How to look down into your soil — take a core!

Diagram that describes the construction of a soil coring tube

If farmers could see the moisture and structure of their soils below the surface, they would be much better able to make decisions on running their farms.

CSIRO scientist Mike Foale developed a tool which enables farmers to take soil cores in the paddock by hand. Mr Foale uses the corer in his work with the Agricultural Production Systems Research Unit. APSRU takes science into the field for farmer-initiated projects with GRDC support. Mr Foale said the corer has shown many farmers, to their delight, what's under the soil surface, for the first time ever.

In this issue Ground Cover describes the coring tool and tells you how to make it.

In our next issue we shall tell you how to use it.

Our illustration shows eight stages in constructing a tube. Most of the equipment needed will be available in the farm workshop. You will, however, need a special die which you can make or have made by a fitter and turner. The specification for the die to form 38 mm and 31.6 mm tubes is as follows: 150 mm long, internal diameter (ID) at the top 42 mm, tapering uniformly to 27 mm ID at the bottom (it tapers at the rate of I mm per 10 mm of length of the die).

In preparing the die the ideal to use would be a hollow bar of ID/OD 25/45 mm or 25/50 mm. Use of a hollow bar reduces the amount of turning required.

The die when complete should be fitted with a steel base plate 150 mm x 150 mm and with a guide tube 400 mm long spot welded to the top. The guide tube ensures that the exhaust tube remains pretty well straight when it is hit (section 4 of diagram) so the formed up is straight in line with the tube.