What to do with a steep, sandy hillside

Hi all!

I am pretty new to the forums and permaculture in general. I’ve found a ton of value in reading past questions. Very impressed with the wealth of knowledge here!

I live on an acre in Southern California. I’d say 2/3 to 3/4 of it are flat but the back portion (1/4 to 1/3) is a steep downward slope.

My wife and I are trying to figure out what to do with the slope portion… which led me to discovering permaculture as we have a desire to establish a productive garden - and would love to choose sustainable and natural and closed system methods!

Our goals are:
* reduce / slow erosion
* cultivate it to the best it can be

The slope is likely between 30-40% grade (i haven’t measured). And we live in a high fire zone so we are required to do weed abatement once a year within 100ft of any structures. Side note - this past spring I did the first “weed abatement” and in hindsight, I think I removed more than necessary and certainly more than was good for the hillside… fully exposing the soil (just in time for our hot summers 🤦‍♂️).

I’ll post some pictures below so you can get an idea of our slope.

The property has several fruit trees (orange, lemon, lime, avocado, guava, pomegranate, figs) that seem to be doing well. We’d love to plant more down this hillside. Or build small terraces for garden rows.

I’ve considered digging swales on contour but it seems that doing so on a slope as steep as mine might not be a good thing. Note, the soil is sandy / silty… so it drains really well. There is no bedrock shortly below the surface that I am aware off. We get so little rain in this climate that doing things that encourage water absorption seems very appealing (as opposed to constructing complicated drainage systems that carry the water off of the property.

As you can see in the pictures below, there are several signs of erosion taking place over the years:
* out building foundation being exposed
* a concrete drainage being filled with soil run-off
* a fence along the hillside getting buried by dirt getting washed down the hill (it’s kinda acting as a weak retaining wall)

I’ve begun to dig out the fence, throwing the dirt up hill (creating a pathway / terrace). In some places, I’ve constructed a small ~2ft retaining wall to hold it in place. I’ve also laid down some borders along the top edge of the slope to help keep the slope from gradually moving towards the front of the property.

I will note that I really have no clue what I’m doing (as you may have already deduced) - so far I’ve been kinda tackling each problem in isolation… not thinking much about it’s impact on my property as a whole. Enter permaculture - I want to change this mindset of mine!

Do ya’ll have any suggestions for me? Any help is greatly appreciated! Thanks!

Your climate looks for me hot enough to grow Vetiver Grass rows to reshape the slope slowly to terraces.

Vetiver Grass is unbeatable for erosion control and will not spread or seed itself.
The roots can grow in sandy soil up to 12 feet and more so it neither minds droughts or water logging.
Also it works as a great water hold back hence more can drain in the ground which allows you a wider range of trees.

When the risk of fire is present mow it down to 10" and you gain a lot of free valuable mulch to build up your terraces with fertile soil.

If you wanna start go on google earth and screenshot your land.
Then paint(box) into this screenshot a roster of 2x2 meter squares  and measure the land levels, so you create a topographical map and can stipulate where you want to plant the barriers.
(I have 6.6 acres so I made 10x10 meter squares)

I attach my topographic map for a better understanding and a link to my post here about starting my Permaculture Food Forest.

https://permies.com/t/205283/permaculture-projects/long-dream-Thailand-Part

Good luck and enjoy your project

Hi, Bradley.
Welcome to permies.

I think there are two ways of preventing erosion: growing plants fast, and growing plants slowly. :)
For growing fast, you need irrigation. Just plant your trees, shroubs and herbs in level lines, or even with a very soft tilt, and make sure they are well fed and irrigated so they grow as fast as they can.
For growing slowly, you need earthworks. If you cannot provide for your plants, then modifying the terrain is the best option. If you have access to rocks, you can build terraces with little stoney walls. They look pretty too. If that's too much work, you can still make 'mini terraces' for each one of your trees.

For fire control, I'd suggest to plant some cacti and succulents, especially for hedges. They don't burn easily and may act as a fire retardant. Portulacaria afra is very forgiving, and Opuntia ficus-india is also edible.

Abraham said "For fire control, I'd suggest to plant some cacti and succulents, especially for hedges. They don't burn easily and may act as a fire retardant. Portulacaria afra is very forgiving, and Opuntia ficus-india is also edible.

This!

https://permies.com/t/190318/Ode-Prickly-Pear

Besides being fire-resistant Prickly Pear has pads and tunas that are edible and delicious.

I also like See's suggestion of vetiver grass for erosion.

This thread might off some suggestions for other fire-resistant plants even though it is not for your area:

https://permies.com/t/177295/develop-list-fire-resistant-plants

I would also suggest asking your County Extension office for a list of fire-resistant native plants.

We use rock (pea size gravel or washed rock) around our house for fire abatement.

The scorched earth policy that appears to have been applied to your land has created the erosion.
As others have said, grow something to hold the soil and vitivar is good.
Some fire prevention advice actually is incorrect and can lead to trouble.
Some facts;
- Fires race up slopes
- fire retarding plants are effective.
- a fire sprinkler system on the building would be helpful.
- pebble mulch will not burn, but will allow water retention and restrict erosion