Targeting technologies – from ‘silver bullets’ to ‘best fits’
Ken Giller
There is broad consensus that both land and labour productivity must be enhanced in
Africa. African agriculture is highly diverse, with major farming systems matched to
the major agroecologies (Dixon et al., 2001). Within each of the broad classes of
farming systems, substantial variability exists. Within any given country or region
there are also more localised agroecological gradients, and large differences between
regions in terms of access to markets. Within every village a wide diversity of
farming livelihoods can be found, differing in production objectives and in wealth and
resource endowments (Tittonell et al., 2005; Zingore et al., 2006). In relation to
inherent productivity, native soil fertility is less than half that found in Europe, as the
vast majority of soils are relicts of 2-billion year old granites, and have few nutrients
left. Where younger, volcanic soils occur these are inherently richer in nutrients, but
have their own soil fertility problems as they generally fix phosphorus strongly. Soil
fertility is also extremely heterogeneous at more local scales: the difference in soil
organic matter between the fields of small farms in Kenya and Zimbabwe over
distances of only 50-100 m are as large (Tittonell et al., 2005; Zingore et al., 2006) as
the differences between the most fertile and least fertile soils at regional or continental
scale across Africa (Windmeijer and Andriesse, 1993). These differences in soil
fertility are partly derived from inherent differences in properties (the ‘soilscape’) but
are strongly influenced by past management, particularly by the rates and quality of
organic manures added to the soils. This heterogeneity in farming systems and
potential productivity and limiting factors must be embraced in any approach to
enhancing agricultural productivity. It is clear that ‘one-size-fits-all’ or silver bullet
solutions that are generally applicable simply do not exist. Whereas much of what is
written on technology development for enhancing productivity refers to baskets of
technologies among which ‘best bets’ can be identified for certain farmer groups in
certain regions, a better conceptualization is to think of ‘best fit’ technology options
for any given situation. Along this line of thinking, Ojiem et al. (2006) derived the
concept of the ‘socioecological niche’ for targeting of technologies, taking cognisance
of the need to recognize heterogeneity among and within farms.
Agricultural research has contributed significant understanding of African
smallholder farming systems, both in terms of the potential options available for
farmers and in terms of a better understanding of the context within which farming
takes place. The number of ‘success stories’ remains limited. There is general
consensus that agriculture must be considered within the frame of the ‘extended
livelihoods’ of the populations within rural areas. The alternatives for income
generation both within localities (often largely in agriculture) and further afield (often
in urban centres) must be considered in relation to future trajectories for farming.
The increasingly dominant paradigm of thinking towards enhancing
agricultural productivity is one of ‘market-led diversification and intensification’.
Whilst linkage to markets (particularly for cash crops such as cotton, tobacco etc) can
provide the opportunities for purchasing fertilizers to drive up productivity, not all
market-led intensification leads to sustainable production systems. A good example is
the influence of urbanization on developing the market for cooking bananas (matoke)
in Uganda. Rapid economic growth, with a concomitant increase in the population of
Kampala has led to rapid expansion of the market for matoke in the city. This leads to
a one-way nutrient transport in the cooking bananas to the urban centre, as the
bananas are produced in traditional systems with virtually no addition of fertilizers.
Thus decline in banana production is likely (and already appears to be happening)
unless alternative methods of soil fertility management can be sought.
Many reports recommend small-scale irrigation schemes as a means of
enhancing productivity. The total land area where irrigation may be feasible is
restricted, and small-scale irrigation schemes have a patchy history due to the lack of
attention to institutional aspects. If successful such initiatives can be important for
production of high-value crops and particularly vegetables.
Although the heterogeneity in African farming is at first sight bewildering,
systematic analysis across farming systems in West, East and southern Africa reveals
repeating patterns of management. These repeating patterns of allocation of nutrient
resources and management methods lead to self-organization among smallholder
farms (Giller et al., 2006). The past management of fields leads to extreme
differences in fertilizer use efficiency, e.g. from 5 kg grain kg N-1 to 50 kg grain kg N1
between fields of the same farm, as has been shown in East and southern Africa by
TSBF (Vanlauwe et al., 2006; Zingore, 2006) and in West Africa by IFDC (Wopereis
et al., 2006). By categorizing field types within agroecological zones in simple terms,
easily recognizable by farmers ‘rules-of-thumb’ can be derived for highly-efficient
management of scarce nutrient resources in these heterogeneous environments.
New approaches to the problem of building soil fertility use the principles of
‘Integrated Soil Fertility Management’ (ISFM), and ‘Balanced Nutrient Management’
recognising that: 1) neither practices based solely on mineral fertilizers or solely on
organic matter management are sufficient for sustainable management of agricultural
production; 2) well-adapted, disease- and pest-resistant germplasm is necessary to
make efficient use of available nutrients (Vanlauwe et al., 2002); and 3) good
agronomic practices in terms of planting dates, planting densities and weeding are
essential to ensure efficient use of scarce nutrient resources (Tittonell et al., 2006). In
addition to these principles we recognize: 4) the need to target nutrient resources
within crop rotation cycles, going beyond recommendations for single crops (Giller,
2002); and 5) the importance of integration of livestock within the farming systems
(Rufino et al., 2006). Participatory plant breeding approaches have made major
advances in the speed of development of new varieties of a range of staple cereal and
legume crops. Improved understanding of seed systems indicates that while the
private sector is important for cereals, many self-pollinating crops require local
initiatives to enhance availability and uptake of new varieties.
There is increasing concern relating to the likely effects of climate change on
the predictability and amounts of rainfall in Africa. Other major drivers of change
throughout sub-Saharan Africa are rapid urbanization coupled with rapid rates of
population growth. Although population in urban centres is growing at some 5-6%,
growth rates generally remain above 3% in rural areas indicating a doubling time of
20 years, even when the effects of HIV/AIDS are taken into account. Thus rural areas
of Africa are highly dynamic: in many areas sedentary agriculture has only been
practised for the past 50 years and have changed dramatically over this period. The
farming systems can thus be seen as ‘moving targets’ upon which new constraints
such as HIV/AIDS have major impacts through loss of human capital, increasing
pressure on the earnings of poor households, decreasing availability of labour etc. All
of these extra pressures render communities in rural areas highly vulnerable to the
effects of climate change.
Thus new approaches for enhancing productivity in Africa must take account of,
and harness, the dynamic nature of farming systems and the heterogeneity between
regions, farmers and their fields. Both mineral fertilizers and organic matter are scarce
nutrient resources, necessitating steps to increase availability of these resources and to
manage them efficiently. A key issue is tailoring soil fertility management to new
opportunities for market development, some of which bring new opportunities and
some new threats for sustainable soil management. The proposed approach represents
a substantial shift in concepts from traditional ‘blanket recommendations’ to focus on
the targeting of best-fit technologies to different farmers and crops within production
systems using simple ‘rules-of-thumb’ derived from scientific principles and local
farmers’ knowledge.
Despite major changes in thinking concerning sustainable development of
agriculture in Africa, implementation of new ideas and approaches remains
problematic. Information transfer to agricultural development workers (NGOs,
extension etc) is slow and most information available from government offices in
countries of sub-Saharan Africa is decades old. The diversity of local conditions in
terms of economic and infrastructural development as well as agroecology suggests
the need for best fit approaches to information delivery services (IFPRI, 2005).
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