What Is Soil? Custom Search What is soil? That's a question that many beginning gardeners ask. It's also one that has many answers. Soil is made from rock flours, organic materials, such as dead leaves, roots, twigs, dead bugs, soil organisms, water, and air. Soil is what holds plants up so they don't fall over. It's also a plant nutrient production system, so that plants have enough of what they need to grow. A single shovelful of soil can contain more species of organisms than live above ground in the entire Amazon rain forest. One cup of it may hold as many bacteria as there are people on Earth. The weight of all the bacteria in 1 acre can equal the weight of one or two cows. Mature trees can have as many as 5 million active root tips. A teaspoonful of forest soil may hold more than 10 miles of fungi. Almost all freshwater travels over or through soil before entering our rivers, lakes, and aquifers. Plants remove 400 to 2,000 pounds of water from soil for every 2 pounds of plant material produced. What's in Soil?ArthropodsArthropods include ants, termites, spiders, mites, centipedes, millipedes, beetles, and a few more insect types. We usually call them bugs! They don't have a backbone. They do, however, have jointed legs. They perform many important tasks in the soil. For instance, they stir it up so that it gets more air. They chew dead plants into tiny pieces so fungi and bacteria can use them. They help spread microorganism throughout the soil. They also are a food source for larger soil organisms. Burrowing AnimalsSome animals, like prairie dogs, ground squirrels, and badgers, like to dig holes in the soil. These animals and their holes are very common on rangelands. Many other animals, such as owls, snakes, lizards, and rabbits, use the holes to live in. Digging helps mix up the soil and allows rainwater to enter. This helps feed thirsty plants and also helps prevent flooding. NematodesNematodes are tiny roundworms that are common in grassland. Some are serious plant pests, but many do beneficial things. For example, they help provide nutrients for plants and also help mix it up. There are also beneficial nematodes that kill plant pests, which reduces the need to use chemical pesticides, which can damage the soil. ProtozoaProtozoa are tiny animals that mainly feed on bacteria. They can use many tiny hairs, temporary feet, or a few whip-like hairs to move through the soil. When they eat bacteria, they help release nitrogen and other nutrients for plants to use. BacteriaBacteria are tiny, one-celled plants. Some bacteria live free; others grow on the roots of plants like clover and alfalfa, making nitrogen for those plants (legumes) to use. Bacteria also help decompose dead plants to recycle nutrients. FungiFungi are primitive plants that don't have chlorophyll. Some types of fungi grow on plant roots. The fungi have many filaments, called hyphae, that are like thin hairs. These hyphae spread through the soil far beyond the roots. This allows the fungi to help the plants obtain more food and water from the soil. In return, the plants make sugars that fungi need for energy. Some range plants, including many native grasses, can't grow without these fungi growing on their roots. Other fungi help decompose dead plants to recycle nutrients. Biological Soil CrustsBiological crusts are bunches of tiny plants and bacteria that grow together on or just below the soil surface. They grow on rangeland all over the world. They're often dark in color when dry. They may become green, orange, or yellow when wet. These living crusts help keep the soil from washing or blowing away. They make nitrogen, which keeps nearby plants growing. And they help keep out weeds. What Is the Soil Food Web?The soil food web is a way of relating soil organisms to each other based on what they eat. The soil food web starts with organic matter. This could be crop residues, pasture or any plant material in the soil. Bacteria and fungi consume organic matter, breaking it down in the process. Bacteria and fungi are in turn consumed by nematodes, protozoa, earthworms, collembola and some mite species. Nematodes and protozoa are consumed by mites. Mites and collembola are eaten by beetles and ants. This consumption process may sound linear, but researchers have found that it is indeed closer to a web, hence the name soil food web. Additional Topics About SoilState and Local Soil Testing Labs What We Can Do for Soil Quality Apply Only the Nutrients That Plants Can Use How To Make Acidic Soil Alkaline Organically From Soil to Organic Fertilizers Info |