chelation in the nitrogen cycle

I'm looking at box marked "metalo-organic and organo-clay complexes" on the diagram of the nitrogen cycle, and I'm drawing a blank. A 'metalo-organic complex' sounds like a chelate, but what is an 'organo-clay complex'? Also, if these are organic molecules in this section of the graph, then why are we treating them separately in the nitrogen cycle from 'soil organic matter'?

Thanks in advance.

Spencer can you tell me specifically which lecture and which slide?

You move quick Sandra! The diagram in question is in lecture 23 (slide 5) and also on Soilweb 200 (http://soilweb200.landfood.ubc.ca/soil-biology/nutrient-cycles/4-nitrogen-n/).

Metalo-organic complexes are indeed chelates
Since both organic compounds and clay particles are charged, they can interact with each other, forming complexes of organo-clay complexes. We did not cover this in our course, but this is something that does happen often in soils.