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Researchers defining phosphorus movement in Ontario soils

Wednesday, August 30, 2017

researchers in farm field

Three short huts with solar panels on them sprout in Bob McIntosh’s wheat field near St. Marys, Ont.

Inside the huts are monitoring equipment that goes right to the tiles that systemically move water from his farm. His farm is one of six across Ontario with the monitoring equipment that allows University of Waterloo researchers to study how water, and especially the phosphorus in it, flows off of farms.

We’re trying to capture the natural variability in the Ontario landscape,” says Janina ​Plach, post-doctoral fellow in Richard Petrone's Hydrometeorology Research Group.

It also shows that a significant portion of phosphorus is lost in the non-growing season.

That’s really a knowledge gap right now, understanding how phosphorus is leaving our soil in Ontario during that non-growing season,” says Plach.

Algal blooms in shallow and warm Lake Erie have been partially blamed on agricultural phosphorus use.

The University of Waterloo research, led by Water Institute member Merrin Macrae, is showing that there’s a lot to know yet about phosphorus movement in different types of soils before Ontario-specific best management practices are developed.

The long-term work is showing that phosphorus appears to move off of farms in different ways than it does in Ohio, the main American farm-region contributor to phosphorus load in Lake Erie.

“In Ontario we’re seeing that the phosphorus losses in Ontario are lower than Ohio and we’re losing our phosphorus in the tile drains in a particulate form. In Ohio, we’re seeing higher levels of phosphorus in the tile drains and it is mainly in a soluble reactive form,” says Plach.

Plach says the differences could be related to management, soil texture or geochemistry, and the research going forward will help determine why there are differences.

However, Plach says that farms that use the 4Rs strategy, which certifies agronomists to help advise their customers in order to place nutrients in the right source at the right rate, right time and in the right place, is a best management practice that has shown to be of value in reducing phosphorus movement off farms. Other practices that limit phosphorus showing up at higher levels in tile drains also include using no-till and subsurface placement of fertilizer versus surface broadcasting.

Read the full story on Country Guide.