Midterm Exam Questions

-Pls note that the the cut-off point for the material that will be included in the upcoming midterm exam is Feb 12 (inclusive). In other words, all topics up to soil organic matter will be on the midterm exam.

-Pls note that NO formula sheets or cheat sheets are allowed at the APBI 200 midterm exam.

-Review session will be held on Monday Feb 24 (9-11 am) in Scarfe Building (2125 Main Mall), room 100

Hello, what type of calculator is permitted on the exam? Is a graphing calculator ok?

Any kind of calculator is accepitbe, including graphing ones

According to the lecture notes, soil water content decreases when matric potential becomes more negative. I am not sure why this is the case. As matric potential decreases(becomes more negative), soil holds water more strongly. Wht would soil content decrease if the water is held more strongly? Thank you in advance.

hello Maja.

1.For the Q4 of 2008 mid term, could you please explain why those two ( sand and massive clay) soils differ in terms of water rentention?
2.why are the soil colliods the most reactive part of soil matrix? Is that because of they have permanent charges and there are many exchangeable ions bond to them? 

thank you .

1) Massive clay only has small (micro) pores, while sand only has large (macro) pores. Consequently, large pores in sand louse water very quickly (as indicated by a prominent drop in its water retention curve)with the deceasing matric potential. On the other hand, small proes of the massive clay, hold tightly on the water molecules and there is very little change in water content with a decreasing matric potential (as shown by its almost flat curve)

2)Soil colloids are small and as such they have large specific surface area and in addition they usually have lots of charges on their surfaces.