Mycorrhizal fungi in current agriculture
"A nation that destroys its soils destroys itself."
President Franklin Roosevelt
I would like to start my first blog with words of wisdom from President Franklin Delano Roosevelt: "A nation that destroys its soils destroys itself”. And only ignorant person will disagree with this statement who does not understand that this natural resource is non-renewable. But how to protect our soil and what do we do for it?
Farmers are faced with new challenges and opportunities every day -- from feeding an expanding global population (in 30-50 years time, 9-10 billion people will be living on the planet) while meeting strict new emissions requirements, to producing more food on fewer acres while minimizing their environmental footprint.
An approach to managing agro-ecosystems for improved and sustained productivity, increased profits and food security while preserving and enhancing the resource base and the environment, that has been gaining more and more followers, is known as conservation agriculture. The main principles of this approach are no-till practices, continuous crop cover and diversification practices – all of them have positive impact on mycorrhizae development, a symbiotic relationship between fungus and plant. Mycorrhizal fungi are recognised as one of the most important soil micro-organisms; they form symbiosis with over 90% of plant species. However, in agricultural development, priority is often given to yields, and the cheapest and easiest way to achieve this is high input of artificial fertilisers, what makes role of mycorrhizal fungi in nutrient acquisition redundant and consequence in root colonisation reduction. These beneficial microbs are best known for phosphorus (P) uptake and its further supply to the plant; and we also all know that 80-99% of this particular macro-element are barely available to the plant. So the questions like: “Why not to use these beneficial microbs to mine P for the plant?” and “Why do we still throw chemicals that will be locked in the soil instead of being uptaken by crops?” are very important, but still remained unanswered.
I have to tell I met few farmers who follow principles of conservation agriculture and their soil is alive – full of micro-organisms. One of the farmers hasn’t applied P for remarkable 15 years, and when I studied wheat roots grown on those fields, I was nicely surprised as those roots were heavily colonised by symbiotic mycorrhizal fungi. Why I was surprised – because I analysed number of samples from various farms that follow conventional way of farming and root samples from their fields, didn’t show any signs of colonisation. And it was sad and scary, because that suggests we have been destroying our soils…
However, not just fertiliser application affect mycorrhiza, modern agricultural methods such us regular tillage that breaks hyphal network, cultivation of monoculture (especially of non-mycorrhizal crops such as brassicas or newly bred cereals varieties) that reduce microbial biodiversity; application of pesticides, especially fungicides, do not encourage beneficial mycorrhizal symbiosis. In order to be advantageous, mycorrhizal fungi must be present in the soil or introduced, and secondly, cultural practices must be improved in order to protect them.
PlantWorks, the producer of mycorrhizal fungi, made decision to move into agricultural sector in 2014, as many farmers was knocking to our door and asking for advices how to improve their soil and return biology into it. Since then our science team have been working with various agronomy companies and farmers directly and developing new products that meet farmers’ needs. We developed a tool called SMART ROTATIONS that aim to assist farmers and agronomists on the appropriate use of microbial management and interventions in farming.
In conclusion, mycorrhizal dynamics are a key component of ecosystem sustainability. Understanding and managing this symbiosis is important for maintaining healthy and fertile soil, and ensuring growth and health of plants.
Technical Manager, Broad-acre Farming Group, responsible for production and QA of mycorrhizal inocula. Also she is part of Broad acre Group that works with farmers and develops and improves and trials biological products for broad acre farming. Also she has particular interest in development of affordable test for determination of mycorrhizal background in arable soils.
References and further Reading:
Angela Hodge (2012) Microbiology Today. Feed the world? Arbuscular mycorrhiza and agriculture. May, 90-93.
Grassini, P., Eskridge, K.M. and Cassman, K.G. (2013) Distinguishing between yield advances and yield plateaus in historical crop production trends. Nature communications.4: 1-11.
Hodge, A. (2004) The plastic plant: root responses to heterogeneous supplies of nutrients. New Phytologist 162: 9–24.
Lekberg, Y. and Koide, R.T. (2005) Is plant performance limited by abundance of arbuscular mycorrhizal fungi? A meta-analysis of studies published between 1988 and 2003. New phytologist, 165: 189-204.