Related to this question, but I'd like to get a 50 lb. bag of pilsner DME from the LHBS to use over the course of 3-6 months. Can it be stored like grain, or are there additional considerations that need to be taken into account?
I'd hazard a guess that in addition to moisture, you might be also be concerned with oxidation. I've seen longer term storage of grains in 5 gallon pails with a nice tight seal work well; apparently a long-term storage trick is to put dry-ice in the bottom of the pail before filling, thus displacing all the oxygen in the bucket. This would also have the side-affect of removing all the moisture as well.
First I'd ask the store what they suggest. People who buy this have probably told them their good ideas of how they handle it.
Wow, that's a lot of DME. Handling DME is a bit tricky. Just pouring it out of a bag it collects and bunches up and gets all sticky at the bag opening. I'd probably divide it up into freezer bags, with 5 or 10 pounds in each, but I'd make sure I didn't do so on a humid day.