358 Enabling Policies and Institutions for Sustainable Agricultural and Food Systems
soil-fertility management. But how should initiatives directed towards soil-fertility
issues be directed? The final section looks at the options, and suggests a strategy
which recognizes the multiple dimensions of soil-fertility management, and a proc-
ess which establishes a more open learning, adaptive process for the design, moni-
toring and evaluation of policy measures.
Diversity of Agroecological Setting and Farmer Practice
The conditions faced by farmers in sub-Saharan Africa are remarkably diverse. The
research sites were chosen to investigate the significance of such diversity for farmer
practice. Thus, the sites selected spanned a long transect in Mali from irrigated Tis-
sana and millet-based Siguiné to M’Péresso in the cotton belt, from highland to
lowland farming villages in Wolayta, southern Ethiopia, and from high potential
Mangwende to Chivi in the low potential region of Zimbabwe. This diversity across
the continent and within the different countries studied is mirrored at village level.
The options available to poor farmers are much more constrained than those availa-
ble to richer farmers who have easier access to labour, land, livestock, credit and cash.
This theme of diversity can be taken further to farm level, where the management of
soils within the farm varies very considerably between parts of the farm. Typically,
certain fields tend to receive far greater concentrations of labour and nutrient inputs,
while others are more extensively managed. Thus, in Zimbabwe, homefields close to
the settlement receive most attention while outfields have limited applications; in
Ethiopia, the darkoa plots supporting dense stands of enset receive regular supplies of
manure and household waste, while further afield maize crops on the shoka plot have
to make do with little or no amendments to the soil. Similarly, in land-extensive
dryland sites in Mali, the soforo infields around the village are often black with dung
by the end of the dry season and offer well-fertilized conditions for crops of maize
and millet. By contrast, the large, shifting outfields, or kongoforo, produce a harvest
for four or five years before being abandoned to fallow and occasional grazing. Where
cotton has become important, the availability of chemical fertilizer modifies this pat-
tern and enables more permanent cultivation of larger bush fields.
This diversity at different scales has very important implications for how best
to support improved farmer management of soil fertility. There are no simple mes-
sages regarding appropriate ways to manage Africa’s soils. While depletion or ‘min-
ing’ of nutrients may constitute a problem for certain fields, there are others which
are accumulating nutrients. The research has helped identify the locations in which
soil-fertility management has become a key issue. Villages such as Siguiné in Mali
can still manage a system of fallowing and nutrient transfers from grazing in crop
land and thereby maintain grain yields, albeit at low levels. For them, low and
erratic rainfall and uncertain prices are at least as much constraints on assuring
food security as the fertility of their soils. The sites in Ethiopia demonstrate a rela-
tively efficient system of managing and recycling of biomass and nutrients, although