Soil Savvy Microbiome

By Gurbir Dhillon Ph.D.

The final segment on beneficial soil microorganisms looks at the complicated and crucial relationship between plants and soil microorganisms. Plants co-evolved with soil microorganisms for millions of years and developed complicated plant-soil-microbe interactions that help execute essential biological functions, including nutrient uptake, resistance to pathogens, carbon sequestration, and ecosystem maintenance and resilience.

view from soil pit
Soil profile from long term forage production land in southern Alberta (Lethbridge)

Multiple chemical signaling pathways manage the interactions  in rhizospheric microbial communities. These microbial communities specific to the host plants are also known as root microbiomes. Host plants can affect root microbiome composition through exuding signaling compounds such as ethylene, salicylic acid, and volatile organic compounds.

In agricultural systems, other factors such as soil type, temperature & moisture, nutrient content, organic matter content, pH, etc., can alter root microbiome composition and functionality. A study1 carried across western Canada found seven species of plant growth promoting rhizobacteria (PGPRs) and two species of fungi enhance canola yield in the Canadian prairies.

This study also found that crop production practices such as fertilization and seeding rate affected the root microbiome composition. At higher canola seeding rates the parasite Olpidium brassicae was less abundant.

Another study2 found pulse crops yield in the Canadian prairies correlated to soil microbial profiles. The effects of agronomic practices on plant root-associated microbiomes needs further study and exploration to enhance sustainable crop productivity with healthy soil systems.

1 – Lay, C.Y., Bell, T.H., Hamel, C., Harker, K.N., Mohr, R., Greer, C.W., Yergeau, É. and St-Arnaud, M., 2018. Canola root–associated microbiomes in the Canadian Prairies. Frontiers in Microbiology, 9:1188.

2 – Hamel, C., Gan, Y., Sokolski, S. and Bainard, L.D., 2018. High frequency cropping of pulses modifies soil nitrogen level and the rhizosphere bacterial microbiome in 4-year rotation systems of the semiarid prairie. Applied Soil Ecology, 126:47-56.