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by Les Brown,
Pay’s Air Service
admin@paysairservice.com.au
In 2003 Pay’s Air Service was approached by one of our clients to see if it would be possible to apply a variable rate application of growth regulant on cotton whilst applying a constant rate of foliar fertilizer. This is what started the R & D into the DIVRA system or direct injection variable rate application.
In the last five years the DIVRA system has taken many forms. It started out as a pressure regulated system to what it is now, a flow regulated system. We have been working closely with Hemisphere GPS (formerly Satloc and Del Norte) during this time to come up with a dual rate flow controller to control both primary and direct injection systems.
We were initially using the M3 and the AerialACE to control the direct injection and a Farmscan to control the primary spray volume (as Hemisphere GPS had not yet created a controller to handle two rates at the same time). This served us well for three years, but we were sure that we could improve upon the AerialACE and the overall setup at that time. We knew things had to change. And change it did. Once Satloc and Del Norte came together as Hemisphere GPS, everything started to change dramatically. We now have a working dual rate system which is composed of two Intelliflow controllers daisy chained together connected to an M3.
The current range for the direct injection as far as flow rates go is between 0.6 to 2.5 litres per ha (0.06-0.25 gpa). This can be altered for individual operators, but the range is limited to around a two-litre range between the lower and higher rate.
Application
Dual Rate flow control has many benefits over the traditional method of variable rate. These are:
• Droplet size is maintained to near constant due to the low rate changes i.e. 0.6 to 2.5 L/Ha.
• The ability to complete two applications in one pass, i.e. fertilizer and growth regulant.
• The ability to spray incompatible chemicals at the same time. *
• The ability to apply chemical to only where it is needed.
* This will be limited to the compatibility of the chemicals when mixed not damaging the plant when applied.
DIVRA on broadacre herbicide
This system has the ability to save the client money on chemical due to now being able to apply chemical only to where it is needed. Due to the recent rises in chemical cost i.e. glyphosate, it could save many litres in an application as you no longer need to apply heavy blanket rates over the whole field. A lighter rate could be applied through the primary spray system and the injection system could apply the heavier rates where needed. This information can be obtained through near infrared images taken of the fields giving the client plant cell density information (PCD). Obviously lighter rates of glyphosate would be applied in the low PCD areas and higher rates applied in the higher PCD areas.
DIRVA on cotton
Another application includes the ability to apply foliar fertilizer and growth regulant on crops such as cotton. We have sprayed thousands of hectares of cotton using this technology. Our client believes that it is of great benefit to be able to apply growth regulant at the same time as foliar fertilizer whilst the cotton plant is at the growth stage where both applications are needed. They also feel that it is more of a benefit to be able to keep the foliar fertilizer at a constant rate over the whole field and only inject the growth regulant to the areas where it is needed. They have now found that they are getting a yield response in the areas that were growing rank that have now been sprayed with growth regulant. Previously they would not apply the growth regulant over the whole field giving them a reduction in yield which is due to not being able to control the rank growing areas. In this instance it may not actually give the client a saving on the chemical or application costs but they are now able to achieve an application that they were previously unable to receive in one application, which may result in an increase in yield. This has been the case for our client in previous years.
Dual Rate applications
As far as applying incompatible chemicals such as foliar fertilizer and fungicides, this is yet to be done. We do have a client asking if it can be done over faba beans by applying both the foliar fertilizer and the fungicide at the same time at constant rates. The Air Intelliflow Dual Rate system is capable of applying two chemicals at constant rates at the same time. For example you would be able to apply the fertilizer at 30L/Ha and the fungicide at 0.8L/Ha but they wouldn’t mix until the injection point. In theory I believe this should work.
Other operators may have other circumstances where this ability may increase their productivity such as loading up with two different batches for two different jobs but only having to land to fill up with water to spray out the second application.
Operator benefits
The Direct Injection Variable Rate Application system benefits operators by having the ability to supply their clients with this technology. Due to the low injection rates, droplet size is maintained to near normal which significantly improves the spray efficacy, which is a problem with the traditional variable rate system of varying the whole flow.
We have been charging a 35 to 40% premium on application costs to use this technology. It is not like other expenses an operator incurs, like setting up a Micronair or CP boom which runs into the tens of thousands of dollars. These expenses have to be absorbed in their existing hectare price. The DIVRA system has the added benefit of being able to pay for itself in the premium charged to the client for its use. Due to the savings from decreased chemical usage or an increase in yield, the extra charge is minimal to the client.
Suppliers
The Air Intelliflow Dual Rate system can be supplied by Hemisphere GPS. This comprises of a M3 and two Intelliflow controllers including valves and flowmeters.
The Air Intelliflow Dual Rate system developed by Hemisphere GPS was designed to be used with Pay’s Air Service patented DIVRA system comprising of booms, tank, pump, boom shutoff solenoid, one-way valve and associated plumbing. The system has been tried and tested on Air Tractor 502 and 802. We are currently designing a system to fit Thrush aircraft.
For further information contact Pay’s Air Service on the following number. +61 2 67539556 (website at www.paysairservice.com.au )
For further information on the M3 and IntelliFlow Dual Rate contact Greg Guyette at Hemisphere GPS at 1-602-363-9225 or gguyette@hemispheregps.com (website at www.hemispheregps.com )
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