We can work with water on a site by either blocking it, letting it pass through or harnessing it in the landscape. With abundant rainfall moving lots of water through a sloped, poorly drained/compacted soil site to what is our small farm plot, we saw some mild erosion after one of the first of the heavy rain storms this season. To remedy the situation, we decided to install a permaculture swale. Permaculture swales differ from the often employed drainage swale for stormwater management in that rather than routing water away it is a means to allow water to be harnessed and slowly infiltrated for making full use of its irrigation abilities. The permaculture swale begins by marking the contour of the land (the level ground that runs perpendicular to the slope of the land) and digging a trench along this contour line. The trench of our first permaculture swale is about 18" wide and 18" deep. The soil dug out from the trench is then piled up just downslope to create a berm. We then mixed the soil of the berm in with compost and mineral amendments and blanketed the bed in mulch. The trench is being filled up with branches and twigs and other mulch materials. The function of the permaculture swale is to store incoming rainwater as it moves downslope, allowing abundant rainfall to fill up in the trench which is then slowly infiltrated into the soil while simultaneously irrigating the berm bed over a long period of time. Compare this ability to having a large rain wash soil down and disturb topsoil. The permaculture swale and bed also allows for soil enrichment by preventing erosion and allowing organic matter to stay put and serve its purpose for soil organisms and resultant topsoil building.
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| Newly dug permaculture swale trench and berm prepared for planting |
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| Starting to fill the permaculture swale trench with fallen wood |
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