How Much Soil Do I Need? (2024)

FAQs

How Much Soil Do I Need? ›

To find the volume of soil required for your raised beds: Measure the width, length, and depth of the raised beds. Multiply the width, length, and depth together. The number you get will be the volume of soil you need to fill your raised beds.

Length in feet x Width in feet x Depth in feet (inches divided by 12). Take the total and divide by 27 (the amount of cubic feet in a yard). The final figure will be the estimated amount of cubic yards required.

Convert all measurements to the same unit. For example, if your bed is 6 feet long, 3 feet wide and 16.5 inches high, convert the inches to feet so your new measurements are 6 x 3 x 1.4 feet. Multiply all the measurements together: 6 x 3 x 1.4 = 25.2 cubic feet. Divide the answer by 27 to get the number of cubic yards.

If your garden is a rectangle or square, doing some basic math to find the volume of soil, mulch, or compost you need isn't all that difficult. Using the graphic below as a reference, you can see we want to multiply in feet the length x width x height ÷ 27 to get the volume in cubic yards of soil that you need.

For a 4x8-foot raised bed with a 6” height, using Mel's Mix: about 5 cubic feet each of compost, peat moss, and vermiculite is needed. It usually takes about two to three bags of purchased fertile mix (1.5 cubic feet each) to cover the bed surface to a depth of 2 inches.

Bulk Soil. Bulk soil is measured in yards. 1 yard equals 27 cubic feet. Think about it as a cube that is 3′ X 3′ X 3′.

A depth of 8 – 12 inches will suffice for most gardening situations. Because of the excellent drainage properties of raised beds, it is possible to grow an abundance of vegetables in a limited amount of space.

(Do not lift and flip the soil over.) Add a mixture of compost and purchased topsoil in a 1:2 or 1:1 ratio, to the top of the bed. There are vendors who sell topsoil mixed with compost. Alternatively, fill the bed with compost and a soilless growing mix in a 1:1 ratio.

Use the Lasagna Garden Method

To start, lay down sheets of cardboard or newspaper for weed suppression and then fill the raised bed structure halfway up with alternating layers of nitrogen-rich materials (like kitchen scraps and grass clippings) and carbon-rich materials (like wood chips and dried autumn leaves).

In general, with proper maintenance, the soil in a raised bed can last for many years. Here are some guidelines for how long raised bed soil can remain viable: Soil that is well-maintained and regularly amended with organic matter can last for up to 10 years or more.

How do I work out how much soil I need to dig out? ›

To calculate how much topsoil you need, simply measure the dimensions of the area you wish to cover and multiply this by the depth required. Measuring in metres is simplest, as this will give you the volume of topsoil you need in cubic metres. For example: A site has an area of 10m x 15m and needs a coverage of 150mm.

To install a new lawn, plan to spread a layer of 3 to 6 inches of topsoil before sowing seed or laying sod, depending on the quality of your existing soil.

Area X Depth = Amount of soil needed. Example: How Much Soil Do I Need for a 4×7 Bed with 10-inch sides? Soil is either sold in bags by the cubic foot or by the yard if buying in bulk. You can easily convert your feet to yards by remembering there are 3 feet in a yard.

This is simply the length times the width of your garden bed. Then, to get the total cubic feet of each raised bed, simply multiply the square feet of your garden's footprint by the height of your raised bed garden. This provides the total cubic feet of garden space that must be filled with soil.

The good news is that adding compost also adds nutrients that your plants will use to power growth and flowering. Peat moss is used to add structure and water holding capacity to your raised beds.

Estimating soil bearing capacity can be done through field tests that measure the soil's reaction to applied loads. Standard penetration test (SPT) involves driving a steel rod into the soil at a constant rate and recording the number of blows required to penetrate a certain depth.

For these measurements, ppm is converted to lb/acre by the following formula: lb/acre = ppm x 0.3 x depth increment in inches. For example, a 10 ppm nitrate N test on a soil sample taken to a 24 inch depth would convert to 72 lb/acre (10 ppm x 0.3 x 24 inches).

How much will 1 tonne of topsoil cover? Topsoils can vary in screening sizes, therefore some topsoils may be denser than others. Generally speaking, 1 tonne of topsoil will cover 0.63 cubic metres or 22 cubic feet or 0.81 cubic yards.

The basic method for measuring soil fertility consists of mixing a soil sample with water and chemically extracting the N, P, and K as nitrate, phosphate, and potassium. The N, P, and K amounts in the sample are determined by comparing the solution to a color chart.