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A Cook's Garden

Stay Off Soggy Spring Soil

By Barbara Damrosch
Special to The Washington Post
Thursday, April 14, 2005; Page H09

When I was growing up in New York City, we would often see apologetic signs in the middle of the street that read "Dig we must for a better New York." Everyone knew that beneath the traffic lay an intricate network of phone lines, gas lines, water lines, electric lines and the great tubes of the subways. We put up with the maintenance work that disrupted our movements above, so that everything could keep on flowing nicely below.

"Dig we must" could easily be the gardener's slogan. We are driven to do it, especially after a long, slothful winter. In a cold, wet, late spring like this one, the hand on the spade is like an itchy trigger finger, unstoppable once the rain lets up.

But stop we must. We're ready for the garden but the garden isn't ready for us.

Within the soil is a network of plumbing and transport that rivals that of any city. The soil's inhabitants, its worms, bugs, reptiles, mammals, microbes, all make pathways from the tunnels of worms and rodents to the awe-inspiring hyphae of the soil fungi -- vast networks of microscopic tubing. These pathways, including those made by plant roots, keep air, water and nutrients circulating throughout the soil. They protect the life in the soil against flooding, erosion and drought. A worm tunnel, for instance, can draw water up from below by means of capillary action (stick a thin glass tube in water and you'll see how surface tension on its sides makes the water rise). When the ground is saturated, the same tunnel drains the water away.

Even the spaces between soil particles are pathways that circulate air, nutrients and water, though this works better in some soils than in others. In finely textured clay soils, the spaces are small and retain moisture. In sandy soils, too much drains away. In loam soils, there is a better balance between space and particles -- about 50-50 -- and under the best conditions half that space is filled with water, the other half with air.

It is clay soils, so common to the Washington region, that pose the biggest problem for spring gardeners.

Soil texture is hard to alter, but soil structure -- the way soil particles clump together -- can be improved by making sure there is plenty of organic matter. This binds up sandy soils and aerates clay ones. Adding well-matured composts, manures and peat helps create that beautiful soil tilth that gardeners dream of. Rich organic soils, which resemble damp cookie crumbs, are full of living creatures, opening up channels so water can drain. Those marvelous fungi produce a magic sticky protein called glomalin -- a major component of soil organic matter -- that helps soil particles clump together. During winter, the freezing and thawing of soil moisture also helps open up its structure. In spring, so far as nature is concerned, the soil is in a perfect condition for plant and seed growth.

Now, imagine for a moment what the consequences would be for our complicated modern city if it were pelted with a shower of meteorites as thick as hailstones, or chewed up by giant rototillers from Mars. This pretty much describes the effect that spring tillage has on wet spring soil. All those carefully built channels collapse, networks of fungal hyphae are destroyed. The soil, especially if it is a heavy clay to begin with, forms clods that will later dry into hard biscuits. The soil surface forms a crust, and places where a spade or plow has been thrust will slick over, then harden, making them difficult for roots to penetrate. It will take a very long time for the earthworms (those that have not been chopped up by tilling) to rebuild their world, and meanwhile the circulation of air, water and nutrients will slow down.

Ever since Adam delved, renegade gardeners have questioned whether human tillage really does what it is supposed to do -- loosen the soil and incorporate organic matter into it. In nature the leaves, manures and other amendments simply fall on the surface and are worked in by the crews of union shop burrowers who already own those jobs.

The merits of till versus no-till gardening have been endlessly debated. Tilling is sometimes necessary when you are starting from scratch with a new garden, though some claim that even then the best way is to just pile organic matter on top and leave the rest of the job to the underground experts.

But everyone agrees that handling moist soil in spring is a blunder. Major work such as grading and bed forming must wait until the soil dries out. Transplanting should also wait for drier, warmer soil.

Soil that has been built up with compost will dry more quickly than minimally improved clay. Dig a trowelful and squeeze it in your palm. If water oozes out, it is still too wet to work.

There is a way, however, to sow extra-early crops such as lettuce and peas, even if the soil is too soggy to make a respectable furrow. Just spread a good inch of well-matured, sifted compost on the surface and make your furrow in that. Later on, applying a light surface mulch will protect the compost from drying out.

In summer or fall if you feel the soil is compacted you might gently disturb it by poking a digging fork or broadfork in and waggling it gently back and forth.

Meanwhile, lifting heavy clods of wet soil is not exactly a spring frolic, even for an eager gardener. And you have a perfect excuse not to.


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