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Amino acids – Molecules that join together to form proteins, the building blocks of all organisms.

Anaerobic – Without oxygen as a part of the environment. The opposite of aerobic.

Antibiotic – A chemical that weakens or stops bacteria, fungi, and other microorganisms from growing.

Archaeologist – A scientist who studies ancient human cultures.

Arid – Dry, like a desert.

Bedrock – Mass of solid rock beneath the soil. Can be parent material if it is close enough to the surface to weather into soil.

Blocky – A soil structure. Soil particles are arranged into shapes that resemble small cubes with sharp or rounded edges.

Clay – The smallest-sized soil particles. Often have plate-like shapes. Feels sticky when wet. Also refers to a soil texture that consists of at least 40% clay particles.

CLORPT – The five factors that influence what type of soil forms: climate, organisms, relief (landscape), parent material, and time.

Columnar – A soil structure. Soil particles are arranged into tall vertical shapes or columns often with rounded tops.

Compost – The remains of plants and animals after they have decomposed. Can be used to fertilize soil and to improve its structure and ability to hold water.

Compounds – The combination of two or more elements. For example, hydrogen and oxygen combine to make water.

Decompose (Decomposition) – To break down a compound into simpler compounds. Often accomplished with the help of micro-organisms.

Developed soil – A soil that has had a long time to form, such as most tropical soils. A mature soil.

Deficiency – Lacking in something important. A deficiency of nutrients in a plant, for example, can stunt its growth.

Dormant – A state in which a plant or animal is not growing.

Ecologist – A scientist who studies interactions between organisms and their environment.

Eluviated horizon (E horizon) – A horizon from which minerals, clay, and/or organic matter have been leached.

Enzyme – A protein that increases the rate of chemical reactions in an organism’s cells.

Erode (Erosion) – To wear away, or remove, rock or soil particles by water, ice, and/or gravity.

Estuary – A semi-enclosed body of water with a source of fresh water and an outlet to the ocean.

Fertility – The ability of a soil to supply essential nutrients to plants.

Fertilizer – A substance added to soil that contains plant nutrients such as nitrogen, phosphorus, and potassium.

Fungus – A kingdom of organisms distinct from animals and plants. Most fungi get their energy from decomposing plants and animals.

Granular – A soil structure. Soil particles are arranged into shapes that resemble granola. Has lots of pores.

Groundwater – Water that collects underground in the pore spaces of soil and rock. An important source of drinking water.

Horizon – A layer of soil with properties that differ from the layers above or below it.

Humus – Organic matter such as highly decomposed leaves.

Leaching – The removal of minerals and nutrients from a soil or a horizon as water passes through it.

Loam – A soil texture with moderate amounts of sand, silt, and clay, sometimes in nearly equal proportions. Good texture for farming and gardening.

Macronutrients – Nutrients needed by organisms in relatively large quantities.

Massive – A soil that has no structure. Soil particles are completely stuck together.

Microbes – Microscopic organisms, such as bacteria and fungi. Microbes represent the most abundant soil organisms.

Microbiologist – A scientist who studies microscopic organisms, or microbes.

Minerals – The inorganic particles in soils that weather from rocks.

Mottles (Mottling) – Spots or blotches of color(s) in a soil that differ from that soil’s dominant color.

Nitrogen (N) – Macronutrient essential to living things like plant growth and building proteins. Often added to agricultural and garden soils.

Nutrients – Elements or compounds that nourish organisms. Essential for growth and reproduction.

Organic matter – Material derived from the decay of plants and animals. Always contains compounds of carbon and hydrogen.

Organisms – Living things such as bacteria, fungi, plants, or animals.

Parent material – The material from which a soil formed. Can be bedrock or materials carried and deposited by wind, water, glaciers, and/or gravity.

Peat – Partially decayed organic matter that accumulates in environments that stay wet.

Ped – The structural unit formed when soil particles (sand, silt, and clay) bind together.

Pedologist – A scientist who studies soils.

Perennials – Plants that live for more than two years as opposed to annuals that grow each year from seeds or biennials that live for only two years.

Permafrost – A soil horizon, or layer, that remains frozen year round.

Phosphorus (P) – Macronutrient essential to all living things like flowers, fruits, seeds in plants, and the nervous system in animals. Often added to agricultural and garden soils.

Photosynthesis – The process by which plants, some bacteria, and some algae use sunlight to convert carbon dioxide and water into food and oxygen.

Platy – A soil structure. Soil particles are arranged into shapes that resemble flat plates.

Pores – The space between soil particles, which can be filled with water or air. A porous soil has lots of pores.

Potassium (K) – Macronutrient essential to all living things like water uptake and pest resistance in plants; muscles and blood circulation in animals. Often added to agricultural and garden soils.

Prismatic – A soil structure. Soil particles are arranged into shapes that resemble columns.

Productive – A term used to describe a soil that has the capacity to grow an abundance of crops.

Relief – The shape of the land surface created by features such as hills and valleys.

Runoff – Water from precipitation or irrigation that does not soak into the soil but flows off the land and reaches streams and rivers.

Salinization – The build-up of salts in soil. Often occurs in arid environments.

Sand – The largest-sized soil particles. Sand feels gritty. Also refers to a soil texture that consists of at least 85% sand particles.

Sediment – Any particle of soil or rock that has been deposited by water, wind, glaciers, or gravity.

Sewage – Waste that goes down a drain (such as those in bathrooms, kitchens, and laundry rooms) to a treatment plant or septic system.

Silt – Soil particles in between sand and clay in size. Silt feels like flour (smooth and velvety). Also refers to a soil texture that consists of at least 80% silt particles.

Single-grained – A soil that has no structure. Soil particles are not bound to each other in any way, such as beach sand.

Slope – A landscape, or surface, that is tilted or inclined.

Sludge – Semi-solid material left behind after sewage has been processed in a treatment plant. May be used as a fertilizer in some instances.

Sod – Grass and the soil beneath it, held together by roots. Can be cut into blocks and used as a building material.

Soil – A mixture of minerals, organic matter, water, and air, which forms on the land surface. Can support the growth of plants.

Soil profile – A section of the soil that has been cut vertically to expose all its horizons, or layers.

Soil structure – The arrangement of soil particles into clusters, called peds, of various shapes that resemble balls, blocks, columns, or plates.

Soil texture – The relative proportions of sand, silt, and clay particles.

Subsoil (B horizon) – The soil horizon rich in minerals that eluviated, or leached down, from the horizons above it. Not present in all soils.

Tissue – A group of cells in an organism that work together, such as muscles in an animal or the outer surface of leaves in a plant.

Topsoil (A horizon) – Mostly weathered minerals from parent material with a little organic matter added. The horizon that formed at the land surface.

Transform – To change from one thing into another or from one state into another, like a liquid into a gas.

Tropical – The area of land and ocean that lies between 23.5° north and south of the equator.

Tundra – An area in cold regions, such as in the arctic or on mountains, where the growing season is very short.

Uptake – The ability of a plant to absorb water and nutrients.

Weather (Weathering) – To break down rocks and minerals at or near Earth’s surface into smaller particles and soil.

Wetland – An area of land where the soil is saturated with water, such as a marsh, swamp, or bog.