As Borek already told you, it would be good if you were to give us some more background for your question.
I told you already in another thread that thorium isn't mobile and therefore won't interact with clays.
For uranium google spits up quite some literature, e.g. : http://tubaf.qucosa.de/fileadmin/data/qucosa/documents/6240/final version of Diss_SB_BM_BPF_Bibo.pdf
What I think is also important is the point that many fertilizers contain uranium or radium, especially phosphate fertilizers as they are produced from uranium containing phosphate ores.