Deep Ripper Trials Show Promise

A deep ripper that can loosen soil one metre beneath cane crops is generating interest in an industry working to improve soil and root health.

Ingham cane grower Paul Mizzi designed and manufactured the deep zonal ripper last year to combat severe soil compaction caused by increasingly heavy farm machinery - a major contributor to poor soil and root health and reduced yields in most agricultural industries. It has been trialled on Mr Mizzi’s farm and four other properties for the past 12 months.

Rippers usually break up the soil to a depth of around 500 to 600mm – so the new technology is almost doubling that reach.

Mr Mizzi received an innovation grant from the Australian Government under its Reef Trust III program to develop an implement that not only penetrates but also 'breaks-up' the compacted soil under the cane-crop zone within paddocks. He hopes it will be a winner for both productivity and the Great Barrier Reef.

Scientifically-designed trials, that will show productivity comparisons, have been established on two farms and will be harvested later in 2019. Meanwhile visual evidence has been promising.

Wet Tropics Sugar Industry Partnership extension officer Leanne Carr said while early results from deep soil testing and biomass sampling showed no significant differences between the deep and conventionally ripped trial plots, there had been visual differences at various stages during the trials.

“We saw a definite difference at germination - the deep-ripped treatments germinated faster and this could be easily seen on the ground,’’ she said.

“Given the very dry period with no rainfall before and after planting, it is possible that the deep-ripped treatments allowed deep soil moisture to come up closer to the surface, providing the germinating cane sett with enough moisture to move the process along compared to the conventionally-ripped treatments.”

Mr Mizzi has seen improvements in later cane growth as well, and in water run-off.

“The deep-ripped cane was taller up until lodging occurred in February and we are noticing now that stool tipping isn’t happening, perhaps because the roots are able to anchor further down,’’ he said.

“While it’s early days, we’ve also noticed in small rain events that water hasn’t run out of the deep-ripped trial areas like the others, indicating the ripper is doing its job of storing water and dissolved nutrients in the paddock for crop use rather than running off into waterways.” he said.

“With soil compaction going through the roof in sugarcane fields over the years due to all machinery becoming bigger and heavier, the cane roots can only get down so far before hitting a hard pan without the help of something like this.”

The deep ripper is an intentionally large implement. The Mizzis wanted to find out whether ripping to one metre was possible in very hard soils and whether it could improve cane production. They designed an implement that would go deep, fracture rather than just slice the compacted sub-soil at depth, cover ground at a practical rate and not break.
Initially, a robust frame with rigid ripper legs was mounted on the back of an earthmoving scoop as a quick way to provide the traction needed for a large tractor to pull it at depth.

Once the concept was proven, the implement was modified to a stand-alone unit and it now has hydraulically-retractable legs that provide both the needed height-lift and depth of operation. The implement can now be used with farmers’ and contractors’ larger tractors.

The Mizzis are convinced of the benefits of removing compaction. As well as running the trials, they are treating all their own cane-blocks as they become available in the crop-cycle, by ripping before the wet season and re-ripping just before planting.

“Our farm is right on the mangrove fringes and only a few kilometres from the ocean,’’ Paul Mizzi said.

“Working towards environmental and productivity outcomes is a win-win for everyone.”

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