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  • Soil Science

    Beware — rototilling actually can do more harm than good
  • A freshly rototilled garden looks so good that it often tempts the gardener to use the tiller early and often. Who can resist that soft, fluffy soil, free of lumps and chunks?
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  • A freshly rototilled garden looks so good that it often tempts the gardener to use the tiller early and often. Who can resist that soft, fluffy soil, free of lumps and chunks?
    So why does rototilling get such bad reviews these days? Many gardeners (including yours truly) have given up use of a tiller altogether. If you want to blame it on something, blame it on soil science.
    Advances in soil science have improved our ability to see and study how microscopic bacteria and fungi interact with plant roots and has helped us understand how this symbiotic relationship related to plant health and growth.
    It was commonly believed that rototilling improved soil's performance. However, we have learned that it actually does more harm than good because it breaks up that beneficial microbial activity. Chopping and grinding the soil also destroys and dislocates the tiny, helpful invertebrates that are busy trying to make the soil good for plant roots.
    Earthworm population will be reduced because the worms get chopped up, too. And that old wives tale about every piece of a worm growing into a new worm is simply not true. They just die.
    While rototilling may temporarily make the soil more workable and nice to look at, after a good rain or two, followed by some of our Rogue Valley heat, the soil will return to its previous texture — or worse. If the tiny channels and tunnels created by worms, beneficial insects and plant roots are destroyed, air and water cannot penetrate as easily, leaving just a heavy mass.
    Rototilling does at least two more undesirable things. It will bring to the surface weed seeds that have been lying deep in the soil, waiting for a chance to sprout. Weeds are patient — some can spend up to 20 years in a dormant state and then begin to grow when given the chance.
    Also, if you have clay in your soil, rototilling, especially if done on a regular basis, will create a hard layer beneath the tiller's reach. This makes it very difficult for any plant roots to penetrate it. Left alone, however, any root penetration that does occur, plus worm and microbe activity, will eventually help break it up.
    And I haven't even mentioned the fuel consumption, noise and air pollution rototillers create.
    So shall we all sell our rototillers at the next garage sale? Perhaps, or perhaps not, as there is at least once when they are useful. It's an ideal machine when used to incorporate manure or compost into the soil when creating a new garden bed (the emphasis here is on "new," not existing). But why not just rent one if that occasion should present itself? Go ahead. Sell yours.
    Coming up: "Summer care of grapevines" will be the topic of a workshop led by Chris Hubert from 9 a.m. to noon on Saturday, May 18. The class will be held in the vineyard at the Southern Oregon Research and Extension Center, 569 Hanley Road, Central Point. Cost is $10. Call 541-776-7371 to register.
    On Thursday, May 23, landscape architect Bonnie Bayard will answer the question "No lawn! What then?" as she shares design ideas for transforming all or part of your yard into a lawnless landscape. The class will be held from 7 to 9 p.m. at the Southern Oregon Research and Extension Center. The cost is $5. Call 541-776-7371 to register.
    Carol Oneal is a past president of the OSU Jackson County Master Gardeners Association. Email her at diggit1225@gmail.com.
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