Tilling of the soil has been a mainstay of agriculture and civilization.  It’s part of a culture; depicted throughout the ages in art and literature.

The Tilled Field by Joan Miró, 1923-1924

The Tilled Field by Joan Miró, 1923-1924

 In fact, the great American statesman, Daniel Webster said that:

When tillage begins, other arts follow. The farmers, therefore, are the founders of human civilization.

Tillage was done manually until the advent of tractors and other mechanical tillers in the early 1900’s made large-scale agriculture possible and small farming manageable.

American farmers have had a long-standing love affair with all things mechanical, and the home gardener is no exception.  They love their roto-tillers.  And, really, what’s not to love? The roto-tiller is a power tool for gardening.  It’s got 208cc (5-6 hp) of power, and carries strong, rugged names like, “Pony”, “Colt”, “Bronco”, “Mantis” and “Roto-Hog”.  It’s every tool-guy/tool-girl’s dream.

Godzilla has a cousin

Godzilla has a cousin

But, as much as I love power tools (and, I do), when I think of a roto-tiller, I visualize a large, loud, flame-spewing monster, wrecking city blocks, smashing buildings into smithereens, and causing panic and mayhem among the inhabitants much like Godzilla.  I call it, Rotzilla.

Rotzilla, when let loose, wrecks the topsoil, smashes soil particles into smithereens, and creates panic and mayhem within the soil structure.

Too harsh you say?  Read on.

The detrimental impact to over-tilling can be found by looking at Oklahoma in the 1920’s and 30’s. Back in the 1930’s, one of the leading advisors in farming, John Deere, stated that:

“In general, the seed bed should be roomy, thoroughly pulverized and compact.”  The goal was to “break up clods and crusted top soil, leaving a fine surface mulch for planting or for plant growth.”

(John Deere’s 1935 book, The Operation, Care and Repair of Farm Machinery)

The problem with fields that were plowed and disced into fine particles was that it left them vulnerable to wind erosion and dust storms. Dry and light grains of soil were picked up by the winds and blown away. Too much tillage led to intense soil erosion. There was nothing left to hold water or nutrients. It was total devastation.  It was the Dust Bowl.


Dust Bowl-Soil Erosion 1930’s

However, knowing that over-tillage led to soil erosion, didn’t stop C.W. Kelsey from offering a compact version of the same soil-pulverizing tiller to homeowners, and in 1937, the roto-tiller was developed.

While the Dust Bowl happened over 80 years ago and impacted commercial farming, the practices still used in backyard roto-tilling, can produce the same results on a smaller scale and eventually trash your soil.

Too harsh you say? Read on.

Jim Stute, crops and soils agent for the University of Wisconsin Extension, Rock County, has even harsher words than I do for the roto-tiller.  According to Mr. Stute:

“There’s no difference between a crack pipe and a roto-tiller. Both are tools of the devil. Both provide instant gratification that leads to addiction, and that addiction causes long-term damage.”

So, take your pick:  Rotzilla or Crack Pipe.  Either way, that roto-tiller can cause very serious damage.

If you’re not sure why roto-tilling is so damaging to your garden soil, here is Mr. Stute’s explanation that appeared in the GazetteXtra, on April 19, 2011, when he interviewed by Catherine W. Idzerda:

“Soil is made up of three particles: Sand, silt and clay.

Sand particles are large; silt particles are medium and clay particles small. Sand particles have a lot of pore spaces, making it easy for water to pass through. Sand is great for drainage, provides air and oxygen, but does not keep moisture.

Clay particles have tiny pore spaces and are able to store water for plant use. Clay also has a lot of nutrients and biomass. Clay holds water and nutrients, but drains very slowly.

The sand, silt and clay particles glued together form what’s called a soil “aggregate,” an ideal medium for growing plants. The aggregates combine the best properties of the individual particles.

The larger pores (sand and silt) between aggregates encourage root growth, giving plants the ability to collect nutrients from the soil. They also facilitate the exchange of gases for plant roots—oxygen in, carbon dioxide out.

The smaller pores (clay) within the aggregate store water and protect microbes, which are responsible for processing nutrients into forms that plants can use.

You need both larger and smaller particles in your soil for good soil health and good plant health.

Now, envision that its springtime and you’re ready to prepare your beds for planting. You’ve dragged the rototiller out of the shed, tuned it up, gassed it up and are ready to create a garden worthy of a Martha Stewart magazine spread.

Most roto-tillers are power driven, so they go at a constant rate across the ground. But the tines go around relatively fast, and get multiple kicks at each aggregation.” Often, people make repeated passes across the garden beds, and when they do that, “those aggregates get beat to dust.”

Remember, those aggregates are crucial to the health of the soil. But, roto-tilling exacerbates a soil’s inherent problems. You’ve broken the sand down, and the clay even more.

Soil crust on conventionally tilled field after heavy rain.

Soil crust on conventionally tilled field after heavy rain.

And then there’s the spring rain. “The rain has a significant impact on the soil surface and further breaks up the aggregates,” Stute said. “It further detaches the clay particles.” As a result, a hard crust forms on the surface of the soil, causing gardeners to get out the roto-tiller to break up the crust into soft soil, adding insult to aggregate injury.

Repeated roto-tilling at the same depth can create a hardpan of soil that restricts root growth.

Soil microorganisms feed on organic matter—compost, manure, cover crops—that have been added to the soil. This process forms the “gum” that sticks the particles together. “This gum is the Elmer’s glue of microbial gums,” Stute said. “It’s water soluble.”

But the real magic happens when fungi that are already in the soil work with plants to improve water and nutrient uptake. The waste product of that process is glomalin, a non-water soluble glue that holds aggregates together. When you over-roto-till soil, it harms the very fungi that create this nonsoluable glue. Soil aggregates pounded to dust don’t stick themselves back together.”

In other words, too much roto-tilling wrecks the topsoil, smashes soil particles into smithereens, and creates mayhem within the soil structure.

 So, can you ever use a roto-tiller?  Yes, but resist the urge to overdo; use it sparingly.

  • Use it to blend in organic matter such as composted manure or dried leaves.
  • Keep the tillage shallow.
  • If you’re just starting out with a first-year garden, and you’ve discovered that the soil is extremely compacted and difficult to plant in. Then you can start by roto-tilling, then add layers of compost and some fertilizer. After that, a pitchfork should work.
  • Roto-till in the fall instead of the spring.
  • Don’t use in a raised bed.
  • For small gardens, use a spade or shovel to add your materials.

The less you disturb the soil, the better.

Next up, other methods I like better. . .