RA 00110.pdf - OAR@ICRISAT

in tests conducted by ICRISAT on farmers' fields.
Grain yield responses were particularly low in the
Sahel region where agroclimatic conditions essentially
limit farmers to millet production (Table 2).
Moreover, in the Sudan savanna, where farmers
have wider options to allocate their scarce fertilizer
to either sorghum or millet, the yield response for
millet was approximately two-thirds of the sorghum
response.
The low absolute response in the principal millet
producing zone, and the low relative response of
millet compared to sorghum (and other cereals) in
the transition zone create powerful economic disincentives
against the use of fertilizer on millet. In the
ICRISAT farmers' tests just cited, average returns to
the recommended fertilizer dose when applied to
local millet cultivars in the Sahel Zone were consistently
negative, and average returns in the Sudan
savanna were only 10% (Table 2).
It is important to note that ICRISAT farmer tests
evaluating the economics of phosphorus fertilizers
applied to millet in the Sahel Zone of Niger have
produced higher returns than tests in Burkina Faso.
Differences are due to higher millet grain prices in
Niger, and because the most available and currently
recommended fertilizer in Burkina Faso is imported
primarily for use on cotton and is therefore not an
efficient formula for millet.
A further analysis of returns over a range of fertilizer
doses has shown that at all doses, average financial
returns were highest in the more humid Guinean
Zone and declined systematically in more arid areas,
becoming marginal or negative in the Sahelian sites
(ICRISAT 1984, pp. 313-314). The risk of financial
losses followed a similar south-north pattern. Moreover,
when sorghum was compared to millet in the
Sudan transition zone, risks were consistently lower
and financial returns to fertilizer higher. Finally, at
real economic prices (subsidy removed), complex
fertilizer would be an attractive investment only in
the southern zones when applied to sorghum at onehalf
the recommended rate, and urea would be economic
when applied to sorghum but not to millet in
the Sahel and Sudanian Zones.
In short, following production efficiency criteria
alone, policymakers at the national level would concentrate
fertilizer use in the northern Guinea savanna
zone, where millet area is relatively unimportant,
and limit use in the Sahel Zone where millet dominates.
At the farm level, where farmers have the
option, priority for fertilizer use would be given to
sorghum (or to other relatively more responsive
crops) well before millet. These conclusions become
Table 2. Average yield increment to the recommended
fertilizer dose, 100 kg ha -1 cotton complex fertilizer
(14:23:15) plus 50 kg ha -1 urea (47% N) in three zones of
Burkina Faso, ICRISAT farmers' tests, 1983, 1984.
Zone
Sahel
Sudan
savanna
Northern
Guinea
savanna
Cultivar
Test
Local
Test
Local
Test
Local
Grain yield
increment (kg ha -1 )
Millet
120
140
280
330
NA
NA
Sorghum
90
30
500
400
510
450
particularly crucial when national fertilizer supplies
are limited (for example from subsidy rationing
effects—see Mclntire 1985), and when farm-level
capital is a constraint. Both conditions are typical of
most W A S A T countries. When either fertilizer
availability or farm capital is limiting, farmers can
nevertheless maximize their profits by allocating fertilizer
between crops according to this marginalist
principle: apply crop-specific doses at which the last
unit of fertilizer applied to each crop produces identical
increases in the value of production.
The farm-level decision to allocate fertilizer according
to marginalist rules of profit maximization
can be demonstrated by modeling an average farm
of 2.5 ha sorghum and 1.2 ha millet in the Sudan
savanna transition zone using response coefficients
estimated from farmers' test data. Only when farmers
are able to spend more than 25 000 CFA to purchase
fertilizer (five times the current average household
expenditure on all variable inputs in that region),
would they begin to allocate fertilizer to millet. With
less available capital, farmers would maximize their
profits by allocating all their fertilizer to sorghum, or
to other more fertilizer- responsive crops. If farmers
were to cultivate a sorghum cultivar with greater
fertilizer responsiveness (such as ICSV 1002 in the
present example), fertilizer would be rationally allocated
to millet only when the fertilizer dose on
sorghum had surpassed 250 kg ha 1 , representing a
total household investment of nearly 90 000 CFA.
For breeders, these results mean that outside of
the Sahel, unless the fertilizer responsiveness of new
millet cultivars can be substantially increased to levels
competitive with the other major cereals, very
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