Soil at school project – Geography department of the University of São Paulo

Forest soils, where soil formation has been influenced by forest vegetation, are generally characterized by deeply rooted trees, significant ‘litter layers’ or O horizons, recycling of organic matter and nutrients, including wood, and wide varieties of soil-dwelling organisms. There are also soils now covered with forest vegetation, often plantations, on lands that were not naturally forested. These soils are probably undergoing processes that give them ‘forest soil-like’ characteristics, e.g., litter layers from trees, woody organic residues from deep roots, and associated soil microbe and fauna populations. Like other soils, forest soils have developed, and are developing, from geological parent materials in various topographic positions interacting with climates and organisms. Forest soils may be young, from ‘raw’ talus, recent glacial till or alluvium, or ‘mature,’ in relatively stable landscape positions. Just as forest vegetation of the world varies greatly, so do forest...

Texture  - The particles that make up soil are categorized into three groups by size:  sand, silt, and clay . Sand particles are the largest and clay particles the smallest. Although a soil could be all sand, all clay, or all silt, that's rare. Instead most soils are a combination of the three. The relative percentages of sand, silt, and clay are what give soil its texture. A loamy texture soil, for example, has nearly equal parts of sand, silt, and clay. Structure  - Soil structure is the arrangement of soil particles into small clumps, called "peds". Much like the ingredients in cake batter bind together to form a cake, soil particles (sand, silt, clay, and organic matter) bind together to form peds. Peds have various shapes depending on their “ingredients” and the conditions under which the peds formed: getting wet and drying out, freezing and thawing--even people walking on or farming the soil affects the shapes of peds. Ped shapes roughly resemble ba...

WHAT IS SOIL? Soils are complex mixtures of minerals, water, air, organic matter, and countless organisms that are the decaying remains of once-living things. It forms at the surface of land – it is the “skin of the earth.” Soil is capable of supporting plant life and is vital to life on earth. Soil, as formally defined in the Soil Science Society of America Glossary of Soil Science Terms, is: The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time. So then, what is dirt? Dirt is what gets on our clothes or under our fingernails. It is soil that is out of place in our world...