Hugelkultur is an ancient form of sheet composting developed in Eastern Europe. It uses woody wastes such as fallen logs and pruned branches in order to build soil fertility and improve drainage and moisture retention.
If you walk through a natural woodland, you will see many fallen logs and branches on the ground. The older these logs are, the more life they sustain. A log that has rested on the forest floor for five or ten years will be covered in moss, mushrooms, wildflowers and even young trees. Poke at it a little and you will notice that the decaying wood is damp in all but the most vicious of droughts.
Hugelkultur is the practice of making raised garden beds filled with rotten or rotting wood. is designed to take advantage of the natural fertility and moisture-conserving qualities of rotting wood, while speeding the process of decomposition up. The heat produced by decomposition also helps protect cold-sensitive plants.
To make a hugelkultur bed, you simply gather some woody waste materials such as dead logs, extra firewood, pruned or clipped branches, and more. The wood can be either rotting or fresh, although already rotting wood is best. Lay the wood in a mound or pile about 30 – 60cm high, and stand on it to break it up a bit. You can also dig a trench to lay the wood in if you prefer. You may cover the wood with other compost materials such as autumn leaves, grass clippings, garden wastes, and manure before adding dirt, or you may simply cover the wood directly with 5 – 10 cm of dirt or prepared compost.
The result is raised garden beds loaded with organic material, nutrients, air pockets for the roots of what you plant, etc. You can either let the bed sit for awhile to rot, or plant it immediately. You can also use the hugelkultur techniques but dig trenches to fill with woody waste, and cover them to leave flat or very slightly raised garden beds rather than piling the wood and soil up to form hills.
As the years pass, the deep soil of your raised garden bed becomes incredibly rich and loaded with soil life. As the wood shrinks, it makes more tiny air pockets – so your hugelkultur becomes sort of self tilling. The first few years, the composting process will slightly warm your soil giving you a slightly longer growing season. The woody matter helps to keep nutrient excess from passing into the ground water – and then feeding that to your garden plants later. Plus, by holding so much water, hugelkultur could be part of a system for growing garden crops in the desert with no irrigation.