"Monocultures of corn and soybeans carpet 75% of the U.S. Midwest, leading to soil erosion, water pollution, and massive greenhouse gas emissions.
However, a new wave of farmers is breaking the monocrop monotony by growing these annuals between long rows of perennial shrubs like American hazelnuts, which keep soils intact while harboring beneficial bugs and sequestering CO2 from the atmosphere.
Hazelnuts are a huge market internationally and have big potential in the U.S. either as a snack or an oilseed, since the fatty acid profile is very similar to olive oil.
Other kinds of perennial crops potentially useful in agroforestry—where annuals and perennials are grown together for mutual benefit—include chestnuts, blueberries, pawpaws and persimmons."