Each time you apply a pesticide on your
farm a number of things may happen to that pesticide.The pesticide may be
taken up by plants, or be ingested by insects or soil organisms, or it may
adhere to soil particles to be carried off in the air or move in water. There is
always some risk to the environment the degree of environmental risks depends
upon four factors. Persistence – how long the pesticide remains active in the
environment. Mobility – how easily the pesticide can move from where it was
applied. Non-target toxicity – how toxic the pesticide is to organisms other than
the pest. And volume of use – how much of that pesticide is used in the
environment. The physical and chemical properties of pesticides as well as
natural processes influence their environmental risk. By considering these
properties and processes before you use a pesticide you will be able to maximise
pest control and minimize environmental risk. First let’s review five properties
of pesticides that can affect their fate in the environment. Pesticides can be
broken down by organisms, chemical reactions, and sunlight. This is called
degradation. How fast this happens depends on the pesticide and the
environmental conditions on your farm. If the soil is warm and moist for example
microbes quickly consume the pesticide and turn it into other molecules such
as carbon dioxide and water. Pesticides that do not break down quickly are
called persistent. An example of a moderately persistent pesticide is
atrazine which has been found in surface and groundwater across Ontario.
Pesticides may bioaccumulate or build up in body tissues such as animal fats.
These pesticides may then bio magnify or build up in the food chain. Adsorption is
the binding of pesticides onto soil particles and organic matter. The way a
pesticide binds to the surface of the soil particle is similar to magnetic
attraction. Soils that are high in organic matter or clay are the most
adsorptive. A pesticide adsorbed tightly in the soil may move with soil particles
eroded by wind or water and is less likely to be degraded by soil
microorganisms. Pesticides can move into organisms like
plants and insects or structures like soil or wood similar to the way that
water moves into a sponge and this is called absorption. Once inside the tissue
of an organism the organism may break down so that it is no longer harmful to
that organism. This reduces the hazard of pesticide residues remaining in food.
Pesticides may change into a vapor when exposed to air similar to how water
evaporates. This is called pesticide volatility. Once a pesticide volatilizes
it can travel for miles. The fate of pesticides in the
environment is determined by a combination of these five properties
plus how pesticides move through the natural processes of drift, surface
runoff, leaching, and soil erosion. You can reduce pesticide movement in these
natural processes by your farming practices. To reduce drift there are many
things you can do such as using nozzles that produce larger spray droplets or
lowering the boom of your sprayer. Surface runoff of pesticides can be
reduced by no-till and minimum tillage practices which also reduce pesticide
movement via soil erosion. Leaching is the movement of water down through the
soil potentially to tile lines and surface waters or to ground water. Adsorptive
pesticides are less likely to leach because they stick to organic matter. To
increase the amount of organic matter in your soil add manure and crop residues.
You can also prevent pesticides from entering the environment by handling
pesticides with care. Store pesticides properly so they do not contaminate
people or the environment. For any spilled pesticides make sure you clean
it up properly. Call the spills Action Center for helpful advice. When you’re
done spraying correctly dispose of your empty containers including triple
rinsing and returning them to a pesticide container collection site. An
integrated pest management approach can help control pests without pesticides. If
you choose to use a pesticide completely read the entire product label and check
for environmental precautions. For instance, you may need to leave a buffer
zone of unsprayed natural vegetation to protect sensitive water sources or
animal habitat. Or to prevent poisoning of bees be sure to avoid applying
insecticides on flowering crops or when bees are foraging.
Before you use a pesticide consider all the pesticide properties natural
processesand practices you can do to protect your crops and the
environment.