Trade-offs in nutrient and sediment losses in tile drainage from no-till versus conventional conservation-till cropping systems

Citation

Macrae, M.L., Plach, J.M., Carlow, R., Little, C., Jarvie, H.P., McKague, K., Pluer, W.T., Joosse, P. (2023). Trade-offs in nutrient and sediment losses in tile drainage from no-till versus conventional conservation-till cropping systems. Journal of Environmental Quality, [online] 52(5), 1011-1023. http://dx.doi.org/10.1002/jeq2.20502

Plain language summary

Nutrient and soil loss from agricultural land has negative impacts on water quality in the Great Lakes Region. Beneficial management practices can be used by farmers to reduce losses from their fields, but even when doing everything “right” there can be events that offset their best efforts. This study led by the Lower Thames Valley Conservation Authority compared tile drainage from two fields, one with conventional tillage practices for the area and one that utilized no-till and planting green into cover crops for four years. While losses of soil and particulate phosphorus were higher from the conventional practices, leaving fertilizer on the surface for one fall resulted in higher dissolved phosphorus losses for the no-till site, such that total phosphorus losses ended up about equal for both fields. This study provides insight into trade-offs in controlling losses of different nutrient fractions using different management systems.

Abstract

Nutrient and soil loss from agricultural areas impairs surface water quality globally. In the Great Lakes region, 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, some of which are transported via tile drainage. This study examined whether concentrations and loads of P fractions, total suspended sediments (TSS), nitrate (NO3−), and ammonium (NH4+) in tile drainage in a clay soil differed between a continuous no-till system combining cover crops and surface broadcast fertilizer (no-till cover crop [NTCC]), and a more conventional tillage system with shallow tillage, fertilizer incorporation and limited use of cover crops (conventional conservation-till, CT). Both sites had modest soil fertility levels. Year-round, high-frequency observations of tile drainage flow and chemistry are described over 4 full water years and related to management practices on the associated fields. There were similar water yields in tile drainage between the two systems; however, losses of TSS, particulate P (PP), and NO3− were consistently greater from the CT site, which received larger quantities of fertilizer. In contrast, dissolved reactive P (DRP) losses were considerably greater from the NTCC site, offsetting the lower PP losses, such that there was little difference in TP losses between sites. Approximately 60% of the DRP losses from the NTCC site over the 4 years were associated with incidental losses following surface application of fertilizer in fall. This study provides insight into trade-offs in controlling losses of different nutrient fractions using different management systems.

Publication date

2023-09-01

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