However, excess nitrates in soil can increase the risk of contamination of ground or surface water. This risk can be reduced through careful application of commercial fertilizers and manure at rates matching plant needs. Proper storage of fertilizers and manure is also required. Livestock producers should exercise care to ensure that their operations do not contribute to excess soil nitrates. Nitrates in Water High nitrate levels in water may be encountered in agricultural areas, often in wells located near a long established barn site.
Nitrates can leach from the soil into underground aquifers, contaminating well water.
The extent of nitrate contamination, and how quickly it occurs, depends both on soil type and on depth of the water source. Nitrates can leach more easily in light sandy soils than in clay-based soils. Contamination is more common in shallow wells than in wells drilled into deeper aquifers. Heavy rains and flooding also affect the amount of nitrate that reaches both ground and surface water. High nitrate levels in drinking water can have adverse effects on human health.