Phil Pfeffer can see the day when a farmer
drives up to his local input dealer to pick up some fungus-based soil inoculant that will boost his crop yields.
But the American researcher says it isn’t about to happen soon.
“I think we’re making progress towards that,” he said in an interview from the United States Department of Agriculture’s research centre at Wyndmoor, Pennsylvania.
“But my estimate is it’s probably a number of years away.”
Arbuscular mycorrhizal fungi attach themselves to the roots of host plants and send out thread-like hyphae, which help the plants take in more water and nutrients, especially phosphorus from the surrounding soil.
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Normally, the fungal colonies can’t be grown without the host plant. But researchers at Wyndmoor are trying to find a way to do so, a development that would permit large-scale production of inoculum for field applications.
Research is now at a basic, technical level, but that’s the only way progress will be made, Pfeffer said.
“It’s a complicated system,” he said.
“There’s lots of pieces to the puzzle and we have to find out how we can put these all together.”
Soil scientist David Douds is supervising experiments at Wyndmoor aimed at finding practical ways for farmers to grow and apply their own mycorrhizal fungi.
“Right now, the most reliable way of growing these things is in a greenhouse pot with a potted plant.”
That’s not suitable for large-scale production of field crops, but Douds thinks there is a solution.
“It will happen some day,” he said.
Wyndmoor researchers have found that applying phosphorus fertilizer reduces the likelihood that the beneficial fungi will develop.
“If a plant can get the phosphorus it needs for optimum growth without using the mycorrhizal symbiosis, it does things to inhibit colonization of the roots,” Douds said.
That in turn has a trickle down effect, because the fungus is less able to propagate itself, reducing the total mass of AMF in the soil.
Studies have found that low-input farms have more of the fungus inoculant in the soil than conventional farms.
Pfeffer said a lot of conventionally farmed soil has only meager populations of the naturally occurring fungi.
“Plants now are able to live on all the fertilizer that we put down and so the plants don’t put out the signals and the mycorrhizae don’t colonize them,” he said.
“We need to replenish those levels.”
