The Hardest Case - The Oxford Topic of Food, Politics, and Society - page 132

The same is true for rural roads. The high cost of rural transport due to poor rural road
systems is one of the greatest constraints to agricultural productivity in Africa. Farmers
have less incentive to intensify production because fertilizer is too expensive to bring to
the farm, and because any surplus they might produce takes too much time and labor to
bring to market. Population growth is making it impossible to replenish soil nutrients
using the traditional system of shifting cultivation, since fallow times get shorter and
shorter as population increases, yet populations are not yet dense enough to justify the
cost of building (and maintaining) an adequate network of rural farm-to-market roads,
and during rainy seasons all household transport must be on foot. Governments in
Africa are also discouraged from investing in agriculture, some argue, because so many
are in countries that are geographically landlocked, and thus unable to imagine building
their farm sectors into a source of lucrative export revenues (Sachs 2001).
Arguments are also made that African governments invest little in agriculture
because they know that topography, soils, and climate in the region are poorly suited
to productive crop farming. Much of Africa is indeed burdened by the extremes of heat
and drought, heavily weathered soils, and a tropical disease environment that reduces
the productivity of both human and animal labor. Africa's high diversity of local eco-
systems makes more difficult the region-wide uptake of simple mono-crop farming
systems similar to the irrigated high-yield “Green Revolution” systems that worked for
wheat and rice in Asia. Soils in Africa tend to be poor even by the standards of tropical
countries, because they are highly weathered, acidic, and generally low in fertility. At the
same time, rainfall tends to be either scarce and unreliable, or excessive. An estimated
two-thirds of the continent is subject to high risk of drought, and some 46 percent has
less than seventy-five days of rain a year, too little to grow even millet. Tree planting,
normally an option for soil conservation, is problematic in the large parts of Africa that
receive less than 1,000 millimeters of rainfall each year. Compared with other tropical
regions, a much smaller part of Africa's land mass is moderated by proximity to oceans.
Most of Africa lacks the monsoon effects that provide more abundant rainfall in much
of Asia (Bloom and Sachs 1998). Local topography also tends to be highly irregular,
complicating the engineering of irrigation systems while boosting road construction
and other rural infrastructure costs. Irrigation costs in Africa are roughly double those
of other continents.
The many pests and diseases in Africa that attack crops, livestock, and farmers are
another natural impediment to higher productivity. As one example, stem borers are a
major pest problem for Kenyan maize farmers, causing estimated losses of 15-45 percent
of each maize crop, reducing Kenya's annual farm earnings by an average of 70 million
dollars. In West Africa, cowpeas grown by women farmers on small plots are a major
source of protein and cash income for 200 million people. Yet insect damage from pod
borers and weevils can affect up to 95 percent of the crop, depending on the location
and year (Murdock 1999). Farm size tends to be small in Africa partly because of the dif-
ficulty of keeping fields free from the invasive weeds that grow rampant. Parasitic weeds
such as Striga attack cereals and food legumes in the arid savanna zones, while perennial
grasses force farmers to abandon prime lands in the moist savanna (Akobundu 1991).