Do something with your dirt pile before your kids do.

What to Do With Excess Dirt

by Brian Barth

Landscaping and gardening are ongoing processes of improving soil, managing plant growth and building useful features such as paths, patios, fences and beds. Sometimes the work of one project opens the door to the next. If you find yourself with a pile of leftover soil after excavating for a path or leveling a planting area, keep it on hand -- it might come in handy down the line. Soil is not easy to dispose of, but there are many ways to quickly repurpose it if it's getting in the way.

Make Potting Soil

Potting soil is often a soilless growing medium composed of peat moss, perlite and other materials that hold water like a sponge. It's perfectly fine to incorporate actual soil into a potting mix, but it needs to be heavily diluted so it won't bog down the roots of plants that live their lives in pots. To make a good quality potting soil with your excess dirt, you'll want to break up any clumps until you have a fine consistency and screen it through a piece of hardware cloth to get out rocks, sticks and roots. Combine equal parts soil, sand, compost and shredded peat moss or coco fiber in a wheelbarrow. Add perlite in about half the quantity of the other ingredients, and mix to an even consistency. Afterward, you can sterilize it in small batches on a cookie sheet in the oven. Cook it at 200 degrees for 20 minutes, stirring every 5 minutes or so, to kill any insects or pathogens that may be hiding out. This potting mix is especially good for larger outdoor planters, but isn't a great choice for houseplants because it won't drain quite as freely as a soilless mix.

Build a Terrace

If you have a large pile of extra soil and a sloped yard, it's a match made in heaven. Spread the soil flat over the sloped area, and stack rocks on the downhill side to prevent the terrace from eroding. Use a rake to make a smooth surface and a metal tamper to compact the soil into a stable base. You could seed the area with grass or just cover it with mulch to make an informal patio. If the soil can be compacted into a really firm base, it can even be suitable for building a real patio with flagstone or concrete pavers.

Make a Planting Berm

One of the easiest projects for a pile of excess soil is to create a planting berm in the nearest empty spot in your yard. A berm is nothing more than a low, broad mound of soil to facilitate good drainage for your plants. Berms make perfect spots for flower borders along the edge of the lawn, for example. Build the berm perpendicular to a slope, as opposed to running downhill, and make it as long as your extra soil allows. The key to a good- looking berm is to keep it low and wide -- it should be no more than 4 feet in width for every 6 inches in height.

Topsoil vs. Subsoil

Topsoil is useful for very different purposes than subsoil, so know what you're working with before you plan a project. Topsoil is always dark brown with a loose crumbly texture. Subsoil is usually some shade of tan, gray or red. Never use subsoil for a potting mixture, because it has virtually nothing in the way of nutrients and is often composed of heavy clay, which will drown your plants. Subsoil is ideal for a terraced patio because it will not settle once properly compacted. You can use it as a base for a planting berm or terrace, but you'll need to add at least 4 to 6 inches of topsoil to support growing plants.

About the Author

Brian Barth works in the fields of landscape architecture and urban planning and is co-founder of Urban Agriculture, Inc., an Atlanta-based design firm where he is head environmental consultant. He holds a Master's Degree in Environmental Planning and Design from the University of Georgia. His blog, Food for Thought, explores the themes of land use, urban agriculture, and environmental literacy.

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