.

Pastoral systems are vulnerable to climatic variability; there is a high incidence of drought
and desertification, leading to loss of biodiversity. Socioeconomic differentiation is
considerable—many herders have lost most of their animals as a result of droughts or stock
theft. Heavy grazing of the rangelands by livestock is believed to be the most widespread
cause of vegetation loss and land degradation throughout the pastoral regions.

Agro-pastoral millet/sorghum. This farming system is generally found in the semi-arid zone
of West Africa from Senegal to Niger and in substantial areas of east and southern Africa
from Somalia and Ethiopia to South Africa, in places where population density is modest but
pressure on arable land is very high. Crops and livestock in this region are of comparable
importance. Rainfed sorghum and pearl millet are the main sources of food and are marketed
in small quantities together with sesame and pulses. Land preparation is done by oxen or
camels, while hand cultivation using hoes is common along riverbanks. Livestock also

    Temperate-area pastoralists such as the Masai are included in the highland temperate systems.
                                                   Page 6 of 25
provide subsistence (milk and milk products), offspring, transportation (camels, donkeys),
savings, saleable assests, bride wealth, and insurance against crop failure. The population
generally lives permanently in villages, although parts of their herds may continue to migrate
seasonally with herd boys and through entrustment arrangements.

The main source of vulnerability in this farming system is drought, which leads to crop
failure, weak animals, and the distress sale of assets. During the past two decades, insufficient
and erratic rainfall has led to low crop yields and the abandonment of groundnuts and late-
maturing sorghum in some areas, along with an acute shortage of drinking water and
firewood. Soil-fertility problems are emerging in the plains because of shortened fallow
intervals and long periods of continuous cultivation, and land shortage is a problem in the
densely populated areas where soils are more fertile. Moreover, pressure on resources is
expected to intensify in coming decades with the growth of human and livestock populations
in the system. In addition to drought and declining soil fertility, crop-related constraints
include weed infestation in cereals and cowpeas (mainly by striga), pests and diseases in
cowpeas and groundnuts, and the high cost and general lack of credit for cotton inputs.
Livestock-related constraints include shortage of dry-season grazing and the weak condition
of draught animals at the time of greatest physical effort.

Sparse (arid). This system covers the extensive desert areas of the region. It contains some
oasis farming and a number of irrigation schemes—notably in Sudan, Tunisia, Algeria,
Morocco, and Libya, where dates, other palms, vegetables, and cereals such as maize and rice
are grown—and it provides opportunistic grazing for the herds of pastoralists from scattered
storms and in good seasons. The boundary between pastoral grazing and sparse agriculture
systems is indistinct. Constraints are those already described for the pastoral, agro-pastoral,
and irrigated systems.

Tree crop. This farming system runs from Côte d’Ivoire to Ghana and from Nigeria and
Cameroon to Gabon, with smaller pockets in Congo. The system’s backbone is the
production of industrial tree crops, notably cocoa, coffee, oil palm, and rubber. Food crops
are interplanted between tree crops and are grown mainly for subsistence. Roots and tubers
(cassava, yam, and cocoyam) are the main staples, while tree crops and off-farm activities are
the main source of cash. Land preparation is by hand. Livestock keeping is limited by tsetse
infestation in many areas. The main animal species are pigs and poultry. Fish farming is
popular in some areas, and off-farm activities are relatively well developed. There are also
commercial tree-crop estates (particularly for oil palm and rubber) in these areas, providing
services to small-holder tree-crop farmers through nucleus estate and outgrow schemes. A
variant of the tree-crop system is the “rice-tree crop” system located in Madagascar—mostly
in the moist sub-humid and humid zones, in which banana and coffee cultivation is
complemented by rice, maize, cassava, and legumes.

Because tree-crop or food-crop failure is uncommon, this system’s main source of
vulnerability is price fluctuations for industrial crops. Other constraints include population
pressure on natural resources, declining terms of trade and market share, dismantling of
parastatal input supply and marketing services, and withdrawal of the public sector from
industrial-crop research and extension. Socioeconomic differentiation is considerable, but
growth potential is moderately high.

Forest based. This farming system is found in the humid forest zones of the Congo
Democratic Republic, the Congo Republic, Southeast Cameroon, Equatorial Guinea, and

                                          Page 7 of 25
Gabon. Farmers practice shifting cultivation: they clear a new field from the forest every
year, crop it for two years (first cereals or groundnuts, followed by cassava), and then
abandon it to bush fallow for seven to ten years. Cassava is the main staple, complemented by
maize, sorghum, beans, and cocoyam. Cattle populations are low. Human population-density
itself is low, and the physical isolation resulting from lack of roads and markets is a serious
problem. Forest products and wild game are the main sources of cash.

Agricultural growth potential is moderate thanks to the existence of large uncultivated areas
and high rainfall, but yield increases in the near future are expected to be modest.
Development entails environmental risks, including soil fragility and loss of wildlife habitats.

