Using water to sow

SANTFA research and development manager, Greg Butler.SOUTH Australia No Till Farming Association (SANTFA) plans to utilise ultra high pressure (UHP) water jets to create the ultimate no-till farming system.

Ultra high pressure jets are already used in many industrial applications as a cutter.

Greg Butler, SANTFA research and development manager, said research had showed interesting results in using the jets in farming systems as openings, similar to knife points or discs.

He said SANTFA had lodged a patent on a liquid coulter, while the UHP jets could also be used as a sowing system in their own right.

“A liquid coulter, which could be supplied by manufactures as an option on new seeding systems or be retrofitted to existing seeding bars, comprises a UHP water-jet integrated into a seeding system,” he said.

The cutting jet would most likely be positioned close to the soil ahead of seeding discs, although it could also possibly work in a tined system.

But going even one step further is an all liquid system.

The concept of ‘Aqua-Till’ goes further than the liquid coulter by replacing the trailing disc or discs in a zero-till seeder with an air-gun to shoot seed into the furrow created by the UHP water-jet.

This has the potential to further reduce draught and soil disturbance.

Mr Butler said the vision for the ‘Aqua-Till’ seeder is to use a liquid coulter to slice through surface material and cut a narrow furrow into the soil, simultaneously depositing liquid nutrient along the seeding row.

The air-gun is positioned immediately behind the liquid coulter to deliver seeds into the furrow depository created by the liquid fertiliser jet stream.

The furrow is then closed with a seed-firmer or similar device such as a closing wheel.

Ideally, he said, the penetration of the liquid coulter and depth control for seed placement by the air-gun would be controlled by a mechanical or electromagnetic soil-density sensor that could be configured for soil type and crop requirements.

The liquid coulter could operate continuously along the row or be pulsed or synchronised with seed delivery from the air-gun.

Pulsing or synchronisation to coincide with seed delivery has the potential to reduce water-rates and power requirements.

Benefits of using a liquid system include better ability to manage stubble and sow into heavy stubble loads along with reduced compaction, smearing and hair pinning that can happen with a metal opener.

Mr Butler said the system would likely have best application if farmers also used the water to mix in liquid fertilisers, although the impacts of using fertilisers and fungicides applied directly into the seed bed is not yet fully understood.

He said early indications suggested it would be beneficial to yield, especially in terms of reducing fertiliser burn and increasing fertiliser uptake.

“This could be very useful, especially for crops like canola, which can be difficult to seed into thick residues and is quite hungry for nutrition but can be desiccated by fertiliser toxicity in marginal moisture.”

Cost efficiency will be one key issue, with most UHP technology presently dedicated to ultra precision applications, however SANTFA is working with an American company to develop a distribution network of UHP products available to seeder manufacturers around the world.

The system is likely to add to the sowing window in marginal conditions, according to Mr Butler.

In wet conditions, a liquid coulter is likely to remain operational when conventional seeding systems need to stop due to issues with residue management and sticky soils.

In dry conditions, the ultra-low disturbance should minimise exposure of moist soil and subsequent loss of moisture to the atmosphere, allowing crops to be established on more marginal moisture than is possible using currently available technologies.

In answer to the water capacity necessary to operate a system, Mr Butler said liquid rates of 80 litres to 220 litre a hectare had been trialled, in line with current carting capabilities.

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