Physical Science Applications in Agriculture
Unit
Physical Science Systems
Problem Area
Agricultural Mechanics and Machine Systems
Chemical Applications:Calibration And Metering
Lesson
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How much chemical do I need?
• Discuss concentrations/formulations, application rates, and how they may be determined for each product.
• What does the company need to tell me about their product?
Learning Objectives1. Explain the purpose of the pesticide
label.2. Identify the information that should be
included.
3. Calculate recommended concentrations/dilutions.
4. Calibrate low pressure sprayers to achieve recommended application rates.
5. Describe the calibration of high pressure sprayers.
Terms
• Active ingredient• Calibration• Common name• Concentration• Dilution• Drop spreader• Establishment
number
• Formulation• General-use pesticide• Hose-end sprayer
Inert• Ingredients• Manual compressed
air sprayer
Terms
• Metering• Net content of
container• Notice of limitations• Precautionary
statements
• Restricted-use pesticides
• Signal words• Solute• Solution• Solvent• Trade name
What is the purpose of the pesticide label?
• Labels on pesticides provide information about the active ingredient. It is the active ingredient that kills the pest.
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What is the purpose of the pesticide label?
• Some products on the market have low amounts of active ingredient.
• Use this information as a basis for deciding which product to buy.
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Three important steps when dealing
with the pesticide label.• Read the label
– All users should discipline themselves to read and reread the label.
– This is the only way to find proper handling and mixing procedure.
– The label should be read completely before any handling of the chemical takes place.
Three important steps when dealing with the pesticide label
• Understand the label– In addition to just reading the label, the
pesticide applicator must understand the information it contains.
– This may require some special training. – If the applicator does not understand some
piece of information, the pesticide distributor should be contacted for clarification before the pesticide is applied.
Three important steps when dealing with the pesticide label
• Follow label directions– Just knowing what should be done is not
enough. – By law,users must follow label directions.– Persons using a pesticide in a manner that
conflicts with the labeling can be charged with both civil and criminal penalties.
STEPS IN DEALINGWITH PESTICIDE LABELS
• Read the label
• Understand the label
• Follow directions
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WHEN SHOULDTHE LABEL BE READ?
• Before Buying a Pesticide
• Before Mixing a Pesticide
• Before Applying a Pesticide
• Before Storing a Pesticide
• Before Disposing of Excess Pesticide or the Container
What information should be included on the pesticide label?
• All pesticide labels must conform to standards set by federal law.
• The goal is for pesticide labels to include all the information necessary for safe and effective use.
• The label is made of two panels, a front and a back panel.
Front Label
Front panel of a label provides basic information.
• Use Classification– This indicates if the pesticide is a general-use or
restricted-use pesticide.– General-use pesticides are those products
that have been designated as the least hazardous pesticide materials.
– Restricted-use pesticides are given this classification based on toxicity, the way the pesticide is used, and the environmental effect of the pesticide.
Front panel of a label provides basic information.
• Trade (Brand) Name—– This is the product’s name given by the
manufacturer. – Different manufacturers or even the same
manufacturer can give a single chemical compound multiple names.
– Ex. Round-up is the trade name by Monsanto for glyphosate.
Front panel of a label provides basic information.
• Formulation—– This is the form in which a pesticide
product is offered for sale to the user.– Active ingredients usually cannot be used
alone in their pure form. – Therefore, inactive ingredients such as
water, oil, surfactants, emulsifying agents, and other diluents are combined with the active ingredients to make the formulation..
Formulation
• Examples of pesticide formulations are liquid emulsifiable concentrates (E or EC), wetable powders (W or WP), dry flowables (DF), solutions (S), granules (G), and dusts (D).
• Further dilution of the formulation with water or fluid fertilizers, is generally required before use.
Front panel of a label provides basic information
• Common Name—– The name assigned to identify the active
ingredient in the product.– Regardless of the number of trade names
a certain pesticide may have, the common name remains the same.
– It may be compared to the use of scientific names when dealing with plants.
Front panel of a label provides basic information
• Ingredients—– This contains the name
and concentration of all active ingredients in the product.
– For the inert (inactive) ingredients, only the combined total concentration must be stated.
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Front panel of a label provides basic information
• Net Contents of Container– This is the amount
of the total product in the container.
– This may be expressed in gallons, quarts, pints, pounds or other units.
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Front panel of a label provides basic information
• Signal Words—– These words are required on every label to
indicate the degree of toxicity and the potential danger of using each pesticide. Signal words are based on the LD50 and LC50 values of toxicity for the pesticide.
Signal Words
• The words Danger or Danger- Poison with a skull and cross-bones (all in red) must appear on the labels of all highly toxic pesticides.
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warning_statement.htm
Signal Words
• Warning is required on the labels of all moderately toxic pesticides.
• Caution must be printed on the labels of all pesticides with a low or very low toxicity pested.unl.edu/pat2.htm
Signal Words
• The child hazard warning, Keep Out of Reach of Children must also appear on the label of all pesticides, regardless of the toxicity.
