Tree Intercropping places #17 on Drawdown’s list of climate solutions. Intercropping on 571 million acres globally by 2050 would sequester 17.2 gigatons of carbon dioxide and, after a total investment of US$147 billion, save $22.1 billion over the 30-year span.
Practitioners of industrial agriculture sow single crops over huge and otherwise denuded swaths of land—which then require regular doses of chemical fertilizer to maintain fertility. Tree intercroppers, by contrast, combine trees with shorter (and often shorter-lived) crops together in a field: “chili peppers and coffee, coconut and marigolds, walnuts and corn, oak and lavender, hazel and roses,” are some of the combinations Drawdown identifies.
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The plant combinations are highly beneficial, especially for the more delicate crop, with the trees acting as wind breaks, habitat for beneficial insects, and trellises. Benefits also accrue in the soil, since “deep-rooted plants can draw up subsoil minerals and nutrients for shallow-rooted ones.”
There are many different kinds of tree intercropping, Drawdown notes. Alley cropping, for example, involves planting tightly-spaced trees or hedges of nitrogen-fixers like river hemp between rows of a nitrogen-needy crop like corn, so that the fallen leaves can act as fertilizer. In parkland intercropping, common in areas with rainy growing seasons, trees like apple-ring acacia that shed their nitrogen-rich leaves once the dry season ends are scattered discontinuously throughout a planting. Thus arranged, the trees provide shade and prevent erosion during the dry season, without competing for water or light once the rains come and the crop starts to grow. As an added benefit, the acacia also provides fodder for livestock.
A time-tested method to increase yields at least threefold without chemical inputs, tree intercropping does require one thing, however: landholders with the patience, humility, and economic wherewithal to “carefully assess and know the land, soil type, and climate at hand”, as “sunlight, nutrient flows, and water availability determine species, density, and spatial overlap of trees and crops,” Drawdown states.
But with that knowledge in hand, and an openness to further discovery and innovation based on the fundamental principle that farming should not be “extractive and hostile to living organism,” landholders who practice tree intercropping can be a part of a true “agricultural renaissance,” Drawdown concludes, “bringing people, regeneration, and abundance back to the land.”