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while Gliricidia was best placed in the well-drained middle slope positions. Tephrosia
yields were similar across slope positions. However, Brewbaker (1990) has demon-
strated that Sesbania may successfully establish in various soils and environments.
In Malawi, Makumba et al. (2006) found that an 11-year Gliricidia intercrop produced
an average of 2.6 times as much grain as sole maize, while a combination of Gliricidia
plus 48 kg N ha −1 produced 3.5 times as much maize as unfertilized sole maize. The per-
formance of sole maize plus 48 kg ha −1 N was similar to the Gliricidia intercrop with no
N added. In two of the study years, Makumba at al. (2006) noted a statistically significant
interaction of the Gliricidia intercrop with the N fertilizer. Akinnifesi et al. (2007) also
found 4.3 times as much maize yield with the Gliricidia intercrop.
Yield data reported by Harawa et al. (2006), Makumba et al. (2006), and
Akinnifesi et al. (2007) differ considerably. The first study was done in farmer's
fields with a combination of farmer and researcher management. The yields reported
here were obtained after 1 year of intercropping. This study contrasts species perfor-
mance at different slope positions, but also illustrates the deficit in SOM and nutri-
ents that is typical in smallholder agriculture in this region. The second and third
studies were done at Makoka Agricultural Research Station in southern Malawi. The
yields given in these studies were averaged over multiple cropping seasons, during
which Gliricidia leaf biomass was incorporated each year. The research station, with
ample means for inputs, land, and labor, is expected to have a much greater yield
over a longer period, while the means of the smallholder to provide inputs are more
restricted and variable across years.
11.2.2.3 Rotational Woodlots
Although intercrops and improved fallows provide some fuelwood and poles to the
farmstead, smallholders with relatively large landholdings may choose to rotate 0.5-
0.8 ha into a woodlot to provide additional wood for the household (Kimaro 2009).
These woodlots are of longer duration than improved fallows. Maize is intercropped
with the woodlot trees for the first 2-3 years; then the trees are left to develop for 1
or 2 years. The trees are then harvested, and maize is planted to take advantage of
the nutrients in the decomposing leaf litter and root mass.
Total maize yields over 2 years after the woodlot rotation were higher (Kimaro
et al. 2008) after A. polyacantha and Gliricidia than after A. crassicarpa and A.
mangium (Table 11.3). Yields after the Australian acacias were only 1.3-1.6 times
those after natural fallow, while yields after A. polyacantha and Gliricidia were
more than double the yields compared with the natural fallow. This difference prob-
ably reflects higher soil fertility improvement during the fallow period (Kimaro et al.
2008). Yields after A. polyacantha and Gliricidia were also similar to fully fertilized
maize, while unfertilized sole maize yields were similar to those after natural fal-
low. In contrast, the amount of aboveground biomass produced was much greater in
A. crassicarpa at 51 Mg ha −1 than in the other three species, with A. mangium and
A. polyacantha producing 38 and 36 Mg ha −1 , respectively, and Gliricidia producing
29 Mg ha −1 . Thus, in choosing species for this rotation, the smallholder must con-
sider the trade-offs between timber and food production.
Nyadzi et al. (2003) reported maize yields on a single cropping year after a 4-year
fallow. The yields were lower than those in Kimaro et al. (2008), while the response
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