Huglekultur: Raised Beds & Carbon Sequestration

If you have an abundance of woody debris and want to improve your soil health, try this German-style raised bed. The word itself is pronounced hoo-gul-culture and means hill or mound culture. The basic premise is to build a mound with woody material and other decaying organic matter and plant directly into it. 

You can add one of these to your gardens for several reasons. They remove excess woody debris from tree pruning or clearing and store this carbon in the soil providing habitat for soil organisms while releasing nutrients, improving soil health, and reducing water usage. 

How to Build a Hugle Kultur Mound 

Building a huglekultur bed can be done in several different ways. Traditionally a trench is dug out of the ground, and the woody debris is placed within it. However, many people have successfully built their mounds directly on the ground or enclosed within a raised bed. These mounds can be made on terraces that contour hillsides to help improve erosion or in areas prone to flooding to enhance land that may otherwise not be ideal for gardening. 

It’s important to remember that certain types of wood should not be used; they are black walnut, cherry, locust, and cedar. These kinds of woods are known to be toxic to plants and animals or take a very long time to decompose. It should also be noted that although all of the images you find of these mounds online depict the logs laying flush, you should consider angling your logs in different directions to optimize moisture-holding capabilities. 

Consider the xylem and phloem, which translocate nutrients and water within plants like straws. These will hold the water in your buried logs, and the more quickly they can be filled with water, the more efficient they will be at storing water. Some logs may be placed facing upward to the sky to catch downward rainfall. Other logs can be laid on their sides where you notice water flows, like downhill. So while the images look nice and tidy, you should really keep your logs pointing in all directions. 

Wood Decomposition & Nitrogen 

Another consideration is the age of the wood being used. If it is freshly cut, it will absorb nitrogen through its first year in the ground because nitrogen is needed for decomposition. If so, you should plant clover and legume species that fix atmospheric nitrogen into the soil or other plants with low nitrogen requirements. Using older decaying logs, you can produce anything you want and not worry about low nitrogen levels. 

Begin your pile by laying down the largest pieces of wood first and then covering them with limbs, sticks, wood chips, and leaves. The optimal height for these beds is a minimum of 2-3 feet but feel free to make them as large as you want. The bigger they are, the longer they will last. It is reported that most of these beds will have completely broken down after 6-8 years. This will change depending on the kind of wood used, the size of logs, the amount of moisture they encounter, and the organisms present. 

Carbon Sequestration 

You store or sequester carbon in the soil by burying logs in the ground instead of burning them. You are also creating unique habitats for soil-dwelling critters, large and small. You will have abundant carbon-feeding microorganisms such as fungus, which will bring in more nematodes, and you may even encounter wood rats and groundhogs. While they may eat some of your plants, this is okay; they are improving your soil tilth aerating the soil and helping break down the logs contributing to healthier soils. 

Sometimes we must remember that we are sharing this planet with all beings. It is not just ours alone to rule and conquer but to share and tend to. As these organisms break down your logs, they unlock nutrients providing your plants without ever having to fertilize them. 

Once you have a large pile of woody debris piled up, you can begin to cover it with varying stages of organic matter, such as a compost pile. This will provide a plentiful array of nutrients just waiting to be broken down by microorganisms providing your plants with a stable nutrient source. Food scraps, weeds that have not gone to seed, untreated grass clippings, animal bedding, and aged manure* and compost are welcome on this pile. 

Finishing Your Hugle Kultur Mounds 

After you have built up your pile sufficiently, you will want to cover it will soil; this is why digging a trench is the traditional method for building these beds. When you dig a trench, you can use the soil dug up to cover your mound. If you did not dig a trench, you would want to bring your soil from elsewhere. This could be purchased bulk soil from a soil yard, or if you are building swales or a pond elsewhere on your property, you could use that. You want enough soil to cover the entire pile well enough that water will not wash it away, exposing the materials beneath. Luckily, you will only need to water your mounds occasionally as they reduce water usage tremendously. 

Remember those xylems and phloems we talked about? As they fill up with water, they turn those logs, branches, and sticks into sponges that slowly release water, continuously watering your plants without picking up a hose. The more logs you have, the more water your mounds can store and the less frequently you will need to water your mounds. 

Depending on your average rainfall, you may never have to water these beds, completely eradicating any irrigation required. Since these mounds are at a slope, any water applied to them will wash away the soil covering the mounds. This means you will want to get these covered with plants as soon as possible. 

Covering with Plants 

Covering your mounds with plants as soon as possible will reduce erosion, kickstart the breakdown of your logs, increase microbial diversity, produce a harvest faster, and provide a unique ecosystem sooner. I recommend looking into native perennials that establish quickly, especially nitrogen fixers like hairy vetch or lupines. Beans such as lava, peas, cowpea, and alfalfa are also excellent choices. 

Yarrow, calendula, borage, comfrey, dill, cilantro, fennel, buckwheat, milkweed, and lemon balm are also great additions for creating pollinator habitats with easy-to-grow nutrient-rich plants that will reseed themselves each year. Plant everything you can, with high plant density, focusing on mixing canopy heights and layering shade-loving plants beneath the understory of taller plants. 

Conclusion 

Have fun and experiment with plants you can enjoy in your food, in a bouquet, or simply as an addition to the landscape. Cannabis does exceptionally well in these mounds and can create excellent shade for things such as basil which is known to increase terpene production or kale, a tasty addition to Italian sausage and white bean soup. These mounds will become beautiful additions to any landscape, and while they may be a bit of work at first, they are straightforward to manage and maintain for years to come with little to no effort. 

I hope this encourages you to try to build your huglekultur mounds, remember you will be storing carbon in the soil, improving its health by increasing its organic matter and creating a habitat for soil organisms, providing long-lasting nutrients for your plants in a water-storing-sponge that will maintain itself. This is an excellent way to steward your land and has been incorporated into many permaculture gardens worldwide, so build one on your land next.