Controlled Drainage to Improve Water Quality in the Holland Marsh, Ontario

Session: 39. - Managing Agriculture Water and Nutrients - Science Solutions for Tomorrows BMPs

Genevieve Grenon, McGill University, [email protected]
Chandra Madramootoo, McGill University, [email protected]

Abstract

The Holland Marsh is an intensive ‘muck’ farming area, north of Toronto, whose drainage outflows into Lake Simcoe. With intensive vegetable production there are growing concerns about non-point source (NPS) water pollution into the West Holland River which drains into Lake Simcoe. One NPS mitigation method being investigated is controlled drainage. In this study, a water management structure was installed at tile drain outlet to control the water table level of a 4-hectare field. The water table was set between 30 and 40 centimeters from soil surface post harvest to allow mineralization of phosphorus (P) to occur. Analysis of the water quality was conducted over two consecutive growing seasons: 2015 and 2016. For these years the calculated total P annual load using the Beal’s estimator was approximately 0.94 kg and 0.80 kg respectively. The majority of the load occurred pre-growing season in the months of January to April, corresponding to the spring thaw. The total P concentration in the water is below or equal to the Provincial Water Quality Objectives (PWQO) of 0.03 mg/L approximately 10% of the 376 samples taken. The results of water quality analysis raise further research questions on the movement of P dynamics in organic soils.

1. Keyword
water quality

2. Keyword
nutrients

4. Additional Keyword
water management

5. Additional Keyword
phosphorus