Farming for Healthy Watersheds
Focus: When a farmer decides which agricultural practices to use, the surrounding watershed is affected.
Materials: none required; recommended that lesson take place in farm or garden setting.
Procedure:
Gather for discussion outlining the farm/watershed connection. (start in classroom then move outside, or do entire lesson outdoors)
What are some of the decisions farmers make?
Examples:
Cover crop or bare field over the winter?
Contoured rows or straight lines?
Chemicals to control pests/add fertility to the soil or organic methods?
What is a pesticide?
According to the U.S. Environmental Protection Agency (EPA), a pesticide is “any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.” Pests are living organisms that occur where they are not wanted or that cause harm to crops, humans, or animals. Examples of pests include insects, mice and other animals, unwanted plants (weeds), fungi, and microorganisms such as bacteria and viruses.
What are the problems with pesticides?
--kill the good along with the bad
--hang around in the ecosystem and cause problems
Pesticides differ in the length of time they persist in the environment after they have been applied. Many pesticides begin to break down soon after being applied, but just how long it takes a pesticide to break down varies from one pesticide to another and can depend on where the pesticide is applied. For example, some pesticides break down in water in a matter of hours, but they may take longer when sitting on plants or soil. And some pesticides are persistent—they do not break down in the environment for a long, long time. Just what a pesticide will break down into will also vary. Some pesticides break down into benign compounds; others have breakdown products that are toxic to living things—and some of those toxic breakdown products are persistent.
Pesticides entering our waterways can be toxic to waterfowl and fish species.
One of the most troublesome group of pesticides are those that are classified as persistent organic pollutants, or POPs. POPs are a set of chemicals that are toxic, that persist in the environment for long periods of time, and that biomagnify as they move up through the food chain.6 When a substance biomagnifies, it works its way up the food chain by accumulating in the fat of living organisms and by becoming more concentrated as it moves from one creature to another. Chlordane, DDT, aldrin, and several other pesticides are all POPs. POPs have been linked to adverse effects on human health and animals, such as cancer, damage to the nervous system, reproductive disorders, and disruption of the immune system. Because they circulate globally through the atmosphere, oceans, and other pathways, POPs released in one part of the world can travel to regions far from their source of origin.
On May 23, 2001, the United States signed the Convention on Persistent Organic Pollutants at a diplomatic conference in Stockholm, Sweden. Under the Convention, countries committed to reduce or eliminate the production, use, or release of the 12 POPs of greatest concern to the global community and to establish a mechanism by which additional chemicals may be added to the treaty in the future. The United States strongly supported efforts to complete this important agreement, which has wide-ranging environmental and health benefits.
DDT is a pesticide POP that can stay in the environment long after it is applied—up to 12 years. The production, import, or export of DDT has been banned in the United States; however, it is still being used in some parts of the world to control malaria. As cost-effective alternatives to controlling malaria become available, the use of DDT will be phased out.
Potato Chips, French Fries, and Pesticides
What is your favorite kind of potato chips?
When you buy that brand of chips, what is important to you about that product?
(flavor, texture, appearance, size, cost, etc.)
If you bought the same brand of chips at another store, would you expect them to be the same? What is you bought them in another town or state?
(consistently the same)
What about french fries from a chain restaurant? Do you expect them to taste the same regardless of which restaurant you’re buying them from?
How is it possible for potato chip manufacturers and fast-food restaurants to provide such a consistent product?
(use the same kind, size, and shape of potatoes, and have a year-round supply)
Imagine you’re the farmer growing potatoes used for chips and french fries.
What type of potatoes would you grow?
(the kind wanted by potato chip/french fry manufacturers)
Would you care about the size of the potatoes you grow or the total number?
(yes! Maximize your profit)
What kind of factors that might affect your crop would you have to deal with?
(weather, pest infestations, soil quality, rainfall, weeds, fungi etc.)
What kind of actions might farmers take to moderate the effects of those factors that could destroy their crops?
(spray pesticides or use integrated pest management techniques, use organic or synthetic fertilizer)
In Farm/Garden
Facilitate group exploration of farm/watershed connection.
When a farmer decides which agricultural practices to use, the surrounding watershed is affected.
Ask what kind of decisions they make to keep their plants healthy and productive…
(water, control pests, protect from predators
What kind of decisions do farmers make to keep their crops alive and profitable?
Examples from garden:
Nearby forest is source of ‘pests’ like deer and rabbits that can browse on their plants and cause damage.
What are some pest management strategies? (poison, kill, trap, relocate, fence out, predator/prey relationships)
What happens if a hawk or bobcat eats a poisoned gopher?
When we release a toxic material into the garden, does it stay there? How might it move? (by water, wind, carried by an animal, etc.)
What is a pesticide?
What are the problems with pesticides?
--kill the good along with the bad
--hang around in the ecosystem and cause problems
Pesticides entering our waterways can be toxic to waterfowl and fish species.
Divide into two teams:
- Pest Damage Survey- look for evidence of browsing by larger animals, leaf damage from insects
- Restoration Crew- identify possible areas for adding native plants, as wildlife habitat or to attract beneficial insects; maybe a hedgerow
Bring groups back together and share ideas.
Journal Prompt:
Name one positive and one negative impact that farms can have on the surrounding watershed.
