Question about question 4 in lab 05
Fragment of a discussion from Course talk:APBI403
In question #3 you need to use density of water for your calculation, but in question #4 you need to consider soil bulk density, since question #4 is asking for re-calculation of element X in the soil.
Question #4 is illustration of the final step in determining how much of an element there is in the soil based on lab analysis. This type of re-calculation is needed to determine application rates of fertilizers or organic amendments.
So, Sandra's explanation above is correct and should be used in dealing with questions #3 and #4.