Groff's Plant Farm Images

What's in the Soil?

Published: Fri Apr 28th 2017


Thinking about our garden/landscape soil, we have often heard the drill. Mulch for weed control, moisture retention and to add organic material. Compost helps govern the moisture/air balance. Fertility and pH requirements differ among plants but attention is most important with vegetables and grass. Water is needed but soggy is bad.

Recently my interest in what else is in the soil has increased. It’s crowded with microbes including fungus, bacteria, nematodes and protozoa among others. Some are good, some are bad. Since we live in a green world, I guess the good out duals the bad much of the time.

I recently had the opportunity to talk to a division winner from the Lancaster County Science Fair who was working with microbes. His goal was different but he made an interesting discovery. Testing garden soil, compost and livestock manure he found the most microbes in the garden soil. One report I read suggested that if we took an ounce of soil and started handing out microbes to each person on earth for a pet we would run out of people before we ran out of microbes. Coming from the internet it must be true. Maybe not, but you get the picture. Soil microbes let some plants fix nitrogen from the air to the soil. Others make nutrients more available, increase disease resistance, control insects, increase nutrient uptake to name a few.

Several commercial examples.More than 30 years ago, a bacteria based spray, called Bt, short for its 15 or 20 letter real name was released. Soil derived it was very effective for cabbage loopers and other worms if used as directed. More recent Bt introductions target other insects including potato beetles.About 10 years ago I heard the claims about a product called Root Shield. Before I got beyond what’s that my daughter took over the business and soon she was dipping starter plants in a Root Shield solution.  Fast forward a few years and she is now using soil already treated with Root Shield.

Root Shield is Trichodema harzianum, a fungus. Now that I got that out of the way, it coils around the roots releasing enzymes that dissolve the walls of fungal pathogens. The improvement in root and plant development is amazing.  (See picture above)

Gardening practices will give variation in microbe populations. Tillage and water are two such practices. Root Shield lies dormant until activated by water. Commercial Bt is active but has only a one season shelf life.

As we continue to unravel what’s in the soil we may move closer to the marriage of commercial and organic agriculture.