COMPANION PLANTING FOR FRUIT TREES
Companion planting (also known as permaculture guilds) is the planting of different species around a central element that have different functions. There are many benefits to companion planting which include:
- Attracting pollinators and other beneficial insects
- Increasing crop productivity
- Increasing nutrient levels in soil and soil fertility
- Helping retain moisture in the soil
- Creating habitat
- Weed and pest control
Companion planting is an important part of the food production systems. It involves choosing compatible species to create a “mosaic of diversity” and biological interactions between the root systems of the plants, the microorganisms in the soil and the mycorrhizal fungi. Biodiversity in the companion planting encourages and maintains a more diverse soil biology and results in healthier soil.
A well-known example of companion planting is known as the “Three Sisters” method, used widely by Native American peoples. Corn, pole beans, and squash are grown together for mutual benefit to all three. Pole beans use the corn stalks for support while fixing nitrogen in the soil. Squash keeps weeds down, covers the soil and prevents moisture from evaporating from the surface.
Some of the plants incorporated into a guild may only have one function, while others can have multiple functions within the guild. Functions include providing food, medicine, groundcover, fertilizer, “mining” the soil, attracting beneficial insects, protecting – pest control etc. Some plants, like Nasturtium for example (Tropaeolum sp.), can perform many different roles at once – it is a groundcover, it has edible leaves and flowers, the seeds can be pickled, it attracts beneficial insects, and has ornamental value.
Nitrogen fixing plants
Nitrogen fixing plants are largely in the Legume family (Fabaceae). Examples include Gliricidia, Pigeon Pea (Cajanus cajan), Ice Cream Bean (Inga edulis), Koa (Acacia koa), Sesbania. A popular nitrogen fixing groundcover is the Perennial peanut, (Arachis species). Through a symbiotic relationship with the Rhizobia genus of bacteria, leguminous plants exchange sugars in the form of root exudate for soluble nitrogen. The bacteria are able to turn atmospheric nitrogen, N2, into a plant soluble nitrogen, N3.
Certain plants (often deep-rooted ones) draw up nutrients from the lower layers of the soil, and these nutrients are then stored in the plants’ leaves. When the leaves are cut back and used as mulch or are composted, the nutrients get released back into the soil and become available to the shallower roots of plants and trees.
Examples of dynamic accumulators are comfrey, lemon grass, vetiver, citronella grass.
Planting a tree guild takes more effort than simply planting the tree by itself and also adds additional cost. If you would like to reduce your maintenance efforts to a minimum, the easiest way is to plant your trees in a traditional orchard style and mow the grass in between. However, in the long run, guilds will likely be more resilient and vigorous, even if solely from a biodiversity standpoint.
Choosing companion plants
There is no precise recipe for a successful fruit tree guild. It is important to find the right combination of plants for your area. Experiment with plants to find out what works best in your location and with your tree, and the specific nutrients it needs.
Nitrogen-fixing plants and dynamic accumulators have a crucial role in your fruit tree guild. Using plants to keep nutrients cycling within your guild would reduce the need of fertilizer use. Groundcovers will suppress grasses and weeds that compete with trees for nutrients and water. Groundcovers will also help to retain moisture in the soil and build soil structure. Examples of groundcovers include peppermint, nasturtium, pumpkin, okinawan spinach, sweet potato, perennial peanut, creeping thyme, gotu-kola (Centella asiatica) etc.