Almanac

Cover Story - February 10, 2010

Good to grow: Getting your garden's soil to optimum health returns dividends

by Dave Boyce

It's not every day that we take a few moments to feel grateful for the atmosphere or the Gulf Stream or the soil's web of microbes and minerals that make plant life possible. The invisible parts of the natural world are so easy to take for granted.

These phenomena are highly complex and vital to our survival, and each has a balance that we're probably better off not disturbing, and yet we are. The atmosphere is accumulating greenhouse gases, the polar ice is melting and taking with it the temperature differentials that drive ocean currents, and industrial fertilizers are depleting soil vitality and the excess is running into rivers and streams and creating dead zones in the oceans — 146 of them according to a 2003 United Nations study.

As individuals, we may lament these imbalances and our scant options for doing anything significant about them, but that outlook would be misplaced when it comes to the soil. We have essentially sovereign power over the part of it that surrounds our homes and supports our gardens and landscaping.

These realms measured in square feet, what do we really know about them? What pleases the billions of tiny subjects that live there? How do their needs and expectations differ from our preferences and assumptions? Do we even care?

There are arguments for doing so. Caring for the planet has to begin somewhere and home is probably as good a place as any. A healthy and active back yard ecosystem will draw legions of small creatures who will stay and rebalance your little piece of California. You might even find a renewed and deeper appreciation of the larger natural world.

With the Portola Valley Garden Club recently celebrating its first anniversary, The Almanac talked with a few of its members about their soil and its relationship to gardening.

But before hearing from them, a look at the importance of healthy soil and how to create it.

Talented microbes

To begin to restore a neglected plot of land, infusing it with compost tea then adding a mulch ground cover is a good start. Compost tea is made by filling a mesh sock with compost and soaking it for 24 hours to 36 hours in a mixture of water, sugar and kelp, says Terry Lyngso of Lyngso Garden Materials in Redwood City.

Mix the tea into the soil and, after a while, the soil will start to acquire character. You won't see them, but countless bacteria and fungi will grow there, Ms. Lyngso says. Another more visible sign is the presence of ground-dwelling insects and worms, lots of them.

"We're so bug-phobic and most bugs are not a problem," she says. "It's a good sign when you start noticing all these other creatures coming in. When you walk into a garden and there's nothing going on, you've got to wonder if there's anything going on in the soil."

Healthy soil also has a looseness about it that allows air and water to penetrate, Ms. Lyngso says. It's the result of the activity of all these little creatures. They create soil aggregates — little bits and pieces of minerals and other material that adhere to each other and create spaces.

Indeed, a reliable check of a soil's status is to pour water on it. If it dissipates rapidly, that's a good indicator, she says.

Aerating the soil is not the microbes' only skill. Within reason, they will also recycle anything carbon-based, Ms. Lyngso says. That's a fairly broad portfolio: carbon is the building block of all plant and animal life on the planet. "Everything is food to it," she says.

Even toxic compounds. Petroleum, for example, is fairly toxic. As a blend of hydrogen and carbon, it is eligible for microbial recycling, as biologist and fungus expert Paul Stamets demonstrated after the 2007 oil spill in San Francisco Bay.

A tanker collided with the Bay Bridge on Nov. 7, 2007, and spilled 58,000 gallons of fuel oil. Knowing that human hair attracts oil, Mr. Stamets deployed mats of hair into the oil, then impregnated the mats with essence of oyster mushroom, Ms. Lyngso says.

The result: the fungus cleaned out the oil by breaking it down, feeding on it and growing into mushrooms that were themselves recyclable, according to a story in the San Francisco Chronicle.

"The soil is our number one recycling system and it really does work," Ms. Lyngso says.

Don't be evil

Soil is also delicate and vulnerable, and good intentions are no substitute for understanding. Fertilizer, for example, should be organic and never overused, she says. The intensified nutrients can act like drugs and create dependencies in the soil and vegetation.

While healthy soil can strengthen a plant's immune system, pesticides and herbicides may sometimes be necessary, but remember that chemicals can kill valuable microbes. Don't overdo it. "People think more is better," she says.

Other "enemies of living soil" include compaction from too much traffic; leaving the soil exposed to the sun, wind and rain; and disturbing it repeatedly, whether by shovel or mechanical tiller, Ms. Lyngso says.

"Every time you turn it over, you're breaking up the homes" of microbial life, she says.

Darrell Bruggink, executive editor of the "No-Till Farmer" newsletter, based in Brookfield, Wisconsin, writes about farming practices that avoid overly disturbing the surface of the soil, whether after the harvest or before planting. He agrees on the sanctity of the soil's surface.

People who regularly till the soil "are beating it up. They're breaking down the soil aggregates," he says in a phone interview. "In reality, (the soil) is losing its ability to sustain itself."

Fallen leaves are a natural mulch and should be left in place to cover and protect soil, Ms. Lyngso says. Leaf blowers are a no-no. In addition to scattering the microbes, the blowing can help to harden the soil's surface, a particular aggravation on the Peninsula with its ubiquitous clay, she says.

Bringing it home

Garden aesthetics are also less important to Portola Valley resident Danna Breen, who describes her ground cover as "a wonderful organic blanket" and adds that she is "almost comfortable" with its look.

Ms. Breen, the community liaison for the garden club, does not segregate flowers and vegetables and never uses a rake, much less a leaf blower, she says. "I have blueberries in with my roses," she says.

It's been a year and a half, she says, since she began using organic fertilizer, composting and planting in layers, known as sheet mulching. Cardboard or a thick layer of newspapers goes down first, topped by a layer of mulch, with holes through it all for the seeds.

"I'm seeing really remarkable results," she says.

Asked if pests raid her garden, she replies: "It depends on what you look at as a pest." She's learned to live peaceably with gophers, for example. "If you reframe it for yourself, they're actually aerating the soil."

In the Portola Valley Ranch subdivision, regulations forbid home vegetable gardens, so residents have a community garden where individuals lay claim to one or more of the 101 raised beds there. A waiting list for beds is not uncommon.

Ranch resident Diana Fischer, who has taken classes at Le Cordon Bleu School, says she gardens year round. Her boxes include salad greens, French beans, currants and four types of berries.

"To make jam the day you harvest the fruit, it tastes great," she says. "I'm a foodie who likes to play in the dirt, I guess."

To avoid exhausting the soil, Ranch resident Lynn Davis says she tries to rotate her tomatoes between her boxes.

The Ranch's community garden receives free compost every year from Portola Pastures, an equestrian facility nearby, Ms. Davis says. The shovels and other tools down there are for everyone to use.

In the spring, everyone gathers to weed. In the fall, they collect the last of the produce, and in November there's a pot-luck dinner, Ms. Davis says.

Brad Peyton, president of the Portola Valley Garden Club, has been gardening for 30 years. He's been at it long enough that he doesn't follow trends like adding rock dust to the soil in the belief that it improves the taste of tomatoes.

Nor is he a fan of no-till gardening. "I want to break up the soil and make sure the roots go in," he says. "I find this works for me."

Asked why he gardens, he replies that it's great to grow things and eat them. "I would rather plant a vegetable than a flower," he says. "It's pretty and I can eat it. I'd much rather plant something I could get some food from."

His place on Brookside Drive is well shaded by redwood trees and his crops probably reflects that reality. He plants greens and root crops, he says, but no corn and no garlic, both of which need lots of heat.

"It's hard growing food," he says. "That's one of the reasons I do it."

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