May 6, 2020
Definition: A semi-circle or half-moon shaped berm that is placed around an established tree to capture water specifically within the tree's root zone. A series of boomerang berms allow overflow from one berm to descend into the catchment area of the next downhill berm.
Forest Garden Tip: Earthworks, including boomerang berms, are water conservation techniques Forest Garden farmers can implement on their land to control and slow the movement of water.
Two major benefits of constructing earthworks are:
Farmers can maximize water absorption on a landscape – Earthworks can help farmers to stop, slow, sink, and spread flowing water so that it can be of use to surrounding vegetation.
Farmers can control and direct the flow of water – Earthworks can be used to direct the flow of water to places that need it more without running the risk of creating erosion channels that will damage the land.
Berms and Swales: Standard berms and swales are perfect for slowing down the movement of runoff leading into your permagarden and allow water to enter and remain in the landscape more evenly. A swale is a long trench dug out across the ground, along the contour, to catch runoff water, soil, and organic matter. The soil you dig out to form your swale is generally used to create a berm of earth on the upslope or downslope side of your swale. It is best to plant perennial vegetation (trees, shrubs, grasses, herbs, etc) along your berms to stabilize them.
Cuvettes for Fruit Trees: A cuvette is a shallow depression in a level landscape completely surrounded by a berm. Cuvettes are designed to hold human-delivered irrigation and to prevent excess rainwater from drowning flood sensitive plants. A single cuvette is made around newly planted seedling trees while double cuvettes are made around adult trees.
Three benefits of making and maintaining cuvettes are to conserve water at the root level, stabilize adult trees by promoting lateral root growth and manage pests