Lab 5 assignment, question #3

Hi APBI 403 / SOIL 503 students,
Greetings from Tampa, FL! A birdie told me that some of you might have questions re. how to recalculate concentration of an element in ug/mL to mg/kg.
As you will see in today's lab on available P, and as is mentioned in the preamble for assignment questions 1-4, all standard solutions are made in water. Hence, all these solutions are water-solutions and as such they have the same density as water ... and one can assume that 1L of a water-based solution has mass of 1 kg. Hope this helps
Maja

Soil chemistry terminology - Since in soil chemistry we use water-based solutions (as extraction solutions such as ammonium acetate that was used in last week's lab and alos as standard solutions), one needs to assume that these water-based solutions (and extracts of elements obtained by using those extraction solutions) have the same density as water. Consequently, it is to be assumed that 1 mL of a soil extract is equal to 1 mg.

Thus in question 3 "extract 5 mL of soil with 25 mL of extraction solution" remember that we use water-based solutions for extracting our samples.