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Competency Area 7: Non-point source pollution AEM

PO 71. Describe the main sources of agricultural Non-point source (NPS) pollution and their origins.

  1. Nitrogen
  2. Phosphorus
  3. BOD (Biological Oxygen Demand)
  4. Sediment
  5. Pesticides
  6. Pathogens
  7. Silage leachate
  8. Chemicals and toxins
  9. Processing and wastewater

Sediment – sources are primarily erosion from cropland, especially when there is no vegetative cover on the fields. Sediments may also originate from laneways, field roads, and unvegetated surface drainage ditches.

Pesticides – sources are pesticide runoff and leaching, especially when rain occurs shortly after pesticide application. Pesticide drift may also find its way back into surface waters.

Pathogens – sources are calf housing areas and manure applications, especially when the manure is surface applied and rain causes runoff prior to the manure having time to dry. Surface water and tile drain discharges are usually more impacted than groundwater, but groundwater may also be affected when manure is applied to coarse textured soils, or to shallow soils overlying fractured bedrock.

Silage leachate – sources are from uncontrolled loss and runoff from silage storage facilities (uncovered bunkers).

Chemicals and toxins – see Pesticides.

Processing waste water – sources are the uncontrolled loss or inadequate treatment and disposal of these wastewaters from livestock facilities (i.e., milkhouse drains).


Sediment buildup in a farm pond

Photo courtesy of NRCS