I am building contained raised beds for vegetables on top of my existing vegetable garden. The existing garden has clayish soil that I amended with 2" of manure last year. I would like to add about 4" of material on top of this and do and turn it into the existing soil. I have municipal compost, composted manure, peat compost (not peat moss), and screened topsoil available to purchase in my area. What would be the best mix for the raised beds?
Also, what is the general rule of thumb for converting pounds of topsoil to cubic feet. Is it 40 lbs equals roughly 1 cu. ft.?
In case anyone is wondering, I’m building the raised beds for better spring soil warming, better drainage, to focus organic fertilizer applications where needed and to create a no-till soil structure.
I have had so much success with French gardening (raised bed). So many advantages:
>head start on growing season; heightened bed gets a week or two added to frost free season.
>ease in cultivating and weeding; less bending required
>better DRAINAGE, by virtue of the design
> ready structure to attach standards, stakes and netting etc
I always used well aged cattle manure, wheel barrels full of wood ash, a few handfuls of dolomite lime (magic stuff) and clean sand (when I could get it). some friends swear by worm castings and vermiculite etc, but you want to minimize the cost all that you can.
Keep the beds lofty light and never compact the soil. Another soil amendment that I used lots was well aged kitty litter with kitties dropping of course. Coffee grounds should make it to the compost pile. So the bottom line here is to have good drainage and to incorporate inexpensive materials.
I obtained these figures from online and something interesting can be noted by comparing your 40 pounds to the higher numbers below.
The healthiest most friable soil for raising vegetables is one that has good drainage. Most plants desire this. Friable soil WOULD be far less dense than unusable soils.
So, the 40 pounds per cubic foot sounds ideal.
Earth, loam, dry, excavated – 78 pounds/cubic foot
Earth, moist, excavated – 90 pounds/cubic foot
Earth, wet, excavated – 100 pounds/cubic foot
Earth, dense – 125 pounds/cubic foot
Earth, soft loose mud – 108 pounds/cubic foot
Earth, packed – 95 pounds/cubic foot
These figures are likely for construction purposes and have no bearing on vegetable gardening. However, one can see that soil can become quite heavy, compacted and basically useless to grow most vegetables in.