Thursday April 17, 2014




Organic nitrogen solutions

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Chantal Hamel, a soil microbiologist who works at Swift Current, Saskatchewan, for Agriculture and Agri-Food Canada (AAFC), is clear: “We must innovate. The nitrogen in synthetic fertilizers is derived from expensive processes. Reserves of phosphorus are measured in decades; the mines will be empty someday.  In addition, the cultivation of biofuels is now competing with food crops and mobilizing soils and inputs. And there will be 8 billion people on Earth in fifteen years!” The alternative is to develop farming practices based on the properties and activities of soil microorganisms to allow crops to feed effectively.

The concept behind Hamel’s work is simple. It is based on the association of soil fungi and bacteria with plants to ensure their mutual survival. The plant captures carbon from the air to produce energy, in the form of sugars, through photosynthesis. Fungi and bacteria, which cannot photosynthesize, need this energy. So, they settle on the roots of plants, absorbing sugars provided by the plant in exchange for minerals that they draw out of the air and soil. This process is free, natural, requires no human intervention and allows both the plants and microorganisms to gain access to the materials that they need to survive.

“The nitrogen supplied by microorganisms does not cost anything, while it is very expensive to industrially capture nitrogen from the air in the form available to plants,” says Hamel.  The Haber-Bosch process, used to fix nitrogen from using extreme pressure applied at very high temperatures is very energy intensive. The energy required for this operation represents 70% of the cost of the generated nitrogen fertilizer. Yet, soil microorganisms can perform this role for free, and merit closer examination than what they currently enjoy.

Organic farming relies heavily on the development of a rich soil to ensure fertility. The living soil is home to billions of microorganisms that live in symbiosis with plants. Chantal Hamel has a research project with the Organic Science Cluster, the goal of which is to define “Predictive tools for characterizing mycorrhizal contributions to phosphorus uptake by organic crops”. She explains the project: “You start at the base and identify fungi in the soils of wheat fields on different sites (SK, NS, MB, AB, ON). The goal is to understand what is growing in organic soils. We need the cooperation of producers to gather information about the farming methods that are used. Since organic farmers keep extensive records as part of their organic certification, we used the directory of organic farmers and seed producers to choose our sample sites, distributing the sampling on various types of soil whose description was already documented in the federal databases. We then study the fungi content of these soil types and models are made to predict the likely contribution of fungi in a given site based on indicators. “

Knowing what’s in a field is expensive, because the biotrophic fungi do not grow in laboratory dishes, only on live plants. They are microscopic and hard to identify. Samples will be screened, centrifuged, separated according to the weight of the constituents and examined microscopically. Analysis of nucleic DNA to identify fungal species is not possible, due to the numerous copies of unique genes inside fungi.  Instead, researchers examine mitrochondrial DNA, which is unique.

Some rhizobia bacteria, associated with nitrogen fixation, are also very interesting and valuable, as they stimulate plant growth. Research will confirm the potential of these bacteria as legume inoculants and will help in selecting the most rewarding legumes for the soil and crops.

The fungus-plant symbiosis is essential for organic production, where plants feed naturally in the absence of the ecological imbalances that may result when synthetic fertilizers are applied. “It remains to convince industry to invest in this type of research. There is a lot of outreach to do to promote innovative projects whose scope is the medium to long term,” says Chantal Hamel, observing the current prevalence of short-term views in many programs.

This article was written by Nicole Boudreau, Organic Federation of Canada, on behalf of the OACC with funding provided by Canada’s Organic Science Cluster (a part of the Canadian Agri-Science Clusters Initiative of Agriculture and Agri-Food Canada’s Growing Forward Policy Framework).  The Organic Science Cluster is a collaborative effort led jointly by the OACC, the Organic Federation of Canada and industry partners. OACC newspaper articles are archived at www.oacc.info one month after publication. For more information: 902-893-7256 or o...@nsac.ca.


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