How do the prairie strips treat sub-surface water flow?
Research as part of our project and other research on buffers and riparian buffers has found that when shallow subsurface flow interacts with the root zone under the prairie strip or other buffers, we can see significant reductions in the concentration of nitrate-nitrogen.
- There may be settings where the shallow subsurface flow is below the root zone such that there is little impact on nitrate-nitrogen concentrations. In situations where fields have extensive artificial subsurface drainage networks the nitrate may be moving below the prairie strip or buffer in the tile. This would reduce any water quality benefits relative to subsurface flow of the prairie strip or buffer.
- There is encouraging research for nitrate-nitrogen reduction using ‘saturated buffers'. This is installation of a tile line along the leading edge of a prairie strip or buffer to promote shallow subsurface flow within the active root zone of the prairie strip or buffer.
- In situations where natural subsurface flow pathways interact with the shallow rootzone below the prairie strip or buffer and where we see nitrate-nitrogen concentrations reductions, it is difficult to quantify the overall load reduction since there are not good measures of the quantity of water flow moving through this pathway. In the future we want to examine additional settings to better understand water quality benefits relative to subsurface water flow.