countries lacking the foreign
exchange to import them, have led
large-scale commercial farmers to
experiment with reduced tillage
and zero-tillage technologies that
do not require such intensive use of
machinery.

Commercial farmers plant maize in
rows, using either hand-operated
seed drills or tractor-drawn
mechanical planters. Early plant-
ing is associated with higher yields
when rainfall is normal, although
maize planted early is subject to
greater risk in drought years. If a
dry spell occurs just after planting,
some farmers can irrigate to help
establish the crop. Large-scale
farmers tend to grow hybrids, since
these materials are well suited to
favorable production environments
and respond well to high manage-
ment levels. Hybrid seed is pro-
duced by private companies and in
some cases by public sector organi-
zations. Certified seed treated with
fungicide and sometimes pesticide
is usually sold through producers'
cooperatives.

Almost all large-scale commercial
farmers apply inorganic fertilizers
to maize. Application rates vary
depending on soil conditions,
averaging around 150 kg/ha
nitrogen (N), 60 kg/ha phosphorus
(P20,), and 30 kg/ha potassium
(IK20) throughout the region
(Low and Waddington 1989;
Anandajayasekeram and Ransom
1989). In most cases, all of the
phosphorus and potassium and
about one-third of the nitrogen are
applied basally, with the rest of the
nitrogen top dressed or side dressed
four to six weeks after the crop
emerges.

Weeds are controlled by mechanical
cultivation and/or with herbicides.
Herbicides are applied with tractor-
mounted sprayers or by air. Where
herbicides are unusually expensive,


many farmers reduce costs by
combining band spraying on the
crop row with tillage between rows.

Large-scale commercial farmers
harvest maize with combine har-
vesters or by hand. Combine
harvesters are faster and techni-
cally more efficient but expensive to
operate, especially in countries
where foreign exchange shortages
have reduced the availability and
raised the cost of imported machin-
ery. When combine harvesters are
unavailable or prohibitively expen-
sive, laborers are hired to harvest
maize by hand. The ears are
picked, deposited directly into
tractor-drawn wagons, and trans-
ported to storage facilities on the
farm. The ears are shelled later
using small mechanical sellers,
and the grain is bagged for sale.

Western and Central Africa-
The associations between specific
maize production technologies and
broad groups of producers are not
as distinct in western and central
Africa as they are in eastern and
southern Africa. Nor does the scale
of maize production vary as much,
partly because fewer settlers
arrived to foster large-scale com-
mercial farming. However, maize
production technologies in western
and central Africa are quite di-
verse, shaped by widely varying
agroclimatic and socioeconomic fac-
tors. The discussion that follows
therefore focuses not on producer
groups but on the principal factors
that determine which technologies
farmers use to grow maize.

Maize production in western and
central Africa is for the most part
still based on shifting cultivation
systems and slash-and-burn meth-
ods. In many areas, three or four
years of cropping alternate with
three or four years of bush fallow,
although in some places fallows
and/or cropping periods are much
longer, depending on population


density and soil conditions. Maize is
typically intercropped with other
food crops, with the predominant
combinations varying by production
zone.

In much of the humid forest zone,
increasing population and shorter
fallow periods have compelled
farmers to adopt a combination of
strategies to prevent soil degrada-
tion. The two most important
strategies are preserving trees in
cropped land and planting a range
of crops that provide good ground
cover early in the rainy season. If
fertilizer is used, it is applied at
very low levels.

In the derived and southern Guinea
savannas, maize can be grown
without chemical fertilizer on good
land, especially if the land is
located close to household com-
pounds where it can be fertilized
with organic refuse. In many areas,
farmers allow nomadic cattle
herders to keep their animals
overnight in a field to improve soil
fertility. Whenever farmers have
access to inorganic fertilizer, they
will apply it to maize rather than to
other cereals. Despite these fertility
management practices, nutrient
deficiencies are common, particu-
larly deficiencies of nitrogen and
phosphorus. Low response to major
nutrients is often exacerbated by
sulfur and zinc deficiencies.

In the northern Guinea savanna,
bush fallowing is still widely prac-
ticed. However, the fallow cycle
seems to be decreasing in some
areas and disappearing altogether
in others as fertilizer use increases.
The major constraint for maize
production in this zone is soil infer-
tility, partially brought about by
annual burnings that deplete soil
organic matter. Maize therefore
depends heavily on chemical
fertilizer, which is sometimes sup-
plemented by manure and by
rotations of maize with legumes. In