After you read the Q&A in last issue’s eZine, we discovered that many of you are interested in talking trash…heaps, that is, when it comes to compost piles. Several readers shared further information about the process of making compost, including one who has taught university level composting. – Editor
“I compost all my wood waste. It doesn’t compost fast, but with the right mixture of grass or other green waste and adequate amounts of water, it will make a dandy product. How do I know? I spent 10+ years as a university researcher/teacher on composting, and I make my own backyard compost.
“So, how is composting done? First, get the right mixture of products. This is a complicated issue that fortunately can be grossly simplified by mixing 1/2 browns with 1/2 greens by volume. Browns are the wood waste. Greens are grass clippings, stuff from the garden, kitchen waste, etc. Green waste can be added all at once or (my preference) over time as it appears. Caution, if you only have sawdust you need an additional bulky brown. Add chipped brush to improve the number and size of air spaces in the mixture.
“Second, make sure the mixture is wet enough. It needs to be at 50 to 60 percent moisture. That means a lot of water for the dry wood you’ve been working with. How do you tell when it is wet enough? Squeeze a handful of the wetted mix. It should leave your hand wet but not release more than a drop or two when squeezed. Maintain this level of moisture throughout the composting process. Depending on your climate, this may mean adding water regularly or preventing exposure to excess rainfall.
“Third, make sure the pile or bin is large enough to retain heat. The critical volume is about 4 x 4 x4 feet. Larger is better. Fourth, occasionally turn the compost (remix). This keeps air in the mixture and lets you see if water is needed. I prefer adding green waste a little at a time because when I do I am actually turning, wetting and observing the composting material.
“Expect this process to require a year or maybe two to really get good usable compost. You should not be able to recognize any wood or green waste in the finished product. It should just appear as a brown. soft, earthy material.
“All this said, recognize that compost happens. Mother Nature will eventually turn complex compounds into simpler materials that will eventually recombine into animal and vegetable life forms. In a tropical forest, this might take a short time, while in an arid desert, it might take a very long time. We desire a more speedy process, so we make compost. But even a pile of sawdust out on the back lot will someday make compost by itself.
“Caution, don’t use treated wood. Caution, don’t put raw wood sawdust or shavings down as mulch. The soil bugs want to break down the wood and, to do so, they need nitrogen. Because you don’t supply nitrogen, the bacteria will steal soil nitrogen away from the plants and the plants will do poorly.” – Herb Brodie
Other readers also had piles of things to say about making compost with wood. – Editor
“Tim is correct about sawdust being carbon. However, sometimes carbon is needed in a compost pile. For example, if one was trying to compost a large animal or a pile of spoiled fruit. Without some carbon, the high nitrogen stuff won’t decompose in an aerobic manner (anaerobic decomposition stinks – which is where stockyards acquire their aroma). The trick is to put the carbon in your compost pile first, sparingly, and not directly on your plants. The chips remain undecayed until matched with sufficient nitrogen material. You might even be able to find someone in your neighborhood/city who needs the sawdust and/or chips.” – Cindy Mathieu
“With regard to the question of using woodshop waste (sanding dust, sawdust, wood scraps, shavings, etc.) around the yard: I’m in agreement with Tim Inman in principle but probably differ a bit in practice. I have to admit that I don’t work with any exotic woods, unless walnut is considered exotic, and the waste from my shop is primarily ‘normal’ stuff from such woods as maple, apple, peach, oak, poplar, ash, and pine. I would easily add any of these, in dust form, to my vegetable garden but would make sure they were mixed well with a generous amount of grass clippings in order to ensure a high nitrogen to carbon ratio. And then I would rototill it all in very well in order to make sure that these ‘organic nutrients’ were well mixed with the generally more inorganic components of the garden soil. As Mr. Inman suggests, the larger shavings and output from the lathe or power planer are applied to my garden paths, where in time they decompose very nicely as well and eventually get pulled into the garden and tilled in. All of the trimmings/prunings from our ornamental gardens (about two acres worth of about every tree and shrub you could imagine) get passed through the chipper shredder and these go on the paths as well and eventually get pulled into the veggie garden.
“I also cook year-round over wood fire in an outdoor stone grill. I use any of the hardwoods, including walnut and all of the various woods from the many ornamental trees (e.g. magnolia, dogwood, stewartia, redbud, fringe tree, etc. etc.) in my grill. I’ve been doing this nigh onto many years longer than many of the eZine readers are old and have never had any ill effects. The food is always flavorful and delicious. These are all climate zone 4-6 trees, however, so I don’t have any experience with any from climate zones 7-10. I truly believe in recycling and the old adage, ‘waste not, want not.'” – Charles Carney
“In response to your article concerning wood chips in the compost, I would like to add that for the last 40 years I have done just that with no ill effects. I mix them very roughly with about the same quantity of grass clippings (which form a very gooey nitrogenous mess)/vegetable matter so the carbon/nitrogen ratio is in balance. I’m also a keen gardener (flowers and vegetables) and find the mixture a very good top dressing. I’ve yet to work in walnut but get through a fair bit of oak/pine/sapele and turn/carve anything I’m able to get my hands on. It all goes on the heap for a year.” – Bernard J Greatrix
“As you should know, a major ingredient of commercial mulch and compost is shredded hardwood from shipping pallets. The key is to actually compost the material and not mix it into the soil as dried wood chips. There is an important distinction between wood chips as mulch and as compost. Un-composted wood chips can be used as mulch to control soil moisture. I have used wood chips as mulch for raspberries for years with good success.” – George Possin
And some readers had additional suggestions in response to Chris Marshall’s query of what you do with your sawdust – most of them related to the animal kingdom. – Editor
“I generate one to two black rubbish sacks full of the stuff from Scandinavian pine with my planer/thicknesser every week. Here’s what I do with it: I give it to anyone who has pet guinea pigs, hamsters, chickens, etc., as it makes ideal bedding for them and saves them a small fortune buying it from the local pet store. I don’t charge for it (although I do receive the odd jar of homemade jam or bottle of wine from time to time from grateful recipients – the owners that is, not the pets!) As a byproduct of doing that, I have also gained several more customers for the actual items I design and build. So everyone’s a winner!” – Rod Patient
“I found that a friend who works with animal rescue groups wastes no time getting to my shop when I tell her I emptied the chip collector or jointed a lot of boards. She uses it for cat litter and animal bedding. I’ve also advertised it on Freecycle and Craigslist as a free pickup item and always get rid of it, mostly to people also involved in rescue groups. Much, much better than sending it to the landfill! Of course, if I’m putting walnut through the planer or jointer, that waste goes directly to the curb on trash day!” – John Hower
“If you have chickens or ducks, you could use it for bedding or nesting material litter for the floor of the pen, as long as it’s not treated timber.” – Les Bauer
Kickback Followup: the Splitter?
This reader had his own views on what went wrong to cause the kickback when one of last week’s questioners put thin kerf blades on his contractor’s saw. – Editor
“I think that the kickback caused when the blade was changed to a thin kerf blade is not due to the blade per se. Think of how a splitter / riving knife is aligned. A straightedge is placed against the side of the saw blade away from the in-place arbor washer. As the cut with the thin kerf blade is made, the kerf is positioned 1/32″ out of alignment from the splitter. What happens then is the splitter puts pressure on the opposite side of the kerf and pulls the post-cut part of the wood into the the blade. The wood is snagged by the back of the blade, picked up and tossed at the saw operator.” – Rich Flynn