Midterm Exam Questions
Hi Maja, I am a little confused about Question 4 b on Practice midterm #1. We are given this information:
pore volume = 0.55 m3 air entry value of soil water tension = 0.005 m volumetric water content = 0.19 m3 field capacity = 0.28 m3/m3 permanent wilting point = 0.11 m3/m3
-->We are then asked to find the soil air volume in m3... I understand that Vf= Va+Vw, and I tried to find Vw using Volumetric water content= Vw/Vt ... but we are not given Vt. Is there another way of finding Vw that I am missing? Or of calculating Vt with the given information?
Hi Maja, I was wondering what are considered ideal conditions for anion exchange to occur. The only thing I was able to come up with was a lower ph, therefore a more acidic soil.
Low (i.e. acidic) pH is part of the answer. The other part is related to the type of the colloids, since not all soil colloids will change it charge with change in pH of the soil solution. Only organic matter and Fe/Al oxides/hydroxides change their pH with a change in pH of soil solution. Elaboration of how that change occurs is also needed as part of the answer for this question (pls see lecture notes from Feb 12)
Soil air volume (Va) can be calculated as Va = Vf – Vw Hence, you don't need Vt. And both Vf and Vw are given in the question
For question 2b on midterm 2006, what is it asking for when it asks for what the type of charge is called?
Re Kyla Sheehan's question about question 4b) exam 2005, only Volumetric water content is given ( and according to Soil Web Volumetric Water Content is the ratio of water volume (Vw) to total soil volume (Vt), (i.e. Vw/Vt). So Volume of water is not given as far as I can tell. I'm not sure how to find Soil air volume with the information given.