Soil and Soil Dynamics

006 - Soil and Soil Dynamics

In this video Paul Andersen explains how soils are formed and classified. Weathering of rock creates particles which are mixed with water, air, and organic material. Soils are classified according to particle size, chemical makeup, and horizon distribution. A brief discussion of soil loss through erosion, compaction, and salinization is included.

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Music Attribution

Intro
Artist: CosmicD
Creative Commons Atribution License

Outro
Title: String Theory
Artist: Herman Jolly

All of the images are licensed under creative commons and public domain licensing:

[MKTV]

Dr. Andersen, I still remember watching your video lecture series on AP Biology from my junior year in high school. Four years later I'm in college taking a very challenging course in soil sciences, and I managed to find this video where you clearly and concisely reviewed many of the major topics in the course. I just want to thank you for all of your efforts to support open source education, and for being such a good teacher.

Thanks, -Mike

[Tdavefnm]

sums up my whole semester in 9 minutes on soil science.

[OliverLower]

A clearly explained presentation which was easy to understand. Thank you

[brayne]

As an environmental/wetland/soil technician, that was a pretty good intro for people who are interested in environmental science. A great deal of environmental work (both public and private) deal with soils. Some advice for majors... don't expect the job resulting from an environmental science degree to be easy (if it does involve the major). Expect political stress in the public sector, while also enduring both physical and mental stress if you choose to take a job in the private sector. Environmental consultation (and regulation in some instances) is not an easy job... expect to deal with extreme summers, unsatisfied clients/citizens, bugs, some good ole fashion auger digging (in rocks if you are unfortunate), and regulatory grey areas. It is part of the job, however, it is all for the benefit of knowing that what you are doing according to the law (whatever that may be in your state) is sustainable.

[dicygirl]

Mr. Anderson is the reason I was able to get my undergrade. I love these videos and how he breaks everything down and explains topics so clearly. I am able to not only understand but absorb the material. You are the best teacher!!

[FaZeZombieslayer]

im watching your videos as homework, but i find them quite interesting and cool. way better than school

[pluckyfella]

6:02: “What is the perfect soil? Well, if we have about 20% clay and we have about 40% of sand and [40% of] silt, we have what is called a loam”. Ah, yes, Horticulture wisdom like lovely music to my ears lol. And good Soil Science stuff ; may I please commend you Paul Andersen courtesy of Bozeman Science. A wonderful video, thank you.

   Sorry for the length, but this is something useful that I have learned from my Horticulture studies, that others might find helpful to solve a soil texture problem that they may have.

Medium Loam IS the best soil, in retaining a temperate amount of water yet drains any excess, always moist but well-drained, has the right cosy conditions for the soil food web to drink water, breathe air, and eat humus, retaining nutrients without leaching due to rainwater just flushing through, has just the right balance of airpores, waterpores and micropores, to make this soil an absolute pleasure to work with, with the least maintenance and the least work, no-dig, chlorine-free watering, no -icides of any kind, all organic, having dozens of earthworms, with abundant fungi and bacteria to counteract pathogenic bacteria and fungi that causes diseases. It also provides the loveliest home for ground beetles and rove beetles, ladybirds and lacewing larvae to live to eat up all of your pests. Adding 5% of the soil's volume as compost helps the crumby, granular structure as well, besides inoculating or feeding the soil food web, though one can add a 1 inch layer of compost once a year. Like humans, plants need to breathe in oxygen and breathe out carbon dioxide but stuck in the soil, thus air must be able to enter the soil, and for most of the carbon dioxide to exit the soil without being trapped and thus poisoning the soil and its creatures, though some carbon dioxide is converted into carbonic acid H₂CO₃ to aid in releasing minerals.

  That is the very first golden rule of Horticulture that I learned in my classes for my Level 2 diploma. The 40-40-20 law. It is also called Medium Loam because it is right in the middle of a circle of Clay Loam at 12 o'clock, Silty Clay Loam, Silty Loam, Sandy Loam, Sandy Clay Loam on the Soil Triangle chart; and also because it is midway between light (sandy) and heavy (clay), and is the happy medium as per the Law Of Temperance, no deficiencies, no excesses, temperate.

  Yes, as the video says : Forget working with heavy clay ; it is no fun, which I know firsthand, and you don't have to suffer the hard way when your spade is working with sticky clayey soil that might just as well be setting glue lol.

  It is good and wise, though sometimes difficult, to temper your soil texture, to change it to Medium Loam, harder to do in larger areas, but doable with some effort and patience. Here is how to do it:
● Find out how much sand, silt, and clay that you presently have in litres, from ascertaining your texture percentages from a combo Jar Test/ Hand-test.
● Find out how much sand, silt, and clay that you SHOULD have in your soil in litres by 40-40-20, taking into account the amounts you already have in the soil.
● Add the deficits in litres to your soil.

For example, let's say that you have a bed or border of 6 feet long by 3 feet wide.
Suppose you have 38% sand, 32% silt, and 30% clay. You want 40-40-20. Thus this has too much clay though, not good, sticky and gets waterlogged fairly easily. I normally use 7 inches as a general depth, but we'll use 6 inches for our illustration.

You use inches to convert into litres later. Convert 6 feet and 3 feet into inches respectively. Let's select a depth of say 6 inches. 72" x 36" x 6" = 15, 552 cubic inches = convert into litres = 254·85 litres ; that is that bed's volume as a whole. 45% is the mineral part comprising of the sand, silt and clay; 5% is the compost.

In our illustration, with 38% sand, 32% silt, and 30% clay, the present amounts would be
43·58 litres of sand,
36·70 litres of silt,
34·40 litres of clay.
(254·85 litres x 0·45%) x 0·38% sand = 43·579.

