Ways Forward? Technical Choices, Intervention Strategies and Policy Options 363for recapitalization are limited due to limited resources, so that farmers can only
hope, at best, to maintain crop yield at a fairly low level.
All sites have experienced various attempts at soil erosion control. In many
cases a top-down approach to technical design and implementation has resulted in
a great deal of resentment. While farmers readily recognize the importance of
stemming nutrient losses through erosion control, the imposition of fixed contour
bunds or terraces has not been widely welcomed. Thus, for example, in Zimbabwe,
the colonial attempts at soil erosion control became a focus for nationalist opposi-
tion during the liberation war of the 1970s, and in Ethiopia, after the fall of the
Derg, many farmers dug up their terraces and replaced them with more flexibly
designed and less land-consuming alternatives. In the cotton zone in Mali, the
CMDT in collaboration with researchers have incorporated soil-erosion control as
a central part of their support to cotton farmers in Mali Sud (Hijkoop et al, 1991).
This has had considerable success in reducing erosion losses and protecting the
income streams of cotton farmers.
More sensitive approaches to land husbandry and soil conservation have
emerged in the last decade, which draw more explicitly on farmers’ own techniques
for managing soils. These often combine the management of soil, water and nutri-
ents in combination, rather than isolating soil erosion as the main issue (see exam-
ples in Reij et al, 1996). Combining physical with biological conservation measures
and changes in tillage practice perhaps offers the most promising route for tailored
interventions in this area. For example, in Zimbabwe research on conservation till-
age has been combined with more conventional approaches to soil conservation
and newer approaches to agroforestry and biomass management on-farm to come
up with a variety of technical options.
Improving the efficiency with which nutrients are used is less often considered
when choosing among a range of technological options, but is nevertheless vitally
important (Nordwijk, 1998). For instance, application efficiency is sensitive to
changes in the mix of inputs applied, where they are placed in relation to the plant,
and timing of application in relation to moisture availability and plant require-
ments at different stages of growth (Woomer and Swift, 1994). A decline or
improvement in use efficiency may make big differences in useful output, without
any change in inputs, outputs or nutrient stock levels, and so can help to offset the
effect of a decline in available nutrients and depletion of stocks for a period. For
example, work in Zimbabwe has shown that a very limited amount of fertilizer
input, perhaps combined with small amounts of manure, if placed in a particular
way and at a time which maximizes uptake efficiency, can produce very significant
yield responses, possibly far higher than a general application of an input in a blan-
ket manner (Piha, 1993).
This suite of technological options for improving stocks and managing the
flows of nutrients can be applied in a variety of ways. Four different intervention
strategies can be pursued, either singly or in combination (Scoones and Toulmin,
1999).