The “Raised Beds” method of gardening is certainly metaefficient, and should be included in our guide here. Raised beds are widely acknowledged as the method to obtain the greatest yields of vegetables per alloted space.
You can read about the benefits here: Aaron’s Home & Garden weblog (Aaron is an expert in Rainwater Harvesting).
Website: Aaron’s Home & Garden
The book Cubed Foot Gardening: Growing Vegetables in Raised, Intensive Beds shows how to build these simple, inexpensive beds and how to grow the most popular vegetables in them, using innovative tricks and techniques that would not be possible to employ in a conventional garden.