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Front panel of a label provides basic information
• Precautionary Statements– Information on first aid
treatment, potential environmental and human hazards, and flammability or explosion hazards.
• Establishment Number– An EPA establishment
number is listed to identify the plant where the individual pesticide was manufactured, packaged, or formulated.
Front panel of a label provides basic information
• EPA Registration Number– Proof that the product is registered with the
Environmental Protection Agency (EPA).
• Name and Address of Manufacturer– Company which manufactures and distributes the
pesticide is clearly identified on the label. – Normally a phone number is given in the
precautionary section, so the company can be reached in case of an emergency.
Side and Back panels provide more detailed information
Side and Back panels provide more detailed information
• Hazardous Materials Warning Labels– Some containers have additional symbols on their
labels, as required by the United States Department of Transportation (DOT).
– These symbols denote the nature of the chemicals.
– The small number that appears in the lower portion of the symbol indicates which class of hazardous materials is represented.
Side and Back panels provide more detailed information
• Directions for Use– This section includes specific guidelines
for properly using the product.
• Notice of Limitations– This section includes statements of
condition of sale, warranty limitation, inherent risks, and liability limitations.
The following is a general setup for the Direction for Use section
a. target pest(s) the product will control
b. sites which can be treated with the pesticide
c. amount of chemical to use per acre
d. type of equipment and application methods that can be used
e. proper mixing procedures
f. when the pesticides should be applied
g. reentry limitationsh. guidelines for
storage and disposal
i. limitations on its use
How do you calculate the recommended concentrations?
• When preparing formulations for agricultural applications, different substances are mixed.– For liquid solutions, the liquid that serves as the
dissolving agent is the solvent; the dissolved is referred to as a solute.
– The mixture is called a solution. – A solution is the homogeneous mixture of two or
more substances where the substances mix as molecules, atoms, and ions.
How do you calculate the recommended concentrations?
• Concentration
– May be defined as the quantity of solute dissolved in a unit volume of a solution or solvent.
– Concentration = quantity of solute/quantity of solution or solvent
How do you calculate the recommended concentrations?
• Dilution – Inverse of concentration. – To determine the amount of material to add
to a spray tank for a specific concentration or dilution, the recommended rate, the capacity of the tank, and the output of the applicator need to be known.
How do you calculate the recommended concentrations?
• An important first step in calibration is preparing the solution or mixture to be metered.
• In agricultural applications, such as chemical applications, we need to know how much ingredient to add to some carrier to obtain a recommendation formulation.
How do you calculate the recommended concentrations?
• You have purchased a wettable powder to apply to your crop.
• You have a 200-gallon spray tank that applies 20 gallons of spray material per acre.
• The label calls for 2 pounds of active ingredient (a.i.) per acre and the wettable powder purchased is 80 percent active ingredient by weight. How much wettable powder do you add to the spray tank?
How do you calculate the recommended concentrations?
• First determine the number of acres that can be sprayed per tank using the following formula: tank capacity/spray rate.
• You need to know how many pounds of chemical are needed per acre.
• The label recommends 2 pounds of a.i. per acre but our product only contains 80 percent a.i. by weight, thus we must make an adjustment using the following formula:
• (recommended a.i./acre) × (100%/%a.i.)
How do you calculate the recommended concentrations?
• How much product must we add to each tank full?
• Use the following formula to calculate:
• # of acres the tank can spray × actual pounds of material required per acre.
How do you calculate the recommended concentrations?
• In another application, we need to apply a liquid pesticide.
• The label will recommend a recommended rate of product to apply.
• Find out how much your sprayer holds and applies per 1,000 square feet.
• How many ounces must we add to the spray tank?
• Use unit conversion and the unit factor method to solve the problem.
How do you calculate the recommended concentrations?
• First convert recommended rate from gallons to pints per acre.
• Convert the pints per acre required to ounces per 1,000 square feet.
• The last step is to determine the amount of liquid pesticide in ounces to add to the spray tank.
• Use the following formula: • Sprayer size × amount of product needed per 1,000
square feet/spray amount per 1,000 square feet.
How do I calibrate a low-pressure sprayer?
• The performance of any pesticide or fertilizer depends on proper mixing and proper application.
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How do I calibrate a low-pressure sprayer?
• Calibration – Insures that the application equipment is
applying the correct amount of material uniformly over a given area.
– No matter what is being applied, we must determine how much is needed, how much area must be covered and what is the output of the application equipment.
• Metering – Ability to vary the rate of the rate of the
application.
Hose-end sprayer
• Bottle that is connected to a garden hose.
• Water flows through the hose and causes suction in the bottle.
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Hose-end sprayer
1. To calibrate the sprayer, fill the bottle to full level.
2. Uniformly spray 1,000 square feet area.3. Subtract the amount remaining in the bottle
from the original amount.4. This will be the amount of spray needed to
cover 1,000 square feet.5. Use Objective 3 to calculate the amount of
product needed for the area.
Manual compressed air sprayer
• A 1–5 gallon spray tank attached to a hand-operated pump that creates pressure in the tank to force solution out of the sprayer.
