Week 15: A Lesson on Agroforestry

08-17-2016 CTGTT Sunflower, tomato harvest
Amidst late summer tomato and sunflower harvests, we welcomed a visit from Meghan Giroux of Vermont Edible Landscapes.

 

08-17-2016 CTGTT Megan in the edible forest
Meghan, among many other things, designed and executed an edible forest corner of the Community Teaching Garden at Tommy Thompson. Here’s Meghan in the corner speaking of the need for this style of planting — perennial crops planted to mimic the structure of a forest — to spread through the entire garden. One giant, shared edible forest, she suggested, with annual veggies growing along the perimeter.

 

08-17-2016 CTGTT Tansy is nice to look at but sure spreads quickly
As for the tansy, Meghan promises that it wasn’t something that she planted. She suggests never planting tansy, which is an ‘opportunistic’ plant, willing and able to spread itself with great vigor! Even though Meghan was cutting the plant down, and speaking on its prolific nature, Meghan emphasized the importance of keeping all of a system’s nutrients within the system. That means taking the tansy plant and laying it down as mulch. Meghan assured the class that even out diseased tomato leaves were okay to leave in the garden – healthy soil should be able to handle that plant’s disease. ‘Leave the detritus on the forest floor,’ she said. ‘It’s a little love shack for all the critters who live in the soil.’

As for the lesson on agroforesty, here’s what I gleaned:

An edible forest is designed using two parameters. One is structure, the layers that make up the forest composition. The second is plant archetypes, the polyculture that works together to create a nutrient rich system.

The agroforest is made up of an overstory, an understory, a shrub layer, an herbaceous layer, a rhizomatic layer, and a vining component. We quickly discovered that each of these categories are loose and relative to the other crops housed within the system. While the red currant bush is most commonly used in the shrub layer, it could easily serve as an overstory in an edible forest of a smaller scale.

With regard to the plants, there are three important archetypes to include: nitrogen fixers, dynamic accumulators, and insectaries & nectaries. Nitrogen fixers have the capacity to pull nitrogen out of the air and send it down into the soil, providing nitrogen for itself and allowing that nitrogen to be captured by nearby plants so long as its needs are met. Dynamic accumulators have long tap roots that reach down into the earth and pull nutrients up into the top soil where it can be accessed by shorter root systems. Nectaries keep non-desirable insects away, insectaries attract the beneficials. Meghan suggested that gardens and edible forests alike should have flowering plants through the length of the season. These flowers should be diverse in terms of color and shape so as to attract the greatest number of beneficial insects.

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