Grains Research and Development

Banded-applied wetting agents

Soil wetting agents contain surfactants that reduce the surface tension of water and improve water entry into repellent soil. Banded wetting agents are applied during seeding to the base of the furrow after passage of the press wheels. The improved water entry aids germination and even crop establishment, but less surface tension can also increase water loss from drainage.

By reducing the surface tension of water, surfactants can decrease the capacity of water to be held by the larger pore sizes in sandy textured soils resulting in increased leaching. To counter this, banded surfactants have been designed specifically to assist in soil wetting during establishment before biodegrading in the soil during winter.

To be successful the wetting agents need to be applied as a continuous band to the base of the furrow. They are applied usually as a solid stream, but sometimes with fan nozzles behind the press wheels. Furrow infill, soil throw from neighbouring seeding tines, or placement onto soil that is still moving can all reduce the efficacy of the banded surfactant.

Furrow shape as determined by press wheel design can impact on furrow stability with ‘V’ or broad ‘U’ shaped press wheels. Tapered walls provide a more stable furrow shape for application of banded surfactant than rectangular cross section wheels with ‘bulging’ sides that can rip up the side of the furrow.

The on-seeder system for applying the banded wetting agent seems more reliable when designed with a pressurised manifold delivering the product to a bracket behind the presswheels with reticulation tubing and a simple nozzle.

 

A seeder bar with plumbing attached to the rear. A close up of a seeder bar with plumbing attached to the rear.

Plumbing is attached to the rear of the seeder bar so that the wetting agent is sprayed in a band into the base
of the furrow behind the press wheels.

 

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