Farmland covered in perennial grass instead of annual crops.

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Intensive Grazing
A Threat to Water Quality?
-Ray Weil, Rachel Gilker (Univ. of Md) Bill
Stout (USDA)
Management Intensive Grazing (MIG)
Using nests of monitoring wells (piezometers) set
to different depths allowed us to sample the
upper 3 ft of groundwater even as the water table
fell from winter highs to summer lows.

• Farmland covered in perennial grass instead of
  annual crops.
• Little erosion or sediment loss
• Cows managed to harvest feed and spread
  manure.
• Low need for imported feed, fertilizer, fuel.

• Sample collection
• Upper 1 m of groundwater sampled biweekly.
• Streams on Grazer 2 farm sampled biweekly plus
  storms.

Cows harvest feed, haul manure
Grass stands still

• Sample analysis
• Filtered (0.25 micron) to separate particulate
  form dissolved nutrients.
• Dissolved nitrate, ammonium and phosphate
  determined.
• Pressurized microwave persulfate digestion used
  for total dissolved N and P.
• Total N NO3-N NH4-N dissolved organic N
  (DON)
• Total dissolved P - reactive dissolved P
  dissolved organic P (DOP)

Stream water P across grazed watersheds (means of
two streams)
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Watershed A