Rooting depth

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.

This test is split into 80% rooting depth – where 80% of roots are concentrated, and rooting depth (total), a measure of where the longest (often outlier) roots have penetrated.

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 plant root depth (80% and total)

  • Photos


  • Spade

  • Ruler / Measuring tape

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 Sectormentor. 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. You can also record the your total root depth in the separate Sectormentor test called ‘Rooting depth total (cm)’ for your reference.