In what is a hugely promising sign for securing and boosting food production, a large-scale field study has demonstrated how treating farmland soil with mycorrhizal fungi can improve crop yields of maize by 40%, without the use of any additional fertilizers or pesticides.
In the Swiss study, researchers mixed Arbuscular mycorrhizal fungi (AMF) into soil, prior to sowing, at 800 trial plots on 54 maize farms.
This fungi occurs naturally in healthy soil and penetrates the roots of plants to form tree-like structures (arbuscules). When they branch out, they increase the plant's root surface area and therefore bolster nutrient uptake.
"On a quarter of the plots, the mycorrhizal fungi enabled up to 40% better yields,” said the study's co-lead, Marcel van der Heijden, a soil ecologist at the University of Zurich and at agricultural research center Asgroscope. “That's huge.”
Investigating why a third showed little increase or even a decrease in yield, the researchers found that healthy soil produced the same (or, in some instances, lower) yields.
"We discovered that the inoculation functioned best when there were lots of fungal pathogens already in the soil," said co-first author Stefanie Lutz from Agroscope.
The fungi are thought to provide a first line of defense for the soil, warding off plant-attacking pathogens that can greatly reduce crop yields. As a result, yields could be maintained in fields with pathogens that would have experienced losses without the fungi, while the beneficial effect of the fungi on yields was lower in fields without pathogen contamination. As beneficial organisms, they also help the plants take on nutrients from the soil.
Based on the broad results, the team then used soil microbiome indicators to successfully determine the variation in plant growth, with 86% accuracy, for any given plot prior to sowing.
“We were able to predict the success of inoculation in nine out of 10 fields, and thus could also predict the harvest yield even before the field season," said co-lead author Klaus Schläppi, from the University of Basel. "This predictability makes it possible to target the use of the fungi in fields where they will work. That's a crucial element for developing these technologies into a reliable agricultural method.”
This discovery could bolster food production, without the need for intensive pesticide and fertilizer use. A 2022 United Nations report found that 40% of the world’s soil is moderately or severely degraded and predicts it could rise to 90%.
Just how to efficiently spread the fungi on a larger commercial scale is yet to be resolved, but "the results of this field trial represent a big step toward a more sustainable agriculture," said van der Heijden.
The study was published in the journal Nature Microbiology.
Source: University of Zurich via phys.org
