Benefits of agroforestry
Research over the past 20 years has confirmed that agroforestry can be more
biologically productive, more profitable, and be more sustainable than forestry
or agricultural monocultures. Temperate agroforestry systems are already
widespread in many parts of the world and are central to production in some
Research has also confirmed that agroforestry systems can include the following
They can control runoff and soil erosion, thereby reducing losses of water,
soil material, organic matter and nutrients.
They can maintain soil organic matter and biological activity at levels
satisfactory for soil fertility. This depends on an adequate proportion of
trees in the system - normally at least 20% crown cover of trees to maintain
organic matter over systems as a whole.
They can maintain more favourable soil physical properties than agriculture,
through organic matter maintenance and the effects of tree roots.
They can lead to more closed nutrient cycling than agriculture and hence
to more efficient use of nutrients. This is true to an impressive degree
for forest garden/farming systems.
They can check the development of soil toxicities, or reduce existing toxicities
- both soil acidification and salinization can be checked, and trees can
be employed in the reclamation of polluted soils.
They utilise solar energy more efficiently than monocultural systems - different
height plants, leaf shapes and alignments all contribute.
They can lead to reduced insect pests and associated diseases.
They can be employed to reclaim eroded and degraded land.
They can create a healthy environment - interactions from agroforestry practices
can enhance the soil, water, air, animal and human resources of the farm.
Agroforestry practices may use only 5% of the farming land area yet account
for over 50% of the biodiversity, improving wildlife habitat and harbouring
birds and beneficial insects which feed on crop pests. Tree biodiversity
adds variety to the landscape and improves aesthetics.
They can moderate microclimates. Shelter given by trees improves yields of
nearby crops and livestock. Shade in summer can be beneficial for livestock,
Agroforestry can augment soil water availability to land-use systems. In
dry regions, though, competition between trees and crops is a major
Nitrogen-fixing trees & shrubs can substantially increase nitrogen inputs
to agroforestry systems.
Trees can probably increase nutrient inputs to agroforestry systems by retrieval
from lower soil horizons and weathering rock. ('Mining' minerals and trace
The decomposition of tree litter and prunings can substantially contribute
to maintenance of soil fertility. The addition of high-quality tree prunings
(ie high in Nitrogen but which decay rapidly) leads to large increases in
The release of nutrients from the decomposition of tree residues can be
synchronised with the requirements for nutrient uptake of associated crops.
While different trees and crops will all have different requirements, and
there will always be some imbalance, the addition of high-quality prunings
to the soil at the time of crop planting usually leads to a good degree of
synchrony between nutrient release and demand.
In the maintenenace of soil fertility under agroforestry, the role of roots
is at least as important as that of above-ground biomass.
Agroforestry can provide a more diverse farm economy and stimulate the whole
rural economy, leading to more stable farms and communities. Economic risks
are reduced when systems produce multiple products.
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