The Lake Simcoe ecosystem has been severely degraded by excessive phosphorus (P) accumulation over the years, with urban and agricultural activities contributing the most. Although multiple mitigation plans such as the Lake Simcoe Protection Plan (2009) have reduced the P impact on the ecosystem, there is much still to be done to meet the target of 44 t/year. In addition, in order to achieve this target, mitigation measures need to focus on non-point source pollution from agricultural activities in the Holland Marsh.
Intensive farming in the Holland Marsh has led to excessive fertilizer usage in order to compensate for low inherent fertility, but the consequence is lake eutrophication. The Holland Marsh consists of over 7,285 hectares; of which 60% is muck soil farming that flows from the West Holland River and into Lake Simcoe. The use of controlled drainage to conserve available water and reduce Nitrogen (N) and P losses from agricultural areas has been found to be successful, particularly in mineral soils. However, there is a gap of knowledge on their effectiveness in organic soils. This research project investigated drainage water management using water table control structures, to test their effects on organic soils and on N and P load reduction. The project also included an assessment of the influential forms of N and P in nutrient transport. The project was conducted at three study locations in the Holland Marsh, of which two had water control structures and one served as a control with regular farmers' practices.
