How farmers are helping rid the Great Lakes of algae

High phosphorous levels

Each summer, high levels of dissolved nutrients (mainly phosphorous) in Lake Erie and its tributaries give rise to large algae blooms in the lake’s shallow western basin.

The issue last reached a crisis in the 1980s, though efforts to reduce phosphates in soaps and detergents eventually helped to dramatically improve water quality.

An annual concern

Now algae blooms have once again become an annual summer concern, even as overall phosphorus levels have been reduced, and the situation could worsen with climate change, should average temperatures continue to rise.

 Manure and fertiliser primary cause

The International Joint Commission – the organisation devised by Canada and the US to act as an independent adviser on boundary-water issues – cited manure and fertiliser run-off as the 2 primary sources of the lake’s plight.

With that, the Commission reported a 40% reduction in water-born phosphorous was needed to bring Lake Erie’s algae concentrations to a safe level.

The organisation also suggested those targets could only be achieved through legislation, with voluntary measures thus far proven insufficient. What any proposed legislation would entail, however, remains unclear.

Diverse solutions

While the threat of legislation looms, many Ontario farmers continue to approach the problem from a position of strength.

Dale Cowan, southwestern Ontario-based senior agronomist with AGRIS and Wanestead co-operatives, says the most significant step farmers can take to improving nutrient management is to understand where loss occurs.

“Surface loss is much more significant than ground leaching. If you’re going to lose nutrient anywhere, that’s likely where it’s going to happen,” says Mr Cowan.

“There’s a greater risk of surface run-off in the early spring and later in the year, outside the growing season.”

Mr Cowan says fertiliser should ideally be applied during planting as nutrient uptake is better, thus less opportunity for run-off and leaching, but while planting-season fertilisation is already a common practice, reality still dictates action.

Whether it’s a full manure pit or just a lack of time and good weather, applications outside the main growing season are sometimes a necessity.

In such cases, Mr Cowan says the risk of run-off can be significantly reduced by tilling broadcasted fertiliser directly into the soil.

Growing season

For those running no-till cropping systems, applying fertiliser in mildly-disturbed bands (strip-till) within the field can also help; producers just have to plant into those bands come the next growing season.

Off-season cover crops and crop residue can also mitigate run-off risk. Whether green or brown, covering plants bring improvements in organic matter and reduce soil compaction, helping to reduce standing water risk. Both practices are already commonly employed by farmers in the region.

High-tech management

Technology allowing greater application customisation is also playing a role. AGRIS Co-operative, for example, has developed a ‘precipitation weather data network’ called AGGrower Daily Dashboard.

It is a cloud-based service that provides up-to-the-minute rainfall and temperature data using 280 strategically placed weather stations across Ontario’s most southern counties, and maps differences in field conditions on a metre-by-metre scale.

According to Mr Cowan, the Dashboard is designed to help all aspects of crop production, from adjusting planting schedules or pesticide applications to better timing of fertiliser application to ensure nutrients stay where they are needed.

“No one wants to get information from a paper 3 weeks after they could have used it. Tools like the Dashboard let you make growing decisions when it matters, with notifications coming right to your phone or tablet.”

Tried and true

Soil sampling, too, helps create more targeted application plans and the number of farmers making use of this tried-and-true technology on a more frequent basis is also on the rise.

“It all relates to ‘4 R’ Stewardship, or applying [fertiliser] at the right rate, time, place, and amount. Keeping things updated gives a much better picture of what’s needed where,” says Mr Cowan.

“We’re encouraging producers to take updated samples if they are more than 3 years old, and have launched a new company-wide programme to double the amount of sampling we do.”

Mr Cowan stresses that applying the ‘right rate’ doesn’t necessarily mean reducing fertiliser inputs. Phosphorous is still an essential nutrient, and if levels in a particular place are low, he says farmers can apply more – with confidence – because it will be absorbed in the soil and used by the crop.

“Well-drained, tilled ground is still a real benefit, too. Poorly drained soil can mean more surface water flow, which is an even worse problem than leaching.”

Case study: Farmer experiments to cut fertiliser losses

Henry Denotter, a grain farmer from Kingsville, Ontario, says cover crops have proven to be one of the most interesting management strategies he has incorporated into his farm.

For 10 years, Mr Denotter and his son have partnered with the local conservation authority and provincial soil and crop improvement association to measure which cover crops are most effective at mitigating fertiliser loss.

[photo: Henry Denotter (left) Jeremy Denotter (right)]

“We’ve tried a lot of different things over the years, and there’s a lot to try yet … not all cover crops are glorious,” he says. “There have been triumphs and disappointments.”

On his family’s dense Brookston Clay ground, Mr Denotter says cover crops with well-developed root systems are the most effective.

Covers that die in the winter, too, are a benefit because there is less to wrangle come the spring, reducing cultivation requirements and subsequent compaction.

“There are a lot of factors at play,” he says.

“Anything we try has to make economic sense for our farm. Once you have the economics, you can play with the agronomics. Every species has a cost… planting green could cost me money if it’s too thick, and more [cover crop] is not necessarily better.”

Like Mr Cowan, though, Mr Denotter says the most significant factor for his farm is fertiliser placement. With that in mind, he and his son use a specialised planter that seeds and fertilises simultaneously.

Still, Mr Denotter says each on-farm solution brings unique challenges – high operating costs being just one – and reiterates the importance of adaptability.

Final word: Understanding farm diversity key

Lake Erie’s algae issues are complex, and the solutions reflect that complexity. Modern technologies such as GPS and variable-rate equipment certainly have a role, but a better understanding of on-farm realities and the diversity within each farm are critical.

Problems can’t be resolved if they are not properly understood, after all.

And as farmers and farm groups look to more adaptive management strategies to reducing phosphorus run-off, the official seal of approval may still have to come from government. One can only hope that legislators will also take a diverse approach.