1. Fill the spray tank with water.2. Spray a 1,000 square foot area.3. Determine the amount of water required to
spray the area.4. Fill the tank and add the recommended
amount of spray concentrate to achieve the proper dilution.
Drop spreader
• A spreader used to distribute a solid granular solution.
1. Set the spreader gate at the desired setting.
2. Fill the hopper with a measured amount by weight of inert material.
3. Uniformly apply to a 1,000 square foot area.
4. Collect and weigh material from the area to determine is the desired rate is achieved.
What are the procedures to follow when calibrating sprayers?• Most performance complaints about
pesticides can be traced to poor application practices.
• Proper calibration helps insure that the area being sprayed receives the right amount of chemical.
• Nozzle flow rate, ground speed of the sprayer, and width sprayed per nozzle are variables that affect the amount of spray material applied per acre.
What are the procedures to follow when calibrating sprayers?• The gallons of spray applied per acre can be
determined by using the following equation:• GPA = GPM × 5940/MPH × W• GPA = gallons per acre• GPM = output per nozzle in gallons per
minute• MPH = ground speed in miles per hour• W = effective width sprayed per nozzle• 5940 = a constant to convert gallons per
minute, miles per hour, and inches to gallons per acre.
What are the procedures to follow when calibrating sprayers?• A more exact method for choosing the correct
nozzle tip is to determine the gallons per minute (GPM) required for the conditions.
• Select nozzles that provide this flow rate when operated within the recommended pressure range.
• By following the ensuing five steps, you can select the nozzles required for each application well ahead of the spraying season.
What are the procedures to follow when calibrating sprayers?
1. Select the spray application rate in gallons per acre (GPA). • Pesticide labels recommend ranges for
various types of equipment. • The spray application rate is the gallons of
carrier (water, fertilizer, etc.) and pesticide applied per treated acre.
What are the procedures to follow when calibrating sprayers?
2. Select or measure an appropriate ground speed in miles per hour (MPH) according to existing field conditions.
• Do not rely on speedometers as an accurate measure of speed.
• Slippage and variation in tire sizes can result in speedometer errors.
What are the procedures to follow when calibrating sprayers?
3. Determine the effective width sprayed per nozzle (W) in inches. • For broadcast spraying, W = the nozzle
spacing.• For band spraying, W = the band width• For directed spraying or for drop pipes,
W=row spacing (or band width)/number of nozzles per row (or band)
What are the procedures to follow when calibrating sprayers?
4. Determine the flow rate required from each nozzle in gallons per minute (GPM) by using a nozzle catalog, tables, or the following equation:– GPM = GPA × MPH × W/5940– GPM = gallons per minute of output required from
each nozzle– GPA = gallons per acre from Step 1– MPH = miles per hour from Step 2– W = inches sprayed per nozzle for Step 3– 5940 = a constant to convert gallons per minute, miles
per hour, and inches to gallons per acre
What are the procedures to follow when calibrating sprayers?5. Select a nozzle that will give the flow rate
determined when the nozzle is operated with the recommended pressure range.
– Use a catalog of available nozzle tips.– If it is decided to use nozzles that are already on
hand, select a speed that allows you to operate within the recommended pressure.
– With the proper nozzle tips selected, the rest of the calibration can be completed.
What are the procedures to follow when calibrating sprayers?
• Determine the required flow rate for each nozzle in ounces per minute (OPM).
• To convert GPM to OPM, use the following equation.
• OPM = GRM H 128
• (1 gallon = 128 fluid ounces)
What are the procedures to follow when calibrating sprayers?• Collect the output from one of the nozzles in a
container marked in ounces.1. Check several nozzles to determine whether their
outputs fall within 5 percent of the desired OPM.2. If it becomes impossible to obtain the desired output
within the recommended range of operating pressures, select larger or smaller nozzle tips or a new ground speed, then recalibrate.
• It is important for spray nozzles to be operated within the recommended pressure range, which indicates the pressure required at the nozzle tip.
What are the procedures to follow when calibrating sprayers?
• Determine the amount of pesticide needed for each tankful or for the acreage to be sprayed.
• Add the pesticide to a partially filled tank of carrier (water, fertilizer, etc.), then add the carrier to the desired level with continuous agitation.
What are the procedures to follow when calibrating sprayers?
• Operate the sprayer in the field at the ground speed measured and at the pressure determined.
• After spraying a known number of acres, check the liquid level in the tank to verify that the application rate is correct.
What are the procedures to follow when calibrating sprayers?• Check the nozzle flow rate frequently. • Adjust the pressure to compensate for small
changes in nozzle output due to nozzle wear or variations in other spraying components.
• Replace nozzle tips and recalibrate when the output has changed 10 percent or more from that of a new nozzle, or when the pattern has become uneven.
Review/Summary
• What is the purpose of the pesticide label?
• What information should be included on the pesticide label?
• How do you calculate the recommended concentrations?
• How do I calibrate a low-pressure sprayer?
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