Influence of latitude on the light availability for intercrops in an agroforestry alley-cropping system

Light competition by trees is often regarded as a major limiting factor for crops in alley-cropping agroforestry. Northern latitude farmers are usually reluctant to adopt agroforestry as they fear that light competition will be fiercer in their conditions. We questioned the light availability for cr...

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Bibliographic Details
Published in:Agroforestry systems 2018-08, Vol.92 (4), p.1019-1033
Main Authors: Dupraz, Christian, Blitz-Frayret, Céline, Lecomte, Isabelle, Molto, Quentin, Reyes, Francesco, Gosme, Marie
Format: Article
Language:English
Subjects:
Agricultural sciences
Agriculture
Agroforestry
Alley cropping
Biomedical and Life Sciences
Competition
Computation
Cropping systems
Crops
Farmers
Forestry
Heterogeneity
Irradiance
Latitude
Life Sciences
Light
Sciences and technics of agriculture
Three dimensional models
Trees
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Summary:Light competition by trees is often regarded as a major limiting factor for crops in alley-cropping agroforestry. Northern latitude farmers are usually reluctant to adopt agroforestry as they fear that light competition will be fiercer in their conditions. We questioned the light availability for crops in alley-cropping at different latitudes from the tropic circle to the polar circle with a process-based 3D model of alley-cropping agroforestry. Two tree densities and two tree line orientations were considered. The effect of the latitude was evaluated with same-sized trees. The relative irradiance of the crops was computed for the whole year or at specific times of the year when crops need more light. The heterogeneity of crop irradiance across the alley was also computed. Surprisingly, crop relative irradiance of summer crops at high latitudes is high, at odds with farmers’ fears. Best designs were highlighted for improving the crop irradiance: North–South tree lines are recommended at high latitudes and East–West tree lines at low latitudes. At medium latitudes, North–South tree lines should be preferred to achieve an homogeneous irradiance of the crop in the alley. If we assume that trees at northern latitudes grow slower when compared to southern latitudes, then alley-cropping agroforestry is highly advisable even at high latitudes with summer crops.
ISSN:0167-4366
1572-9680
DOI:10.1007/s10457-018-0214-x