What Makes Topsoil Black?

While there are actually several different shades of topsoil throughout the world, true topsoil is black due to the presence of humus. Humus results from decayed organic materials and makes the soil very rich in nutrients.

Definition

Topsoil is defined as the top two to eight inches of the earth's soil. It has an abundance of nutrients and organic matter, usually resulting in a dark, earthy color.

Location

Since topsoil is the outermost portion of soil, it takes on a black tone after mixing in with dirt and partially decomposed material.

Composition

Black topsoil is also referred to as black earth. It's made up mainly of humus, phosphorous acids and ammonia. These ingredients also contribute to the dark appearance.

Significance

The black texture formed by decomposed materials makes the soil especially nutrient rich, creating a perfect environment for plant life.

Fun Fact

Topsoil is acidic in nature. As it becomes more alkaline, the color shifts to lighter shades, such brown or a lighter red color. The acidic content gives it a darker appearance.

References

• Topsoil Color Explained
• Black Soil Definition