Soil is the outermost layer of our planet. On average, most soil is about 1 meter thick. But where does the soil come from? Soil goes through several processes to become, well, “dirty.” Weathering is the name given to the process by which rocks are broken down to form soil. There are several types of atmospheric processes that rocks undergo to form soil: physical, chemical and biological. In physical weathering, rocks are broken down into increasingly finer particles by means of physical attributes, such as water or freezing. When igneous rocks cool and begin to crack or fracture, water can flow through the cracks and break the rocks into smaller particles to create soil. In colder regions, ice can actually break rocks into finer particles. Or even ocean waves can hit rocks to create soil. In chemical weathering, rocks are broken down by means of chemical attributes, such as acidification. Acid rain contains high levels of hydrogen ions, making the pH level of the precipitation very acidic. In biological erosion, the effect of living organisms breaks down rocks in the soil, like the effects of plant roots. The roots of growing plants can place stress or pressure on rock to form soil. For example, the video showed lichen plants and ferns growing from igneous rocks, which can break down to create soil. Soil has distant layers of earth that lie on top of each other, parallel to the soil surfaces; this is known as soil horizons. These horizons can be encountered by burrowing from surface to bedrock in this order: O, A, E, B, C and R. These horizons are identified based on their physical attributes, primarily by their color, structure, texture, particle size , as well as the central part of the card. Composition and aging are much slower than if temperatures were warm. The four components of soil work together to provide optimal conditions for water, air and nutrients available for plant growth. Soil is made up of air, water, mineral particles, organic matter and organisms. Half of the soil is made up of pores. Generally, the pores are filled half with water and half with air, although the proportion varies greatly depending on climate, water use by plants, and soil structure. Most of the solid part of the soil is made up of mineral particles. Soil is basically the storehouse of nutrients that plants need to survive. Dissolved minerals and water are absorbed into the plant's root system and are continually replenished by nutrient reserves contained in the minerals and organic matter in the soil. Sometimes, nutrients can be added by farmers, adding fertilizers one or more times a year.
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