Double digging may be of some benefit where drainage is an issue and may be needed once but seldom is necessary more often. In your sand double digging would have spurious benefit.

In Florida, where drainage is poor, double-digging will do nothing in any case. You'd have to pile up a high bed, which would dry out terribly unless irrigated.

GP, IME, the trick in florida is to mulch and mulch, after the initial amending/fertilizing. I related last winter on the FL forum about a fellow down the street who had the most superb plot of collards - I have rarely seen such healthy brassicas anywhere - and he had about a good foot of pine needles/leaves under them. He simply bought starts at a box-store in november, set them out with a little slow-release chemical fertilizer (just relating what he told me, not condoning synthesized fertilizer) to get them growing well, and then simply mulched them with municipal leaves continually.

I had pure sand at my previous home in Michigan, and one foot of wood chips/manure/leaves were just the start. In my garden, I probably put two feet of OM over 11 years. But IMHO, and at least there, double digging was completely unnecessary. If there is enough material, the worms will churn it in as it decays. I wonder if hugelkultur is more advantageous in sites like that, as you effectively add water sponges to the soil, and anyway you need the massive OM.

I have major doubts about hugelkulture in peninsular florida - IME there wood buried in the sand lasts and lasts beyond all reason. I have plots with chunks of wood and bark from 7-8 years ago still intact, inches below the surface.

⦠and why is that? is the place somehow not conducive to fungal growth? I noticed the same thing at my previous site, where apple and pear stumps did not decay much over several years in the driest (sandiest) parts of the yard. Only Turkey Tail fungi made it there. But in the drip irrigated part of my yard, with yearly addition of manure and other goodies, fungi were abundant.

My best guess is that sand gets so dry, it sends fungi into a dormant state many times in the course of the year, strongly restricting their growth. I once had to excavate the front yard in September, it was bone dry all the way to 8 ft. So maybe hugelkultur in sand needs a little help. In clay it needs no help.

Well, I don't know about the MI climate (which is generally pretty similar to the rest of the northeast, right?), but in peninsular florida the well-drained sand - as opposed to low areas where the sand is either over an impenetrable clay layer or more commonly right on top of the saturated limerock - is so perishingly dry, combined with the generally dry air during the dry season, hot sun, so the evaporation rate plus drainage is astounding. You can go out to the pasture a few minutes after a rare winter rainstorm and the sand in most areas is bone dry.

I suspect your assessment regarding fungi not being able to get going is correct (the type that quickly break down woody material), at least in areas with constant disruption, such as where the sand is bare, or a pasture that is being mowed regularly. When I walk around in the forest nearby I see that conditions are dry, of course, but because layers (pine needles, leaves, twigs) can build up there is some slight retention of moisture and one will see all sorts of fungi growing on the ground and on any wood on the ground. Yet if you put your hand into the sand it feels very dry. It's a very fragile environment.

Probably if one dug a pit, filled it with mixed woody materials, covered with sand, and watered it during the dry season one could get some decomposition going, but nothing like in more northern climes, or heavier soils.

You know, the solution I had in mind. You have to have drip, and some spongy material...