Learn how to identify and reduce soil erosion in gardens with a few simple steps (that are best gardening practices too!).
How to tell if you have soil erosion
Walking on my block this week, I saw a not uncommon site: gullies through soil of a small garden. The garden was on the side of the street next to the curb and the gullies reminded me of dried-out riverbeds. It was clear that a lot of the soil had been washed out of the garden and into the local sewer system.
Soil erosion, to varying degrees, happens to all gardens and lawns. Water, wind, farming, and even the act of gardening take away topsoil over time. While the gullies that I saw or cracks in the soil are some of easiest ways to spot likely erosion, failing plants or even just wet patches / puddles are potential warning signs.
The top of your soil—topsoil—is really important to a garden because it is how nature replenishes nutrients and organic matter to the soil below—healthy soils move nutrients lower over time. When the top layer of soil is taken away, the rest of the soil can’t get the nutrients or structure that it needs to grow healthy plants.
Soil erosion is also a concern for where the soil is carried. In my example, soil was carried onto the street and then local sewer system. Sediments that are transported to storm drains most often end up in local waterways like the Chesapeake Bay, and can choke aquatic life and increase water temperatures. The soil also likely carries water pollutants—bacteria, nutrients, and heavy metals, for example—that further hurt water quality.
How to repair and/or reduce soil erosion
There are a variety of ways to help reduce soil erosion.
Plant things! Grass is good, but trees, shrubs, and perennials are better because they provide more shade for the topsoil, absorb more water, and their roots grow deeper into the soil to more firmly hold it in place. If it’s a veggie garden, consider cover crops when not in the growing season.
Add compost. The soil needs organic matter to be healthy and help your plants thrive. In addition, compost holds up to 20 times its weight in water—this helps store the water for your plants, reduces the amount of water that might wash away, and limits the amount of topsoil that the water carries with it.
Mulch, mulch, mulch! We’ve covered the benefits of mulch in another blog post—almost all of which are pertinent here. Perhaps most immediately, mulch adds a protective barrier between your soil and the wind and water that can carry it away.
Stop tilling soil / minimize disturbance. While it's important to help aerate your soil, a lot of vegetable gardeners till their soil each year. Soil science has taught us that this much disturbance is bad for our soil, and regenerative agriculture practices have done a nice job incorporating this best practice.
Divert water. There are a lot of creative ways to divert water so that it doesn’t wash away your topsoil. Some common ones that I hear frequently: cleaning and fixing gutters, adding a rain barrel(s), and redirecting a downspout.
Reduce the slope. You can flatten the land by adding a retaining wall or building terraces. No doubt, this is usually a bigger undertaking and it may be best to reserve this for the most extreme cases.
The first three things on the list—plant things, using compost, and adding mulch—are all part of a gardener’s best-practice toolkit and are readily available in our area. This makes it easy to reduce or stop small erosion problems while growing better plants at the same time.