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Are you thinking about buying a rototiller? How about instead purchasing a chipper/shredder? Now, that’s a machine that’s going to make easy work of chopping up your garden clippings including tree limbs. it’s going to make it into the greatest mulch you could possibly own. The latest research shows that rototilling your soil actually damages soil structure and doesn’t do anything good for the soil biology. On the other hand, the end result of using a chipper/shredder is going to provide you with a quality of mulch that we like to call, “gardeners’ gold”.

Northern California Organic Gardening Consultant Steve Zien has some rather strong thoughts on this subject. Go back and listen to his comments back in Episode 89 of the Garden Basics podcast, from 2021.

Thinking that perhaps his opinions may have mellowed on the chipper-shredder vs rototiller choice over the last four years, I recently asked for his thoughts. Nope. No change. Here’s what he had to say (in bullets):

Chipper shredder

Pros:

• Eliminates or dramatically reduces green waste

• Helps eliminate the need for a rototiller

• Provides material for mulch or compost

• When shreddings are applied to soil surface:

• Feeds soil biology – resulting in improvements in:

• Soil structure (pore space diversity)

• Improve movement in soil by water, air, roots, soil biology

• Soil water holding capacity (drought resistance)

• Nutrient holding capacity

• Biological diversity of soil microbes

• Greater variety of nutrients, vitamins etc. available to plants

• Improves pest resistance

• Plant health improves (drought resistance, pest resistance)

• Nutrient availability to plants improve

• Availability of natural growth hormones, vitamins improves

• Nutrient content of vegetables improves

• Sequesters carbon – contributes to the reversal of climate change

• Weed management benefits

• Mulch created by chipper/shredder moderates soil temperatures

• Erosion protection (mulch slows the force of falling rain)

• Mulch created by chipper/shredder repels some pests

Cons:

• Expensive

• Hard work. And, when done, you then have to apply the mulch to soil surface

• Don’t chip diseased material

Rototiller:

Pros:

• Get to smell actinomycetes

• Mental connection to past horticultural practices (although no longer recommended)

• Creates fine seedbed – but soil quickly becomes compacted making it difficult for sprouts to develop

Cons:

• It’s hard work

• Expensive

• Destroys soil structure

• Compacts soil (reducing aeration, drainage, limit root development)

• Fine clays quickly fill in pore spaces

• Increases runoff – transporting soil, nutrients and pesticides into our waterways

• Kills beneficial soil biology

• Makes it harder for your plants to grow

• Harder to obtain water, nutrients, growth hormones, vitamins

• Increases pest susceptibility due in part to:

• Reduced crop health

• Pest management provided by soil biology

• Reduces nutrient content of food crops

• Results in the need for additional irrigation, fertilization, pesticides

• Mother Nature’s natural rototillers (earthworms) are killed by the blades.

• Creates biological imbalance - abundance of bacteria vs. fungi (raises pH)

• Loss in biological diversity in the soil

• Reduction of soil health (results in reduction of plant health)

• Reduces ability of soil to function

• Releases greenhouse gasses (CO2) to atmosphere – contributing to global climate change

• Reduces organic matter content

• Reduces soils water holding capacity – need to irrigate more/more runoff….

• Makes plants more susceptible to drought

• Reduces food for soil biology

• Reduces soil productivity

• Reduces soil cover

• People feel they need to till every spring because previous tillage created a compacted, dead soil below

• Brings up weed seeds so they can germinate

Obviously, Steve has a bleak future as a salesman at Troy-Bilt.

What About Electric Chipper/Shredders?

For that, we turn to Debbie Flower, who owns an electric chipper-shredder, the 15 amp Sun Joe. Her review:

My chipper is a Sun Joe 15 amp Electric Wood Chipper/Shredder plug-in, model #CJ602E. I have had the pleasure of using it a few times. It is a compact, easy to store machine. The 6” wheels and light weight make it easy to move around the yard.

Debbie has a lot more thoughts about her electric chipper shredder, including the downsides of electric. Listen to today’s newsletter podcast to find out more.

My thoughts about electric-chipper shredders are closely aligned with Brad Gay’s opinion (paid subscribers will hear his comments in the podcast). Reviewers of this electric chipper shredder say they have issues including the shredding problems mentioned by Debbie, and the overheating problem she mentioned. As Brad said, it’s cheaper to replace a belt on a gas chipper/shredder when the machine gets overwhelmed to the point of freezing up with material jammed in the hopper, than it is to replace a burned out electric motor. And make sure you plug the unit into a 20 amp outlet, not 15, to avoid tripping either the house circuit or the overload circuit on the machine. And as with any outdoor electric-powered garden implement, make sure you have the right gauge extension cord which is determined by the power pull of the unit as well as the length of the extension cord.

Reviews of Sun Joe chipper shredders by owners on Amazon also complained about the unit’s inability to chop thin branches, as well as the difficulty to replace the blades, which need to be sharp to do an effective job. Still, most reviewers were very satisfied with this particular Sun Joe 15 amp chipper-shredder. One reviewer did offer a helpful suggestion to avoid clogging situations: “If you feed large branches up to 1” (or more) you really have to hold on to them and only let it take a little at a time, pull it up off the cutter (still inside the safe area) then feed more. One reason it jammed is that when it passes the safety cover it’s still several inches long, which is good safety wise, but it will fall over onto the cutters when you’re no longer holding on to it. That ends up turning that 1” diameter stick into a 1 1/2” + oval. (turn a cylinder on an angle and it’s a long oval) Feed something small along side it and it will keep it vertical. That can help. I learned to just chip smaller stuff.”

Below the paywall, here’s what awaits paid subscribers:

• Why choosing a chipper-shredder with the right sized flywheel is so important.

• Replaceable exit chute screens can give you the size mulch you want.

• How to protect yourself when shredding long vines, such as grapevines.

• Information on PTO-powered chipper shredders.