Lilly Cook is the chapter reporter at North Shelby High School in Missouri.
Jones is also a member of the school’s flag football, track and cross-country teams. She has been on the chapter’s soil judging team and competed in the state soil judging contest for the last two years. Lacey Jones is a member of the Virgin Valley FFA Chapter in Mesquite, Nev. He has been the state high individual for both events multiple times. He has been on his chapter’s soil judging and homesite evaluation teams for four years and has led the teams as a CDE chair for the past three years. Ryan McMurray is the president of the Moapa Valley FFA Chapter in Nevada. These six FFA members have successfully competed in soil judging career development events (CDEs) and share their soil horizon expertise for this graphic. The R horizon is commonly made up of sandstone, granite or limestone. The R horizon is characterized by tightly bound, unbreakable materials, unlike the looser layers above it. In other places, it could be as little as 6 feet below or less. In some places, the R horizon might be 60 feet below the topsoil. The R horizon, also called bedrock, is the lowest layer. It is very close in structure to weathered parent material bedrock. It is usually unaffected by the soil formation process and doesn’t have much layering. The C horizon is usually the deepest in the pit and the closest to bedrock. Soil structure in this horizon is often blocky or prismatic due to the higher clay content. The B horizon contains more clay than the topsoil and contains lower levels of organic matter.
This leaching process is known as illuviation. The B horizon, or subsoil, is referred to as the zone of accumulation due to buildup of minerals leached out of the A and E horizons. The E horizon is not present in all soil profiles and can be found on sites with a high temporary water table or forest soils. The texture is generally similar to the horizon above it but lower in clay content than the horizon below.
The E horizon is a zone of eluviation, where organic matter, clay or both have washed out of the layer, usually giving it a lighter color and making it feel ashy or chalky to the touch. It is one of the layers we test for texture in the soils contest. The A horizon may be a result of soil disturbance by plant and animal activity. Most commonly called topsoil, the A horizon is a layer of mineral soil that has a defined soil structure, and it is mostly made up of humus (decayed organic matter). The O horizon also serves to absorb water and build soil structure. The O horizon is formed over a process of hundreds of years from organic materials that slowly decompose. This organic matter is vital to the growth of crops and other plants because it holds nutrients such as carbon, phosphorus, nitrogen and sulfur. The O horizon is typically at the top of the soil structure and is made up of mostly organic matter. Six FFA experts tell us what’s up with the layers of soil under our feet. Supervised Agricultural Experiences (SAE).
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