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Herbicide Adjuvant Guide

IRRIGATOR Banding Soil Wetter

IRRIGATOR Banding Soil Wetter


IRRIGATOR is a specialty soil wetting agent for hydrophobic soils. The problem of water repellent soils is well known in Australia and particularly in Western Australia. Despite this, limited focus has been placed on finding a solution until recently. The use of furrow sowing techniques in combination with surfactants has been trialled for many years in the Western Australian wheat belt to improve crop and pasture germination. However yields have often fallen despite dramatic increases in the number of seeds germinated.

SACOA's partners have investigated a range of formulations to optimise yields and solve this issue. The result of this research is IRRIGATOR.

IRRIGATOR's Advantages Over Traditional Soil Wetters

IRRIGATOR offers a number of advantages over other soil wetters. These include:

  • Higher degradability than current soil wetters.
  • Minimal leaching risk.
  • Easier application, minimum water rates required – 15 – 50L/ha.
  • Compatibility with certain nutrients such as trace elements and other crop protection products (NOTE: IRRIGATOR is not compatible with liquid urea eg, Flexi-N).
  • Future potential: Investigation work is ongoing with other crop protection products including fertilisers, trace elements,
  • biopesticides and fungicides.

The Issue of Hydrophobic Soils

Water repellent soils are poorly penetrated by opening autumn rains in Mediterranean climates such as in the WA wheat belt.

The causes:

  • Hydrophobic organic waxes coat soil particles eg, from legume production;
  • Low soil clay content (< 5%); Past native vegetation;
  • Soil types with a high percentage of very fine soil particles ie, have an increased surface area.

Effects on crop establishment:

  • Staggered germination;
  • Poor crop and pasture seed germination;
  • Diversional flow of fertiliser and herbicides.

Potential solutions:

  • Claying provides an adequate long term solution but slow and costly;
  • Furrow sowing assists in water harvesting;
  • Addition of soil wetting agents such as SACOA's IRRIGATOR

An Overview of Surfactants and Band Spraying

The advantages of choosing the right surfactant for the right conditions include:

  • Certain soil surfactants can help overcome hydrophobic soils.
  • They can provide increased initial wetting and re-wetting.
  • Improvement of crop establishment.
  • Reduced evaporation.

Some Wetters Are Too Persistent In The Soil

Problems relating to persistence exist with some surfactant types, so always use sufficiently degradable products. One example is the horticultural style soil wetters that can be excessively persistent for broadacre applications.

Extended persistence in the soil can cause leach water soluble nutrients, longer-term yield reductions and reduction in micro herds (ie, beneficial soil microbes).


The application of IRRIGATOR involves minimal soil disturbance with precision sowing and spraying and it works from germination through to crop establishment. This process is illustrated in the diagram below.


Product Use

It is recommended that SACOA IRRIGATOR is diluted in water and the solution applied to the soil by spraying.

The table below recommends application rates for broadacre cropping. Recommended rates are influenced by the severity of soil / water repellency so optimum use rates may need to be established through field trials.

Seeding Conditions Application Rate Water Rate
No till furrow seeding with press wheels at 30 cm spacing 0.5 - 1 L/ha
No till furrow seeding with press wheels at 15 cm spacing 1 -2 L/ha 15-30L/Ha
  • Cereals: can be dry or wet sown.
  • Lupins, pasture species and canola: more suited for dry sowing.