California topography varies greatly. Many towns are built across rolling foothills, so steep slopes need creative solutions to keep erosion at bay.
In the photo we see three solutions used on a forty five degree slope. The first job was placing the permanent plantings. This hillside used several trees, including a Haas avocado. All the tree choices keep their leaves year round, so they provide shading, too.
You can see with the avocado tree that a horizontal basin has been built up with stones on the perimeter. Besides holding the good soil in place this basin holds irrigation and rain water.
Drip irrigation provides a steady supply of water and the hard black lines come up from a spigot at the lower level and are buried under the rocks. It is important to place the vegetation first because it is very difficult to move the stones.
The second aspect to be installed is the railroad ties. First the slope is smoothed, then cut in for the depth of each tie, spaced between two and three widths apart. The horizontal bare earth is dug out a couple of inches and covered with a layer of shredded bark to further control erosion.
Then the stones are set into the hillside. Beginning at the foot, the stones partially rest upon each other all the way up the slope. At the top on the horizontal portion more stones are set in place to act as pavers around the tree. In the future this design will be helpful in more easily picking the fruit.
Erosion control can be both effective and attractive with some forethought in designing all elements in the total slope before you begin.
Article and photo by Susan Helene Kramer
Sunset Western Gardening Book
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