Does topsoil slotting increase yield?
Topsoil slotting uses soil inclusion plates attached to the rear of deep ripping tines.
The practice has been shown to increase the yield from deep sandy soils more than deep ripping alone, however the value of the topsoil slotting plate is still being determined.
Three years after investigations began at several locations across the Wheatbelt there is evidence of a trend to greater yields with deeper ripping combined with topsoil slotting.
Ripping treatments were applied once in 2015 and since then the paddock has been managed by the grower, under controlled traffic, to observe how long a yield response from ripping can be maintained.
The following highlights the results from three selected locations.
Binnu
A challenging season at Binnu in 2017 did not provide significant yield differences between any of the treatments though differences in greenness and biomass were visible throughout the season.
The deeper ripping with topsoil slotting plates provided an additional 7% yield over deeper ripping alone, although this only amounted to an estimated 30kg/ha.
Ongerup
The gritty grey clay at Ongerup is a challenging soil to farm profitably.
When dry, it has very high soil strengths and is difficult to rip.
Clods are still present three years after being dragged to the surface during the ripping process of 2015.
The trial site is susceptible to water logging and the soil is sodic at toxic levels below 300mm.
The deeper ripping penetrated to 400mm and has met with the toxicity.
Where topsoil slotting plates are present the organic matter buried to depth has provided some buffering of this sodicity.
This has combined with the increased drainage from the deeper ripping to provide yield improvements over nil ripping.
Deeper ripping with slotting has increased yield by 23% over the control treatment (no ripping), and by 9% over the deeper ripping alone.
Munglinup
The sand over gravel at Munglinup was deep ripped to 600mm.
Responses from this site have been large with controlled traffic maintaining a yield response of 20% in the deeper ripped with topsoil slotting treatment.
Here slotting appears to provide an additional 4% over deeper ripping alone.
Ongoing data collection
These trials have one season remaining to collect observations and data.
With this further information it is hoped the value of topsoil slotting can be determined to help growers make decisions on how top soil slotting and deep ripping fit into the farming system.
This information is brought to you by the Grains Research and Development Corporation (GRDC) funded project Minimising the impact of compaction on crop yield, Project No DAW000243 managed by the Department of Primary Industries and Regional Development (DPIRD).
More information can be found at the Deep ripping for soil compaction page of the DPIRD website.
For more information contact Wayne Parker, Research Officer, Geraldton on +61 (0)8 9956 8511.