In Recorder terms you need to have one Samples for each soil core/fraction. That is to say in your example you need 20 samples for each sample point (200 in all). The information about each 'Sample' such as the core number and the fraction are then identified as sample_type, sample_reference or if necessary by sample measurements. The issue is then not how to split the samples, but how to group them together. You can do this with Sample Relation which could be used to link the Recorder samples together to get all the information for one of your samples. Alternatively, you could use the Location Hiercarhy to do this by creating a Location for your sample point and allocating this to all the core/fraction samples, so that you can bring them together for reporting. Also using the Location hierarchy you could also link together all the samples which make up a transect.
The best approach is probably to key examples of the various approaches into the Observation hiercarchy
to see how the data will look. I suspect that the Report Wizard is not going to be much use in getting to this data so you will will need to use XML reports.
Mike Weideli