For our common clay-loam topsoils, it seems the first important step is to increase water infiltration(soaking in) rather than puddling or washing away over the surface...
I believe that grass clippings provide some of that physical characteristic necessary to help that happen...
What else would add mass to the topsoil that would aid in the water soaking in???
Would corn/soy meal be needed IF there were already plenty of grass clippings on the soil, in the turf???
Now that I know that clay's texture(platelets) has nothing to do with water infiltration, percolation, or drainage,,, I wonder what does...