added value of raised beds?

My main hobby is gardening. I eat from my garden, 450 m^2, year round, and even have lots of extra space to play around, grow flowers or experiment.

I see many new (US) instructables with raised beds, inspired by a popular book (Batholomeuw). It claims to have higher yields, and lower requirements of water, and work.

In Europe, we are unfamiliar with this method (unless for elderly or handicapped people).

It raises a few questions, but only to be answered by folks having experience in BOTH traditional methods AND the raised bed garden:

In normal circumstances, do the claims of this method uphold?

Adding the soil mix: 1/3 vermiculite (=clay), 1/3 peat and 1/3 compost. What kind of compost? Where does it come from?

About the yearly renewing of the soil|:- again, where does the compost come from?

For compost making: Is the household excess sufficient, or does extra material has to be added??

Why are these questions important?

Gardening in the traditional way is nearly carbon neutral, unless all physical work is mechanized.

But (the concept of) soil ecology is very precious; just covering it and putting this mix over it almost alarms me!

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Let me put some of it into perspective if you are only accustomed to gardening in your particular region/area/neighborhood in the world.

I live in Central Texas which is basically where the South American continent slammed into the North American continent creating some interesting topography. To make it a little bit worse, this area also used to be the site of an ancient sea. Ok, there's a lot of rock around here, and it's naturally prairie land for the most part. It's flat and rocky.

Some people have 1" of soil. Some people have 8". There's not loads of soil around here which has made it a commodity, and people will literally buy/sell dirt. Because soil is quite precious, a lot of people create raised beds for their vegetables and will plant natives and well-adapted plants elsewhere because the natives don't like or need the rich soil you find in the typical vegetable bed.

Vermiculite isn't clay - it's expanded minerals. Peat comes from bogs and wetlands. Compost can be any number of things.

I don't believe in putting vermiculite/perlite in the soil because it's expensive and unnecessary if you can buy locally produced products. Sand, gravel, etc. are fine substitutes although they weigh substantially more. Around here, there's lots of rock, so finding it isn't too difficult.

I don't believe in using peat unless absolutely necessary because bogs and wetlands are destroyed to obtain it. Coconut coir can be a substitute but so can composted wood mulch or humate (composted brown leaves).

It can be composted manure (animal or human). It can be vegetable base. Around here, you can buy Dillo Dirt which is a City of Austin product and is composed of lawn refuse that the city collects and human poo. You can also buy turkey/chicken manure, cow manure, sheep manure, etc. It is not cost effective to ship compost any great distance, so compost is generally produced and sold within a 10-30 mile radius - by American standards, that's not any great distance. If you are smart about composting, you can do it all yourself especially if you scavenge from neighbors putting out their yard waste.

A raised bed is like putting soil on top of the soil. The soil underneath isn't destroyed or killed, and the life inside that soil will migrate into the raised bed and will probably have happier digs.

Every single time you garden, you disturb the "natural balance" of things. There is no such thing as a "natural" garden. The only way to eat "naturally" is to forage, barefoot and naked, but I don't think anyone's going to do that.

I personally use a lot of locally produced products in the garden such as cow manure and composted wood chips because it's cheaper. I also double dig which produces a raised bed as a result of fluffing the soil and adding amendments to it. However, I am capable of double digging as I am not sick or frail, and I have enough soil in my yard to work with. And I believe the concept of double digging came from France...

ANYWAY! It all really depends on how/where people source their materials and why they need to source those materials for there to be any sort of concern for the environment and what not unless you are of the belief that everyone should forage and the human population could do with a good culling. Basically, I wouldn't recommend people using vermiculite or peat in their gardens for environmental/cost reasons. There are better/cheaper alternatives.
BobS (author)  AngryRedhead5 years ago
Thank you for your great answer. Clearly I need to do some more travelling; I seem to get a little stuck in Holland. (I did some gardening in Florida and set up a garden in Surinam) In our part of Holland the soil layer is about half a mile thick! Same at the Surinam coastline (sediment from the Amazon). I work with 1x1 ft pavement tiles as paths, but have to raise them every 3 years (rodents etc dig under the tiles undermining the path, a cake of soil gets on top of them and nests of rooting weed start hiding. Not a terrible job to do though. Most of the garden gets worked over at least once a year. The only part of the garden where weeds are a problem is in the perennial flower beds. My organic input is ca 2 shovel loads of cow dung from a hobby farmer (2 cows) nearby every year put I let it sit with all discarded plant material.
Although not totally naked, I do a lot of barefoot gardening in summer!
seandogue5 years ago
In my experience, raised bed gardening was inspired by the Victory garden, a TV shows produced by PBS during the 1970s and 1980s. I don't know anything about the book that you cite and don't know anyone who was inspired to raised bed gardening by that book.

