Measure that girth!

The benchmarking project has had a real boost by contracting Ivan Barnett to liaise with orchardists and carry out some field work.

May is the month for measuring trunk diameters. All orchardists can do this, and the more that do the better. By comparing the growth of trunk diameter per year with other orchards through the benchmark project each orchardist can gauge how effective their management is at promoting tree health and growth. This helps each of us develop best management and learn what walnut trees respond to.

To contribute data to the project orchardists should randomly select 25 trees of a particular cultivar and age from a given block, note these trees for future reference, and measure the trunk diameter at about 600 mm above ground level. For smaller trees the easiest way is to use a vernier caliper (see the photo) available for a few dollars at hardware shops. Plastic calipers are ideal as they are less likely to damage the tree bark. For larger trees use a tape measure (such as a dress-makers tape) and record the circumference in millimeters. We then convert the circumference measurement into diameter (mulitply by 7 and divide by 22).

Measurements should be recorded in millimeters (no decimal places). Orchardists can then find the average for their block by adding all the diameters and dividing by the number of trees.

Perhaps the easiest way to add your data to the research project is to simply enter it directly on the webpage: – alternatively it can be recorded on paper and sent to Ivan Barnett, 5a Waterholes Road, Springston, Christchurch. Please include your name, location, block sampled, cultivar type and tree age.

We will focus a little more on this at the AGM in June.

About Graeme N

Graeme is a social complexity researcher at the Institute of Environmental Science and Research (a NZ government research organisation). He and his wife also own and operate a walnut orchard near Lincoln in Canterbury, NZ.
This entry was posted in Benchmarking, walnuts. Bookmark the permalink.

1 Response to Measure that girth!

  1. sandrar says:

    Hi! I was surfing and found your blog post… nice! I love your blog. 🙂 Cheers! Sandra. R.

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