Agriculture Reference
In-Depth Information
Studies in Africa have documented increases in maize grain yield (Table 11.3)
under
Faidherbia
(Barnes and Fagg 2003). In Malawi, 50% maize yield increases have
been recorded under
Faidherbia
trees compared with sole maize (Saka et al. 1994).
Thirty percent to 70% yield increases have also been observed under
Faidherbia
on most staples in Ethiopia, including maize, sorghum, and wheat (Poschen 1986;
Dechasa 1989; Hadgu et al. 2009). Yield increments of 100%, 70%, 40%, and 10%
for sorghum, maize, wheat, and teff, respectively, were also reported (Dechasa 2010).
Improvements have been made to traditional agroforestry practices with
Faidherbia
. This practice has resulted in significant contribution to food security
as farmers who have adopted
Faidherbia
produced 1.5 Mg more maize per hectare
than conventional practice (Haggblade and Tembo 2003). In this regard, Zambia
has taken a lead in systematically utilizing the potential of
Faidherbia
, releasing
a national recommendation to plant
Faidherbia
trees at a density of 100 trees ha
−1
in crop fields as a permanent canopy to increase soil fertility and crop productivity
(Garrity et al. 2010). The density may later be reduced to 25-30 trees ha
−1
as the trees
mature. To date, >200,000 families have adopted this practice (Garrity et al. 2010).
The government of Ethiopia has recently launched an initiative to plant 100 million
Faidherbia
trees. Alongside promoting natural regeneration of this important tree in
farmers' fields, planting
Faidherbia
at such a scale on smallholder farms is expected
to have significant economic and environmental benefits and add climate resilience
to farming systems, particularly in semiarid areas of Ethiopia.
Faidherbia
is a slow-growing tree, often taking 20 years or more to contribute
to crop growth (Poschen 1986). Yield increases also differ with location (Saka et al.
1994). Combining fast-growing multipurpose shrubs such as
Gliricidia
and
Sesbania
with parkland trees should speed soil fertility increases and also increase wood and
fodder availability. Integrating fast-growing shrubs along with natural regeneration
of
Faidherbia
may alleviate the concern of some smallholders regarding the slow
establishment of
Faidherbia
seedlings.
Moreover, trees should be spatially and systematically configured (Figure 11.8) to
match species to sites and farmer circumstances. Hadgu et al. (2009) noted a pattern
of land use intensification in Tigray, northern Ethiopia, which reduced the density of
Faidherbia
, and was accompanied by an increase in timber cultivation and a decline
in barley yields.
(Note in Figure 11.8 the loss in ecosystem services associated with cutting
Faidherbia
within a field.) The effect of the trade-off between barley production and
timber on food security should be considered at the farm level. More data are also
required on other promising parkland tree species such as
Moringa stenopetala,
Balanites aegyptiaca
,
Millettia ferruginea
,
Cordia
spp.,
Croton
spp., and
Ziziphus
spp.,
with regard to their effects on crop productivity. Studies similar to those on
Faidherbia
should also be done with such promising tree species.
Agroforestry practices used in appropriate agroecological niches hold great prom-
ise for recuperating soil fertility while providing greater food and feed production in
agricultural landscapes. Intercrops are more appropriate in areas with high popula-
tion densities, while improved fallows and rotational woodlots are more appropriate
where land can be allocated to fallow and/or wood production.
Faidherbia
parklands
have mostly been developed by farmer-managed natural regeneration in river valleys
