A berm is a raised strip of soil or earth, often used in gardening, landscaping, and permaculture to manage water, improve soil health, and create microclimates. Berms can vary in size and shape, but they are typically built as long, narrow mounds or ridges.
In the context of permaculture and eco-gardening, berms are commonly paired with swales (shallow ditches or trenches) to capture and distribute rainwater more effectively. Here’s how berms are typically used:
Water Management
- Berms slow down the flow of water, preventing runoff and erosion.
- When paired with a swale, they allow water to infiltrate the soil and recharge groundwater, supporting deep-rooted plants.
Soil Health
- Berms can improve drainage in waterlogged areas or retain moisture in drier ones.
- They’re often built with organic material (like logs or compost) to decompose and enrich the soil over time.
Microclimates
- The mound creates different growing conditions: one side may be sunnier and warmer, while the other side may retain more moisture and stay cooler.
- This is ideal for growing a diverse range of plants suited to varying conditions.
Wind and Noise Barrier
- Tall berms can act as windbreaks, protecting delicate plants.
- They may also reduce noise pollution if used near roads or urban areas.
Berms are typically made from a mix of soil, organic matter, and sometimes inert materials like rocks or logs. The core structure often consists of compacted subsoil or clay to provide stability, topped with a layer of fertile topsoil to support plant growth. To improve drainage and fertility, organic materials such as compost, decomposing leaves, wood chips, or straw may be incorporated into the berm. In some cases, logs or woody debris are buried within the berm to create a slow-release nutrient source as they break down, a technique known as hugelkultur. Mulch is often added to the surface to reduce evaporation and suppress weeds. By combining these materials, berms become a functional and nutrient-rich feature in the landscape, promoting water retention, soil health, and plant growth.