Rooting depth 80%

80% rooting depth is a measure of the distance that plant roots can pass through the soil unimpeded, to check that there’s not something limiting deep vertical root growth.

Rooting depth is included for benchmarking & analysis in the Soilmentor Regen Platform

Conditions which may limit root growth include compaction or hardpans, abrupt changes in texture or pH, salinity, sodicity, nutrient deficiencies, aluminium (Al) toxicity, low oxygen levels or a high or fluctuating water table.

What to record

  • Measurement of the depth that 80% of plant roots reach to in the soil (in cm)
  • Photos


  • Spade
  • Measuring tape / ruler (cm)

How to do the test

1. Dig out a section of soil under plants with your spade (approx 20cm depth or deeper if necessary).

2. With a ruler / measuring tape, record the depth at which you estimate that 80% of plant roots are concentrated in the soil, and record this number (in cm) in Soilmentor. There may be a few ‘outlier’ deeper roots, but you can discount them if more than 80% of roots stopped growing at a shallower depth. 

3. Record the number of your rooting depth (cm) in the Soilmentor app.

4. You can also record the your total root depth (mm) in the separate Soilmentor test called ‘Rooting depth total (cm) for your reference. This measurement will not be used in the Regen Platform. 

Watch the video below to see the rooting depth method in action!