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Nitrate as Crop Plant Nutrient: In order for
plants to make complex nitrogen compounds, the plants need a supply of
simple nitrogen compounds and most plants prefer nitrate over ammonium. So
over the eons as agriculture has developed, man has applied fertilizer to
crops to enhance their growth and productivity. Nitrogen fertilizers have
been applied in very large amounts to field crops since the 1950's in the US
and many other countries.
Over-fertilization Results in Nutrient Rich
Run-Off: Since crop plants often can not utilize all the nitrogen
applied to the fields, some is left in the soil and can leach into ground
water. In addition, not all the applied nitrogen gets into deeper soil and
some is washed off the fields in the form of runoff and it flows into
surface waters such as streams and rivers. The runoff problem is often
greatest when manure is used as a fertilizer, such as it is now in many
sites in the US where large commercial farms are used to produce cattle,
pigs and chickens and these companies provide the manure to farms who grow
the feed for the animals.
The Nitrate Problem: The accumulation of nitrate in the
environment results mainly from:
In addition, nitrate-containing wastes are produced by
many industrial processes including paper and munitions manufacturing. Burning
of fossil fuels in power plants and cars, SUVs and all internal combustion
engines results in the production of nitric acid and ammonia as air pollution.
Farm Animals at Risk too: High levels of nitrate in
livestock feed and drinking water can result in reduced vitality and increased
stillbirth, low birth weight, and slow weight gain and even death of the animals
affected. Chronic
nitrate poisoning is correlated with abortions, still births and stunted
calves. Abortion is attributed to maternal and fetal methemoglobinemia resulting
in fetal anoxia (particularly in the last trimester of pregnancy). More
recently, unpublished data indicates serum progesterone is reduced in chronic
nitrate toxicosis in cattle and, possibly, horses. Chronic nitrate toxicosis
causes loss of condition, loss of weight, reduced milk production and weakness.
For information on Nitrate Toxicity in
Ruminants (Newsletter Animal Disease Diagnostic Lab, Purdue)
http://www.addl.purdue.edu/newsletters/2001/winter/nitrate_tox.shtml
Also see:
Table
of Nitrate Units used in Ag Reporting (PDF)
NECi has Nitrate Test Kits
for Agriculture (Ag-NTK) |
