Ask *them* which of their products is the preferred one to fill a raised bed.

How deep would your beds be? From their page it sounds like they have a decent product, but I always take caution as I have been sold a pig in a poke before. Remember, they are in sales, and you have to decide if they put out a good product.

If what their brochure says is on the money, then yes, you should be able to fill the beds with that. In my mind you might want some of the soil under the beds mixed in, but if your soils are very poor or you are planting in amongst trees, then raised beds full of compost should do the trick.

The compost needs to be rich, black, have an earthy smell, and must not contain any large pieces of woody material or chunks of un-broken down plant material.

What I don't like about the brochure is that it gives no information about the pH of the compost, what the parent material was, or what the nutrients of the product are, the only thing I see at all is that it is "70% organic matter"... which doesn't really tell you anything. Organic matter is great, but with a good compost you are looking for a balance of pH (Their comments about their compost balancing acidity leads me to believe the compost has a high pH, above 7.0, Gardeners look for 6.2-6.8), K-P-K, Organic Matter, and some way of knowing how long the product was composted, or how much of the compost has yet to break down. Any cellulose or "woody" material in the compost will tie up N as it breaks down, which would require you to fertilize more with Nitrogen your first few years planting in it.

Good info from Chris above. Normally you do not want beds that are more than 50% compost max. Compost breaks down annually so has to be added to on a regular basis to keep the beds full.

You can find many more discussions about this over on the Soil & Compost forum here and likely others there with personal experience with this particular product.

What caught my attention on their website was their statement that for vegetable gardening Incorporate 1" to 2" of it to 4" to 5" of soil to obtain a total depth of
5" to 6" in the planting bed or container.

So that right there would mean that no, you would NOT fill the beds with it. Plus you'd want the beds to be deeper than 5-6" anyway.

Dave

Any product with a very high percentage of organic matter is going to disappear in a very short time as it does what it is intended to do...decompose and return the dissolved elements back to the earth for utilization by microbes and then plants. When this begins to happen, your raised bed will have a harder time in functioning as a system....the first product it will have a hard time delivering to the plants' roots is oxygen. Then, it won't be a 'raised' bed anymore, but a sunken pit.

The company itself suggests just a smallish percentage of their product be mixed with the SOIL. In truth, a very small amount of organic compounds in any soil does a great deal of work....but a healthy, viable, working soil SYSTEM requires the mineral component...particles of sand, silt, and clay. The consistency of our soil system is dependent, more or less, on the ratio of sand:silt:clay.

You might want to find out what the percentages of sand, silt, clay, and OM are in their soil mixture. That product might be useful to you. Then you can topdress with the compost product periodically.

I'd suggest that you have a professional evaluate the quality of your existing, native soil and help you determine how much of this product will be of benefit. Initially, you would probably want to mix your soil with this product to make a homogenous mixture to plant in. Mind you, the volume of the bed will decrease as the OM content decomposes over a few weeks or months. Top dressing, over time, with more OM can be of benefit.

And, by the way, using ANY product to enrich the backfill when planting woody plants has long been dismissed as not only unnecessary, but in some cases, harmful to the trees and shrubs being planted. The company brochure cites some procedures that are very outdated and detrimental to the long term success of new plantings.

By the way, I've quickly run through the whole website, very interesting. Do you know if they use any of the sewage biomass from that part of their facility in with their compost?

Also, I was somewhat misleading above. I have raised beds that I originally filled with mostly cheap top soil from a big box store. (the kind that comes in bags and was almost a solid brick of mud when I opened it...I know a little better now) I did mix it with some bags of "compost" from the same store, but I couldn't give you a percentage. Those beds are now around 1/2 their original volume and need more added - so I'd actually be mixing this in, pretty close to 50-50.

jean001a - their website (not just the sales brochure) says the 2 products are the same, just one is bagged and one is bulk.

Chris_CL - The beds are 12" deep. They state elsewhere on their website that "pH is nearly neutral".

Rhizo_1 - I'm almost positive they're using the sewage biomass. One, because they are located next to our wastewater treatment plant and two because of this from their website: "Biosolids are primarily organic materials produced during wastewater treatment which may be put to beneficial use. Composting is the biological degradation of organic materials under controlled aerobic conditions. The process is used to stabilize wastewater solids prior to their use as a soil amendment or mulch in landscaping, horticulture, and agriculture. Stabilization of wastewater solids prior to their use serves to destroy pathogens (disease causing organisms), minimize odors and reduce vector attraction potential." Pretty sure they're using them.