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Background
After evaluating a large number of
Florida's watersheds including rivers, streams, lakes, and estuaries, FDEP
identified nutrients as the main contaminants impairing the state's water bodies, including groundwater.
One of the major sources of these pollutants is agricultural production,
stemming from improper management practices and heavy fertilizer and pesticide
application.
Nutrients as Pollutants
The two major nutrients originating from agricultural practices
that can pollute water are nitrogen and phosphorus. They come from many
sources like
commercial fertilizers, animal manure, leguminous crops, and
decomposition of organic matter.
Nitrogen
Nitrogen is a naturally-occurring element in soils, but
there is usually not enough of it to meet crop-production needs. Thus, it
is added to the
soil through inorganic and organic fertilizers. Leguminous crops and
incorporation of crop-residues also improves soil N availability.
Mineral N is found predominantly in one of two forms, either ammonium or nitrate. Nitrate is highly mobile,
can move rapidly through the crop-root
zone, and may eventually reach groundwater. Ammonium is
adsorbed to soil particles or is rapidly converted to nitrate. Thus, all
soil N is
potentially a cause of concern as a pollutant.
Phosphorus
Unlike N, P is not highly water-soluble in soil. Decades of application of P fertilizers
or animal manures to
agricultural land has increased residual P in soils, especially near the
soil surface. Sediments containing this P can erode and enter surface
water systems through runoff and seepage. Inorganic P in dissolved form
causes eutrophication in lakes. Particulate P also increases the algae production.
Pesticides
Pesticides, herbicides, and fungicides used to control pests, weeds and
disease in agricultural crops also cause potential pollution problems
if not applied properly. Runoff, wind-transport and
atmospheric deposition all help transport both active and inert
components of these chemicals. Their presence affects both terrestrial
and aquatic life, as they can contaminate fish and food sources for
humans.
Management Efforts and Resources
Growing concerns have resulted in the research and development of
practices that limit the movement of nutrients and pesticides to our waters. Nutrient
management practices have several components: 1) application of nutrients
at rates that help achieve realistic crop-yield goals; 2) choosing the right time
for nutrient application; 3) using agronomic techniques such as
multiple cropping.
Integrated Pest Management (IPM) is a practice that includes inspection of
crops on a regular basis and the use of various non-chemical methods to regulate
pest populations. By using IPM practices, application of chemical pesticides
can be
reduced.
Precision farming, also known as site-specific farming, is gaining
popularity among modern farmers. Nutrients and pesticides
can be used more efficiently, as precision farming includes the use of
global positioning system, Geographical Information System (GIS), soil, plant
and pest sensors, and remote sensing.
Resources that address nutrient and pesticide management practices are
shown below:
More information on nutrient and pesticide management can be found by
searching
Environmental Protection Agency homepage.
Florida Sea Grant also is functional in reducing nutrient and
pesticide contamination of our coastal waters.
Florida Department of Environmental Protection has a
Cleansweep Operation for Pesticides that allows a one-time safe and
economical way to dispose unusable pesticides.
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