UBC Wiki - User contributions [en]

Thread:Course talk:APBI200/Suggestions for final exam questions/reply (5)

2016-04-14T01:27:16Z

DavidXiao: Reply to Suggestions for final exam questions

I would like to vote for any question on nitrification, ammonification and their role in the nitrogen cycle! ;)

Thread:Course talk:APBI200/Notes for Essay - Lab 8

2016-04-12T21:44:54Z

DavidXiao:

1. Does anyone have a rough age for the different horizons of the ubc podzols? I'll assume the agriculture a horizon is around or less than 100 years old.

2. Does the glacial till parent material come from glacier movement originating from the north shore mountains or further east?

Thread:Course talk:APBI200/Notes for Essay - Lab 8/reply

2016-04-12T21:44:28Z

DavidXiao: Reply to Notes for Essay - Lab 8

3. How is the C layer of these soils formed? is basal till, weathering and deposition of bedrock by glacier movement an adequate explanation?

4. Why does rainfall not significantly decrease the pH of these soils? excess rainfall leaches base cations from the soil, increasing the percent of Al3+ and H+, as well as rain being naturally slightly acidic. the pH we got was a consistent 6.5 which is neutral. What is the natural pH of the parent material? is it relatively neutral?

Thread:Course talk:APBI200/Notes for Essay - Lab 8

2016-04-12T21:23:22Z

DavidXiao: New thread: Notes for Essay - Lab 8

1. Does anyone have a rough age for the different horizons of the ubc podzols? I'll assume the agriculture a horizon is around or less than 100 years old.

2. Does the glacial till parent material come from the coast mountains or from glacier movement originating from the north shore mountains or further east?

User:DavidXiao

2016-04-08T01:12:15Z

DavidXiao: Created page with "super dirt nerd"

super dirt nerd

Thread:Course talk:APBI200/answer key for Discussion Qs/reply (2)

2016-04-08T01:11:32Z

DavidXiao:

Hey jia, I have some notes for both discussions if you can find me on facebook, i left you a message on your wiki user discussion page

User talk:JiahuiXiong

2016-04-08T01:07:45Z

DavidXiao:

Did anyone take notes for the last PPT for the clay with different meanings (bonus question asked before class ends)i did not take notes for that because i thought it would show on the PPT but it does not.

add me on facebook and i'll send you discussion 1 & 2
https://www.facebook.com/david.xiao.9

Thread:Course talk:APBI200/answer key for Discussion Qs/reply (2)

2016-04-08T01:02:44Z

DavidXiao: Reply to answer key for Discussion Qs

Hey jia, I have some notes for both discussions if you can find me on facebook, i left you a message on your wiki user page

Thread:Course talk:APBI200/Q 3 Problem set No. 3

2016-03-31T06:59:08Z

DavidXiao: New thread: Q# 3 Problem set No. 3

see this question -->

Calculate kg of calcium and potassium per hectare (10000 m^2), when soil bulk density is 1350 kg m-3, and a soil sample was obtained from the 0-20 cm layer. The concentration of calcium is 50 mg kg-1 and concentration of potassium is 103 mg kg-1

do we give our answer in hectares at a depth of 20cm? ha 20cm or hectare meters? (hectares at a depth of 1m)

will the markers understand our answer?

Thread:Course talk:APBI200/net mineralization rate equation

2016-03-12T05:19:17Z

DavidXiao: New thread: net mineralization rate equation

Can someone help me understand this equation for net mineralization rate?

dN/dt = -kN

I understand dN as the change in organic N per unit soil volume, and k as the decay coefficient, and dt as change in time. if k has the units of 1/t then both sides of the equation are the same thing, what is the point of this equation? and how is it used? can someone relate this to C:N ratio and explain how i can use this formula in a calculation?

thank you!

Thread:Course talk:APBI200/Question 4 of the lab/reply

2016-02-25T05:18:25Z

DavidXiao:

yes S/m is the unit Siemens/meter and dS/m is deci Siemens/meter (demi = 10)

Thread:Course talk:APBI200/Question 4 of the lab/reply

2016-02-25T05:17:31Z

DavidXiao: Reply to Question 4 of the lab

yes S/m is the unit Siemens/meter and dS/m is deci(10) Siemens/meter

Thread:Course talk:APBI200/Question 4 of the lab

2016-02-25T04:57:58Z

DavidXiao: New thread: Question 4 of the lab

Question 4 looking at the table 2. (Classification of soils based on salinity indicators) we're given, I can see that ESP for soil 1 in Question 4 of the lab is < 15, but what are the other values that we are given? i see dS/m is 9.2, is this related to S/m for electrical conductivity?

Thread:Course talk:APBI200/Problem Set No.2

2016-02-03T06:16:27Z

DavidXiao: New thread: Problem Set No.2

For Q1 and 3, we are asked about dominant pore size. does "finest dominant pore size" mean more small pores? can we answer Q3 with "big" or "small"?

Thread:Course talk:APBI200/Data Collection/reply (2)

2016-01-27T21:50:30Z

DavidXiao: Reply to Data Collection

thank you!

Thread:Course talk:APBI200/Data Collection

2016-01-27T07:43:33Z

DavidXiao: New thread: Data Collection

I rewrote my notes but did not copy the data collection stuff required for the volume of core calculation by accident. (core height, core diameter and oven dried weight of soil,) can anyone fill me in?

