EFFECT OF THE SYSTEM OF RICE INTENSIFICATION (SRI) ON ...

APPENDIX B. Soil sampling methodology.
Procedure: The centre of each field was located and marked with a bamboo stick and thereafter the
other sampling locations were plotted. 19 subsamples were taken from each field in the same star
shaped pattern to form one composite sample for each field. 19 points were chosen due to achieve a
systematic sampling procedure for all 30 fields which were shaped very differently. The 19 dotted
star shape pattern coped very well with all field sizes and shapes and helped increase the accuracy
of the composite sample for each field. As the fields were very heterogeneous the 19 star systems
also covers all areas of the field. It would also have been accessible to sample less than 19
subsamples for each field however the level of accuracy is increased with more subsamples.
A vertical core sample from the topsoil/plough layer, 20 cm, was collected with a stainless steel
auger tube fabricated at the National School of Agriculture at Preak Leap, Cambodia. The steel tube
auger is 3 cm wide and the tube is 50 cm long. At the top is located a handle in order to push the
tube into the soil.
Each subsample was sampled by pushing the tube perpendicular down through present water into
the soil. Each subsample consisted of 240 cm 3 soil incl. present stones and plant residues.
In order to be able to push the soil out of the tube a small steel spoon was used to press out the soil
and then collected in plastic bags. After sampling one field the auger tube and the metal spoon were
cleaned with water and then rinsed with rice alcohol 90% vol.
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