I am wondering if it would be possible to elaborate on what is expected of us on question 4 of the lab assignment (#7). Are we supposed to choose the soil order that best fits the data and then list its diagnostic order(s)? Or do we identify all the horizons listed in the data that COULD be diagnostic horizons for various soil orders based on the thickness associated with each of them, and then choose one soil order that best fits the data? Also, in regards to identifying the soil order, am I correct in assuming there is one that is the best fit given the data provided or could there be multiple possible soil orders and we are supposed to list all of them?
For question #4 in the lab assignment #7, we expect 2 very short answers - 1st in which you will identify the diagnostic horizon(s) and 2nd in which you will identify the soil order. We do not ask for any elaboration in that question.
In some soil orders there are 2 (or more diagnostic horizons) since there are 2 (or more dominant soil forming processes). This is true for real-life situations and for some of the soil profiles listed in your question #4.
Let me give you an example of a soil profile with its horizons shown from the soil surface to parent material, to illustrate soil with couple of diagnostic horizons. Pls note that this is a different example than those mentioned in the question #4:
Both Bg1 and Bg2 are diagnostic horizons, for this soil that belongs to Gleysolic order.
So, one 1st needs to identify the diagnostic horizon(s), which imply the type of dominant soil forming process, and then one can identify the order. This also means that you guys have to learn what are diagnostic horizon(s) for each of the 10 orders and also what are the soil forming processes represented by those diagnostic horizons.
Last edit: 23:07, 27 March 2020
Virtual lab 7 is posted - see lab assignments in the course wiki or assignments in Canvas
1. Watch the lectures (posted on the course wiki) related to soil classification (March 23, 25 and 27)
2. Read the lab manual (i.e. pages 71-85) which provides information on soil horizons and the Canadian soil classification system including summaries for each soil order (complimentary to your lectures)
3. Review the video clip which gives an overview for this virtual lab (link is provided under assignments in the course wiki and in canvas)
The lab assignment itself is posted in both pdf and microsoft word format. Once you complete your assignment upload it to canvas using the assignment tab. Due date for lab #7 has been extended to April 2, 2020.
At 8:21 in Part 2 of the Wednesday, March 25th lecture, Maja skipped over the slide on the luvisolic order without saying anything. I think she might have accidentally progressed two slides forward instead of one. Will this slide be covered in a future lecture, or should we self-study and learn about it on our own?
Upss ... sorry about that & thank you for letting me know! I'll add a small, additional video about Luvisolic order by the end of today (Mar 26).
In the meantime, relevant info about this order, can be found in the lab manual (lab #7) and also in this video https://classification.soilweb.ca/luvisol/
Hello! For the lab assignment, specifically, question 1 in which you are asked to describe the specific soil-forming process, is the question asking us to list which "element" is added (ie Bt forms with the enrichment of clay) or is it asking for soil-forming process in terms of additions, translocations, transformations, and losses? Also, for question 2, should the answers be specific horizons with suffixes or just A, B,or C? What I mean by this is for part b)"the horizon is the uppermost mineral horizon that is often enriched with organic matter originating from the overlying organic horizon and from plant roots" - from my notes I can tell this can either be just A or Ahe.
Thanks very much!!
For question #1 in the lab assignment #7, you need to provide the name of the specific soil forming process. Remember, those 4 (broad) groups of soil forming processes include several specific soil forming processes. The specific soil forming processes are mentioned in the lecture on 10 soil orders. For each order, I mentioned what is the most dominant soil formation process. Hence, you might want to review all of those lectures, before you start working on this lab assignment.
Regarding question #2, it really depends on the specific question.... some answers could be without suffixes, while others must have include suffixes....
I'm doing the lab right now, and one of the monoliths that I'm looking at has vertical bars preceding some of the horizon symbols. What do these bars signify?
In our Canadian soil classification system, there are many additional descriptions (and associated suffixes and prefixes) of soil horizons, besides those mentioned in your lab manual & my online lecture notes. Those Roman numerals, shown as prefixes, are one of those examples that we skipped in this course.
Since they are not explained in lecture and/or lab, you can skip them in your explanation too.
I'll provide here a simplified explanation of the Roman numerals, but this is NOT of relevance for our Introduction course. So, read it if you are interested, but otherwise pls ignore.
