Phosphorus management – What really has to change?

Those in agriculture are being asked by both the provincial and federal government to reduce the amount of phosphorus that runs into Lake Erie by 40 per cent. This does not mean a 40 per cent reduction in the amount of fertilizer we use, but rather we are being asked to reduce the amount that runs off from our agricultural facilities by 40 per cent. This difference is important.

Farmers are pragmatic folks and look for practical solutions to problems, but phosphorus management is a complex topic. As much as phosphorus likes to bind with soil particles, it can also move with the soil if it erodes or can dissolve in waters that flow off the land or down into the soil. This makes it somewhat confusing to figure out which practices we might need to modify in order to reduce phosphorus runoff.

In my opinion there are four basic areas we need to focus on, where farming practices might be contributing to the problem:

• Soil Erosion.  We must stop water from flowing in large volumes across fields and down slopes.  We need to learn how to re-incorporate grass waterways back into glyphosate-resistant field crop systems.

• Building soil health and its ability to hold nutrients. We must look at our tillage regime, use of cover crops and crop rotations to increase organic matter, and improve the water-holding capacity of our soils to both store nutrients and reduce what runs off our farms.

• Nutrient use. By now most of us have heard of the 4Rs (right source, right rate, right time, right place) but each operation needs to focus on those Rs that matter most to their situation. Let’s assume we are soil testing and putting on the correct source and amount of nutrients, so we need to focus on correct time and placement of nutrients to minimize the amount of phosphorus that is moving off our fields. We know we need phosphorus for optimal plant growth, but at the same time we need to figure out when and how to put it on, so that it won’t be susceptible to movement.

• Agricultural Point Sources. Tile outlets, pond outlets and building outlets can be an opportunity to reduce or eliminate phosphorus outflows with new kinds of technological solutions. The Holland Marsh Growers’ Association, Flowers Canada, Ontario Greenhouse Vegetable Growers and The Ontario Greenhouse Alliance are currently researching water treatment options and contributing to a base of knowledge that will allow growers greater choices in affordable options to re-circulate and treat water streams. 

The issue of phosphorus in the Great Lakes is going to test our industry. There are a number of commodity-specific programs underway to demonstrate the sustainability of agriculture. But talking the talk is easier than walking the walk. We will need to prove that we can reduce the environmental impacts beyond our farm boundaries. Thus far, sustainability initiatives have been largely unchallenged as they seek to address customer, government and consumer concerns about sustainability. The phosphorus issue will push commodity-driven farm sustainability programs, and industry-supported programs such as the 4Rs to prove that they can address whatever the criticism might be about a specific issue: nutrient use, antibiotic use, animal welfare, social responsibility or in this case the reduction of nutrients that flow off our agricultural operations.

What actual farm practices should farmers be looking at on their farms?

• Are you using a good crop rotation that maintains soil organic matter or is soy-on-soy a regular occurrence on your farm?

• Have you looked at the drainage patterns on your field and done everything possible given your farm’s drainage pattern to reduce overland flow of water? Even if that means you have to farm differently than your neighbours?

• Look at when and how you (or your supplier) uses manure or fertilizer. Is it the best time of year to apply and is it incorporated or side dressed where possible? Are nutrients applied while a green crop is on the field that will bind the nutrients? Or is it put on a barren brown field where it is susceptible to runoff or snow melt? What changes could you make in how or when you apply nutrients to keep your fertilizer away from the water?

We must refine our systems so that the nutrients our plants need are kept out of the waters that flow off our farms. The issue of Great Lakes phosphorus and a 40 per cent reduction target is not going to just blow over. If we are really committed to sustainability, agriculture must respond to the challenge and commit to specific measurable actions to help play our part in a reductions strategy.

For more information on water and nutrient projects at Farm & Food Care Ontario, contact Bruce Kelly at



Publish date: 
Monday, February 1, 2016

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