Build a Compost Shredder Chipper

Image Gallery Start with a self-propelled rotary mover.  PHOTO: MOTHER EARTH NEWS STAFF

Compost is one of the gardener's most versatile allies. This nutrient-rich humus not only is organic and free for the making but can serve equally well as a fertilizer, tilth builder, or biodegradable mulch for soil-and-weed control.

The hitch is, of course, that the decomposition process responsible for turning trash into treasure can take months. However, that long wait can be reduced to a matter of days if the organic feedstock is properly prepared. And the key to that preparatory procedure is shredding everything that goes into a compost heap. You see, by breaking up the material with a compost shredder chipper and increasing its exposed surface area, you can improve bacterial action . . . and ultimately contribute to the speed and quality of decomposition.

Now serious gardeners have been known to go out and spend in excess of $1,000 for shredder/chippers to handle their composting chores . . . but you can achieve almost the same results at an out-of-pocket expense of $40 or $50, just by making minor modifications on a secondhand lawn mower!

What you'll need is a working self-propelled rotary mower (the kind with the small power takeoff (PTO) shaft at the side of the engine) . . . some sheet metal (the "skin" from an old washer or dryer would work fine) . . . the chainwheel, chain, and guard from a junk bicycle . . . a small sprocket to fit the engine's PTO shaft . . . a 15" piece of 1/2" rod . . . two 1/4" pipe floor flanges . . . a couple of 1/2" X 25" lengths of electrical metallic tubing . . . and some assorted fastening hardware. (If you just can't locate a good self-driven mower, a conventional rotary model will do, though you'll have to carefully hand-feed material into it when using the device.)

Start your project by looking over the mower and making certain there's enough room on its deck to allow you to add a feed chute at the front. If there appears to be a problem, try turning the engine 180° on its platform and remounting it. Once the correct position is established, cut a 4 1/2" X 8 1/2" opening in the top of the deck, centering it directly in front of the power plant. Then, using the sheet metal, form up a 16"-tall, wide-mouthed (11 1/2" X 13"), tapered hopper, with a 3" shield at the top and some mounting lips at the bottom . . . using our illustration as a guide.