Roman numerals indicate lythological discontinuity within the soil profile. This lythological discontinuity is due to a different mode of deposition, which means that some soils will have horizons that have formed on different types of parent materials, and those parent materials got deposited on the top of each other.
Just watched the soil bloopers.
Hi, Professors and TAs. I am confuse on behalf of how bonus assignment will be marked. As shown in wiki, we can upload up to 3 assignments, one per category, but it had also state that if we submit more than one only the most recent one will be marked. May your explain how this is gonna work, thank you!
The maximum number of bonus assignments that we will mark is 3 (one assignment per category).
Some students are keen to submit more than 1 meme (or more than 1 news articles), which is perfectly fine, but regardless of how memes (or news articles) are submitted only 1 submission per category will be marked.
Hello Maja and Sandra,
I was just watching the lecture videos for lecture 29 on classification and soil horizons. First off I just want to say thank you to you guys, so far so good and I think that you guys are doing a great job given the online circumstances.
I just noticed though that on the Part 3 video for this specific lecture, the video seems to stop at slide number 22 where Maja talks about "W" - water, and then the video ends. I know there's not much content left after that (2 slides), and can figure out the next slide or two left on my own, but I just wanted to know about the very last slide where it says "Can we have a ..... horizon? And then the following are listed:
"Af, Ahb, Ot, Bfh, Czk, and Btgj".
For myself and I'm sure others, which of those cannot exist?
Cheers and thanks again.
Thank you for letting me know. In order to watch the full video that is longer than 15 min (like the one that you mention), you have following 2 options:
a) watch it on a computer, since computers have more memory than phones, or
b) download (free) DropBox app to your phone, and watch the video through the app.
Without DropBox app, one can only get a 15-min preview, which happened with the video for Part3.
As for which combinations of horizons can exist, wait to review lectures for Mar 25-27, since you need additional info from those lectures to be able to answer this question.
Hope this helps
Hi, I found a soil news that interest me a lot, however, it is published on January 29th, 2019, which is 13 months ago, is it still okay? (I understand the instruction says within a year, but is it okay to be slightly longer than one year)
Online lectures for next week (Mar 23-27) are posted in wiki at Lecture notes page. Please note that you do NOT have to attend online lecture in real time, but please do review them. The topic of soil classification is very important and you need to learn the basic principles.
Online lab #7 on soil classification is also posted in wiki (at Lab assignment page) and lab assignment #7 will be posted in Canvas very soon.
If you have any questions about these online lectures, please do not hesitate to post them here in "Discussion forum".... just remember - to post anything in wiki, you need to login with your CWL
Take care & stay healthy and safe
Hello! I have just finished the lecture slides from today (March 23) and was wondering about the abbreviations, or letter used to describe soil horizons. Can you only use a capital letter with a lowercase letter(s) (ex Ah, Bh, Bmk, etc.) when describing a soil, or can you use just a capital letter to describe a soil? During the slides, it was mentioned that the C horizon is the only horizon that has a specific horizon with just a capital letter (C - no particular properties, similar to parent material).
Thanks very much!!
Thank you for reviewing those online lecture videos. It is good to know that at least someone has seen them ;-)
In soil science literature (and elsewhere) you will see mineral horizons (ie A, B, and C) both with & without lowercase letters. Which version is used, depends on the context in which one is referring to those horizons. In a general context, when it is not important to indicate the soil formation process for a specific horizon, we can just use capitol letters (A, B, and C). However, in soil classification context & when it is relevant to mention and/or emphasize the soil formation process in a specific horizon, then lowercase must be used.
The C horizon is one exception, since in that horizon there may not be any soil formation processes going on. And when that is the case, we simply use label - C. On the other hand, A and B horizons, always have at least one soil forming process.
Hello! I have just submitted my soil meme, however it did not upload "alone" but rather as an addition to "soil supports all life on earth ---Yunica(xinyu) Wang" 's meme. Is there any way to fix this, or will this format be okay?
Thank very much!!
Thank you for letting us know. It's OK to keep your meme (good one by the way) as is. When checking memes for bonus marks, Sandra & I go to the 'history' page in wiki where names of everyone who posted something are shown. And your name is there (I just checked).
