OSCIA is excited to share that the On-Farm Applied Research and Monitoring (ONFARM) Modelling Reports were completed at the end of June and are available through the ONFARM website. ONFARM water quality and land management data collected by the partnering Conservation Authorities were used by the University of Guelph’s Watershed Evaluation Group to develop an IMWEBs model for several subwatersheds. The model predicts the stream flow moving through the subwatersheds, as well as associated sediment, phosphorus, and nitrogen loads on an annual basis.

The modelling evaluated the impact of three beneficial management practices (BMPs): conservation tillage, cover crops, and fertilizer/manure incorporation on these parameters. Model output included the impact of historical and current BMP implementation, and the potential impact for nutrient reduction from full-scale implementation of each BMP across the watersheds.

Modelling showed that sediment transported by overland flow averaged between 0.31-1.0 tonnes/ha for these watersheds annually. Total nitrogen loss at the subwatershed outlets varied from 19.5-33.71 kg/ha; for context, consider the cost of losing 38 to 65 lbs/ac of urea a year – that’s something worth holding on to!

From the start of GLASI (the previous BMP implementation program focussed on these watersheds) and continuing through ONFARM, the model estimates BMP use has reduced total phosphorus loading by 1-5% from cover crops, 4-6% from conservation tillage, and 9-30% from fertilizer incorporation compared to conventional practices. Full-scale adoption of all three BMPs was predicted to reduce well over half of all total phosphorus loading in these watersheds.

Switching from broadcasting fertilizer or manure to using injection, subsurface placement or immediate incorporation has shown the most potential to reduce phosphorus loss and was the most cost-effective of the three BMPs examined.

Download the reports here.

For more information about ONFARM, please contact ONFARM@ontariosoilcrop.org.