Annual row crop systems dominate agriculture around the world and have considerable negative environmental impacts. Incremental improvements to the prevailing system have been the primary focus of efforts to reduce these negative impacts, though are likely insufficient in solving the ecological challenges of row crop agriculture. This dissertation explores alley cropping (AC) – an agroforestry practice integrating trees with crops – as a transformative land-use solution to mitigate climate change, restore ecosystem services, and improve agricultural profitability. Through an inventory of all field experiments of AC to date, I identify several major gaps in AC research. In particular, AC has held a narrow focus on systems that integrate only one timber tree species with one annual grain species. I explore broadening this focus and identify key considerations for the scalable implementation of woody polycultures and tree crops for food and fodder. To evaluate the direct benefits of such systems, I then assess the potential of diversified, food-producing AC to mitigate unintended nitrogen losses in a side-by-side field experiment with row crop agriculture. I show that transitioning to AC can rapidly tighten the nitrogen cycle even during establishment years. Finally, I evaluate the economic competitiveness of the most common temperate AC system – black walnut trees for timber with annual grain alley crops – against the widespread maize-soybean rotation. Even without monetization of environmental benefits, I demonstrate that AC can improve landowner profitability across a substantial portion of the Midwest US. By exploring the frontiers in temperate AC, this dissertation highlights a multifunctional, transformative land-use alternative for temperate agriculture.
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Frontiers in alley cropping: Transformative solutions for temperate agriculture
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