U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Document Type


Date of this Version



Published in Soil Management: Building a Stable Base for Agriculture (2011) 351-370. DOI:10.2136/2011.soilmanagement.c23


Humans have long exploited the climate-altering eff ects that trees provide through shade from a hot sun and shelter from strong winds (Hall et al., 1958). Behavior that initially produced greater physical comfort evolved into purposeful planting, selection, and tending to increase and expand the multiple benefits trees can provide including food, fiber, fuel, and medicinal products. Agroforestry systems (AFS) integrate woody perennial plants with agricultural crops or animal production on the same land area. A fundamental advantage of AFS is that the combination of trees with understory plants or animals has greater potential for production of food, forage, and fiber than any one element alone. A numerical scale to express this multiple-product concept as a land equivalent ratio was developed for AFS by Keesman et al. (2007). Agroforestry systems have great potential to increase per unit land area productivity as the trees exploit resources (light, water, and nutrients) through their multilayered architecture, deeper rooting, and extended growing seasons that may not be as readily captured by annual crops. The inherent benefits of agroforestry also include enhanced ecosystem services, increased ecological and economic diversity, and the ability to protect or restore vulnerable or degraded soils. These multiple benefits illustrate AFS’s great potential to contribute to achieving the Millennium Development Goals to reduce hunger, poverty, disease, and environmental degradation (Garrity, 2004).