LIVING SOILS are exceptionally complicated and agriculture’s understanding of the science of how plants coexist with fungi, nutrients and their natural condition is only beginning to be understood, says James Cahill.

The University of Alberta experimental plant ecologist sees plant nutrition as a four-step process. The abilities plants must use to derive their food include: (1) assess its condition, (2) occupy a habitat, (3) find and capture resources and (4) allocate resources.

“The first step tends to be that the organism has to have some ability to assess its condition — is it nutrient starved?” he says. “Plants alter future growth based upon their nutrient needs. It’s not as simple as saying, ‘We have low nitrogen in the soil so we’re going to add some nitrate.’ 

“Plants are also going to make adjustments in response to being in the soil with low nitrogen. Those adjustments may or may not increase yield, but they’re very likely to increase the fitness of the plant.”

Second, to understand how a plant actually occupies that habitat in the context of food, it must be recognized that plants don’t move as a whole, Cahill says. Each individual root tip has the potential to make its own decision, which means in different parts of that habitat that same plant can be making different choices at the same time. 

The sum of those choices ends up being crop yield, he says. Plants are making really fine decisions at a very small scale, at the millimeter scale in…