Course talk:APBI403

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N-Acetyl-Glucosidase?021:10, 8 December 2017
Respiration: Q8, regarding the graphing019:21, 7 December 2017
Re 101:30, 7 December 2017
Corrected biology reports000:34, 6 December 2017
Conversion factor, lab 11223:29, 3 December 2017
A question about soil biology final assignment023:30, 27 November 2017
Soil Biology Lab 3120:21, 25 November 2017
Data sharing for soil biology labs004:55, 15 November 2017
Fe conc. in Soils409:20, 12 November 2017
Soil chemistry summary report deadline extended (again) - due on Nov 13014:37, 10 November 2017
one more question re. summry chemistry report018:17, 8 November 2017
lab 07 question5 121:00, 7 November 2017
Metal and phosphorus data for the chemistry section summary217:57, 7 November 2017
Soil Chemistry Paper117:55, 6 November 2017
A question about soil chemistry final assignment320:51, 3 November 2017
Lab 7 Question 2a123:22, 2 November 2017
Samples are ready for weighing000:54, 2 November 2017
Lab 6 question 2.b100:06, 31 October 2017
A question about Assignment 6605:26, 30 October 2017
Texture data -- summary report204:47, 30 October 2017
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Has anyone found anything on N-Acetyl-Glucosidase? I've been looking for it online, but so far no luck. Or is it supposed to be N-Acetyl-Glucosaminidase? It'd be greatly appreciated if you could share what you found on it. Thanks!

21:10, 8 December 2017

Respiration: Q8, regarding the graphing

"8. Plot the continuous curve of Rs [x-axis] versus Ts [y-axis]..." I thought Ts (independent) should be on the x-axis. Could you clarify why Ts goes on the y-axis in this case?

19:21, 7 December 2017

How do we calculate Re, do we have NEP, NEE or GEP?

21:14, 30 November 2017

Matty, for question 2 - do a relative comparison of Rh and/or Rrhiz to Re

01:30, 7 December 2017

Corrected biology reports

Hi Sue. Would it be possible to get back the corrected reports for the soil biology part of the course, before the deadline of the biology summary assignment? Or should we expect to write the summary report without the corrected lab reports?


00:34, 6 December 2017

Conversion factor, lab 11

For lab 11 we need a conversion factor to go from dV/dt to dCO2/dt which was supposed to be on the multi-meter box. I don't think the forest group recorded it - is there a way to obtain it?


06:22, 29 November 2017

the number is probably different, but you don't get it maybe you could use grasslands... its 11.3

21:13, 30 November 2017

I got it from Sandra, it's 8.1. But thanks!

23:29, 3 December 2017

A question about soil biology final assignment

Could I use the average value of pre and post-harvest if I choose to compare data between organic and mineral horizon?

23:30, 27 November 2017

Soil Biology Lab 3

Hello, In lab 3, what does "assay wells" in Fassay refer to? Which wells are these exactly?

Thank you Diana

20:02, 25 November 2017

Found the instructions on connect. Please ignore the above post.


20:21, 25 November 2017

Data sharing for soil biology labs

Has a table been created so we can share our data from soil biology lab 1 and 2 ? I can't seem to find it...

04:55, 15 November 2017

Fe conc. in Soils

Does DTPA-TEA method equally extract irons in both ferrous and ferric states? I thought it could explain the low Fe in Bf and Bhf of Podzol if DTPA-TEA method favors extracting ferrous states, assuming Fe in Podzolic B is predominantly in ferric state.

03:03, 10 November 2017

Hi Taku,
Good question. And yes, DTPA-TEA method does extract bot ferrous and ferric Fe forms, since both of them are plant-available forms.

06:32, 10 November 2017

OK. Thank you, Maja! I think I'm going to figure out something else...

03:12, 12 November 2017

But if the DTPA-TEA extracts both, low Fe in Podzol B cannot be explained like this.

