Over 20 years ago, after fighting wire grass (coastal bermuda) and poor sand for many years, I ran one of my first major gardening experiments, pouring a concrete skirt around a series of in ground beds. This area is adjacent to an old concrete carport floor. The material in the bed area was amended with copious amounts of organic material, both commercial as well as home made compost. The approach turned out to be a great solution to the grass problem, but not so much for the poor, sandy soil. After what seems like hundreds of cubic feet of amendments, the soil is still essentially dry and sandy.
A couple years after forming the in ground beds, a series of three large planter boxes were placed on the concrete pad. Since that time, those boxes, sitting directly on the concrete have been by far my most productive areas, nothing else even comes close.
Now the oak tree roots from 75-100 feet away have found the in ground beds, plus have even found their way into the above concrete beds, moving in through small cracks in the 30 year old slab.
In accepting this reality, and as part of a transition toward developing an 'eldy' friendly gardening area, I'm resurfacing and slightly expanding the entire area to make a gardening patio. This is not very consistent with my 'organic' permaculture leanings, but represents a compromise that will give a much better gardening experience in future years. Actually the foot print is only somewhat larger with the new concrete mostly sitting over the existing slab, so very little additional degradation in that regard. This 27 foot by 35 foot space only represents a tiny fraction of our 130 acre site which is managed almost exclusively via low impact, eco friendly ways. Perhaps a bit of a rationalization, but probably is also a balanced way to look at the decision.
Here is a before photo.
Here is a photo of the new slab. New beds to follow. Not sure if I'll replace the arbor or not.
Progress will be posted as the project moves toward completion.