Rootzone Depth is the depth down to which roots are present. The rootzone may be deeper than the topsoil since roots of lime tolerant crops will grow down into a carbonate layer especially free-draining carbonate layers.
When you examine your soil profile look for healthy roots within each soil layer and record them. Record the rootzone on the basis of the number of roots per 10cm square.
| 0 | No Roots |  |
| 1 | Few per 10 cm x 10 cm Square | (1 - 10) |
| 2 | Many per 10 cm x 10 cm Square | (10 - 25) |
| 3 | Common per 10 cm x 10 cm Square | (25 - 200) |
| 4 | Abundant per 10 cm x 10 cm square | (Over 200) |
(Source: Swan Hill Irrigation Management Course, Book 1, Chapter 1,B and C.) | Diagram: depicting the rootzone depth of a plant. |
