Friday, April 3, 2020
Services » Variable Rate Application






Variable Rate Application

Sometimes it is desirable to apply products over a field at different rates due to varying soil or weed conditions. This may be a fertiliser which can be applied at higher rates on poorer soils and less rates on the heavier soils. It could also be a herbicide which can be applied where the weeds are and left off the weed free areas.

Air Ag has the equipment to apply solids and liquids at variable rates. We can also apply one product at a consistent rate and another product at a variable rate. An example is applying a cotton insecticide over the whole field while applying a growth regulant at a variable rate, depending on the size of the cotton.

Benefits of variable rate application are: 

  • Reduced use of very expensive pesticides by only applying them where needed
  • Reducing variation in crop size, or maturity by applying growth regulators  to vigorous areas
  • Improving overall yield by applying fertilizers only to the soil types that will respond to fertiliser input. 

The steps to achieving a variable rate application are.

  • Determine the different rates of product you need on the different areas of the field.
    • First create a map of the treatment area showing the variations.  This is achieved in many ways. You can use  yield monitors to show variations in the yield which would coincide with the variations in fertiliser to apply. You could also use aerial photos to identify areas of heavier foliage or weed areas or identify stressed areas of crop. You could also use soil analysis to identify different soil types
    • Second you need to 'ground truth' the data. That is you need to go to each area on your map and make a decision what the rate of product you need
  • Prepare a prescription map. This is a electronic file that can be loaded into the aircraft GPS system and tells the onboard computer when to vary the rates. 

This can  be a time consuming process and takes some technical expertise. There are now consulting agencies that can assist you with this process. Your agronomist or chemical retailer may also be able to help  you with this, and you can always come and see us.



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