Root crop. This farming system extends from Sierra Leone to Côte d’Ivoire, Ghana, Togo,
Benin, Nigeria, and Cameroon. The area merges into the “tree crop” and “forest based”
farming systems on the southern and wetter side and into the “cereal-root crop mixed” system
on the northern and drier side. Rainfall is either bimodal (i.e., with two rainy seasons) or
nearly continuous, and risk of crop failure is low. As in the tree-crop systems, price
fluctuations for industrial crops constitute an important source of vulnerability, and emerging
soil-fertility problems are another. Agricultural-growth and poverty-reduction potential are
moderate because technologies for this system are not yet fully developed. Nonetheless,
market prospects for export of oil-palm products are attractive, urban demand for root crops
is growing, and linkages between agriculture and off-farm activities are relatively well

Maize mixed. This farming system is the most important food production system in east and
southern Africa, extending across their plateau and highland areas where the climate varies
from dry sub-humid to moist sub-humid. In west Africa, similar systems are found in the
highlands of western Cameroon and Nigeria. In this farming system, which contains
scattered, mostly small-scale irrigation schemes, the main staple is maize and the main cash
sources are migrant remittances, cattle, small ruminants, tobacco, coffee, and cotton, plus the
sale of food crops (maize, pulses, and sunflower). Cattle are kept for plowing, breeding, milk,
farm manure, bride wealth, savings, and emergency sale. In spite of scattered settlement
patterns, community institutions and market linkages in the maize belt are relatively better
developed than those of other farming systems.

The main sources of vulnerability are drought and market volatility. In fact, the whole system
is currently in crisis because of the shortage or high prices of inputs (including seed and
fertilizer). As a result, yields have fallen and soil fertility is declining—small holders are
reverting to extensive production practices, which are not very sustainable given the small
farm sizes. Off-farm income has consequently become important for most households.

Cereal-root crop mixed. This farming system, found mainly in the Guinea savannah, shares
some characteristics with the “maize mixed” system (such as 120-180 growing days with, in
some cases, mono-modal rainfall). But it has characteristics that set it apart: relatively low
population density, abundant arable land, lower altitude, higher temperatures, presence of a
tsetse challenge (thereby limiting livestock numbers in much of the area, with a consequent
absence of animal traction). Cereals such as maize, sorghum, and millet are important in this
system, but wherever animal traction is absent root crops such as yams and cassava dominate
cereals. A wide range of crops is grown and marketed, and intercropping is critical.

The main source of this system’s vulnerability is drought. Although land is sufficiently
abundant to permit crop rotation, there are already signs of fertility decline and increase in
                                          Page 8 of 25
acidity in some soils, sometimes associated with prolonged use of inorganic fertilizers
without attention to maintaining organic matter levels. Weeds such as striga have become
more difficult to control, and in the northern part of the area, prolonged use of mechanization
for land preparation has resulted in loss of soil structure and organic matter.

Highland perennial. This farming system, found mainly in Ethiopia, Uganda, Rwanda, and
Burundi, supports Africa’s highest rural population density (more than one person per hectare
of land). Land use is intense and holdings are very small (average cultivated area per
household is just under one hectare, but over 50 percent of holdings are smaller than a half-
hectare). The system is based on perennial crops such as banana, plantain, enset (Ethiopian
“false banana”), and coffee, complemented by cassava, sweet potato, beans, and cereals.
Cattle are kept for milk, manure, bride wealth, savings, and social security. The main
constraints are diminishing farm size, declining soil fertility, and increasing poverty and
hunger. People cope by working the land more intensively, but returns to labor are low.

Highland temperate mixed. This farming system is found mainly in the highlands and
mountains of Ethiopia, Eritrea, and Lesotho, but it also occurs to a small extent in Kenya,
Angola, Cameroon, and Nigeria. Average population density is high and average farm size is
small (1-2 hectares). Cattle are numerous and are kept for plowing, milk, manure, bride
wealth, savings, and emergency sale. Small grains such as wheat and barley are the main
staples, complemented by peas, lentils, broad beans, rape, tef (in Ethiopia), and Irish potatoes.
The main sources of cash are from the sale of sheep and goats, wool, local barley beer, Irish
potatoes, pulses, and oilseeds. Some households have access to soldiers’ salaries (Ethiopia
and Eritrea) or remittances (Lesotho), but these mountain areas offer few opportunities for
local off-farm employment.

There are major problems in this farming system. Soil fertility is declining because of a
shortage of biomass, and cereal production in particular is suffering from the lack of inputs.
Household vulnerability stems mainly from the risky climate; early and late frosts at high
altitudes can severely reduce yields, and crop failures are not uncommon in cold and wet
years. Agricultural growth potential is only moderate, but there is considerable potential for
diversification into higher-value temperate crops.

Commercial—large and small holder. This farming system extends across the northern part
of the Republic of South Africa and the southern part of Namibia, mostly in semi-arid and
dry sub-humid zones. It has two distinct subtypes—scattered small-holder farming in the
“homelands” and large-scale commercialized farming elsewhere—with maize dominating in
the north and east and sorghum and millet in the west. Cattle and small ruminants are raised,
though the level of crop-livestock integration is moderate. Vulnerability is high in the small-
holder subsystem in that a considerable fraction of the region has poor soils and is drought-

Coastal artisanal fishing. Artisanal fishermen have lived for thousands of years along the
coasts of the Mediterranean and the Atlantic, where they’ve conducted small-scale
operations; but as modern technology and capital have been injected into the offshore-fishing
industry, the artisanal fishing system has shrunk. In West Africa, that system currently
stretches southward from the Gambia and the Casamance region of Senegal, along the coast
of Guinea-Bissau, Sierra Leone, Liberia, Côte d’Ivoire, and Ghana, to Nigeria, Cameroon,
and Gabon. Artisanal fishing includes sea fishing from boats, seine-net fishing from beaches,
setting of nets and traps along estuaries and in shallow lagoons, and catching of crustaceans
in mangrove swamps. This enterprise is complemented by multi-storied tree-crop gardens
                                           Page 9 of 25
with root crops under coconut and fruit trees. Poultry and goats are the main domestic
animals, though cattle-keeping is rare because of tsetse infestation, and land preparation is by
hand. Off-farm opportunities are connected with tourist resorts along the beaches and with
large tree-crop estates.

