I have 12 ounces of 2-year-old trim. It’s pretty darn dry. I would like to use it to cook with but I’m worried about burning it during decarbing. Due to the volume and dryness, what would you suggest?
The process of decarbing is not likely to burn it, regardless of how dry it is.
That said, as old as your plant material is, it is likely already decarbed to a large degree. Age will also cause decarboxylation, not just heat. Hopefully, anything that has not decarbed due to age will decarb during the process of making your infusions such as marijuana butter or marijuana oil and in the process of cooking your recipes.
A disadvantage of older plant material is that many or all of their delicate terpenes are gone or seriously degraded. But many of these would burn off during cooking even with fresher cannabis. And even without the benefit of terpenes, you can still make some mighty potent edibles.
Over time the THC in cannabis will convert to CBN. At 2 years old this conversion is likely only partial. If your cannabis is more than 4 years old all of the THC may have become CBN. That’s OK, use it anyway and you will be rewarded with edibles that will be especially useful for helping you fall and stay asleep. CBN is also anti-inflammatory and can help reduce pain, among other health benefits. Likewise depending on why you are making edibles, cooking with older plant material can be beneficial and therapeutic.
So, to circle back to your original question, if it were me in this instance I would probably cook with it as is without first decarbing.