For my part, I like it because it improves drainage and allows me a deeper bed of soil than I could otherwise expect in my locale
AndyGadget5 years ago
Hi Bob, you've got a fair sized plot there.  Mine is a lot more modest and consists of 10 10' x 5' (3m x 1.2m) raised beds (some double length) plus a couple of narrower ones around the edge for currants and goosegogs.
I've also got two large compost bins with 18" (0.5m) paths between it all so I never have to stand on the soil - very useful in wet weather.

When I first set up the beds around 10 years ago I double-dug the soil and added loads of organic matter.  Each year now after the autumn tidy-up I add a layer of the rottenest farmyard manure I can find (local source) and loosely dig it in to the top couple of inches of the surface. 
We compost all vegetable kitchen waste, weeds, a few grass clippings and old bedding from the guinea-pig hutch.  This gives us a couple of cubic yards (metres) of compost a year.

Every spring I turn the compost heaps and spread completed compost over the surface and loosely dig in again.  I only dig the first 4" or so and the worms do the rest.  The result is a wonderful loose and extremely fertile soil which is great for sowing and planting.

The advantages are the wonderful texture and fertility of the soil and very few weeds.  The few which do appear are easy to control as the full area is easily accessible.  I've never gardened any other way so can't really compare yields but I'm very happy with the amount this produces with minimum effort.
I forgot to mention the comfrey patch which is in the very loosely controlled wild area and harvested a couple of times a year.  This, and wood ash from the bonfire are rich sources of potassium for the compost bins.
Raised beds allow you to adjust the soil composition to meet the needs of what is being grown. Some plants like higher PH levels, others like more sandy soil, etc. It also allows some very creative and unique landscaping opportunities. A raised bed can make it easier for some people to reach and tend the garden by reducing the amount of bending over that is required. An excellent source for this type of gardening is "Square Foot Gardening" by Mel Bartholomew.

Here, compost is mostly made from yard waste (grass clippings, leaves, straw, mulch, etc mixed with kitchen waste such as coffee grounds, egg shells, & vegetable peels. Do not use meat scraps! The mixture is stored in an aerated bin that is regularly mixed or stirred to speed decomposition. The mixture is often blended with manure or other fertilizer and added to the soil beds.
Vyger5 years ago
climate can make a difference with this also. Raised beds allow the soil to warm up faster. And they allow the dirt to dry out if you have a lot of rain.

I do the opposite. I plant in furrows. Then I use flood watering and not sprinkling to water. The problem here is that its more arid. So I want to conserve as much water as possible. Sprinkling evaporates a lot of water into the air and also goes on the ground where nothing is planted. Furrow flooding keeps the water where I want it and discourages weed growth because the surrounding dirt is to dry to germinate weeds.Here is a little bit more about it.

orksecurity5 years ago
The only real difference between raised bed and dug-into-the-surface is that you're establishing a physical barrier to discourage invasion by weeds. Outside of that, you can use exactly the same kinds of soil, same kinds of fertilizer/compost, and so on.

You have to fertilize in-ground crops too, you know.

No additional carbon hit, as far as I can tell, except for the garden timbers you use to border the raised bed.
rickharris5 years ago
Have both - If you garden by hand raised bed make for no dig gardening. You can adjust the soil to your hearts content - You can cover beds easily with polythene/fleece etc.

If you use a rotovator raised beds are useless!!

Compost is available from many sources, spent Mushroom compost, garden compost you make, Local authority recycled compost (may be good - may contain lots you just don't want.

raised beds can be easier to work as they give you a smaller area to tend, also may be high enough to reduce back strain.

may be difficult to reach across, mine are 9 foot railway sleepers so I need to stand on the compost.

Over all if I could afford it i would go fully raised beds. BUT wouldn't swap one for my poly tunnel.