Question from Ica:
My friend is a brewmaker and has tons of the filtered barley grains they use to make beer. Would this be a good soil admendment? Also should it be composted or can it be added directly to the garden?

Answer from Pat:
Spent brewery grains are an excellent additive to the compost pile, but they vary in characteristics. Some beer companies are learning to use them to make compost and other companies are also recycling them for use as mushroom compost. They can also be used to feed worm bins. Composted brewery grains are one of the ingredients in Milorganite and contribute a lot of its nitrogen.

Most spent brewery grains when used in the compost pile can be classed as a nitrogenous waste (a fast, hot, “green” ingredient, like grass clippings). Layer with some carbonaceous materials such as dry leaves to make a nitrogen-rich compost. Brewery grains can be especially beneficial if you have a bin composter since they are nitrogenous and 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 already when you first pick them up, so get them as quickly as you can after use. Some grains also have allelopathic qualities, that is, like corn gluten meal, they can prevent seeds from germinating. Composting them may not kill this action. Thus 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. Before using this compost in the vegetable garden, try planting some radish seeds in a container of potting mix mixed with the compost to make sure the seeds germinate easily.

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 you asked, since 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. On the other hand, spent brewery grains that have been allowed to dry out or cake and get hard should not be added directly to the garden soil. These would subtract nitrogen from the soil in order to rot. Also they will act more like carbonaceous waste in the compost pile. You will need to add water to them so they can puff up again and get going. (When brewery grains are hard and dry some gardeners even recommend layering them with grass clippings to add nitrogen to them, but this does sound odd since the grains themselves are classes as nitrogenous. Under normal circumstances the grains should provide the nitrogenous waste and what you would need to add, if anything, is carbonaceous waste.)

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.

Related Articles:

1. How to Create a Hot Compost Pile
2. New Gardener – Composting for Two
3. Horse Manure Compost
4. Pre-Compost or Trench Composting
5. Growing Plants in Containers: Dealing with Spent Soil