Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: October 15, 2010
Publication Date: May 16, 2011
Citation: Sauer, T.J., Hernandez-Ramirez, G. 2011. Agroforestry. In: Hatfield, J.L., Sauer, T.J., editors. Soil Management - Building a Stable Base for Agriculture. Madison, WI: American Society of Agronomy. p. 351-370.
Interpretive Summary: Modern agriculture in developed countries generally involves growing a single crop in a field that has to be reseeded each year or growing one type of tree, vine, or bush in an orchard. In nature, often multiple plants grew together and regrew each year. Agroforestry involves trying to combine natural plant growth patterns with modern crops to have trees and crops growing together. The advantages of agroforestry are that when trees and crops are together they can use sunlight, water, and nutrients more efficiently than when they are grown separately. The trees also affect the local climate by providing shade and shelter from wind. Once established, agroforestry systems establish organic matter and nutrient cycling processes that reduce the loss of carbon and nutrients so there is often less need to bring in organic matter like animal manures or nutrients from fertilizers. The types of agroforestry systems vary with climate and soils and are often modified at the local level to fit the conditions and resources that are available. This research is important for landowners who wish to reduce the cost of outside inputs into there operations, diversify the types of commodities they produce (food, fiber, and fuel), improve the quality of soil in degraded or vulnerable lands, and improve wildlife habitat and visual aesthetics of their land.
The impacts of agroforestry systems (AFS) on soil management in temperate, subtropical, and tropical biomes support the beneficial, holistic role of tree components in agricultural land-use systems. Compared to annual monocultures, AFS can enhance several soil physical properties improving soil resilience and reducing soil erosion losses. Likewise, in AFS, soil fertility and nutrient use efficiency of companion crops can be improved by trees through the release of nutrients from leaf, root, and woody components as well as via biological N2 fixation and cycling (if N fixing trees are included), and uptake and recycling of various nutrients from deep subsoil horizons. Contribution of AFS to biological diversity and activity, typically through sheltering effects coupled with both increases in amounts of SOC and enhancement on food web dynamics can also be substantial. These various prospective advantages may reflect underlying mechanisms in the functioning of AFS oriented to optimize the utilization of resources (e.g., light, water, nutrients) in both time and space. Current research should increase the focus on identifying the best spatio-temporal combinations of system components (e.g., trees, crops, pastures, animals) to make AFS functioning and structure more efficient with the aims of attaining optimum profitability/productivity with maximum environmental services and reduced economic risks. When assessing AFS performance as a whole, careful balance between crop productivity goals and benefits from the tree component needs to take into account potentially hidden beneficial, long-term contributions of trees to the overall system.