Applied Agricultural Science and Technology
Class Notes Key
Proper Use of Agricultural Chemicals
Modern agriculture depends upon the proper use of chemicals to aid in the production of crop plants and
livestock. Crop and livestock chemicals are safe if handled and applied as recommended. However,
some of these chemicals can also be very harmful if used or cared for improperly.
The two major types of chemicals used by agriculturalists are fertilizers and pesticides. Fertilizers
provide nutrients needed for plant growth and are by far the most widely used of all agricultural
chemicals. Fertilizers may be organic (derived from plant or animal materials) or inorganic (chemical in
dry – solid, liquid or gas forms).
Pesticides, which control unwanted insects, plants, and other pests, cause more injuries, contaminate
more water, and pollute more air than do fertilizers, but account for less than 3% of all the agricultural
chemicals sold. Common types of pesticides include insecticides (insects), herbicides (weeds),
fungicides (fungi), rodenticides (rodents), avicides (birds), and bactericides (bacteria).
CLASSIFYING PESTICIDES ACCORDING TO THEIR TOXIC EFFECT
Toxicity refers to the degree of the poisonous effect to warm-blooded animals. The higher the toxicity,
the more poisonous is the pesticide. Signal words are used on labels to indicate the toxicity of the
chemical and include danger, warning, and caution.
DANGER – chemicals of high toxicity, which may cause death, have an approximate lethal
dose of 1 taste to 1 teaspoon. The label of a highly toxic pesticide will show a skull with
crossbones and carry the word “Poison” printed in red.
WARNING – chemicals of moderate toxicity, which may cause serious illness, have an
approximate lethal dose of 1 teaspoon to 1 fluid ounce.
CAUTION – chemicals of low toxicity, which may cause illness, have an approximate lethal
dose of 1 ounce to more than 1 pint.
WAYS THAT POISONING OCCURS
Pesticides have various effects on the body including skin irritation, nausea, blindness, other illness, and
even death. Toxic materials enter the body by ingestion, dermal contact, and inhalation.
Ingestion – poison enters the body by swallowing. Ingestion may be avoided by
Keeping pesticides in the proper containers with the proper label.
Waiting until the safety interval has passed before eating anything treated with pesticides.
Posting a sign in the garden area showing when it is safe to eat the produce.
Thoroughly washing your hands and face with soap and water before eating.
Refraining from smoking, chewing gum, or eating snacks while working with pesticides.
Not using your mouth to clean the low-pressure nozzles or other parts of the equipment.
Dermal Contact – absorption of chemical through the skin. Absorption can take place when mixing,
applying, or handling a pesticide, by wearing contaminated clothing, by the drifting of the pesticide, or
by entering an area where the reentry interval has not expired. Dermal exposure is prevented by
Avoiding splashes, spills, drift, and reentry of pesticide.
Not reusing contaminated clothing.
Wearing the proper type of clean clothing each day and change clothing during day if necessary.
Wash the tractor seat cushion of it becomes contaminated.
Using below 50 psi when spraying and applying pesticides when the wind is less than 3 ½ mph.
Inhalation – breathing in spray particles, vapors, and dust. Three most common ways to inhale
pesticides are smoking tobacco that has become contaminated, breathing smoke from burning pesticide
materials, and being in the drift during spraying or dusting. To prevent inhaling chemicals, one should
wear a respirator when applying chemicals and avoid smoking materials.
Protective Clothing and Equipment – wearing the proper protective clothing when working with
chemicals will help prevent poisoning. The following clothing will help to prevent exposure to
chemicals (see figure 1):
Hat or cap
OVEREXPOSURE OR PESTICIDE POISONING
Overexposure or pesticide poisoning can produce a variety of symptoms including:
Mild Poisoning – headache; skin, eye, nose, and throat irritation; weakness; nausea; diarrhea; and
Moderate Poisoning – poor muscle coordination; rapid pulse; blurred vision; flushed skin;
stomach cramps; vomiting; and muscle twitches.
Severe Poisoning – convulsions; lack of ability to breathe; loss of consciousness; secretions from
the mouth; and fever.
When first aid instructions are not available on a pesticide container, the following general first aid
procedures can be applied.
Have someone contact a doctor, a poison control center, or a hospital while first aid is being
administered. DO NOT leave the victim unattended.
If the victim has stopped breathing, administer artificial respiration.
If poisoning is the result of dermal contact, remove clothing and thoroughly wash the affected
area with soap and water.
If the pesticide contacts the eyes, wash the eyes with low pressure running water for at least 15
If poisoning is the result of swallowing, call the nearest poison control center, family doctor, or
hospital for emergency instructions. Be prepared, if at all possible, to identify the pesticide
product using the label.
On successful application of the above first aid procedures, transport the victim to the nearest
STORAGE AND DISPOSAL OF PESTICIDES AND THEIR CONTAINERS
Pesticides should be stored in a building or room that can be locked and posted with warning signs. The
following are suggestions for storage and disposal of chemicals:
Use original containers with storage labels intact;
Place containers in small stacks;
Store powder and granular pesticides on shelves to prevent caking;
Store insecticides apart from herbicides and completely away from feed, seed and other supply
Keep away from fire and do not smoke in pesticide treated areas;
Wear protective clothing when working in storage area; and
Dispose of containers according to label directions.
IMPORTANCE OF PESTICIDE LABEL
Federal law requires labels on all pesticide containers, except for relatively non-toxic products. These
labels contain information for the proper use, storage, and disposal of the chemical and should be
carefully read. Below is a sample label that contains the information that should be studied each time
the chemical is used.
SAFETY PRACTICES IN HANDLING FERTILIZERS
The handling of fertilizers usually is not considered as dangerous as handling pesticides. However,
when handling fertilizers safety practices should be followed and extreme care is required when
handling anhydrous ammonia and aqueous ammonia. When working with solid or dry type fertilizers,
follow the safety practices below.
Wear protective clothing such as cap, long sleeve shirt, heavy trousers, gloves, and respirator.
Stand upwind when filling fertilizer hoppers.
Pull the fertilizer spreader to keep dust from blowing toward the tractor and operator.
Do not check the spreader at close range when the spinner mechanism is in operation.
Wash and bathe by using soap and water and change clothes daily when working with fertilizers.