Macrae, M.L., Plach, J., Little, C., Carlow, R., Jarvie, H., Pluer, W., Bittman, D. (2022) Comparison of nutrient losses in tile drainage between two contrasting management systems in clay soil in a cold agricultural region. ASA/SSSA/CSA Annual Meeting, Baltimore, MD, USA, Nov. 6-9, 2022.

Nutrient and sediment losses from agricultural areas are impairing surface water quality globally. In the Great Lakes Region of North America, increases in the frequency and magnitude of harmful and nuisance algal blooms in freshwater lakes have been linked to elevated phosphorus (P) losses from agricultural fields, a considerable proportion of which are transported in tile drainage in clay soil. This field study examined whether concentrations and loads of phosphorus (P) species, total suspended sediments (TSS) and nitrate (NO3-) in tile drainage in a Brookston clay soil differed between a continuous no-till system with cover crops and surface broadcast fertilizer (NTCC), and a more conventional tillage system with shallow tillage, fertilizer incorporation and minimal use of cover crops (CT). Year-round, high-frequency observations of tile drainage volumes and chemistry were monitored over a five-year period and related to management practices on fields. There was no difference in drainage water volumes between the two management systems over the study period. Losses of TSS, TP and NO3- were consistently greater from the CT site than the NTCC site, which coincided with a greater rate of fertilizer application at the CT site. In contrast, DRP and TDP losses were considerably greater from the NTCC over the study period. The majority of the DRP losses from the NTCC site were associated with incidental losses following the surface application of fertilizers in fall. This study provides insight into trade-offs between different nutrient species associated with different management systems.