Course talk:APBI403

Having a lot of difficulty with sorting the enzymes into one of the 4 classes provided, any tips?

Anyone else confused by Q1? Does "Calculate the activities of phosphatase in the organic and mineral horizons of the ag and forest soil samples" mean report and compare Ag and Forest samples in Appendix 7 or from the information shared by our groupmates?

Hi all,

Where can be find details pertaining to individual enzymes? (in reference to filling out the table)

Hi,

I am confused to how we enter the data in a way that can be shared with everyone

As of now we are missing data for half of the grassland and soil.. Just wondering how long we should wait for

What format should we be entering our data? Should we include a whole table of species names, abundance etc or just the numbers? (# species, Hmax etc)

Grad student presentations for SOIL 503 on Nov 13, 1:00-3:00 will be in room McMl 139 On Nov 14, 1:00-3:00 we will be in room McMl 170

Hi all, does anyone know the soil order of the soil series mud bay? It doesn't say it in the background info, and I can't find it online (maybe I'm just missing it...)

Hi Hannah, Mud Bay soil sample does not belong to any official soil series. So, it is not included in any of the soil surveys. It is most likely a Regosol (i.e., a weakly developed soil).

Note that Q7 in the soil respiration lab asks you to plot the natural log (ln) of Rs

For Q7, it says to plot using (Ts-10)/10 [x-axis], however on the excel doc it says only Ts for the column heading. I thought maybe you use Ts in excel and subtract 10 then divide by 10, but if you do it that way then Ts = 10 C is not in the graph.

Sarah, 1) You are on the right track Plot ln Rs versus the exponential(Ts-10)/10 Fit a straight line through the data points --> y = mx + b where y = ln Rs; m is the slope of the line, x = (Ts-10)/10 and b = intercept

The slope gives you Q10 The intercept gives you ln Rs at Ts=10 (or where the exponential = 0)

Ohhh! Thanks a bunch.

What is a continuous curve? Seems like you want a scatter plot because you wrote “(i.e. scatter in your plots)”, but to me that isn’t a continuous curve. I though maybe you meant to add curved trendline or to just use a line graph, but I really don’t know. Can you clarify please?

Yes, I mean a scatter plot of Rs versus Ts

I am confused with the units in eq 6. First, I am thinking that dCO2/dt is the average slope from Q2. If so, the units are ppm/sec or mass/volume/sec, right? If that is the case then how do you get F (µmol m-2 s -1)?

F (µmol m-2 s -1) = (m-3 x m3)/m2 x µmol/?/sec

Thanks.

The constant in etn 6 pV/A has units of umol/m2 dCO2/dt is the rate of change in concentration (per second) Thus units for F = umol m^-2 s^-1

Hi Sandra,

Question 1 asks to indicate the slope for the straight line segment of each replicate. Using excel or google sheets, you can add the y=mx+b equation to the graph but only from the trend line. Is this what you are looking for? If not, any idea how to isolate two points on excel and find the slope?

Amy

Hi Amy, to the best of my knowledge a linear trendline in xls takes the entire line; thus manually isolating your 1st and last point, and calculating the slope might be simplest. Fundamentally in question 1, I am looking for consistency in replicates.

I don't think I wrote it down, but do we have a volume for the chamber? We need it for equation 6 to answer question 3 in the respiration lab report. Thanks!

never mind i got it (for the rest of the people who don't know its in the manual)

For your reference, I have uploaded an example of a good final report (soil physics) from one of your classmate. See Assignments in canvas, Soil Physics final lab report. While the content will be different for final reports in soil chemistry and soil biology, the layout and structure of the report will give you an idea of what we are looking for.

Were we given the blank reading for available phosphorus? I just realized it is in the equation and I don't have it written down anywhere.

Blank reading was zero (0)

Please note that you will need to extend the standard curve (ie line) for the standard solutions of available P to capture readings of your samples. Some of your samples (but not all) had higher absorbance readings than the highest standard solution that Lewis made; hence, this recommendation.

Hi,

For #3 in CEC lab, I wrote down...

"equiv. wt = 195 = atomic weight of element/valence of element"

This doesn't make sense to me. Is it 195 for all exchangeable cations? Can someone help?

Thanks, Sarah

Hi Sarah,

As mentioned on p.35 of the soil chemistry lab manual, each element has its own equivalent weight. Hence, equivalent weight needs to be calculated separately for each of the 4 cations that we determined in the last week's lab, using atomic weight of element in question and its valence. Atomic weights of elements, can be found in the periodic systems shown on p.37 of the lab manual.

In the final report, I'm comparing agricultural and forest land uses of the same soil order. I compared the 3 Podzol soil from UBC farm, but I'm not sure whether we also need to compare 2 Gleysol and 2 Luvisol? Thanks so much.

Sophia, You have two choices. Either 1) compare the 3 different land uses on the same soil at UBC Farm OR 2) compare one land use e.g. agriculture on 3 different soil orders

Hi,

I noticed that for the final soil physics lab due tomorrow, the assignment sheet itself lists that it is due at 11:59 pm oct 11, 2019, but on canvas the due time is 1:00. Which time is correct?

Thanks Audrey Due time has been changed to Friday Oct 11, 11:59 pm (i.e. the later time) for consistency

In final physics report, regarding soil texture. I read the soil textbook of Brady that the soil texture needs a long time to be changed and it is difficult to be changed artificially.

I am thinking about the influence of roots to soil texture, whether it is a correct direction? What about topography like slope? but we do not have information about slope. Could you give me some hints?

Xin, you are correct that texture naturally changes very slow, and that management generally does not affect texture. Bio-chemical weathering of soil particles to change texture, as you suggest, is slow. Thus I am unclear what specifically you are thinking of with respect to roots.

Topography, i.e. slope, in a wet climate can result in erosion and downslope deposition of fines. As was discussed for UBC Farm forest site (this site is a lower slope position which is very wet in winter). In general management has limited impact on texture. However, depending on the site(s) you have chosen, activities such as road building, construction etc. can greatly disturb sites. Thus in many urban areas the upper soil horizons in particularly are changed.

Hope this helps, Sandra

"Material and methods: note that the section on materials and methods should be very short (i.e., it is sufficient to refer back to the lab manual), but be clear in stating how you are making your comparisons"

Should we assume that all the data was analyzed using the same methods as we used in the lab (for example, for soil texture that the simplified method was used), or should we mention all methods that can be used? Also, what do you mean by "be clear in stating how you are making your comparisons."? I'm not sure how to tie this into material and methods section.

Hannah, you can assume standard methods were used for all parameters provided. What I would like in methods is a short statement about what you are analyzing (if that is not already in the intro) and how, i.e. are you using summary statistics for individual parameters, comparative graphs or ?