Weight of Soil Per Cubic Yard

Disturbed Soil

• Measuring the weight of a disturbed soil is different than calculating the weight of an undisturbed cubic yard of soil. Disturbed soil always has more air in it than undisturbed soil. When a soil is dug up, it becomes loose and loses the denser structure it had when it was in the ground. Soil that is disturbed will thus have a greater volume and less weight per cubic yard than an undisturbed soil. It is important to realize when determining how much soil you need that disturbed soil will settle a lot. If you are ordering fill dirt, be sure to ask what the estimated percentage of settling is.

Soil Texture

• The three sized materials that make up the mineral portion of the soil are called sand, silt and clay. Sand is the largest and clay is the smallest. The percentage of these sized materials in a soil determines its texture. Sandy soils are grainy and have clods that fall apart easily. Silty or loamy soils feel like flour and have stronger clods. Clay soils are very dense and have clods that are very hard. A soil with lots of sand will be lighter than a soil with lots of clay. Most soils have a loam texture with equal parts of sand, silt and clay.

Soil Moisture

• The more water a soil can hold, the heavier it will be. A clay soil is not only denser than a loam or sandy soil but it can also hold more water. Clay soils have a higher surface area than soils with mostly silt or sand. With more surface area, water has more area to stick to. Even though there are larger pore spaces between sand particles, the water is not held in a sandy soil as firmly as in a clay soil. If you weigh a soil that is wet, it will be significantly heavier than when it is dry. If you are ordering soil by weight, be sure to ask what the moisture percentage of the soil is so that you can calculate the weight of water.

Weighing Soil

• To calculate the weight of a cubic yard of undisturbed soil, measure a one foot square on the surface of the soil. Dig out the square of soil down one foot and carefully save all of the soil in a preweighed bucket. Weigh the bucket of soil and subtract the weight of the bucket to get the weight of the freshly disturbed wet soil. Allow the soil to dry for three to four days depending on how wet it is. Weigh the dry soil. Multiply the dry weight of the soil by 27 to find how much a cubic yard of your soil would weigh. Divide the difference in weight between the wet and dry soil by the weight of the dry soil, subtract this answer from 1 and multiply by 100 to get the percentage of water in the soil. For example, if your wet soil weighs 25 lbs. and the dry weight is 16 lbs., 25 minus 16 equals 9, divided by 16 is 0.56, 1 minus 0.56 is 0.44 and multiplied by 100 is 44 percent water.