Suspension Fertilisers


The application equipment was developed and patented by Mr Ray Patchett, an aerial operator from New Zealand. The application system that Ray produced over 10 years resulted in the ability to apply, finely ground, (100% under 120 micron 95% under 75 micron), naturally occurring rock based elements such as Lime, Gypsum, Dolomite, Elemental Sulphur, Reactive Phosphate Rock and a wide range of trace elements. The system also allows for the addition of microbiological stimulants and seed and can all be incorporated in one pass reducing application costs significantly. The components are applied in a wet format minimising off target losses that would be expected when using powders.

How the system works

The system is fitted to standard Agricultural Aircraft. The use of a specifically designed high volume pump delivers the material being applied to the patented boom and nozzle system at low pressure. The engineering design incorporated into the boom allows the system to be turned on and off without blocking. The airflow over the nozzle plays an important part in the even distribution of the particles to the ground. After soil samples have been analysed, products are determined which best suits the needs of the soil being treated. These products are finely ground (100% < 120 micron and 95%, 75 micron) and mixed in a mixing unit on site, ready for dispersal by the aircraft.

  • The advantage of grinding these elements prior to application is that large amounts of the energy required for their diffusion to the plant has been provided prior to the application therefore making the elements more readily available.
  • The increase in efficiency of products as the particle size decreases has been widely documented also the need to distribute the particles in a very even manner as there is virtually no horizontal movement of the elements once they enter the soil profile. This application system delivers a very even application thus ensuring availability to all plants and not just a percentage.
  • The system has the ability to mix on site, a range of elements needed for the soil being treated. The products are mixed at a ratio of about 70% product to 30% water making it the consistency of thick paint.
  • The water can be partly replaced by microbiological stimulant or liquid trace elements as required thus eliminating the need for extra applications.
  • A mixture of products can be applied at rates up to 400kg / ha in one pass offering sufficient quantities to ensure higher crop and pasture productivity.
  • The highest quality fine ground rock based elements are used it means that all products applied are highly reactive and readily available in the growing season.
  • Application dust losses are eliminated when the fine ground products are mixed into a suspension.
  • Lower transport costs are a result of transporting only the highest-grade product and not having the need to transport the carrier. i.e. water
  • The cost of application is for the dry product applied per ha.
Application rates

A comprehensive soil test is advised before any consideration is given to application rates. Consideration also needs to be given as to whether a total nutrient application is required or lime alone. When this system was first developed a lot of work went into lime requirements given different circumstances. These considerations in the main were exchange capacity of the soil, soil PH, the neutralising value of the limestone and the economic returns expected whether cropping or grazing.

Rates of gypsum have been applied from 200kgs / ha to 400kgs / ha. Trials carried out on cotton country in North West New South Wales and Southern Queensland during the cotton season 2002 / 2003 gave an economic yield response. While gypsum alone was applied, in future it is envisaged incorporating trace elements, such as Zinc into the mix for a far superior application to what is being achieved under conventional means. While there are no tried and proven application rates at present, the results achieved with 200kgs and 400kgs / ha application rates, has meant an ongoing demand for this type of application to Sodic soils in the North West of New South Wales and Southern Queensland.

Points to reconsider when using the suspension system:
  • The ability to incorporate a total nutrient package
  • No soil compaction
  • 100% of area covered
  • Quality product used
  • Seed can be included
  • Prescription mixing on site field by field
  • Quick and timely application
  • Natural rock based elements in a readily available form
  • Reduced run off
  • Economic return on application in first year

For all your suspension application needs call the experts, Rural Air Work today for an obligation free quote.

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Suspension Fertiliser Application