 Sub-surface
water aquifers
are not degraded by nutrients in the same way as surface
water because productivity is largely restricted by a lack
of light. However, buildup of nitrate, a highly mobile form
of nitrogen, can cause a condition called methemoglobinemia,
or blue baby syndrome in young stock and babies fed milk
formula made from high nitrate water. Drinking water
standards restrict nitrate-nitrogen concentrations to 10
parts per million to avoid this effect. Research has shown
that nitrates from swine manure cannot be directly linked to
any of the few cases of blue baby syndrome. Also, pork
production contributes very little to ground water nitrate
concentrations, but there is continuing research.
The movement of nutrients from agricultural fields to
water resources is a complex topic, and lessons learned
about one nutrient generally do not apply to other nutrients
because of dramatic differences in the
chemistry of elements such as nitrogen, phosphorus and
potassium.
How might nutrients
from pork operations affect water quality?
Pork producers are
stewards of the land and are able to minimize nutrient loss
during manure storage and land application. Producers
maximize the efficiency of
nutrient use by animals and crops through crop feeding
practices. In addition, producers are minimizing the
erosion from their fields using conservation practices.
The nutrients returned to cropland promote sustainability of
the farming operation. |
Over-application
of fertilizers, poor erosion control and poor timing of
fertilizer application can all contribute to large increases
in nutrient loss from a field. Consequently, pork producers
develop nutrient management plans to prevent the types of
situations that could lead to large losses of nutrients to
our water resources. Manure characteristics make it more
challenging than other fertilizer sources to apply in a
timely fashion for crop production.
If a water source is
found to be contaminated, can the source be determined?
 Elements
and nutrients found in municipal human sewage, commercial
fertilizers and livestock manure are all naturally occurring
compounds. When present in groundwater or surface water,
these compounds may be indistinguishable. For example,
sewage from a septic tank contains the same basic elements
and nutrients found in manure. As a result, it is difficult
to determine the source once compounds have impaired a
watershed.
There are testing methods to determine the species of
animal from which fecal bacteria contamination may
have come. One such method, called ribotyping,
matches the DNA pattern of the bacterial isolate in the
water with known host patterns in the database. The
test method is available to the public, but the cost is
quite high. |