Urban based. There are numerous farmers in and around the cities and large towns of the
region (with a total urban population of over 200 million)—it is estimated that in some
metropolitan areas, 10 percent or more of the residents are engaged in urban agriculture. This
farming system is very heterogeneous; it includes small-scale but capital-intensive
commercial vegetable-growing, horticulture, dairy farming and livestock fattening, and part-
time farming by the urban poor to cover part of their subsistence requirements. But under
inappropriate management, urban farming poses potential environmental, food-quality, and
human-health risks. Also, urban land-tenure and water-use regulatory regimes, and even the
legality of urban farming, can pose major constraints to urban agriculture in some cities.
Overall, however, this is a very dynamic farming system that has considerable growth
potential, though it requires an enabling environment.


Agricultural productivity, which is expressed as returns to the factors of production (land,
labor, or capital), can be evaluated at different levels of aggregation—from the farm all the
way to global measures. For the purposes of this study, it is important to examine
productivity trends at the farming-systems level.

Because the most widely available agricultural data for Africa, such as those in the FAO
agricultural statistics database, are at the national level, it was necessary to interpolate down
to the farming-systems level. Using the distribution maps of Dixon et al (2001), the
proportion of cultivated-land area of each African country that hosts a particular farming
system was estimated, and only the countries that had 50 percent or more of their land in that
system were used—it was expected that the higher the proportion of a country that fell within
a given farming system, the more representative its production statistics would be.5

Examination of land productivity for some of the farming systems (Figure 2), using five-year
averages from 1961, show the following:

       Root-crop yields have grown modestly in the farming systems in which they are the
        principal commodities—e.g., cassava in the tree crop, forest based, and maize mixed
        systems; yam in the cereal-root cropped mixed system; and cocoyam in the forest
        based system. There was hardly any growth in yields where these commodities are
        grown as secondary crops, as in the agro-pastoral or highland perennial systems.

       Since the 1970s, cereal-crop yields (maize, millet, sorghum, rice, and wheat) have
        grown significantly in the irrigated and commercial systems.

       Rice is the only cereal whose yields have consistently increased across farming
        systems, especially since the middle 1980s. But the increases have been modest in
 One disadvantage of this approach is that data for Nigeria was not used in this analysis, as no farming system
accounts for more than 50 percent of the country’s total crop area. This means that evidence of the increased
yields of maize grown in the Savanna (cereal-root crop mixed system) during the 1980s and 1990s (Smith et al,
1994) is not reflected here.
                                               Page 10 of 25
        those farming systems in the humid zones (forest based, cereal-root crop mixed),
        where most of the rice is grown under rainfed conditions. The growth in the sparse
        (arid) and agro-pastoral systems since the 1980s reflect the fact that rice is grown
        mainly under irrigation there.

       The annual growth in cereal-crop yields generally shows a drop in the second half of
        the 1980s and 1990s, especially for maize in the maize mixed system (where it is
        grown mainly under rainfed conditions).

       Tree crop yields have shown little or no significant increases in average growth over
        the last five decades.

       The effect of civil conflict on agricultural productivity is illustrated in the dramatic
        decline in crop yields since the 1980s in the highland perennial farming system
        (Rwanda and Burundi), especially for the food-security root crop of cassava.


As shown in Table 1, Dixon et al (2001) assessed the farming systems in terms of their
demographic importance, prevalence of poverty, and growth potential. For their promise in
actually reducing poverty and realizing agricultural growth,6 five farming systems in Sub-
Saharan Africa were selected for analysis of strategic options:

       Maize mixed
       Tree crop
       Irrigated
       Cereal-root crop mixed
       Agro-pastoral millet/sorghum.

The authors note that development of the first two systems is expected to lead directly to
agricultural growth and poverty reduction alike. Development of the third and fourth would
have a greater impact on agricultural growth, and only indirectly alleviate poverty. The fifth
system offers the possibility of modest poverty reduction, but the agricultural-growth
dividend would be limited.

