Descripción5. Photo 5 After the hole is made with the augers, an aluminium tube (2 inch outer, 1.9 inch inner diameter) is driven into the ground with a sledge hammer. The lower end of the tube is sealed with a pointed cap. The upper end is protected during hammering with a steel "cork" which is seen in the photo. To get the same measurement geometry the upper end of the tube is left to protrude above the ground to the same height for all tubes used in a particular experiment. When the tube has reached its correct height attention is paid to arranging the soil around the tube so that rain water will not run unnaturally towards the tube and down its sides, thereby causing erroneous results of the measurements. Also the crop around the tube must be cared for. Compare photo 4 and 6, 7. (22/3 1978). From left to rights Mr Haute (?), Mrs A. Maeda. Mr A. Shamte.
Photo - Positive
