Rough up the surface of the soil before building the berm/raised bed. Doing so will help the better soil/compost on top mix in and improve the original soil underneath. If it were me and I were doing large beds, I'd have someone with a tractor disk up the area before adding anything on top. Don't try to till the soil into powder, just rough/break it up a little. Any sudden changes in soil type has the potential to cause a tree's roots to not penetrate into the next layer.

Don't forget Bigorangevol's gypsum recommendation to improve the soil before building up the beds! Actually, spending a year or two working on the soil before planting, could be paid back many fold by much better tree health and performance and faster growth in the following years.

I'm not sure using newspaper underneath added soil is going to help all that much. It might if you were adding a very thin layer of soil, but if you add more than just a few inches of soil, the grass will be killed equally well with or without the paper. Adding paper may not work anyway because the uneven surface (assuming you rough up the soil as recommended) is going to allow the damp paper (if it's covered by soil, it's going to be damp/wet) to quickly break apart unless you use a very thick layer of paper. A thick layer (number of sheets depends on soil moisture, type of paper, etc) of paper could indeed cause the roots not to penetrate into the next layer of soil and reduce oxygen levels in the area covered by the paper.

I would use Roundup before building the bed. You'll have to find a warm day for it to work at its best. Roundup will kill all the vegetation, will have absolutely no ill effect of the future plantings, will allow you to more easily work the site without worrying about weeds popping up form the original vegetation, and is very safe if used as directed. If you do use Roundup, only use the regular stuff. Roundup Extended Control could have a negative effect on newly planted things if mixed into the soil. The Extended Control type should only be used on soil surfaces after planting.

Thanks for the advice!

Since the weather is simply glorious today, I plan to excavate the sod layer and the first few inches of clay and roughen up the remaining surface with a steel-tined rake, get the bed-frames built and begin re-filling with the "lasagna layers". I have several bales of peat, compost, and a large wagon of grass clippings already collected.

We'll see how it all works out, and if all my preparation helps. Hopefully I will not drown any more innocent plants!

I don't think you will have any problem with your plan and the fig tree. Figs have been known to grow in limestone. Don't know to much about the pomegranate except I have a couple growing in clay.
Norm

I just read a report from somebody who recently went on a trip to Italy. She saw a mature fig tree growing in the cracks of a roof on one of the famous buildings in one of the cities she visited. =:-o