I am currently looking over Soil Chemistry 1 lecture (soil pH, salinity, and ion absorption) and was wondering if the plants are able to access and use nutrients from both the exchangeable and active acidity or only the active acidity? I know that plants can only access nutrients in the soil solution, and am unsure of whether or not exchangeable acidity is included in soil solution?
There is a bit of confusion here about couple of concepts. So, let me address 1st nutrient availability and then acidity part of your question.
Plants can only take up ions from soil solution. Ions that are on the exchange complex (ie electrostatically adsorbed on negatively charged soil particles) need to be replaced (or exchanged through reversible reactions of ion exchange) with other ions from the soil solution. Through that exchange ions that were on the exchange complex are pushed into the soil solution, where they are available to plants. While ions are on the exchange complex, they are NOT available to plants.
Active and exchangeable acidity only refer to Al and H ions, not nutrients. But from where (soil solution vs. exchange complex) Al and H ions are available to plants, the explanation is exactly the same as described above.
Do we need to download any special software to write the online midterm, or will it just be held through Canvas?
Blaise The exam is via canvas. No special software is required for this midterm exam. IF you have not already done so, please look at the practice exam. You will have 50 minutes to write the exam & the exam needs to be written during your regular class time.
Hello! I'm hoping to match up my understanding about nitrogen transformations from lecture and from the relevant content on Soil Food Web. Would it be accurate to say that N transformations include: immobilization, mineralization (which incorporates aminization, ammonification, and nitrification), ammonium fixation, ammonium volatilization, and denitrification? All of these seem to involve a transformation of the chemical form of nitrogen in question, except, perhaps, for ammonium fixation, where the NH4+ appears to just get trapped in the phyllosilicate or humus complex. Thank you.
In the answers to practice exam question session #2, the answer to question number 3 says high CEC occurs at low pH. I am confused, because I believe high CEC should occur at high pH, since more H dissociate from functional groups on SOM at high pH, thus increasing the CEC. Could you please explain where my thought process goes wrong?
Last edit: 03:00, 20 March 2020
Please read the provided answers carefully.
Question 3: What soil properties enhance nitrate (NO3-) leaching losses from soil?
1. Humic climate 2. Significant nitrate in the soil 3. Coarse texture 4. Low AEC
although we recognize that the wording may not be very clear in relation to AEC
This is the quote I am referring to "Soil properties that would enhance nitrate (ie an anion) leaching are: ... High CEC (which also means low AEC), such as soils high in clay + high in OM at low pH ".
It is totally possible that I have simply misinterpreted this sentence. Could you explain what this sentence means?
Blaise, you are correct that sentence should be modified. In soils with high clay and high OM at HIGH pH - CEC will be high (which also means AEC will be low). The answers posted on the wiki have been modified and reposted.
Can someone explain how potassium fixation by phyllosilicate clay minerals occur? I'm not able to understand the diagram in the slides.
Potassium fixation is analogous to ammonium (NH4) fixation: the process amounts to “lock up” K ions in the interlayer spacings of 2:1 phyllosilicates. Weathering at the crystal edge can make fixed K available, but this release can occur only slowly. A significant portion of applied K-fertilizer may become fixed and therefore made unavailable in soils containing abundance of these type of 2:1 minerals (called fine-grain mica or ilite).
HEY!! I just had a quick question about exchangeable acidity and BS. Since exchangeable acidity is the acid cation on CEC and BS is about the base cations on CEC. Does it mean when exchangeable acidity is high, BS is low? (They are opposite?)
Yes, that is correct. High base saturation (BS) implies that there will be a high number of base-forming cations (Ca, Mg, K, and Na) on exchange sites, and it also means that number of acid-forming cations (Al and H) will be low on those same exchange sites.
I'm not really able to understand how mycorrhizal fungi help plants get more phosphate ions? I kinda get the part of them having greater surface area coverage but other than that I don't understand why they are useful. Could someone help?
In soils with low solution phosphorus concentration and high phosphate fixation, slow diffusion may seriously limit the ability of roots to obtain sufficient phosphorus. The hyphae of symbiotic mycorrhizal fungi help overcome this problem. The fungi "explore" the much larger volume of soil than even fines root hairs can, absorb the available phosphate ions, and by cytoplasmic streaming inside the hyphae, transport phosphates to the host plant. This makes the plant much less dependent on the diffusion of phosphate ions through the soil.