  Systems selected either have high poverty with moderate growth potential or high growth potential in spite of
limited poverty. Farming systems with high poverty but low growth potential were excluded.
                                               Page 11 of 25
         Figure 2: Trends in crop yields (metric tons/hectare) in selected farming systems in Africa, 1961/65—1996/2000.
         (Figures in the legend represent annual percentage growth in yields during two periods: 1961/65-1976/80 and 1981/85-

            Forest based                          Cassava, 0.29, 0.63                       Sparse (arid)                      Maize, -0.88, 1.10

                                                  Maize, 0.54, -0.13                                                           Millet, -1.63, -0.34
    10                                                                             5
                                                  Rice, 0.09, -0.57                4                                           Rice, -1.44, 1.26


                                                  Coco yam, 0.15, -0.74            3                                           Sorghum, -2.03, -2.23
                                                  Beans, 0.68, -0.47               2                                           Wheat, -0.14, 2.29
     2                                                                                                                         Dates, 1.68, 0.43
     0                                                                             0
         1961-    1971-   1981-    1991-                                               1961-        1971-    1981-    1991-
          65       75      85       95                                                  65           75       85       95

             Irrigated                             Sorghum, 0.32, 2.00                                                         Cassava, -0.44, 0.47
                                                                                                   Root crop based
                                                   Rice, 0.20, 2.71                                                            Maize, 3.4, 1.99
    30                                                                             10
                                                   Maize, 1.97, 3.30                                                           Millet, 2.24, -1.71
    25                                                                                 8
                                                   Wheat, 1.92, 3.19                                                           Rice, 1.08, 0.02

                                                   Dates, 0.34, 1.98
    15                                                                                                                         Sorghum, 0.43, -0.28
                                                   Veg./mel., 0.21, 1.13               4
    10                                                                                                                         Pulses, 0.29, 1.16
     5                                                                                 2                                       Yam, 0.34, 0.59
     0                                                                                 0
         1961-    1971-    1981-    1991-                                                  1961-     1971-    1981-    1991-
          65       75       85       95                                                     65        75       85       95

                                                                Page 12 of 25
                                                                                                                              Maize, 0.79, -0.96
                     Agro-pastoral               Cassava, -1.13, -0.5                         Highland perrenial
                                                                                                                              Cassava, 2.12,-3.56
        5                                        Maize, 0.58, -0.24               12
                                                                                                                              Millet, -0.21, 0.70
        4                                        Millet, 1.22, 0.85                   9                                       Rice, -0.77, 0.52

                                                 Rice, -0.16, 2.69                    6                                       Sorghum, --0.92, -0.32
                                                 Sorghum, 1.22, -1.71                 3                                       Wheat, 0.79, 0.21
                                                 Pulses, 0.54, -0.68                                                          Coffee, 1.75, -0.75
        0                                                                             0
             1961-      1971-    1981-   1991-                                            1961-    1971-    1981-    1991-
              65         75       85      95                                               65       75       85       95

               Source: FAOSTATS, 2001
             Cereal - root crop - mixed          Cassava, 1.37, 2.09                                                            Maize, 3.07, 1.18
                                                 Maize, -0.36, 3.83                                                             Rice, 3.34, 0.02
        12                                                                            3
                                                 Millet, 0.04, 1.92                                                             Sorghum, 5.87, 2.60
         8                                       Rice, -0.94, 1.35                    2


                                                                                                                                Wheat, 3.91, 4.53
         6                                       Sorghum, 0.72, 1.68                                                            Pulses, 4.29, 0.37
         4                                       Pulses, 0.98, 4.48
                                                 Yam, 1.29, 0.92
         0                                                                            0
              1961-      1971-   1981-   1991-                                            1961-   1971-    1981-    1991-
               65         75      85      95                                               65      75       85       95

                                                  Cassava, 2.80, 0.87                         Tree crop based                     Cassava, 1.32, 1.66
                Maize mixed                       Maize, 2.63, -0.04                                                              Maize, -1.26, 1.88

    12                                            Millet, 1.22, 0.54            10                                                Millet, -0.79, 0.21

    10                                            Rice, 0.98, 0.69                                                                Rice, 1.55, 3.37
     8                                            Sorghum, 0.16, 0.64                                                             Sorghum, 0.35, 1.96

     6                                            Wheat, 6.92, -0.08                                                              Coffee, -1.51, 1.47
                                                                                      4                                           Oil palm, 1.68, 0.51
     4                                            Cotton, 2.69, 0.77
     2                                                                                2                                           Cocoa, 1.25, 1.58

     0                                                                                0
             1961-      1971-    1981-   1991-                                            1961-    1971-    1981-     1991-
              65         75       85      95                                               65       75       85        95
                                                                      Page 13 of 25
Of the eight farming systems delineated in North Africa, Dixon et al (2001) highlighted the
following four as having the greatest potentials for poverty reduction or agricultural growth:

        Irrigated
        Highland mixed
        Rainfed mixed
        Dryland mixed.

An alternative way of prioritizing farming systems in Africa for interventions to improve
food security is to use the two indicators of “Agricultural Value-Added” and “Underweight
Children.” The first represents the agricultural-productivity potential of a system, while the
second reflects its population’s malnutrition status. Directing interventions to systems in
which malnutrition and productivity potential are high, in other words, should give the
greatest return on investment for improving food security

Table 2 shows indices of agricultural value-added, the number of underweight children, the
percentage of underweight children, as well as a composite index combining both number
and percentage of underweight children for the ten predominant farming systems in Africa.
All parameters are indexed to the highest value for the farming systems. In Figure 3, the
index for number of underweight children and the composite index are plotted against the
agricultural value-added. Farming systems in the right or upper part of the graph can be
considered priority systems for food-security interventions. All priority systems defined in
this way correspond to the priority systems defined by Dixon et al (2001).

