May 5, 2022
While riparian buffers can be part of a successful agroforestry program, alley cropping is another agroforestry system that can work well.
Alley cropping is the planting of two or more groups of single or multiple rows of trees or shrubs on wide spacings, leaving broad aisles in which agronomic, horticultural or forage crops may be grown. Other common terms for this production system include intercropping or multi-cropping.
One of the main goals of any agroforestry system is to provide the landowner with supplementary annual income while crop and/or timber trees grow to fruit-bearing age or to the point that timber can be sold.
Tree species used in alley cropping usually include high-value nut trees like walnut, pecan or chestnut, or high-value hardwoods like oak and walnut. Fruit-bearing shrubs, woody plants that provide floral products, vegetables, and row and forage crops are examples of companion plants that may be incorporated into an alley crop system to provide annual income. Additional benefits include soil and water conservation, a more diverse farming operation, improved wildlife habitat, and aesthetics.
ALLEY CROPPING: Alley cropping is the planting of two or more groups of single or multiple rows of trees or shrubs on wide spacings, leaving broad aisles in which agronomic, horticultural or forage crops may be grown.
There is no “one size fits all” in alley cropping. Each system should be designed to match the goals and desires of the landowner. Things to consider when deciding how large an area to devote to alley cropping include:
how many rows to establish
the arrangement of trees within the row
the amount of land area removed from production by tree and shrub rows
management practices like weed control and pruning
enhanced erosion control on sloping land
newly created wildlife habitat
However, regardless of the system selected and implemented, there are a number of physical and biological interactions between the rows of woody species and the companion crop that need to be understood and included in the overall design, such as tree species, their growth habits and how these traits will affect the crops grown. Several factors in the layout of the alley cropping system will affect competition for light, soil moisture and nutrients — including tree arrangement, single or mixed species, number of tree rows, alley width between rows, and row spacing.
That can also affect allelopathy, which is the process where plants produce biochemicals that have a negative effect on the growth of adjoining plants. A common example is the production of juglone by black walnut trees that inhibit the growth of other plants. On the positive side, over time, pine needles can help acidify the soil, aiding in the growing of acid-loving and fruit-bearing plants such as blueberries.
To mitigate light competition, consider the trees species that will be planted, their plant phenology, dense foliage vs. fine foliage to allow for light penetration, and east-west row orientation to maximize sunlight. Reduce root competition by knowing the trees’ rooting characteristics: Are they fast-growing roots, and deep or shallow rooting?
As with any new endeavor, it is always good to start small and expand as you gain experience and skills. Agroforestry practices require specific and detailed management and marketing skills, and knowledge. What I’ve shared here just scratches the surface.
For more detailed information on agroforestry and alley cropping, contact your local Extension office or the University of Missouri Center for Agroforestry, USDA Agricultural Research Service, Natural Resources Conservation Service, USDA National Agroforestry Center or Savanna Institute.
Miller is a horticulture professor at Joliet Junior College in Joliet, Ill., and a senior research scientist in entomology at The Morton Arboretum in Lisle, Ill. Email your tree questions to him at [email protected]. The opinions of this writer are not necessarily those of Farm Progress/Informa.
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