All Things SOIL TAXONOMY

soil is everywhere no matter where you go on earth soil will always be somewhere beneath your feet and that's a good thing without soil plants would have no way to access nutrients and the world would likely be a lot less green so I think it's about time we all appreciate soil a little more so here's all things soils first have you ever stopped to think about what soil actually is well me neither but here we go at one time in Earth's history early on there was little to no soil on earth instead the surface was rocky and barren and unlike rock and water soil didn't come to earth on an asteroid instead it had to be manufactured here as soon as our infantile earth cooled the process of weathering and erosion kicked into gear weathering is the breaking of rocks into smaller rocks either by a physical or a chemical process and erosion is when these smaller rocks are carried away from the bigger parent rocks usually by wind or water depending on the size of the weathered rock it can either be considered a clay a silt or a sand with anything bigger being gravel out of these three though clay is by far the smallest while sand is the biggest and silt is somewhere in between together these three sizes of weathered and eroded Rock make up soil and depending on the ratio of these three different sizes of particles the soil will have different properties there's this nifty graph to help figure out what you have based on the soils composition so if a soil is 25 percent sand 40 percent silt and 35 percent clay it's considered clay alone if it's 10 percent clay 40 percent sand and 50 percent silt it's silty loam we could do this all day and all these different combinations have different properties in most cases however loam is what you want your soil to be as it's best for most types of plants to grow in if a soil is more clay like it will retain more water the plant roots will have difficulty growing through it if it's more like sand it'll be worse at holding water but easier for roots to grow it again silt is kind of just the in-between and has characteristics of each extreme to lesser degrees overall you want a good balance of each one as these soils settle on top of bedrock they form into layers called horizons this process takes place over many thousands of years as Rock is weathered and eroded and moved from one place to another and of course things like this are never exact as nature tends towards randomness for most places five distinct horizons can typically be observed the uppermost is the Oh horizon Oh for organic and this is where most of the dead plant matter called detritus is then there's the a horizon that's where the real surface soil is it's sometimes called the bio mantle because this is also where most soil organisms reside the B is the subsurface and usually is the farthest plant roots will go for soil the C horizon is where the bedrock is slowly degrading into soil so it's mostly large rocks and gravel with some soil in between then the our horizon our for rock it's just rock sometimes if there's a lot of soil leaching and eve horizon will develop this is where sand and silt are deposited while clay will continue further down into the B horizon forming a thin light layer between the a and the B and now here's where things get fun based on the development of these layers plus one or two other conditions you can start to classify soils all over the world into soil orders there are a bunch of these so you better strap in so in the beginning when there's soil with absolutely no development of horizons it's an into salt these are very young and actually the most common type of soil on earth give the soil a little more time however and it will become an inceptive salt which has slightly more development of its layers with the beginnings of a B horizon then based on the climate given more time and in scepter saw can become a variety of different soils at high latitudes in the Arctic or even mountain ranges you'll have jealous Souls these soils will have permafrost close to the surface so the soil doesn't move around a lot meaning its horizons remain undeveloped as well these are found mostly within northern Russia and Canada moving slightly closer to the equator well next find spawn assaults which occur in coniferous and boreal forest biomes these will be acidic due to pine needles falling to the ground and decomposing into acidic compounds because of this they're low in fertility these are primarily found in Scandinavia and the Canadian East Coast then we have alpha cells which have fair horizon development they're rich in iron and aluminum and are typically under broadleaf and deciduous forests and also some human Mediterranean climates these are mostly in the east coast of the United States and the Russian heartland a low alpha cells you'll have ulta soles which have a lot more iron in them making them very red these occur in subtropical locations very humid places like the American southeast and Southeast Asia I'm roughly the same plane ara ridicilous while Altos all's occur in very human places or riddles are desert soils with extremely low amounts of water just think arid or it assaults these are not sanded deserts however this is what an original looks like and this is shifting sand they're different because there's little to no water in these environments most of the small clay particles have been blown away by the wind leaving mostly heavier sand silt and gravel these are found in the Sahara Arabia Australia northern China and the western United States also roughly in this area are mala sauce these are dark soils and in terms of agriculture the most fertile soil order these occur in grassland regions like the American Midwest the Pampas region of South America and the steppe region of Russia lastly in terms of latitude we have oxisols these have low nutrient availability and aren't a very fertile but they do have the most horizon development of any soil order although it's hard to see because there's so much iron in the soil turning every layer this reddish orange color these are rain forest soils linked to the Amazon and the Congo then we have a few more soils that don't really fit into the latitude scheme these sort of just occur where they occur in this vague category first you'll have an de saucé think like the volcanic Andes Mountains this is recently volcanic soil ejected from a volcano these are surprisingly rich in nutrients and given enough time create lush landscapes think about the volcanic islands of Hawaii and Japan then we have histah Sol's these are wetland soils that means they're caked in water and usually feature peat there's also going to be a lot of undegraded organic matter which can form an impermeable layer if too much builds up due to the build-up of this organic matter these will also be highly acidic they're also unstable and dangerous to build structures on most of these can be found in Canada and river deltas and lastly we have vertosols these also have a lot of clay in them but they often dry out when they do the ground will crack and split and look like this when this happens soil on top will get blown into the crevices inverting the soil layers and preventing real horizons from forming the largest concentrations of them are found in India and Sudan there are of course more ways to describe soil and in fact for every order there's a sub order a great a subgroup of family and a series but holy crap we don't have enough time for that here's a map of the actual distribution of these soil types across the planet you'll see most of the new soils are close to the poles this is because until recently the poles were covered in glaciers from the last ice age so they haven't had much time to develop I'll leave a link for a bigger version of this map in the description you'll notice that the soil distribution is kind of sporadic and patchy and that's because latitude and humidity aren't the only things that determine where different orders of soil are found in soil science there's a common acronym porked that's used to remember the factors that influence soil formation first there's climate so rainfall and temperature and also humidity the climate of an area is largely determined by its latitude but also elevation and its surroundings then o means organisms like how pine trees will change in alpha saw into a spot us all over time with their acidic needles also soils need things like bacteria and fungi in order for plants to thrive R is relief or change in elevation mountains will channel water into valleys so you may find a hysto saw at a low elevation but an alpha saw or even an errata saw further uphill P is for parent material so if a soils parent material is volcanic rock you'll get an Indus all if the soils parent material is limestone it likely dissolved away and is therefore probably a clay and will also be rich in calcium and lastly T is time given enough time the into cells and septa cells will become more developed soil orders I think that's it I hope you enjoyed this video came right out of a college notebook of mine so these are all based on the USDA soil taxonomy and other places might have different ways of categorizing soils there's actually a ton more to learn about soils also so if you want to see a video called even more things about soils give this video a like and subscribe that's it for now thanks

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Views: 263,922

Rating: 4.9385543 out of 5

Keywords: Soil, dirt, soil taxonomy, soil science, taxonomy, classification, education, clay, silt, sand, earth, gravel, biomantle, entisol, inceptisol, gelisol, spodosol, alfisol, ultisol, aridisol, mollisol, agriculture, canada, usda, united states, russia, china, australia, sahara, oxisol, andisol, andes, histosol, vertisol, clorpt, parent material

Id: BArbrfmsxeQ

Length: 8min 20sec (500 seconds)

Published: Thu Jul 05 2018