101 Questions answered
Optimising Depth for Soil Health and Productivity
This depends on how deep the compaction is. Ripping needs to work into the compacted layer, ideally towards the bottom of it. Ripping too shallow doesn’t offer a good enough return on investment on the work (it doesn’t break up enough soil to get the yield boost to offset the cost of ripping), while ripping too deep can damage soil structure. When there is too much weight above the ripping point, the soil compacts and smears rather than lifting and fracturing. Plus, ripping too deep comes with extra fuel and machinery wear and tear for no extra gain and in some cases, extra pain.
Start by finding out how deep the compacted layer is. A penetrometer gives good detail on depth of compaction and if it’s bad enough to warrant ripping. A rough rule of thumb is roots start to struggle when the soil penetration resistance is >1500 kPa. In a pinch, a push rod or sharp stick will show how deep the compacted layer starts.
Take measurements when the soil is wet, but not saturated. Soil gets harder as it dries so if you test when the soil is dry you will get high readings. This fact sheet on diagnosing sandy soil constraints has detailed instructions on using a penetrometer.
Choose the ripping depth to work into the worst of the compaction. For example, if the compacted layer is from 20–40 cm, work at 40 cm depth. Most rippers will have a maximum working depth of about 60 cm. If you are ripping shallower than this, consider narrowing the spacing between tynes to ensure uniform decompaction through the profile. Ripping shallow with wide tyne spacings will not provide sufficient profile loosening. Otherwise, select a different tool that is better suited to the job, such as a combination ripping+spading machine or chisel plough.
For an in-depth look at what to consider when choosing rippers, check out the ripping technology fact sheet.