Table 2: Indicators for priority setting in ten major African farming systems
                             Agricultural    No of Underweight   % of Underweight   No and % of
                             Value-Added     Children Index      Children Index     Underweight children
                             Index                                                  Index
Farming System
Irrigated                    100             22                  33                 28
Maize mixed                  73              83                  73                 81
Tree crop based              67              35                  62                 50
Commercial                   61              7                   25                 17
Sparse/arid                  55              11                  77                 46
Forest based                 34              44                  81                 65
Cereal/root crop based       28              100                 93                 100
Root crop based              14              65                  77                 74
Highland perennial           12              52                  91                 74
Agro/pastoral                9               65                  100                85
Sources: WDI 2003 (data on agricultural value-added) and CIESIN 2003 (malnutrition data)

                                            Page 14 of 25
Figure 3: Indicators for priority setting of African Farming Systems

                                       Malnutrition and Agricultural Production Value Indices for major Farming
                                                                   Systems in Africa

                                 120                                                                                                         Using number of
                                                                                                                                             underweight children index
 Agriculture Value Added Index


                                                                                                                                             Using index that gives
                                  80                                                              Maize mixed
                                                                                                                                             50% weight to number of
                                                                    Tree crop based
                                           Commercial                                                                                        underweight children and
                                                                                                                                             50% to the % of
                                  60                                                                                                         underweight children
                                                        Sparse Arid

                                  40                                          Forest based
                                                                                                              Cereal/root crop based

                                  20                                                    Root crop based

                                                   Highland perennial

                                       0           20                  40             60             80              100               120
                                                                    Children Underweight Index

   Source: Data from Table 2


In this section we examine eight broad sets of factors that affect productivity across the major
farming systems and that science and technology policies must address.

Soil degradation
It is estimated that 46 percent of soil degradation in Africa results from water erosion, 36
percent from wind erosion, 9 percent from nutrient losses, 3 percent from salinization, and 4
percent from physical deterioration. Twenty-six percent of the degraded soils in Africa (128
million hectares) are classified as being strongly or extremely degraded, meaning that the
terrain is irreclaimable (5 million hectares) or would require major investments and
engineering works for reclamation. Overgrazing is the most important cause of soil
degradation, accounting for 49 percent of the area, followed by agricultural activities (24
percent), deforestation (14 percent), and overexploitation of vegetative cover (13 percent).
All these types of degradation cause a decline in the productive capacity of the land, reducing
potential yields.

Depletion of soil fertility is a major biophysical cause of low per-capita food production in
Africa (Sanchez 2002). Over decades, small-scale farming operations have removed large
quantities of nutrients from the local soils without applying sufficient quantities of manure or
fertilizer to replenish them. This has resulted in a very high average annual depletion rate—
22 kg of nitrogen, 2.5 kg of phosphorus, and 15 kg of potassium per hectare of cultivated land
over the last 30 years in 37 African countries—a loss equivalent to US$4 billion in fertilizer.

                                                                                             Page 15 of 25
Forest Degradation
Forests now cover some 520 million hectares, or about one-third, of Africa’s land area (FAO
1997a). In the humid tropics of central Africa, that proportion is almost half (48.3 percent). An
estimated 2 million hectares of west and central African tropical forest land were lost each year
in the 1990s, the annual loss rate being equivalent to about 0.5 percent of the total 380 million
hectares under forest in the 1980s. Forest cover continued to decline in Africa between 1990 and
1995; the annual rate of deforestation across the continent was estimated at 0.7 percent, with the
highest (1.0 percent) in west Africa and the lowest (0.6 percent) in central Africa. Two major
results are that nearly 65 percent of the original wildlife habitat has been lost and that rainfall
has been reduced. At present, reforestation efforts are unable to come even close to offsetting the
loss of natural forests.

Forest degradation in Africa is dominated by transition from closed forests through intermediate
stages of depletion to shrub and short fallow (FAO 1997a), This indicates that the extension of
small-holder slash-and-burn agriculture under the pressure of population growth is the primary
source. However, the relationship between rural population density, agriculture, and
deforestation is not a simple one. There are many other complicating factors, including urban
household dynamics and the cost of alternative energy sources, which in turn are affected by the
overall state of the economy.

Climate change
Scientific evidence on global warming suggests that over the next century a rise of average
temperature—somewhere between 1.4 and 5.8 degrees Celsius—will occur (Wilson 2001).
Such an increase in mean ambient temperature, if sustained, will cause significant changes in
forest and rangeland cover; species distribution, composition, and migration patterns; and
biome distribution. The African continent is particularly vulnerable to the impacts of climate
change because of widespread poverty, inequitable land distribution, and overdependence on
rainfed agriculture (IPCC 2001). Most models predict more frequent and severe extreme-
weather events in the tropics generally, including both localized drought and flooding. Some
drought episodes, particularly in southeast Africa, are associated with the El Niño-Southern
Oscillation phenomena, which have occurred more often in the last several decades.

