Vertical hugelkultur & wood chips vs horizontal hugel

Here's a quick comparison of fava beans growing in a hugelkultur bed.  The beans were planted in November, about 4 months ago.

The bed pictured, just beyond the fence, is 12'x3'.  The 4' of the bed on the right was my first attempt at hugelkultur. It has mostly horizontally buried logs with no wood chips dug in. The rest of the bed was dug with vertical stumps and wood chips.

See: http://lowcostvegetablegarden.blogspot.com/2012/10/garden-bed-construction.html. 

No fertilizer was used.

Notice how the fava beans grew much better and thicker in the part of the bed with wood chips and vertical stumps.

Here's a closeup of the favas in the vertical stump & woodchip part of the bed. The stalks are much sturdier and thicker here.

Here's a closeup of the favas in the mostly horizontally buried log portion of the bed.

Burying Stumps in Sandy Soil

Here's an idea for using hugelkultur in sandy soil.
Ideally for sandy soil you'd want lots of rotten wood dug in for water retention.
However, if you only have dry (not green) unrotted wood available, you could still get benefits from hugelkultur right away.

Bury stumps, branches, split firewood, vertically in the ground about 3-4" below the soil surface.
Then plant right over the buried wood. The plant roots should grow down underneath the wood. The wood will retain a lot of water and slowly "drip" it out the bottom unto the roots, feeding them with a decomposed wood stream and any fertilizer you add (urea, urine, bloodmeal, fishmeal, ...).  This is what I observed in "stump containers".  See:
http://lowcostvegetablegarden.blogspot.com/2012/09/eggplant-stump-branch-pot-comparison.html
http://lowcostvegetablegarden.blogspot.com/2013/02/rose-hugel-pot.html


Overtime as the wood rots it should hold even more water and since it is large chunks of wood, they won't wash away deeper into the sand with rains.

My own soil is clay, so I've never tested this, but just thought about it after visiting my parents in sandy soil Florida. I would not do this in clay soil.  In clay soil, I bury the stumps about 1' under the soil surface.  The stumps wick away excess moisture without drying out the soil.  Underneath stumps in clay soil, it gets very wet.  In the 1-2 inches right underneath a stump in clay soil, I found, that roots will not grow, because it is so wet & mucky.