News
Reducing nutrient loss

The Ontario Federation of Agriculture (OFA) and the Great Lakes and St. Lawrence Cities Initiative have joined forces to develop and implement a farmland water management and drainage strategy to reduce phosphorus (P) loss in the Thames River basin in southwestern Ontario.

This is a proactive project in response to government commitments at the federal and provincial levels to reduce the amount of phosphorus entering Lake Erie by 40 percent.

As much of the Lake Erie phosphorus load is coming from agricultural and municipal sources, working together on part of the solution made sense.

Drainage of farmland is primarily driven by the need to get water off the land during the growing season. In recent years, there has been increasing interest in improving the quality of water draining off farmland. The impact of run-off is particularly acute in the western basin of Lake Erie, which is experiencing the growth of enormous harmful algal blooms, due in large part to elevated levels of reactive soluble phosphorus. These blooms have already caused some public drinking water systems to be shut off out of concern for the presence of microcystin, a toxic bacteria that can be present in the algae. The Thames River, which connects to Lake St. Clair and ultimately the Detroit River, has been identified as a priority source of P loadings into western Lake Erie from the Canadian side.

The strategy being developed will urge and support landowners to adopt improvements to water management and drainage on their lands that will reduce phosphorus loss from their fields. Licensed drainage contractors, drainage engineers, drainage superintendents and municipal councils who all have a responsibility for aspects of drainage installation, maintenance and oversight are also being engaged as critical partners in the development of this strategy.

We do not want to reinvent the wheel. There is a tremendous amount of knowledge and experience we need to tap into. The two organizations have enlisted the support of a broad cross-section of farming and drainage interests to help develop the strategy by building on what has already been done.

Groups like the Drainage Superintendents Association of Ontario, the Ontario Certified Crop Adviser Association, Conservation Authorities, Land Improvement Contractors of Ontario, the Land Drainage Committee, Ontario Agri Business Association, the Drainage Improvement Group, academics, non-governmental organizations, and federal and provincial government agencies have all joined in the strategy development process through an advisory committee and four subcommittees. The strategy will be developed based on their recommendations to the Great Lakes and St. Lawrence Cities Initiative and OFA.

We anticipate the strategy to be developed by June, and implementation will begin in the fall of 2016.

While the details of the strategy are still being worked out, it is clear that it must address the two biggest challenges: reducing phosphorus loss when, and where, it occurs most.

Research suggests that most phosphorus loss occurs during the non-growing season and during big storm events. Most best management practices (BMPs) are geared towards the growing season, and are not necessarily able to manage the flow from intensive rainfall. New or modified BMPs may be needed, as well as consideration of new techniques and technologies. A subcommittee is tasked with investigating which BMPs would be most effective in the Thames River basin context – buffer strips, cover crops, modifications to inlets, the installation of blind inlets, stormwater ponds and artificial wetlands all may be considered.

Identifying where phosphorus loss is occurring is an ongoing challenge, given the lack of monitoring data available in the Thames River basin. The Canadian and Ontario governments are working on modeling to help identify these areas, which will assist our efforts, but this will take time. In the meantime, our strategy may have to settle for a “good enough” map of phosphorus sources. Some early suggestions from our science subcommittee recommend a combined approach, using the best available water quality data to identify tributaries with elevated phosphorus levels and cross-referencing these locations with GIS mapping of land cover and farming practices that are known to contribute to water and phosphorus movement into waterways.

Even in our very preliminary discussions, we have identified the opportunity to bring together thinking for the entire system from fertilizer application through land management and then drainage management. While we are looking at the tail end of the phosphorus movement chain, and the Fertilizer Institute, the Ontario Agri Business Association, and the Ontario Ministry of Agriculture, Food and Rural Affairs will be addressing the front end of the chain in terms of fertilizer application through the 4Rs program, there remains a significant middle section of the chain – soil and water management on private farmland – that needs to be integrated in this discussion in a comprehensive way. Participants in our committees are pressing us to consider how our strategy can help integrate these three aspects of phosphorus movement.

These are just some of the challenges our strategy is facing as we forge into this complex land and water management conundrum. While the challenges are daunting, the potential is exciting.

If we can figure this out for the Thames River basin, or even show progress in limiting phosphorus loss from farmland, starting from the drainage system and working back onto the land, perhaps our strategy can inform actions elsewhere in Ontario and the Lake Erie basin. DC

Nicola Crawhall is deputy director of the Great Lakes and St. Lawrence Cities Initiative and is leading the development of the Farmland and Water Management Strategy.