Arid to semi-arid subregions and the grassland areas of eastern and southern Africa, as well
as areas currently under threat from land degradation and desertification, are the most
vulnerable. A reduction in precipitation projected by some climate models for the Sahel and
southern Africa, if accompanied by high inter-annual variability, could be detrimental to the
hydrological balance of the entire continent and disrupt various water-dependent
socioeconomic activities. Variable climatic conditions will simply render the management of
water resources more difficult both within and between countries.

Higher temperatures will also be accompanied by rising sea levels and more frequent
occurrences of flooding, droughts, and violent storms, causing changes in agricultural
practices. Several African coastal zones, including those of Senegal, The Gambia, Sierra
Leone, Nigeria, Cameroon, Gabon, and Angola, are already under stress from population
pressures and conflicting uses and will be adversely affected. Studies also indicate that a
sizable portion of the northern Nile delta will be lost to agriculture through a combination of
inundation and erosion.

Climate change exacerbates soil degradation in the dry areas (pastoral, agro-pastoral, and
sparse [arid] systems). Prolonged drought has already led to adverse ecological
                                          Page 16 of 25
consequences, including loss of grass cover in some areas; elimination of bushes and acacia
stands with shallow roots; the lowering of groundwater tables, especially near wells and
watering holes; an increase in shifting sands; greater wind erosion of fine soil components;
and higher evapotranspiration rates accompanied by the drying or cracking of soils (ISNAR
1995). Recent evidence suggests that rainfall variability may be a more important
determinant of the health of rangeland and its soils than overgrazing (UNEP 1997).

Agriculture also suffers from the indirect effects of climate change: increased numbers of
pests and pathogens, accelerated soil erosion because of more intense rainfall patterns, and
rising levels of ozone may all damage crops. Fish production systems are expected to be
further stressed, and livestock will suffer not only from rising and more extreme temperatures
but from shortages of forage and feed.

Irrigation and water scarcity
Productivity increases have been significant and consistent over the last five decades in the
irrigated farming systems. However, the impact of this system on Africa-wide trends is
severely limited by the continent’s geophysical constraints—only 1.15 percent of the
agricultural land is irrigated in Africa, with the proportion less than 0.5 percent in most
farming systems (Table 3). Some observers, pointing out that the 12.7 million hectares under
irrigation are only 30 percent of the potentially irrigatable land, conclude that the full
potential of this system in Africa is far from being realized, However, several qualifications
must be noted (FAO 1997b):

   Over 60 percent of the irrigation potential is located in the humid regions, with almost 25
    percent in the Congo basin alone. These are regions in which the potential for rainfed
    agriculture is also high and where irrigation is mainly supplemental.

   In the regions where irrigation has been important for agriculture, over 60 percent the
    land is already irrigated, including most of the areas with the best and lowest-cost
    potential. New developments will therefore require larger investments—in terms of water
    regulation or transportation, for example—or will take place in less productive soils.

   Investment costs for new irrigation schemes can be substantial, varying between $5,000
    and $25,000 per hectare in Africa. On average, such investments are substantially more
    expensive than similar ones in Asia.

   Over 50 percent of the areas currently under irrigation need to be rehabilitated if they are
    to achieve their sustainable potential. Innovative new approaches are needed, with an
    emphasis on smaller and more flexible water-management systems and greater
    participation of farmers in irrigation procedures.

Table 3: Land in irrigated farming systems in Africa, 2000

                               Agricultural Area (1000 hectares)

Farming systems                Land Use           Irrigation     % irrigated
Cereal-root crop mixed         62,874             163            0.26
                                          Page 17 of 25
Highland perennial            3,890              79             2.03
Maize mixed                   108,629            360            0.33
Root crop                     11,525             37             0.32
Forest based                  38,594             27             0.07
Tree crop                     49,289             182            0.37
Agro-pastoral                 8,050              71             0.88
Sparse (arid)                 111,395            1,145          1.03
Large commercial              99,640             1,498          1.50
Irrigated                     3,291              3,291          100.00
 Africa                  1,101,166               12,680         1.15
Source: Computed from FAOSTATs

For much of Africa, more water-conserving farm-management systems—which incorporate
the planting of drought-tolerant varieties, the choice of species with higher water-use
efficiencies, and the use of crop and simulation modeling for getting optimal results from
available inputs—will be needed. But they will not be sufficient because countries still need
to devote more resources to increasing the supply of water. Most of the additional investment,
however, should not be in classic large-scale irrigation systems. There is considerable
potential for capturing rainfall through improved soil-surface management practices, small
water-harvesting systems, and small-scale irrigation systems (in inland valleys for
intensification and crop diversification, and in upland systems for punctual lifesaving
irrigation of rainfed crops).

Effects of dismantling parastatal programs and reducing subsidies
Following independence, most African countries pursued agriculture with the help of direct
public-sector interventions. Governments established marketing boards, subsidized
agricultural inputs and urban food costs, set uniform prices across space and time, prohibited
private grain trading, and controlled currency markets at artificially high exchange rates that
ensured inexpensive imports of industrial products and food (but that made export crops
noncompetitive in international markets). By the early 1980s, the financial burdens of these
policies, reflected in growing fiscal deficits and rising external debts, became unmanageable.
Distorted price structures failed to reflect underlying supply and demand conditions, thereby
frustrating investments, while burdensome regulations and economic disincentives also
helped sideline the agricultural private sector.

