Not the beer itself, of course, but the grains used to make it– barley, corn, oats, rye and wheat. They’re a great source of nitrogen once they’ve been malted and used to make that cold bottle of Bud. Brewery grains pair particularly well with a bin composter, like the Jorg Composter I mentioned in my last blog, since they are are easy to compost but need tossing to maintain their warmth. You may have to add some wood shavings to keep the compost from getting too smelly.
Brewery grains are likely to be very smelly when you first pick them up, so get mulching them as quickly as you can. Some grains also have allelopathic qualities, like corn gluten meal, that can prevent seeds from germinating. If you are composting corn gluten, I would use this compost in areas of the garden where you don’t intend to plant from seeds and where you would like to prevent weeds from growing.
Spent brewery grains are not a good material for mulching due to the fact that they are too smelly and also attract animals. Spent brewery grains that are very soft, wet, and smelly can be dug directly into the soil as they are already well on their way to breaking down and will release nitrogen in the form of gas directly into the ground in a form that plant roots can absorb.
One easy way to compost these left over grains and increase the organic matter in your soil is simply to dig trenches, for example between the rows in your vegetable or cut-flower garden, pour the grain in there, cover it over with soil, and let the worms do the composting.