Nitrate (NO3) is a compound that contains nitrogen and water. Nitrogen comes from decomposing organic materials
like manure, plants, and human wastes. Often the nitrogen
(N) comes from ammonia (NH3) or ammonium (NH4).
Basically, plants need nitrogen to make amino acids and proteins, which
are essential for plant growth. Plants cannot use organic nitrogen directly.
"Microorganisms in the soil convert the nitrogen locked
up in crop residues, human and animal wastes or compost to ammonium (NH4). A specific group of microorganisms convert ammonium to
nitrate (NO3)" 58.
Since
nitrate is water-soluble, excess nitrate not used by plants can
leach through the soil and into the groundwater.
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The
widths of the red arrows show relative amounts of nitrate leaching
into groundwater. The wider the arrow the more nitrate. |
Nitrate is also found wherever biotic things are
breaking down or decomposing like animal waste, and
septic system absorption fields or mounds.
The main sources
of nitrogen in groundwater are highly fertilized crops and lawns, and large amounts
of human and animal waste (septic systems, sewage, and manure).
Studies have shown that nitrate in Wisconsin's and Portage County's
groundwater comes from:
- agriculture-90%,
- septic systems-9%, and
- lawns and other-1% 7
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