A rough method we use here in Australia is to take a pellet of pollen and place it on your thumb nail and crush it with your other thumb nail.  If it crushes, it is too wet. If it does not then it is dry.  I have been told that the moisture content to aim for is around 10%. 

I have used oven dry methods where the sample is placed in the oven and dried until all the moisture is removed.  The problem here was to find out if you divided the difference in weight by the original weight or the oven dry weight.  I found a difference of opinion on this.  When calculating the moisture content of timber (lumber) you use the oven dry weight.  So the formula for calculating the moisture content of timber is the difference in the weight between the original weight and the oven dry weight divided by the oven dry weight then multiply by 100 to bring to percent.

FWIW.

Trevor Weatherhead
AUSTRALIA