Composting logs buried in a trench then layered above. The logs as they decompose provides heat to the roots of plants providing a much longer growing season.
The beds can be buried completely under ground or you can build them higher to have no stoop gardening as shown in the picture below.
This method also retains water better so you don’t have to water as much. As the log compost the beds will sink a little each year but you can add new compost every year if you want to.
Hugelkultur: Composting Whole Trees With Ease
Sepp Holzer’s Permaculture: A Practical Guide to Small-Scale, Integrative Farming and Gardening–With information on mushroom cultivation, sowing a … ways to keep livestock, and more…
Permaculture Design: A Step-by-Step Guide
Gaia’s Garden, Second Edition: A Guide To Home-Scale Permaculture