Soil science as part of agroforestry
World Agroforestry (ICRAF) has as its mandate all agricultural land use that involves trees, beyond what is considered to be forest. The latter distinction is rather fluid, both temporally and institutionally, as the example of long-rotation shifting cultivation may show. Agroforestry itself ranges from croplands with a few trees added through to systems where tree crops (considered to be agricultural, such as coffee, cacao or rubber) provide a perennial vegetation layer, augmented with upper canopy layer trees utilized to modify microclimate, yielding economically valuable products. The consequences for soil conditions and functions vary along this range.Agroforestry research has from its start operated on the active and often contested interface of the need to increase agricultural production, overall and per unit area, and the need to find more sustainable ways of managing natural resources. Agroforestry is typically associated with ‘integrated’ rather than ‘segregated’ solutions to meet the dual imperative, with specific attention to the understanding and management of trade-offs at the scales of farmers, the landscape, (sub-) national governments and the global policy arena. Soils have a key function to both issues of land productivity and environmental effects, and soil research of one type or another has been part of nearly all research activities of ICRAF from its start.