Science Station Properties of Soil

Welcome Hello students!! Welcome to today’s lesson. We will discuss: the properties of soil, including texture and capacity.

Definitions First, let’s begin by discussing a few words to make sure we understand what they mean. You have heard these words before but let’s review them anyway.

Definitions Properties – the way we will describe something, in this case, the way we will describe soil.

Definitions Properties – the way we will describe something, in this case, the way we will describe soil. Texture – the way something feels and looks.

Definitions Properties – the way we will describe something, in this case, the way we will describe soil. Texture – the way something (soil) feels and looks. Capacity – the amount that something (soil) can hold, such as water.

Definitions Soil – the ground that is on Earth.

Soil Properties The most obvious property of soil is color. There are a ton of different soil colors. Scientists have come up with 170 different colors of soil. Most of them are shades of brown, black, gray, red, and white.

Soil Colors

Soil Properties Another obvious property of soil is texture, the way the soil feels and looks. You can tell that soils are different just by looking at it and picking it up.

Soil Texture Some soil might have mostly large pieces with just a few small pieces mixed in.

Soil Texture Other soil could be mostly small pieces with just a few big pieces mixed in.

Soil Texture A lot of soils have the same sized pieces throughout all of it.

Soil Texture No matter if the soil is made up of different sized pieces or the same sized pieces, these all explain texture or the way something might feel in your hand. If you picked up a piece of sand from the beach it would feel very rough and grainy. If you picked up wet dirt from your backyard it might feel sticky. These examples both explain the texture of soil.

How far do you think soil goes down? If you were to dig a hole in your back yard, how deep of a hole do you think you could dig? Soil

Well, you won’t be able to get very far before that soft soil turns really hard and that is more like rock. You wouldn’t even be able to use a shovel to get this up. Scientists have to use big tools to get this deep. Some holes have been dug that are 7 miles deep. That is over 11 kilometers!

Discovery Education on Soil “What’s the difference between soil and dirt? Dirt is what you find under your fingernails. Soil is what you find under your feet. Think of soil as a thin living skin that covers the land. It goes down into the ground just a short way. Even the most fertile topsoil is only a foot or so deep. Soil is more than rock particles.” It includes living things like micro-organisms and has worms in it!

Discovery Education on Soil “Let’s take an elevator ride from the surface to the bedrock below. We’ll pass several distinct layers, or horizons, as we go. Together, these layers form the soil profile. Going down!”

Discovery Education on Soil Ground level/Topsoil: Plants grow and animals live here. A thick cover of plants can keep the soil cool and keep it from drying out. Decomposers recycle dead plants and animals into humus.

Topsoil

Discovery Education on Soil Subsoil: This is a mix of mineral particles (which are healthy for plants) and some humus (which is soil that cannot be broken down any further) near the top. This is the layer where most of the soil's nutrients are found. Deep plant roots come here looking for water.

Subsoil

Discovery Education on Soil Weathered parent material: This horizon can be very deep. There's no organic matter here at all. We're out of reach of all living and dead organisms down here. It's all rock particles, full of minerals.

Weathered Parent Material

Discovery Education on Soil Bedrock: The bedrock formed before the soil above it. It will wait here until erosion or an earthquake exposes it to the surface. Then some of it will be weathered to become the next batch of parent material. The soil-making process will start all over again. Information from

Bedrock

The Whole Picture

Topsoil

The Whole Picture Topsoil Subsoil

The Whole Picture Topsoil Subsoil Bedrock

The Whole Picture

Capacity Now let’s discuss the capacity of soil. The capacity of soil describes how much water and nutrients soil can hold.

Capacity One of the main jobs of soil is to store water so that plants can receive water and nutrients when there is no rain. Different soils store (keep) water better than others. Some soil lets the water evaporate from it very quickly. Other soils can store water for a long time.

Capacity If there isn’t a lot of rain and someone doesn’t water the plants, the soil can get very dry and the plants will get stressed and possibly die.

Capacity Clay holds water very well. However, it doesn’t supply (give) the water to plants very well, so this isn’t a very good soil for most plants.

Capacity Sand doesn’t hold water well at all. This also is not a good type of soil for most plants.

Capacity Silt is another type of soil. Silt holds water well and gets the water to the plants well. This is a very good soil to use for most plants.

Next Time Clay, Sand, and Silt are three different types of soil. Loam soil, another name for soil, is even more well-known. In the next few lessons we will begin discussing the differences in these types of soil and their abilities to help plants grow and survive. See you next time!!