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About Agroforestry

Agroforestry

Agroforestry is the growing of both trees and agricultural / horticultural crops on the same piece of land. They are designed to provide tree and other crop products and at the same time protect, conserve, diversify and sustain vital economic, environmental, human and natural resources. Agroforestry differs from traditional forestry and agriculture by its focus on the interactions amoung components rather than just on the individual components themselves.

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. Many other benefits have been shown. Temperate agroforestry systems are already widespread in many parts of the world and are central to production in some regions.

Success of agroforestry is largely determined by the extent to which individual forest and agricultural components can be integrated to help rather than hinder each other. The choice of tree and crop species combinations is critically important when setting up systems.

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Benefits

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 regions. Research has also confirmed that agroforestry systems can include the following benefits:

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.

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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, reducing stress.
Agroforestry can augment soil water availability to land-use systems. In dry regions, though, competition between trees and crops is a major problem.
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 elements)
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 crop yields.
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.