Volume 16, Issue 36 - September 4 - September 10, 2008

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The Bay Gardener by Dr. Frank Gouin

Is Your Soil Alive or Dead?

Sustain it with organic matter that feeds soil microorganisms

At a recent Deale Farmers Market, a customer asked me why she could no longer grow tomatoes in her garden. I asked her if she’d had her soil tested recently.

“Why should I?” she asked, when she could grow tomatoes well enough in that same garden 10 years ago. Her following comment made me laugh: “The color of the soil looks the same to me.”

I next asked if she had ever added compost or peat moss to the soil and whether she spades the plant residues into the soil when the gardening season is done.

She answered that she used fertilizers, not compost. When the gardening is done in the fall, she rakes away all residue and bags it for county pick-up.

After 10 years of gardening in the same spot following that practice, it is no wonder she can no longer grow tomatoes. Unless you are regularly adding organic matter to maintain a healthy population of soil microorganisms, the soil becomes biologically dead.

The only way you can grow tomatoes in biologically dead soil is to adopt hydroponic practices, which require soil sterilants, lots of fungicides and strict fertilizer regimes.

The less organic matter that is present in the soil, the more cultural problems you will experience. A good garden soil should have a minimum of three percent organic matter. I try to maintain between five and seven percent organic matter in my garden soil so as to minimize my need for fungicides and fertilizers.

Most likely this woman’s tomato plot has a high population of soil-borne diseases. I suspect the spores for early blight and anthracnose blight on tomatoes are just waiting to infest her new plants.

Ask Dr. Gouin your questions at [email protected]. All questions will appear in Bay Weekly. Please include your name and address.

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