Louis De Jaeger
9 mei 2024
The right groundwater level for your food forest
Fruit trees do not like a groundwater level higher than 60 cm, as their roots can rot if they are too wet. The solution for a groundwater level that is too high is to excavate canals and swales. The water runs into the canals and collects in swales or pools. Keep the water on your property and let it slowly soak into the soil via pools, ponds, swales and wadis. During periods of heavy rain, far too much fresh water flows directly to the sea and in the summer we have a shortage everywhere. The trick is to increase the water storage capacity of the soil (read: increase the organic matter content), so that we can retain excess water in wet periods until drought hits us again.
Raised beds in your food forest
By using raised beds, you can also plant fruit trees in areas with excessively high water levels. You dig out the paths and use this earth on your future beds. The path you walk in the summer becomes a ditch in the winter where the water can quietly soak in.
What is the difference between a canal, swale, wadi, pool or pond?
A canal (or ditch in NL): a watercourse, stream or ditch that drains, supplies or temporarily retains water. Usually a linear or non-straight linear element. The slopes are usually on the steep side.
A swale (or retention ditch in NL): a sunken piece of land with usually soft banks that serves to retain water, to allow it to infiltrate on site or to transform very slowly if there is a pronounced relief.
A wadi: approximately the same as a swale, with the major difference that a substrate is applied to allow water to infiltrate the soil more quickly if there is no pronounced relief.
A pool: a body of water that may or may not have been excavated by humans, which is usually used as a drinking place by livestock, as a water storage facility or which serves as a natural function. The water is naturally retained thanks to the groundwater level, but can also dry up when the groundwater level is low.
A pond: a water feature excavated by humans that usually has an ornamental or recreational function. A pond usually uses a foil or specially applied layer to retain the water.
Swales and wadis are often used interchangeably and both can have an overflow.
What to pay attention to when excavating?
Always think twice before carrying out earthworks in your (future) food forest. First, you disturb and compact the soil. In addition, it is also very labor intensive and an expensive or time-consuming investment. If you choose to do so, make sure that the different layers of the earth are not mixed. Always first dig away the fertile top layer from the place where you are going to make a hole and where the soil will be. After the desired earth moving, use the collected top layers on top of the fill site. This way, no precious fertile soil is lost beneath a less developed deeper layer.
Would you like to learn more about food forest design? Then read 'Design your own food forest' by Commensalist founder Louis De Jaeger or book a no-obligation phone call with one of our Commensalists.