Download PRIMARY INDUSTRIES How do I spray my weeds Checked 2

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MATHEMATICS PATHWAYS STAGE 1 Folio Task
Allied Health/Community Services INDUSTRY PATHWAYS PROGRAM
How do I spray my weeds?
Suggested weighting: 20%
Approximate duration: 2-4 Weeks
Created by: (October ’09)
Valley View Secondary School
Notes to the teacher
Mathematical skills which may be required to complete this task.
Using a Calculator
Calculating distance
Calculating Time
Calculating speed
Order of Operations
Calculating Rates
Rounding Off
Number Properties
Addition, Subtraction,
Multiplication
Division by a Whole Number
Introduction: All sprayers need to be fitted with appropriate spray nozzles so the desired output can be
achieved. They also need to be calibrated regularly to work efficiently and economically. Regular calibration
ensures the right amount of chemical will be applied to the target without costly wastage. The following will
enable you to:
 select the correct nozzle for the boom spray for a particular output
 calculate how much chemical and water to use
Task description.
You (the farmer) are to spray a ‘crop’ (broad-acre, orchard, green keeping/recreation round/turf, mid-row in
vineyard, pasture) for a broadleaf weed. Depending on your industry context/specialist area, identify:
1. What ‘crop’ are you spraying?
2. What is the area to be sprayed? (How was this determined?)
3. Select a broadleaf weed relevant to your situation.
Identify the herbicide that is registered for use in your situation and submit a copy of the drum label as part of
your assignment.
Source or calculate answers for the following:
1. What is the application rate for your chosen herbicide?
2. What is the minimum amount of water to be used per hectare?
3. Select the boom spray that would be appropriate for your situation.
a. What is the width of the boom?
b. How many spray nozzles (assumed to be at 500mm spacings)?
c. What is the tank capacity?
4. Selecting an appropriate ground speed for your tractor [Most boom spraying is done at speeds of
between 5–12 km/h, depending on the paddock surface. Select a speed to suit the most difficult part of
the paddock and operate at that speed over the whole paddock.]
To select the appropriate spray nozzle, the Litres per Minute per Nozzle needs to be calculated. This can be
done using the following formula:
= Total Litres per Minute
Number of Nozzles Used
(This can be determined from the following:)
This is a draft, unauthorised working document. Feedback is appreciated.
This is a draft, unauthorised working document. Feedback is appreciated.
Total Litres per Minute = Row Width (M) x Tractor Speed (Kilometres Per Hour) x Desired Application Rate (Litres Per Hour)
600 (constant)
5. What is the Litres per Minute used per Nozzle?
6. Select the appropriate spray nozzle by using the accompanying Rate Chart. Match your chosen tractor
ground speed and the suggested output per hectare to identify the correct nozzle.
7. What is the total output for your boom spray: a) per minute and b) per hour?
8. You purchase and install the nozzles, then measure the actual output and find that it does not match
the factory theoretical output. What could you change to get the desired output of chemical/water per
hectare?
9. Now you have the equipment set up correctly, you need to calculate how much chemical to add to
your spray tank:
a. How many hectares will your tank capacity spray?
b. How many litres of chemical are needed for this area?
10. You can now work out how many tank loads you will need to do the job:
a. Calculate the total amount of chemical needed for the area to be sprayed.
b. Calculate the total number of tank loads to supply this volume.
11. From a rural supplier (submit the supplier’s name and town):
a. Get the size of the containers for the chemical.
b. Get a price for the appropriate sized container.
c. Determine how many containers are needed for the spraying job.
d. Determine the cost of the spray.
Possible extensions:
A. Transfer calculations to a spreadsheet.
B. Set up the spreadsheet with a separate data entry section and include formulae so that the calculations
can be used for any herbicide or paddock area.
C. If spray equipment already has nozzles, work out the tractor speed and pressure to suit existing setup.
Suggested possible sources of information.
Internet search:
Local businesses:
Vocational trainer:
Suggestions to students in analysing this task through mathematically modelling a realistic situation
Clarifying:
Fully explain your scenario and problem, including any assumptions and boundaries.
Modelling:
Form a mathematical model or strategy which closely investigates your problem.
Solving:
Use a mathematical tools and methods to find a possible answer to the problem.
Interpreting:
Interpret your solution by comparing it to real life situation. Is the solution around the mark?
Checking:
Check your solution against your original scenario using an alternative method, or
measurement. Discuss how appropriate your solution is to the work situation.
This is a draft, unauthorised working document. Feedback is appreciated.
This is a draft, unauthorised working document. Feedback is appreciated.
Reporting:
Evaluation:
Report clearly and in detail, on all considerations, research, data, issues, and areas of
extension, mathematical determinations conclusions and possible constraints.
Reflect on your solution and determine areas where there could be improvement, refinement
or development. Generalize the solution or methodology to other similar situations.
This is a draft, unauthorised working document. Feedback is appreciated.