Agroforestry or agroforestry ( English agroforestry or agroforesting ) describes a (sometimes multi-storey) agricultural production system that combines elements of arable farming with those of forestry .
Agroforestry systems are seen as ecologically advantageous compared to complete clearing , particularly in areas that are naturally overgrown by tropical rainforest . They are rich in species, stabilize the water balance and protect the soil from erosion and degradation . However, due to their variety and the rather low yields , the marketing of the products is often difficult, which affects the profitability of such systems.
Definition and characteristics
Agroforestry is the conscious inclusion of trees and shrubs in agriculture (short definition by J. Vogt 1999). Land use focuses on perennial wood plants and agricultural crops or animals.
An essential criterion for the qualification of a land use system as an agroforestry system is mostly the simultaneous use of a combination of woody plants with arable or animal husbandry and the resulting targeted generation of interactions between the individual components that are advantageous for agricultural production.
In addition, according to Nair (1985), agroforestry systems are subdivided according to their main components:
- silvoarable systems - trees with arable crops
- silvopastoral systems - trees with animal husbandry
- agrosilvopastoral systems - trees with arable crops and animal husbandry
Benefits of agroforestry
- Habitat for animals (beneficial insects and pests; the greater the biodiversity, the less susceptible an ecosystem is to disturbance).
- Reduction of the soil erosion of a field due to the wind resistance of the trees (this also reduces evaporation at the same time; more wind close to the ground leads to greater evaporation).
- At the same time, trees and their roots facilitate the penetration of water into the soil and thus contribute to reducing water erosion. They also serve to prevent flooding by minimizing surface runoff after rainfall, and can help reduce water pollution from agricultural fertilizers.
- Increased shade, which in the case of combined animal husbandry (combination of pasture land with trees) serves the protection and comfort of the animals. At the same time, the shade keeps the soil cool, especially in summer, which in turn leads to reduced evaporation (only possible with larger trees; important factor in dry areas).
- Delivery of free fertilizer (i.e. little or no purchase of artificial fertilizer), as trees (depending on the species) with their roots deeply anchored in the ground transport plant nutrients upwards and after the leaf fall these nutrients in turn to the top soil layer and thus via destructors ( Remineralizers) to the crops that are rooted there. Since this natural fertilizer is also more suitable for the soil fauna (has a stimulating effect), it is strengthened and in turn ensures better soil quality (crumb structure).
- Cooling in summer through the evaporation effect through the leaves of the tree (as above, the effect is only created by a certain tree size). The roots are also able to carry water upwards from deep water layers. This protects plants from excessive heat stress (for example during extreme events such as the heat wave in Europe in 2003 ). Soil organisms are also affected by excessive heat, which can be prevented by cooling.
- When considering the life cycle of a tree, the farmer can achieve a significantly greater profit by selling the wood (as veneer, firewood or construction wood ) than with a purely agricultural or purely forestry use.
- Trees in agroforestry systems are much more easily accessible than in forest areas and can therefore be better cared for and “ harvested ”.
- Since the rows of trees are relatively far apart, these trees receive considerably more light than within a forest area. In addition, such favorable growing conditions exist until they are harvested. As a result, the trees grow very evenly, in contrast to the usual forestry practice, in which trees are regularly removed from a tree community, which leads to growth spurts in the neighboring trees. In trees from agroforestry systems, a fine and even grain of the wood is created, which not only increases their sales value, but at the same time leads to greater wood strength (higher construction timber quality).
- Appreciation of the landscape, which appears more diverse than monotonous monoculture areas.
- The nutrient cycle is preserved.
- In addition to carbon storage, the soil is recultivated and humus is built up, which also has great potential for binding CO 2 ( Hüttl 2008).
Disadvantages of agroforestry
- The large number of products, each with relatively small quantities, makes marketing more difficult and thus increases the transaction costs for the producers.
- Farmers also have to deal with and / or further educate themselves in a lot more subject areas related to the rearing of trees (rearing, tree pruning , felling technology, marketing). Which can also be an advantage in the long term, as the farmer has a broader knowledge with which he can react to changes.
- Raising the trees increases the workload per hectare of field area and year. This also includes an increased maneuvering effort for the harvesting machines because of the trees.
- Since the trees can only be “harvested” after a certain age, this can, under certain conditions, initially lead to a loss of yield per hectare. The positive effects of the agroforestry system - d. H. its additional benefit, which can compensate for part of the loss, only becomes noticeable after a few years.
Research in Europe
In the last few years, a research program of the European Union has dealt with the possibility of combining annual arable crops and tree crops (with very long rotation times ) for Europe as well . The researchers came to the conclusion that agroforestry could generate significant additional yields of up to 30%. The production of a cultured with a mixture of poplar and wheat area of one hectare equal to the production, the only one in the separate cultivation area consumption of 1.3 hectares would be (0.9 ha wheat and additionally 0.4 ha poplars). The combined agroforestry system is successful with the simultaneous cultivation of nitrogen- binding woody plants and arable crops . Sometimes the trees are planted in rows (three, four or even ten meters apart); In such an alley cropping, the agricultural crops are grown in the gaps.
The World Agroforestry Center was founded in 1978 (then International Center for Research in Agroforestry: ICRAF) to promote research and information exchange on the subject of agroforestry. It pursues the goal of contributing to poverty reduction and food security through ecologically adapted production methods. A research group is also based at the French Institute national de la recherche agronomique . In the United Kingdom , the Agroforestry Research Trust and its director Martin Crawford should be mentioned in particular. In Germany there are research groups at the Albert-Ludwigs-Universität Freiburg , the Georg-August-Universität Göttingen and the TU Dresden .
The European Agricultural Fund for Rural Development (EAFRD) supports the initial establishment of agroforestry systems on agricultural land.
German Association for Agroforestry (DeFAF)
In order to better utilize the potential of agro-forestry in Germany, the German Association for Agroforestry eV was founded as a registered association in 2019 .
The association sees its task in improving the administrative and political framework conditions for agroforestry in Germany. As a non-profit association, this organization would like to network stakeholders interested in agroforestry from all areas of life with one another and with farmers, scientists and representatives of the administration and other associations and provide information about the agroforestry in Germany. The work of the association is not tied to any particular agricultural management method. It supports agroforestry in both conventional and organic farms and is open to anyone interested in agroforestry.
One goal is to anchor a clear definition for agroforestry in laws and the resulting opportunities for subsidy programs and support from the federal government.
- Permaculture, forest garden
- Farmer Managed Natural Regeneration (a reforestation technique that revitalizes dead tree roots and stumps)
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