03:18, 12 November 2017

I'm kind of looking at this by the opposite way. Fe in the Podzol B appears relatively low because most of other mineral soils have very high Fe. Crescent, Delta, Ladner soils are underlain by rocks containing a high concentration of sulfide minerals which most likely is composed of pyrite. The oxidation of pyrite increases Fe2+ in soil solution which is further oxidized to become Fe3+ both of which are extracted with DEPA-TEA, which can also explain why Gleysol in this area is so acidic in natural conditions.

But, also, I think Fe2+ and Fe3+ well-solubilized by DOM are lost from Podzol B by lateral seepage during the wet season. As for the Podzol Ap, I think some disturbances after the clearing of original forest increased Fe content.

09:20, 12 November 2017

Soil chemistry summary report deadline extended (again) - due on Nov 13

Hi everyone,
It just dawned on me that Monday (November 13) is a holiday (in lieu of the Remembrance Day), so I'm happy to extend your deadline for the soil chemistry report to Nov 13 by midnight.
Also, I will not be done with marking of lab #7 assignments until Sunday morning, so that is another reason for this additional deadline extension.

19:33, 27 October 2017

one more question re. summry chemistry report

Q. Is it okay to use only one pH value (eg. measured in CaCl2) and one organic matter value (eg. oven dried) for each sample in our analyses?
A. Oven-dried value for soil organic matter is the correct value to use when reporting on soil organic matter. You were give the air-dry values so that you can determine the difference between the 2 set of values which would then allow you to comment on the hygroscopic water content.
As for 2 sets of soil pH values, you can use one of them, unless you want to discuss the difference between two sets of pH values (similar to last week's assignment).

05:40, 8 November 2017

lab 07 question5

Hi Maja, What is the unit of t electrical conductivity that we got in the last week? Should we do some calculations of the data or we just put our data directly? Thanks for your reply.


20:48, 7 November 2017

The unit for your readings of electrical conductivity (EC) is mmho/cm (which is equivalent to dS/m).
No calculation is necessary for EC, just report your data

21:00, 7 November 2017

Metal and phosphorus data for the chemistry section summary

In the instruction PDF for the chemistry section summary, it says "... using ALL the data ..." Does this mean we are expected to use the phosphorus, EC, and metal contents data (DTPA-TEA) too? I was wondering this since the weekly assignments did not include the interpretation of these data.

22:49, 6 November 2017

Yes, Taku you should use those data too.
The weekly assignment did not include that data to shorten that last weekly assignment and allow you more time to work on the summary chemistry report.

16:59, 7 November 2017

OK. Thanks, Maja!

17:57, 7 November 2017

Soil Chemistry Paper

Hi Maja,

I was wondering if you would consider forage grass as the same land-use as potatoes/onions. Like is it still considered agriculture land? and if it is, would a forage grass site not experience as much human management compared to the onions/potatoes which may require more management?


23:34, 5 November 2017

Hi Mathew,
Since we don't have much info on the management practices done on any of these sites, it is OK to consider both forage grass and vegetable - potatoes fields as part of the agricultural fields.

17:54, 6 November 2017

A question about soil chemistry final assignment

It said we should consider 13 samples as mineral soil or organic soil. Can we group Podzol and Solonezt together as mineral soil even they are different soil types?

06:38, 3 November 2017

No, pls don't do that since they are very different

12:38, 3 November 2017

Hey Xiaoying,

I was just wondering how you determined the soil order of the 13 soil samples if the tables didn't show what order they belonged too?

17:36, 3 November 2017

I look into the background information of 13 samples. Some tell me soil orders but some not. I think the features of soil which provied by background information and connect them to the features of basic 10 soil orders, then I can figure out which order the sample belongs to.

20:51, 3 November 2017

Lab 7 Question 2a

Anyone else have ideas as to why we chose loss on ignition method? I could only come up with it being potentially cheaper than dry combustion since a special induction furnace isn't used and it can be safer than wet combustion since acids are not used.