By the mid-1980s, the World Bank and International Monetary Fund endeavored to create a
more favorable environment for economic growth by launching broad programs of structural
adjustment and requiring a complex of reform conditions for much-needed loans. Reforms
were designed to reduce government controls and reintroduce market forces as the main
drivers in the provision of agricultural inputs, in guiding production decisions, and in
distributing farm products. Market-oriented reforms eliminated subsidies on agricultural
inputs, removed fixed prices for food, curtailed exchange-rate overvaluation, and lifted
restrictions on the internal movement of food crops.

Underlying these sweeping reforms was the assumption that the private sector would respond
to the new price signals and opportunities, both in input and output markets, and that this in
                                         Page 18 of 25
turn would stimulate increased production, generate market surpluses, and raise incomes.
However, the benefits of this process have been far less—and the costs much greater—than
expected. The private sector generally did not fill the gaps in input and output markets
created by the withdrawal of public-sector operations. Many factors were at work here,
including insufficient entrepreneurial experience and capacity, the absence of market-
information systems, weak financial institutions, the lack of institutions to enforce contracts
and cover risks, and high transport costs (caused by infrastructure that had been badly
degraded during years of neglect). Further, in many countries the structural reforms that had
been ambitiously announced were only partially implemented, or they were modified or even
reversed, creating uncertainty and risks for new business ventures.

The aggregate supply response to the reforms has thus been extremely weak, especially for
food crops. In most African countries, the prices of agricultural inputs increased dramatically
(as a result of subsidy eliminations, exchange-rate devaluation, and the collapse of public
input-distribution programs), making them unaffordable for most poor farmers; and support
of extension systems was reduced as part of efforts to balance government budgets. Financial
markets did not develop to help poor farmers, seriously limiting effective demand for
improved seeds and chemical fertilizers.

The negative impacts of structural adjustments were clearly reflected in sharply reduced
fertilizer use in many countries, and the collapse of what in the 1980s appeared to be the most
promising new crop technologies. In the 1980s and early 1990s, small-holder maize and
cotton production expanded rapidly in west and southern Africa as a result of the diffusion of
improved early-maturing maize hybrids and cotton varieties facilitated by government
policies aimed at promotion of national food self-sufficiency; these policies had been aided
by fertilizer subsidies, seasonal production credit, and parastatal marketing support (Smith et
al 1994). But by the mid-1990s, both production systems were in decline and large-scale dis-
adoption occurred. Small-holder cotton lost much of its attraction with the dismantling of
parastatal programs that supplied small farmers with seeds, fertilizer, and chemicals on credit
at the beginning of the season. Reduced fertilizer subsidies, weakened extension systems, and
falling market prices for maize sharply reduced maize profitability and farmers’ incentives to
purchase improved seed and fertilizer. Both crops were further hurt by large subsidies
provided to producers in OECD countries that further reduced world prices. Figure 4 clearly
shows the downturn that occurred in the already low levels of fertilizer use in Africa
since the 1980s. Recovery has only occurred recently, with recovery limited to the irrigated

                                         Page 19 of 25
Figure 4: Trends in the use of fertilizers in farming systems in Africa

                                             Total NPK


            100.0                                                         Cereal-root crop mixed
                                                                          Forest based
                                                                          Highland perennial

                                                                          Maize mixed
                                                                          Root crop
                                                                          Sparse (arid)
                                                                          Tree crop
              1.0                                                         Irrigated
                    1961- 1966- 1971- 1976- 1981- 1986- 1991- 1996-
                     65    70    75    80    85    90    95 2000


Source: FAOSTATS 2001

Undue emphasis on high-input systems
Productivity trends demonstrate that the benefits of science and technology in Africa have
been captured most consistently in the commercial and irrigated farming systems, where
purchased inputs are most widely used. In the more traditional upland farming systems, there
has been some limited success with root crops, especially cassava in systems where they are
the principal crops. But overall, the proportion of farmers fields’ planted to improved
varieties in 1998 in Africa were about 40 percent for rice, 17 percent for maize, 26 percent
for sorghum, and 18 percent for cassava. These numbers are generally much smaller than in
Asia (65 percent for rice, 70 percent for sorghum) and Latin America (65 percent for rice, 46
percent for maize, 7 percent for cassava) (Evenson and Gollin 2001). The fact is that the
Green Revolution research paradigm in Africa resulted in productivity gains only in a
relatively small number of places—in those farming/production systems most similar to the
monoculture systems of Asia.

Large structural differences help explain the general failure of the Asian Green Revolution
model to take root in Africa. Major investments in irrigation, transport systems, and markets
had already been made in Asia well before the new high-yielding seeds were introduced in
combination with low-cost fertilizer in the 1960s and 1970s. At the onset of the Green
Revolution, many Asian farmers with access to cheap fertilizers were already approaching
the genetic yield potentials of their varieties; thus it made sense to direct research toward
extending those limits through breeding.

                                            Page 20 of 25
In Africa, by contrast, where few farmers have access to either irrigation or affordable
chemical inputs, and where yield-reducing factors contribute to large pre- and post-harvest
losses, farmers’ actual yields are typically a fraction of their genetic potential, even for the
current varieties. In this situation, research may be more effective if focused on the yield-
reducing factors—for example, on developing stress-resistant varieties and adopting lower-
input cultural practices. Moreover, given the diversity of production environments and
farming systems, crop-improvement research needs to emphasize agro-ecological approaches
that develop new varieties to fit into local niches and involve extensive farmer participation
(DeVries and Toenniessen 2001).

