Scientist aims to unravel secrets of soil biology

Understanding soil bacteria can help develop biological alternatives to chemicals for nutrients 
and pest control, says researcher

LONDON, Ont. — A microbiologist at Agriculture Canada’s re-search centre in London looks to better harness the power of soil biology.

Ze-Chun Yuan and his team are screening 3,000 soil bacterial isolates and have found a dozen bacterial species with potential.

At least one of them, Paenibacillus plymyxa CR, has multiple positive functions. It is isolated from the rhizosphere surrounding corn roots and fixes nitrogen, promotes cell division through the production of a phytohormone and produces antimicrobial compounds to fight disease.

“It’s unusual to have one bacterium that has so many good functions,” Yuan said. “The population in farm fields tends to be very low so we think we can increase it by adding it to the seed.”

Small plot trials of corn, wheat, soybeans and canola are to be established this year at the research centre. A farmer co-operator is to be brought on board so that larger field trials can be conducted next year.

Many questions must be an-swered.

For instance, how long can a large population of bacterium such as P. plymyxa CR1 be maintained once it is established, and what cultural practices can be used to maintain it.

Other benefits for field crop production include improving access to soil nutrients such as phosphorus and potassium and controlling disease and insect pests.

For example, Yuan said certain bacteria and fungi emit volatile gaseous compounds that help discourage the presence of insect pests.

“We’re still in the process of identifying these volatile gases,” he said.

“It is very challenging work because you need to use deep chemical analysis.”

Soil biology’s importance to crop growth long been recognized, but it’s only been in the past few years that scientists have begun to unravel the specific function of individual species or how various species work in concert.

For example, it’s estimated that only five per cent of soil bacteria species can be cultured.

Yuan feels that biological alternatives to chemical fertilizers and pest control can be developed as soil life is better understood.

“We can do things a better way,” he said.

“We don’t want to damage our ecosystem. The future generations need a healthy environment.”

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