Soil is the foundation upon which we build, it is the canvas upon which we paint, and the medium upon which most plants rely for support and nutrients. In one square millimeter of soil there are over one billion organisms. The health of this complex habitat is essential to every ecosystem and restoration project.
Whether you are working to improve forage and cover in a pasture, re-vegetating a roadside slope, or restore a clear cut, the soil must be protected for vegetation to take hold and the site to recover. Bare soil is easily erodible and is vulnerable to a number of different threats. In this entry we’ll look at one of the key agents of erosion – Rain Splash.
As raindrops fall the pressure from the air on the bottom of the drop pushes it out of true and creates an inverse cup. When this drop impacts the soil the air pocket blows out the sides, dislodging soil particles and dispersing them up to 3’ away. Multiply and repeat this process a billions times for any given storm and the exposed soil on your site gets pulverized, detached, and ready to wash away. Over ground flow then takes these small, detached particles and transport them off the site.
The key to protecting your soil from rain splash erosion is covering the soil.
When a raindrop impacts against any sort of cover, its energy is dispersed and can’t detach soil particles. A marked example of this can be seen below where the gravel covered and dispersed the energy of the rain while the exposed soil was detached and washed out of the site.
Cover can take many forms from leaf litter, woody debris, rock, synthetic mulches, or living plants.
Whatever you choose to use, the important thing is to cover your soil!
As the chart above shows, a little ground cover goes a long way. With as little as 10% ground cover, erosion of bare soil can be reduced by 50%. With 50% coverage of bare ground, erosion can be reduced by over 90%.
So whether you’re hydro-mulching exposed slopes, planting cover crops on an exposed acreage, or just mulching your garden beds, cover your soil.
Protect the soil! It is the skeleton of your site and the heart of the ecosystem in which you are working. With protected, stable soil, you are well on your way to putting your site back on trajectory to health and sustainable future.
Charts were taken from The Nature and Properties of Soils by Nyle Brady & Ray Weil
Peter, thanks for inviting me to this blog. Your passion really comes across in your writing, and you have a lot of scientific info to share. I never knew about the mechanics of rainsplash erosion. I recently read an old Rodale book on soil conservation and health from the 1970's, it was an eerily prescient warning about the problem of topsoil loss and a good primer on feeding and stabilizing soil. Let's keep working together to recesitate our soil! - Tom
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