Building soil fertility with spent brewers grains

View the project final report

Commodities

Practices

• Crop Production: fertilizers, nutrient management
• Soil Management: organic matter

According to the Brewers’ Association, since 2012 the number of craft breweries has increased to over 4,200 in the United States [1]. Initial studies investigating spent brewers’ grains [SBGs] in compost production shows their promise as a source of organic matter for local vegetable farmers. However, this is challenged by SBG’s high moisture content, (upwards of 80%) which quickly leads to anaerobic conditions if left unchecked. Current successful farm-scale solutions require aeration or desiccation machinery that is cost prohibitive to many small farmers for entry. This grant study seeks, instead, to employ a safe method of anaerobic composting called bokashi that works with that high moisture content of spent grains. Bokashi ferments biomass much like silage production, then readily breaks down through aerobic decomposition once tilled into the soil. The aim is to see whether this process can offer a model to small farms of a viable way to collaborate with local breweries, taking a waste product and turning it into fertility with minimal capital input. Research will be photographed/video logged, then shared via the 12 Facebook farming groups I participate in. It will also be posted to a blog my farm’s website. Additionally, as a MOFGA journeyperson, if the results are promising, I will reach out to the organization to talk about presenting the findings at the 2018 Farmer to Farmer Conference.
[1] Brewers’ Association Statistics. (n.d.). Retrieved from https://www.brewersassociation.org/statistics/number-of-breweries/

This grant study seeks to investigate whether bokashi is an effective composting method for incorporating bokashi’d spent brewers’ grains [SBGs] into a farm’s fertility program.

What is the effect of bSBGs on field fertility and soil microbiology?

How does the use of bSBGs affect plant growth/yield? What is the labor breakdown needed to produce/apply bSBGs?

My main objective is to compare the effect that applications of bSBGs, and bSBGs blended with an balancing carbon source for a 30:1 C:N ratio, have on soil and field plantings. The bokashi’d SBG plots will be compared against two control plots: one with an application of fresh spent brewers grains, and one in which no amendments are added. I will look at changes in nutrient availability, soil pH, microbiological life, cation exchange capacity, and % organic matter, as well as yield analysis of crops that represent a diversity of cultivated plant families: lettuce, baby kale, beets, husk cherry, and soybean. Soil temperature and moisture measures will be taken. Qualitative differences in appearance, as well as pest, weed, and disease pressure will also be noted.