John Carney-Manitoba Livestock Manure Management Initiative:
With tile drainage, rather than nutrients running off of a field on the surface, there's the added possibility of nutrients percolating through the soil and coming off the field through the tile drain itself
.
If the soils are saturated nutrients could leach through more rapidly or if there's macropores, things like burrows from earthworms, they can also form channels that liquid manure could conceivably come through tile drainage.
Some concepts that are used to control those risks, in some areas there's been some tillage done prior to applying liquid manure on tile drained lands which breaks up those macropores and prevents the risk of liquids transiting through those macropores
.
Other factors are that, if rainfall is predicted, it would likely be advisable not to be applying manure, onto particularly tile drained lands, although rainfall is always considered when looking at manure application.
Another thing with tile drained lands is you may consider how saturated are the soils to start with when you're planning the timing of your manure application.
Carney anticipates a completed report to be available for release by June of this year.
Source: Farmscape