Agriculture Reference
In-Depth Information
Good
nutritional
content
for
human
means for diversifying production systems. By
integrating trees in their farms and rangelands,
farmers reduce their dependency on a single sta-
ple crop or having suffi cient grass for their ani-
mals. For example, if a drought destroys the
annual crop, trees will still provide fruits, fodder,
fi rewood, timber, and other products that often
achieve high commercial value. A study of 1,000
farmers from 15 districts in Kenya found that
fruit trees contributed 18 % of crop revenue and
tea and coffee contributed an additional 29 % of
revenue. A study in Zimbabwe concluded that
indigenous fruits provided higher returns to labor
than annual crop production (Mithoefer and
Waibel
2003
). A study from Nepal on the impact
of agro-forestry on soil fertility and farm income
showed that agro-forestry intervention nearly
doubled farm productivity and income (Neufeldt
et al.
2009
).
consumption
Can protect the soil
A lack of competition between the trees and
crops
Five stages to the design and implementation
of an agro-forestry system are presented in
Table
12.6
.
Agro-forestry can improve the resilience of
agricultural production to current climate vari-
ability as well as long-term climate change
through the use of trees for intensifi cation, diver-
sifi cation, and buffering of farming systems.
Trees have an important role in reducing vulner-
ability, increasing resilience of farming systems,
and buffering agricultural production against
climate-related risks. Trees are deep rooted and
have large reserves and are less susceptible than
annual crops to interannual variability or short-
lived extreme events like droughts or fl oods.
Thus, tree-based systems have advantages for
maintaining production during wetter and drier
years. Second, trees improve soil quality and fer-
tility by contributing to water retention and by
reducing water stress during low rainfall years.
Tree-based systems also have higher evapotrans-
piration rates than row crops or pastures and can
thus maintain aerated soil conditions by pumping
excess water out of the soil profi le more rapidly
than other production systems if there is suffi -
cient rainfall/soil moisture (Martin and Sherman
1992
).
Trees can reduce the impacts of weather
extremes such as droughts or torrential rain. For
example, a combination of Napier grass and
leguminous shrubs in contour hedgerows reduced
erosion by up to 70 % on slopes above 10 % incli-
nation without affecting maize yield in central
Kenya (Mutegi et al.
2008
). Research has also
demonstrated that the tree components of agro-
forestry systems stabilize the soil against land-
slides and raise infi ltration rates (Ma et al.
2009
).
This limits surface fl ow during the rainy season
and increases groundwater release during the dry
season.
Agro-forestry can also play a vital role in
improving food security through providing a
12.4.1 Advantages
Agro-forestry has a broad application potential
and provides a range of advantages, including:
Agro-forestry systems make maximum use of
the land and increase land-use effi ciency.
The productivity of the land can be enhanced
as the trees provide forage, fi rewood, and
other organic materials that are recycled and
used as natural fertilizers.
Increased yields. For example, millet and sor-
ghum may increase their yields by 50-100 %
when planted directly under
Acacia albida
(FAO
1991
).
Agro-forestry promotes year-round and long-
term production.
Employment creation. Longer production
periods require year-round use of labor.
Protection and improvement of soils (espe-
cially when legumes are included) and of
water sources.
Livelihood diversifi cation.
Provides construction materials and cheaper
and more accessible fuel wood.
Agro-forestry practices can reduce needs for
purchased inputs such as fertilizers.
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