Our soil in our illustration should have
45·87 litres of sand,
45·87 litres of silt,
22·94 litres of clay.
(254·85 litres x 0·45%) x 0·40% sand = 45·873 litres.
Required amount minus current amount = amount to add. RA - CA = AA.

45·87 litres of required sand amount - 43·58 litres of sand = add 2·29 litres of sand.
45·87 litres of required silt - 36·70 litres of silt = add 9·17 litres of silt.
No need to add any clay here; adding the deficits of the missing elements makes the clay 20% by proportion anyway. You don't count what you have an excess of OK? Just add the deficits. Be aware of say 90% silt with 10% clay; you will need to add more silt to 100% and another 10% sand to counterbalance the 10% clay to 40-40-20.
As for the compost, that works out as 254·85 litres x 0·05% = 12·74 litres of compost. After adjusting your soil, adding a handful of montmorillonite or vermiculite clay with your 5% compost helps improve the CEC.

 Beware of the erroneous myth of "forming concrete from changing your texture in adding sand and clay" as it takes a special kind of sand or builder's sand mixed with a special mixture of cement, usually Portland Cement, to make concrete, as most sands cannot make concrete. So long you have 40-40-20, not using building sand, it will not form concrete OK? More than 50% silt and very low clay can form a hard paste that resembles concrete blocks, but that is way too much silt anyway. Horticultural /natural sand and natural silt doesn't form concrete.

 Getting the sand is relatively easy ; you can buy clay as pellets from amazon or a nursery or naturally if legal; but getting the silt can be quite difficult, unless you can find a gently-sloping high riverbank of a tidal river coming in/out from/to the sea at low tides at quarter-moons with pure silt or mostly silt and lawfully dig up shallow spadefuls along a span without any harm to the environment or wildlife, or contact your Internal Drainage Board or local de-silting company to get some (the high tides is replenishing the silt layer anyway). If you do get silt from an inlet river coming in from sea, it may be slightly too salty at first in affecting seed germination and stunting growth, yet adding LIME to the silt and soil in temperate amount will remove excess sodium, say 75-100 grams of lime per square metre.

In the UK, some selfish, greedy 'environmental services" idiots wrongly regard silt as "environmental waste" — absolute bullsh, as nature recycles everything, so clean it and re-use the silt for your garden our allotment -- screw the stupid world out of touch with nature. Ask the Environmental Agency of your area for permission if you have to, as sometimes, there is the risk of introducing nasty non-native crayfish eggs or very invasive foreign plants like the Himalayan Balsam laid in the silt, hence in some cases silt needs to be treated silt and/or cleaned silt (just simply heat at 100°C — problem solved). Silt looks grey-yellow on riverbanks in aerial photos, and feels very smooth like flour. Excess silt clogs up rivers, so de-silting companies are always removing silt somewhere, at least in England where I live, if you can obtain it from them, the hard bit being finding it! In the US, the Mississippi River is notorious for its humongous excess of silt.

  Adding tonnes of compost is only a second-best, imperfect method that is not permanent, very costly, always deteriorating and needs constant replenishing, while it does not change the texture at all, only opening up airpores temporarily as per structure, a depressing fight against nature all the time. Inorganic stuff is permanent ; organic is not, so why go to all the trouble of adding tonnes of temporary compost a few times a year every single year that costs a bloody fortune to make a pseudo-loam on top of crap soil that is practically now the subsoil? It is OK if you are rich and retired though not ideal a method! lol. Charles Dowding must be bloody joking or mad if he expects me to put 680 litres of compost per bed of TWELVE 12' x 4' beds for a 6 inch thick bed of compost EACH for supposed 'organic gardening', for my allotment, costing a grand or £1000 (144" x 48" x 6" = 41, 472 cubic inches = 679·60 litres; 680x12 = 8, 160 litres), that needs topping up regularly. Sod that; a 'clear solution' it is not. I am not a retired millionaire! In soil microbiology, there's currently too much focus on structure and completely ignoring soil texture, the prime thing. Change the texture. The soil food web really only exists at its very best in Medium Loam anyway. It is best to go for a much more permanent amendment in the long run that you only need to do once, with perfect results with the least work long-term. Apologies again for the length lol. Agape. Andrew.

[atifazim]

It was not helpful, it was very helpful. My professor explained me this in the class but I didn't understand anything but you made it so simple and easy.

[michaelmead]

As a Certified Crop Adviser with a Masters degree in soil science and 40 years of experience, this is the best 10 minute video I've ever seen on basic soils. Great Job Mr Andersen!!

[nosleepdelirium]

8 years later and still THE best videos for a companion for college classes. no nonsense

[carlinbh]

That was very helpful, thanks! I'm from Brazil and I'm studyng geography to be a teacher. Thanks for the subtitles in english, It helped me a lot!

[whoareyou]

I am hooked to soil science, I am loving this information and wanted to thank you for sharing!

[wellness]

Outstanding! researching where to take online classes with this guy!

[muqffxd]

2023
Hats off sir..❤ It is still relevant and benefiting even in the age of chatgpt and bard.

[soniagarcia]

Finally a clear explanation in only English! Thx a lot.

[tirelesssoul]

👍👌👌👌
9 mins videos = 90 pages information
Clear and good

[MooMooMath]

Another example of why Bozeman Science is so helpful.

[MommaKnowsBestest]

This has been so helpful with my family

[theonewiththename]

was just sitting in my living and out of nowhere just started thinking about soil and what the heck it actually is, wow this was overwhelming in the coolest way

[thebroomsweepergaming]

2:25
*Rock:* Mr.Anderson... I don't feel so good...