Agriculture Reference
In-Depth Information
ratios were higher. This may be due to the very low initial SOM (0.4-0.8 g kg
−1
) in
Nyadzi et al. (2003), and to the fact that response ratios tend to be higher in the first
year of cropping than in the second year.
Although short- or long-lived species may be used for agroforestry practices, the
management and structure of the tree component is very different in parklands com-
pared with improved fallows, intercrops, or rotational woodlots. While the agrofor-
estry component in the short-term systems is coppiced or harvested in 1- to 5-year
cycles, parkland trees are allowed to develop into mature large-scale specimens,
with crops and livestock benefiting in various ways from the understory location.
Parklands are integrated into various crop and livestock systems across Africa from
north to south, and from east to west.
11.2.2.4 Parkland Systems in Eastern and Southern Africa
Parkland tree species are usually naturally occurring tree species (Maranz 2009),
which are also protected and managed by farmers (farmer managed natural regen-
eration—FMNR) (Haglund et al. 2011). The main parkland tree species available
in eastern and southern Africa include
F. albida
,
Cordia africana
,
Croton macro-
stachyus
,
Acacia tortilis
,
Moringa stenopetala
,
Terminalia brownii
,
Acacia senegal
,
Acacia seyal
,
Ziziphus mauritiana
,
Balanites aegyptiaca
,
Ficus sur
, and
Millettia
ferruginea
(Hailu et al. 2000; Kassa et al. 2010).
Some studies reported that parkland trees do not provide short-term crop yield
benefits, which could be attributed to the competition for resources between trees
and crops (Bayala et al. 2012). However, parkland trees are protected by farmers
for their sustainable and long-term multiple benefits, including direct products such
as fodder, fruit, fuelwood, medicinal, or vegetable products. They are also valu-
able for long-term ecosystem benefits, such as C accumulation, reduction in soil ero-
sion, maintenance of soil structure and fertility, improvement of crop microclimate,
reduction of wind incidence, and provision of shade (Dechasa 2010).
11.2.2.5
Faidherbia albida
: A Successful Parkland Species
Among parkland tree species, the potential of
Faidherbia
, an indigenous African
acacia, is well recognized. It is widespread on millions of farmers' fields through-
out the eastern, western, and southern regions of the continent. It is highly com-
patible with food crops because it is usually dormant during the rainy season
(see Figure 11.5). Thus, it exerts minimal competition with annual crops, while
enhancing crop yields and soil health (Barnes and Fagg 2003). In eastern and
southern Africa, most smallholders cannot afford to buy inorganic fertilizers,
often because of cash constraints.
Faidherbia
creates a unique opportunity for
increasing smallholder productivity by input of high-quality leaf residue for
increased soil fertility (Garrity et al. 2010), reducing the need for inorganic N
fertilizer. As many smallholders are engaged in both crop and livestock agricul-
ture and their available fodder resources are often inadequate (Giller et al. 2009),
Faidherbia
also increases livestock production through supplying high-quality
fodder. It also enhances C storage in farmed landscapes.
Faidherbia
is considered
a keystone species for climate-smart (evergreen) agriculture in much of Africa
(Garrity et al. 2010).