Thread:Course talk:APBI200/Weight of core and dry soil, Q1, Problem set no. 1/reply (3)

2016-01-18T20:27:08Z

DavidXiao:

i understand now that the "core" refers to the equipment used to make the measurement, in that case it is relatively straightforward.

Thread:Course talk:APBI200/Weight of core and dry soil, Q1, Problem set no. 1/reply (3)

2016-01-18T20:24:43Z

DavidXiao: Reply to Weight of core and dry soil, Q1, Problem set no. 1

i was told that the "core" refers to the equipment used to make the measurement, in that case it is relatively straightforward.

Thread:Course talk:APBI200/different meanings for clay/reply

2016-01-17T19:52:36Z

DavidXiao: Reply to different meanings for clay

in the lab manual, textbook, and lecture notes there is a table that shows you different textural classifications of soil based on percent clay vs percent sand. is this what you mean?

Thread:Course talk:APBI200/Problem Set 1 Q4/reply (3)

2016-01-17T04:29:26Z

DavidXiao: Reply to Problem Set #1 Q4

i had this question too... there seems to be no way to give an answer more specific then a range.

assuming the the density of quartz is around 2.65 g/cm³ i can give a good answer if its just quartz rocks and air, however the question wants to know for a typical content of clay minerals and quartz so i cant find a weight to do the question with.

but if we assume the (dry) bulk density of a mineral soil is normally about half that density, between 1.0 and 1.6 g/cm³, we can take 46% away from that to get 0.736g/cm³

otherwise just give the equation with the values you do know i guess..

Thread:Course talk:APBI200/Weight of core and dry soil, Q1, Problem set no. 1

2016-01-17T02:54:40Z

DavidXiao:

why does the weight change when compacted? it should remain the same but the volume should change. Why should soil increase in weight when compressed? my understanding is that squishing soil will make water and air leave the soil making the soil lighter not heavier.

what is the difference between weight of core and dry soil, and weight of core? the question indicates that a double cylinder, drop hammer is used to obtain 750 cubic centimeters of soil. This I assume is the weight of the core.. so what then is the weight of the core '''''and dry soil''''' where does all this soil come from? from the tires of the truck?

thanks!

Thread:Course talk:APBI200/Weight of core and dry soil, Q1, Problem set no. 1

2016-01-17T02:52:07Z

DavidXiao: New thread: Weight of core and dry soil, Q1, Problem set no. 1

''Defining Merit In Systems of Accreditation

2012-09-09T23:49:51Z

DavidXiao: new headings

==History==

===Imperial Era (50BC to 1900AD)===

===Communist Period (19-- to 19--)===

===Post Deng Xiao Peng===

Course:HIST481/The “Diploma Disease”

2012-09-09T23:47:27Z

DavidXiao: /* Defining Merit in Systems of Accreditation */

==The "Diploma Disease"==

==Defining Merit in Systems of Accreditation==
[[''Defining Merit In Systems of Accreditation|link for main article'']]

[[Category: History]][[Category:HIST]]

Course:HIST481/The “Diploma Disease”

2012-09-09T23:46:59Z

DavidXiao: /* Defining Merit in Systems of Accreditation */

==The "Diploma Disease"==

==Defining Merit in Systems of Accreditation==
[[''link for main article|Defining Merit In Systems of Accreditation'']]

[[Category: History]][[Category:HIST]]

''link for main article''

2012-09-09T23:41:21Z

DavidXiao: new page

===History===

====Imperial Era====
====Communist-Modern Era====
====Post-Deng Xiao Peng====

Course:HIST481/The “Diploma Disease”

2012-09-09T23:40:08Z

DavidXiao: /* Defining Merit in Systems of Accreditation */

==The "Diploma Disease"==

==Defining Merit in Systems of Accreditation==
[[''link for main article'']]

[[Category: History]][[Category:HIST]]

Course:HIST481/The “Diploma Disease”

2012-09-09T23:39:53Z

DavidXiao: Link to new page

==The "Diploma Disease"==

==Defining Merit in Systems of Accreditation==
''link for main article''

[[Category: History]][[Category:HIST]]

Course:HIST481/The “Diploma Disease”

2012-09-09T23:27:40Z

DavidXiao: testing

==The "Diploma Disease"==

==testing contents function==

[[Category: History]][[Category:HIST]]

Course talk:HIST481/The “Diploma Disease”

2012-09-09T23:12:50Z

DavidXiao: Talk page autocreated when first thread was posted

Thread:Course talk:HIST481/The “Diploma Disease”/Accreditation and Merit

2012-09-09T23:12:50Z

DavidXiao: New thread: Accreditation and Merit

"Jean Baudrillard once suggested an important correction to classical Marxism: exchange value is not, as Marx had it, a distortion of a commodity’s underlying use value; use value, instead, is a fiction created by exchange value. In the same way, systems of accreditation do not assess merit; merit is a fiction created by systems of accreditation. Like the market for skin care products, the market for credentials is inexhaustible: as the bachelor’s degree becomes democratized, the master’s degree becomes mandatory for advancement. Our elaborate, expensive system of higher education is first and foremost a system of stratification, and only secondly — and very dimly — a system for imparting knowledge."
http://nplusonemag.com/death-by-degrees