Innovation to improve subsoil

Improving the condition of the subsoil has potential to reap a $67 million benefit for farmers in southern Victoria.

That is one of the findings from a recently completed project conducted by Southern Farming Systems and the University of Melbourne where they constructed, designed, and tested a machine that could harvest and deposit organic material underground. The project was supported by the Australian Government’s National Landcare Programme.

Despite being in a high rainfall area, many crops and pastures run out of water in spring because the ability of the soil to store winter rainfall is limited by the subsoil layer at 20 to 40 centimetre depth.  Improving the subsoil increases the soil water storage, leading to better growth late in the season.

The practice of improving the soil is commonly referred to as subsoil manuring and has been investigated for more than a decade.

These small scale experiments proved the concept works, but taking it to a farm scale has been challenging, according to Geelong consultant Simon Falkiner.

“The materials and machinery used so far are uneconomic on a commercial scale, so we had to find alternatives,” Simon said.

“The two promising developments have been the idea of growing as much material as possible on the paddock that is to be treated.”

Using a combination of fast growing cereals and legumes, more than 10 t/ha of dry matter could be grown on the paddock.  Any problem weeds also become valuable material to bury underground.

“The second challenge was to create a machine that could harvest this material and bury it underground, all in one action,” Simona said.

In partnership with a team from the school of engineering at the University of Melbourne, a prototype machine was designed that mowed the green forage, picked it up, and deposited the material behind tynes that had ripped 40 to 60 cm into the ground.  Large blades and a roller then covered the green material with the disturbed soil.

A number of farmer demonstrations were established in late 2014 but unfortunately 2015 did not result in any improvements in yield due to the failed spring.  Luckily 2016 was a better year and although harvest is still underway, there were major visual differences in late season crop growth.

The subsoil machine (with operator) is available for hire from Southern Farming Systems.

Contact Simon Falkiner at 0407 319 967 for more information.