Browsing: Soil

Soil Colors

Have you ever paid attention to the different colors of soil? Well, they are colored by the materials and minerals that are found in them. Many of the colors we see are because of the oxides of iron. As an example, in the southern United States, there is a red tint to the soil in a lot of places because of hematite, an iron oxide mineral. Some soils will have a more brown color because of maghemite, an iron mineral; some are more yellow because of goethite, an iron oxide; some others will be a grayish green color because of hydromagnetite, an iron mineral.

soil-colourWith every color of the soil, the kind of iron oxide that is present is based on the soil’s conditions when the oxide was formed, such as potential organic matter, water content, and the temperature. Hot soils help hematite to form when there is a lot of oxygen present. When small amounts of oxygen are present because the soil is often saturated, hydromagnetite is formed.

There are other materials within soil that can cause colors that we see. Different salts in the soil can cause it to have a white crust. These salts are found naturally in some soil environments. High levels of organic materials that are partially decomposed can cause some top soils to have a black color.

Color is a powerful tool that is used by the soil scientists to help them understand the formation of different types of soil since the color is determined by the conditions the soil is formed under. It gives very good hints to the scientists that are studying it.

Many people wonder how iron effects our ability to grow crops and other things in the soil. The iron is actually a very small part of what makes up the soil, so it doesn’t influence it a lot. You can think of it like the paint in a home. The paint makes up a very small part of the home itself, but it can influence how the home appears. This is the same way iron oxide is in the soil. It pretty much just determines how it looks.


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The Effects of Tilling

Have you ever drove past a farm and seen a farmer tilling the fields? When they till (also known as cultivate and plow), they are moving around the soil particles, slicing into the soil, pushing the soil around, or flipping the top soil layer.

6276697-a-tractor-tilling-soil-in-a-field-stock-photoIn the days of old, people would plant seeds in small holes they made in the soil. They would use their hands to pull up weeds. Occasionally, they would use a shovel to mix in nutrients. These days, though, farmers use tractors. Small gardeners tend to use a rototiller that moves the soil around for them. Why do they till the soil, though?

One reason the farmers till the soil is for weed control. They want to destroy the roots of the weeds. Another is to prepare the seedbed. Tilling can help the soil become more favorable for the seeds. And last, for incorporating different sources of fertilizers in the soil. Occasionally, farmers will also till to help control water evaporation from the soil. Is tilling really necessary though?

In the United States, the Dust Bowl was created from drought and farmers tilling the land too much, leaving the soil dry and bare. The wind blew and took away the topsoil. This taught us that too much plowing can hurt the soil. It can decrease the organic matter of the soil and keep it from holding water. Because of this incident, scientists started looking for some better ways that would protect the soil. They found that when farmers leave plant residue on the surface of the soil, it helps to protect it from rain and wind. Also, when the soil isn’t disturbed, the organic matter is helps the soil to recover and better resist erosion.

A lot of farmers will now leave the residue from the plants and till less than in the past. They can use equipment that allows them to plant seeds into unplowed soil now as well. They are beginning to understand that soil that is tilled is less healthy. Hopefully, they will continue to listen to the research in this matter and change their practices to keep the soil healthy.


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Animals That Live in the Soil

Have you ever stopped to wonder what animals live in the soil we walk on each day? Maybe you have thought about what conditions are important to those animals. Well, here is your answer.

There are a lot of diverse animals that make their life in the soil. The earth’s soil is a living, breathing resource. It not only helps us to grow food, but also fuel and fiber. None of these things could be done without animals helping out with the soil though. Animals such as insects, burrowing animals, turtles, and gophers live in the soil. The condition of the soil is quite important to these animals.

earthworm-and-soilMany animals that live in the soil use it for their protection from predators and the weather. Earthworms are found living in the soil commonly. They are helpful because they aerate the soil through their movements that mix and turn the soil. Their burrows create large pores in the soil that allow water to flow through the soil rather than run off of it and cause erosion.

Ants also live in the soil and help it. Have you ever seen an ant colony?  They are amazingly made with many tunnels and chambers that they use as their kitchens and living areas. The worker ants in the colonies are always building more areas to keep up with their rapidly growing numbers. By doing this, they create pores in the soil that allows water and air to get to plants and help them to grow.

Animals that live in the soil have a beneficial relationship with it. They get things from the soil but also return things back to it. The soil’s biodiversity is critical to the health of the soil and the health of the world. We humans need to respect these animals and the soil they count on each day. The animals in the soil provide many benefits to the soil, making them an important part of agriculture and the ecosystem. These animals help with putting nutrients into the soil, degrading organic matter, mixing organic matter into the soil, maintaining and improving soil structure, and controlling pathogen populations.


Our job is to keep the soil healthy for the animals who then, in turn, keep it healthy for us.

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The Properties of Soil

Have you ever asked yourself what soil is made of? Well, it’s made of different types and sizes of solid particles. Some of those are organic while others are minerals. The spaces between the particles can be filled with water or air.


Over time, the soil’s mineral particles begin to change due to weathering. Many things weather rocks, such as hot and cold weather, plant roots, ice, and water. Size is the only thing that changes through this physical weathering process. On the other hand, chemical weathering can change minerals or rocks into other minerals or rocks. They become something completely different. Here is one way to think about it: Take a cookie and break it in two. Each piece is still the same cookie but smaller. You can break it over and over again, and it’s still the cookie. That is just like physical weathering. Put the cookie in your mouth, though, and the saliva begins to mix with the cookie. This will begin the process of digestion. Once this happens, the cookie is no longer a cookie. You couldn’t put it back together again. This is like chemical weathering.

Another part of the soil is humus. Organic particles in the soil make up humus. The organic particles are decomposed parts of animals, plants, and microorganisms. The soil “eats” the organic tissues from the plants and animals. The soil gets energy from these and then will create waste. Humus is the waste product that is produced from the soil.

thumb-ebf72f9951b04c5d05330f906135c161The particles in the soil are separated by their size. If a particle is over two millimeters, it is gravel. If it is between 2 and 0.05 millimeters, it is considered sand. Silts are between 0.05 and 0.002 millimeters. If the particles are under 0.002 millimeters, they are clay. The ratio of mixture of these particles determines the texture of the soil. Clumps (peds) are formed when the individual particles are held together by humus. The soil structure is determined by the size and shape of the peds.

As you can see, air, water, organic solids, and minerals make up soil. The properties of the soil are affected by the microorganisms, animals, and plants that live in the soil.






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