% ash oven dry calculation

Does anyone know if we are supposed to add or subtract the % ash air-dry to find the % ash oven-dry?

The equation in the lab is missing the symbol after (100/[100-% moisture])

Hi Amy, I just checked the lab manual file posted here, and nothing is missing in any of the formulas shown under section 4.2.

In order to calculate % ash(oven-dry), you need to multiply [100/(100-% moisture)] by % ash (air-dry)

Thanks Maya.

When I plug my numbers into this equation, I get a value over 100. I'll ask you about it in class tomorrow.

There is a mistake somewhere in your calculation ...... SOM + ash need to add up to 100%