I'm thinking maybe the product of ash that can be used for elemental analysis might be a bonus but I'm not 100% sure. If any of you have any other ideas I'd love to hear them! thanks!

05:45, 2 November 2017

Hi Matthew,
I was hoping that someone else will be willing to share their ideas, but alas...... they are all quiet. But you are definitely on the right track with your reasoning.

23:22, 2 November 2017

Samples are ready for weighing

Hi everyone, I just put all crucibles and Al-boats in 3 desiccators, which are now placed next to 2 balances in MCML102A lab. You can come at any time after 9 am either tomorrow (Nov 2) or Friday (Nov 3) to weight your sample.
Once you are done weighing, discard your soil samples into one of collection bins in MCML102A
When taking samples out of desiccators, pls be careful not to spill your sample over other samples

00:54, 2 November 2017

Lab 6 question 2.b

Hello, I don't understand what exactly we need to compare in question 2.b. It says "differences in pH values obtained by the two methods". Do we need to subtract pH (water) from pH (CaCl2) and compare these differences to organic matter content?

23:12, 30 October 2017

Yes, that is exactly it. And in the discussion to accompany that comparison, you should explain why certain samples have quite a large difference between pH values determined in water and in a salt (CaCl2) and others don't. Also, what does that difference tell us about soil's capability to resist pH change when we add bases (eg lime) and acids (eg N-fertilizers) to the soil.

00:06, 31 October 2017

A question about Assignment 6

Dear Maja, I am confused about the features of oven-dry organic matter content. Is there any relationship between the exchangeable Al charge and oven-dry organic matter content?

15:49, 28 October 2017

Not sure to what question in lab assignment #6 are you referring to? <dr> Here are some notes re. soil organic matter, its determination, and charge formation:
Soil organic matter content is determined by drying in a muffle furnace (not oven) and that is one of the methods of determining soil organic matter. Furthermore, soil organic matter is one of the soil components that carries quite a bit of charge, but Al is not part of structure of organic compounds. Charge on organic compounds is formed on functional groups (eg carboxyl and OH groups) and type of charge (ie negative, positive or none) is driven by pH of soil solution that surrounds organic compound in question.

16:40, 29 October 2017

The difference of value between two methods and oven-dry organic matter content. I think some components of organic matter will volatilize during oven-drying. How oven-dry organic matter content relate to the difference of value between two methods? And the difference of value should be the concentration of H charges or the number of PH?

22:06, 29 October 2017

Hey Morgan,
Question #1 in the lab assignment #6 is asking to "... compare the two sets of values for soil pH and explain the differences in the values obtained by the two methods." Hence, two sets of values that should be compared are soil pH determined in water and soil pH determined in a salt (ie CaCl2).
As for determining soil organic matter by loss on ignition method, the basis for that method is that ALL organic compounds are burnt off at the temperature of 600C.
Soil pH determination is done on air-dried samples (as is the typical procedure in preparing samples for soil chemical lab analyses), not on oven-dried samples.

23:09, 29 October 2017

Dear Maja In Question #2 b), it uses oven-dry organic matter content.Why use oven-dry organic matter not air-dry organic matter?

02:28, 30 October 2017

In Friday's lecture, I explained the reason why soil organic matter determined by the loss on ignition method on air-dried samples needs to be corrected. Please take a look at the lecture notes for last Friday (Oct 26) that are posted in Connect.

04:25, 30 October 2017

Texture data -- summary report

There are a couple of texture data that add up to be greater than 100%. I was wondering if they were typos? Or, am I missing something... Podzol, alder forest, Cg => 102% Podzol, cultivated mid slope, C => 101% Gleysol, Delta, 7.5-15cm => 110%

00:43, 30 October 2017

HI Taku I see everything rounded to 100% with the exception of Cresent 7.5-15 cm, % silt should be 65%. Spreadsheet has been corrected.

03:32, 30 October 2017

Thank you!

04:47, 30 October 2017
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