Measurement and modelling of tillage and water erosion within intensive potato production systems of northwestern New Brunswick, Canada

In Canada, there is growing acceptance that tillage erosion is a serious form of soil degradation and a threat to the sustainability of agriculture across the country. To date, the potential for tillage erosion within potato (Solanum tuberosum L.) production systems has not been investigated. To address this issue, field experiments were conducted in northwestern New Brunswick to generate tillage translocation and erosivity values for primary, secondary and "tertiary" (i.e., field operations conducted during planting, hilling and harvesting) tillage implements commonly used for potato production. The potential for tillage erosion was equally high for the mouldboard plough, chisel plough and offset disc, and larger than that for the vibrashank. Surprisingly, tertiary field operations moved soil further and were more erosive than primary and secondary tillage operations, alone or combined. Overall, the risk of tillage erosion during the production of potatoes is considerably greater than that for other major cropping systems in Canada.Water erosion is also a serious problem within the potato producing regions of Atlantic Canada. However, to date, no previous studies have looked at the impact of both tillage and water erosion on total soil erosion within potato production. Using repeated-measurements of the fallout radionuclide cesium-137 (137Cs), annual soil losses between 1990 and 2005 at a New Brunswick benchmark site were 13.6 Mg ha-1 yr-1, with approximately half of the mapped field having soil losses greater than the tolerable soil loss limit of 6 Mg ha-1 yr-1. A new Directional Tillage Erosion Model (DirTillEM) was used to account for the apparent effect of tillage direction and field boundaries on soil redistribution at this field site. Overall, DirTillEM predictions improved relationships between 137Cs redistribution and estimated soil erosion over those determined by two previously published water and tillage erosion models. It is clear that tillage direction, lateral translocation of soil, and field boundaries must be included in future modelling efforts. In conclusion, choosing implements and developing beneficial management practices that reduce both water and tillage erosion must be fully integrated into soil conservation strategies for potato production systems in Atlantic Canada.