Insufficient focus on labor productivity
Agricultural research systems for Africa have often produced technologies inappropriate to
the factor endowments of most of the region’s small farmers. Often there has been too much
emphasis on increasing land productivity and not enough on the need for sustainability,
stability (reduction of annual fluctuations in output), and multiple outputs (crop
diversification in order to reduce income risks). Most often neglected is the potential effect of
recommended technologies on labor productivity.

Early emphasis on labor productivity was provided, among others, by Spencer and Byerlee
(1976), who showed that although Asia-like rice systems in Sierra Leone increased yields
under small-farm conditions by more than 150 percent, returns to labor increased by less than
70 percent. Ehui et al (1990) showed that improved land-management systems such as alley
cropping, which are designed to reduce soil erosion and increase yields, are only profitable
where population density is high and labor costs low. This has been confirmed more recently
by a number of authors—including Sanchez (2002), who acknowledges that although
improved tree fallows perform well, they are not attractive to farmers in the margins of the
humid tropical forests. These farmers have better land-use alternatives, owing to lower
population pressure (Kwesiga et al 2002, Place et al 2002).

Technologies assessed only in terms of their yield-increasing effect can actually lead to
erroneous recommendations in labor-short environments. Ruhigwa et al (1994) showed that
grass mulching, a potential high-yielding plantain technology, yielded negative returns to
labor (Figure 5). Similarly, Chianu et al (1999) showed that improved fallow-management
systems would have no advantage over the traditional bush fallow system when fallow
periods were reduced to the minimum (Table 4).

                                         Page 21 of 25
Figure 5: Costs and returns in alternative plantain-production systems in Nigeria




                                                                                  Alley Cropping
                                                                                  Grass Mulching


             Mulch Lab     Total Lab     Yield (t/ha)   NPV ($/ha)   NPV ($/100
            (100 pd/ha)       (100                                      pd)

        Source: Ruhigwa et al (1994)

Table 4: Net labor productivity (naira per person-day) by land-use intensity under different
experimental fallow systems in Nigeria.

Land use                  Fallow System1
intensity                 Bush fallow               Cover cropping            Alley cropping
                                                                              Crop production      Crop production
                                                                                                   plus fuelwood
Zero fallow                69                       69 (0)                    49 (-29)             49 (-29)
1-year fallow             138                       178 (29)                  54 (-61)             94 (-32)
2-year fallow             183                       212 (16)                  74 (-60)             148 (-19)
3-year fallow             203                       217 (7)                   79 (-61)             173 (-15)
Values in parenthesis are percentages by which net labor increases (where positive) or decreases
(where negative), following a switch from bush fallow to either alley cropping or cover cropping.
Source: Chianu et al (1999).

There are only a few studies, such as those referred to above, in which labor productivity was
directly measured when improved technologies were assessed in on-farm trials before
recommendations were made to farmers. Byerlee and Jewell (1997) point out that experience
from many countries shows that seasonal labor productivity is an important constraint for the
acceptance of improved crop-management practices such as plant spacing and weeding. Even
when land is in short supply, seasonal labor shortages often decisively affect farmers’ choices
of technology. Unless technologies are assessed from the perspectives of labor use and
productivity, therefore, research and extension systems will continue to recommend
“improved” technologies inconsistent with most African farming systems. There is little
                                                        Page 22 of 25
justification for such an approach today, as methodologies exist for collection of meaningful
labor data in on-farm trials (e.g., Spencer 1992).

Impacts of HIV/AIDS
Since the start of the epidemic, nine out of ten new infections and 83 per cent of all
HIV/AIDS-related deaths have occurred in Africa. Adult HIV/AIDS prevalence rates exceed
10 per cent in 13 African countries. In Zimbabwe, Botswana, Namibia, Zambia, and
Swaziland, between 20 and 26 percent of the adult population aged 15- 49 years is living with
HIV/AIDS. This situation is having an increasingly devastating effect on labor availability in
Africa, and it poses new challenges for the region’s agricultural research and development
strategies (Ryan and Spencer 2001).

At the household level, the most immediate impact of HIV/AIDS is to reduce the availability
of labor—not only among those who have contracted the disease but of other household
members whose time is diverted from productive activities to provide patient care. Studies
from east and southern Africa show how HIV/AIDS-affected households shift from the
cultivation of labor-intensive and often high-value crops to more food crops that require less
labor and less area. This implies the need to raise agricultural productivity by developing and
disseminating labor- and capital-saving technologies as well as drought-resistant crop
varieties that stabilize yields. Particular attention needs to be given to targeting female heads
of households.


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       143 in Africa’s Emerging Maize Revolution, D. Byerlee and C.K. Eicher, eds. Boulder,
       Colorado: Lynne Rienner Publishers.

Chianu, J., Spencer, D. S. C., and J. T. Atobatele. 1999. “Labor Use and Productivity in New
      Fallow Systems as Alternatives to Slash-and-Burn Agriculture in the Derived
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                                          Page 23 of 25
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