Released: March 08, 2005

Shed the Shovel Until Soils Dry

MANHATTAN, Kan. – The trouble with early spring is that ancient ancestors’ farming genes assert themselves, inspiring sometime-gardeners to venture forth with shovel or rented tiller.

“Avid gardeners also know that gardening success starts from the ground up. Unfortunately, working the soil now is not a good idea. You could destroy its structure for years to come,” said Bruce Chladny, Kansas State University Research and Extension horticulturist.

Winter’s snows and early spring’s rains have been replacing the moisture Kansas soils lost recently through years of dry heat. So, most landscapes now are wet and mucky, Chladny said.

“Except during drought, this isn’t unusual. It’s why experienced gardeners often prepare their gardens and other planting beds in fall,” he said. “After all, working the soil does increase soil drainage and makes planting easier. You also can incorporate fertilizer or, even better, add organic matter.”

In spring, however, tilling can – and should – be a waiting game. Even troweling down to plant a single pansy in wet soil may create problems that the pansy’s roots never overcome.

“Working the soil when it is too wet causes its clay particles to bind together. The result is rock-hard clods. And, if you use a tiller, you may actually cause a hard pan to form just below the soil surface,” Chladny said. “As a general rule, soil is too wet to work if you can press a handful of it into a muddy ball. It’s okay if it’s a little cool and damp, but crumbles.”

Other ways novice gardeners can get into trouble with soil is by tilling too much and adding the wrong improvements.

Overworking the soil can be as bad as not tilling at all, the horticulturist said. The object is to create pebble-sized clods, not dust.

“Overzealous use of a rotor tiller in soils with high clay content can break the microscopic soil fragments apart, actually decreasing internal drainage, making it more difficult to plant and decreasing garden productivity.” he said. “Basically, you can turn good garden dirt into an always-muddy mess.”

Typically, the only amendment new gardeners incorporate is fertilizer – whether their soil needs it or not. But, the single best practice they can do to improve soil is to add organic matter.

“Even though it’s just a small part of the total mass, organic matter has a profound effect on the physical and chemical properties of soil,” Chladny said. “It increases water- and nutrient-holding capacity. It helps make minerals available for plant use. And, as it accumulates, it binds clay particles into larger aggregates, making the soil easier to work and improving its aeration and drainage.”

He recommends that gardeners who want to improve soil this spring do so only with finely shredded or ground organic material that’s fully decomposed.

“If you’re buying, rather than using your own compost, I’d suggest that you avoid manure-based materials, because they’re often only partially composted. Instead, concentrate on such things as bagged peat moss,” Chladny said.

Most Kansas soils naturally contain less than 5 percent organic matter. It comes from the decomposition of once living plants and animals and is what makes prime gardening soil look gray-black.

“On new garden areas, I’d suggest applying 50 to 100 pounds of compost per 100 square feet each year – preferably in fall. Limit any manure applications as your organic soil amendment to half that amount,” he said. “You can apply a bit more than those amounts to soil low in organic matter to help build its reserves – particularly when winter’s freeze-thaw cycles will help break them down. And, after 10 years or so or with soils high in organic matter, you can just apply the minimum for maintenance.”

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Kathleen Ward
kward@oznet.ksu.edu
K-State Research& Extension News