Physical Science Applications in Agriculture

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.

pested.unl.edu

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.


• 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.


• 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.


• 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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• 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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• 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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• 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.


• 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


• 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.


• 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.


• 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


• 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.


• 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.


• 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?


• 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 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.


• 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.


• 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.


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.


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)


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.


• 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.


• 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.


• 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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Physical Science Applications in Agriculture

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