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Uses for free biomass

Wood chip pileOn a homestead, there's a nearly unlimited need for compost, mulch, and bedding for animals.  But which type of biomass should be used where?  The characteristics below will help determine each material's best use in your garden.

In the July volume of Weekend Homesteader, I explained how a material's carbon to nitrogen ratio (C:N ratio) determines its usefulness as mulch or compost.  The short version is:

Materials (like manure) that are high in nitrogen compost quickly and feed your plants within the first year.  A C:N ratio of 30:1 is found in high quality compost.  It's possible to have too much nitrogen in some biomass to apply it directly to your garden without composting, so materials like chicken manure (C:N of 8:1) are better used to heat up a compost pile.

Materials (like wood chips) that are high in carbon compost slowly and work better as mulch.  A C:N ratio of 60:1 is too low in nitrogen to apply directly to your garden even as a mulch until allowed to compost for a year or more.

Another factor to consider when deciding what to do with scavenged biomass is the presence of seeds.  Seed-free biomass --- like coffee grounds --- can be applied straight to the garden, but if you use seedy grass clippings as mulch, you'll be sorry.  I made the latter mistake a few years ago and ended up with a massive weeding job when the mulch sprouted a lawn around the roots of my sweet corn.

Weekend Homesteader paperback But don't turn up your nose at uncomposted manure or other potentially seedy biomass --- there are several ways to make good use of the materials without creating a weeding problem.  If you've got the time, you can simply compost them.  A well-build compost pile will get so hot inside that it will kill any weed seeds, allowing you to use the result on your garden with impunity.  Another alternative is to lay the seedy materials on the ground as the base of a kill mulch, in which case the seeds will never sprout.  (See the May volume of Weekend Homesteader for more information on kill mulching.)  Finally, if you have chickens, your flock will love picking through weedy biomass on the floor of their coop, mixing in their high nitrogen droppings to create stellar compost.

The final problem you might run into when using free biomass is poisons.  Try to collect your grass clippings from uglier lawns rather than from beautiful green swards treated with herbicides.  You might also want to steer clear of tree leaves grown downwind of industrial facilities.  Colored inks, especially those found on paper heavier than newsprint, may occasionally contain heavy metals.  As long as you compost questionable biomass well, fungi will deal with most of these chemical problems for you --- heavy metals are the only issue that seems to be too much for fungi to handle.

Learn about other fun, cheap, and easy fall projects in Weekend Homesteader: October.

This post is part of our Scavening Biomass lunchtime series.  Read all of the entries:

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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