What have you done with your very steep slope?

Curious to hear everyone's experiences with very steep slopes/ hillsides/ mountainous terrain(like more than 45°). Edit: I overestimated our slopes, sorry. I am hearing they are more like between 20-30°.

What uses have you found for your steep slope?

Do you keep animals there?

What about erosion and heavy rainfall events?

Did you modify the terrain?

What worked out and what didn't?

These were not done on a 45° slope, maybe 40°?, but could work on a steeper slope.
Our stone terraces on this steep hillside garden have far outlasted anything else at our old 'homestead' (other than the wisteria).
https://permies.com/t/39732/permaculture-projects/Reviving-homestead-wisteria
Built in the early seventies, they were quite productive for many years.
We moved from there in the mid eighties...these photos were taken five years ago when we went there and did some machete work.  




We had a free range herd of alpine goats at the time and much steeper hillsides and vertical bluffs in their range.  We only had one episode where one goat took a path that ended on the side of a bluff and could not turn around.  The rescue involved lowering my husband with ropes, putting a sling under the goat to lift her enough to reverse.  Just one time...otherwise they seemed at home on the steep rocky bluffs.

This is a another fairly recent image from our old place of what is at least a 45° slope behind the cabin...our goats had cleared everything including this hillside which was loose rock. A tree planting friend planted some extra loblolly(?) pine there one year and so far they are holding their own along with a diversity of other things.  The hillside is steep enough that to walk up it we either zig zagged or walked with our feet sideways.  Coming down was riding the rocks in a squat  I've got bare hillside photos somewhere I'll try to add later.  

I don`t know the grade but my backyard looks a lot like the picture above with the stone terraces, except my terraces are made of wood. I have about 12 beds in terraces that I made when we moved in on topsoil. No trees except the few small ones I planted.
Lessons learned: even if the wood is treated, it will eventually rot. Lining with black plastic means you will be picking black plastic out of your dirt a few years down the road. I painted some wood with tar the last time I put in a new bed and that seems to have worked a bit better. For holding up the wood, use rebar, repurposed reinforced concrete pillars, or something, not even treated wood, which all has rotted out in the last 5 years.
I mulch a lot and the first year kept a good eye out to see what happened with erosion. I have paths between the beds, some grass, some broken pottery, and the one with the largest risk of erosion i poured concrete on top to make a paved walkway (i have clay and the mud was getting to also be a problem, so solved two right there). The only animal I have is the dog and he`s trained to walk on the path, which works about 50% of the time, unless he has the urgent need to poo....
It`s the yard I have, not too many options.
Do I remember you were planting stuff at a school and having critter troubles? How did that all pan out?

We are still in the process of terracing both the front (south facing) and back (north facing) slopes, I am using rocks from the land and cedar logs closer to the valley.
Some terraces are 3 feet wide and they go all the way up to 8 feet wide depending on the grade where they have been installed.
Up on the ridge I can space the terracing at 20 feet wide and I hope to eventually get everything done (our place will be reminiscent of Machu Picchu).

Redhawk

Not to hijack the post, but Redhawk, when the time comes I would be very interested in seeing what you've done with your north facing slope.

Thus far, quite honestly, we've simply done our best not to fall down it. It ends aboutt 100yds downhill, in a pond, of questionable safety (clay soil, here, and it looks too slippery to get back out!) & depth. So, I'm looking to you fine folks, for ideas as to how we might answer this issue, when were finally get around to this part of out property, in (I'm guessing) about 3 or 4 years.

Thanks everyone for your replies!

Sounds like terraces are the way to go. There are plenty of stones around here for sure.

Judith, thanks for posting pics, and your goat story made me smile. We are thinking about goats eventually. Will need serious fencing infrastructure first as our lands abut residential neighborhoods.

Tereza, thanks for sharing your experience, and thanks for asking about the school. So far tomatoes are being left alone, but we'll see what happens when they get fruit....I guess it's more about the act of planting stuff for now. Teachers sound excited about the idea of a caged garden, but at the same time don't want to make more work for themselves. Japanese teachers notoriously have very high expectations put upon them and an unrealistic workload. We plan on fencing a large lot of ours about five minutes walk from the school next year and will offer space for the students.

Redhawk, thanks for sharing your situation. There are some places nearby with terraced rice paddies still being farmed by hand. I'm hesitant to dig too much because we get more than 3000mm of rain each year. It's rained every day for a month.

Will be a few years process, but I will post updates as we try things out.

We installed a terrace and i am sold on terraces now. The vegetation is 4x bigger on the lower side of the terrace than above it. It will be a thicket of trees and shrubs when when fall planting comes around.

They direct water but infiltrate it also. In my case it is a straight shot to my pond, but i have seen them zig zag down a slope to get to a water feature. Zach weiss and sepp holzer use them. If you watch some youtube videos of Elemental Ecosystems you can see how he encorporates them.

This is a quick drone flight showing terraces

Watch "Elemental Ecosystems - drone flight - Ecuador one month after installation" on YouTube

Thanks Wayne.
What a nice example of directing water as well as terracing. We have frequent heavy rain events during the rainy season and then typhoons in the fall. This info will be helpful in our design.

We recently took over care of this step garden slope.  

Negatives:  The rock walls aren't well stacked and in heavy rain stones fall down, non-useful plants like brambles love the cracks and are a pain to get out, in the winter rainwater seeps into the flat bit between the house and the start of the hill and it's full of not delicious things like rhododendrons.

Positives:  At least five years of total neglect and a wave of invasive plants didn't overwhelm it and within the first 9 months it is semi tamed and is starting to have productive herb and berry beds

Looks idyllic!

Genevieve, thanks for sharing your step garden!

I'm always surprised at what I find growing in the cracks of stone walls around here; whole tea bushes even.

We have a 30% grade slope.  Things we've learned:

1.  Keystone blocks work fantastic for building terraces.  The first course needs to be dug into firm soil, at least 2 inches below grade.  After that, each successive course should be tipped slightly back into the hill.  I found it tremendously gratifying work.  We go no higher than 5 or 6 courses (5 inch blocks).

2.  Fig trees have an amazing root system that holds everything tightly in place.  Planted in the wrong place, figs tend to be invasive.  But using them on a steep slope is a great way to hold the soil firmly in place.  The only downside to planting figs on a steep slope is that it's hard to climb up and check them daily, and with figs, you only have about a 24 hour window to pick them before they get overripe.

3.  Avocado trees do well on a slope as well, and unlike figs, you don't have to check them regularly to see if the fruit are ripe.  Avocados hang on the tree and do not ripen until you pick them.  Perfect.  

4.  Mulch tends to migrate downhill with time.  Well duh.  But that means that you just mulch the top from time to time and you let it make its way down.  Walking wood chips.

5.  Our hill is south facing, and so it gets tremendously hot, even in the winter months.  I've read that for every 5% grade you have on a south-facing hill (in the Northern Hemisphere), it's equivalent to living 150 miles further south.  So, for our 30% grade, it's the equivalent to living 900 miles south.  Thus, you've got to make adjustments for that kind of extra heat on the soil.  We pile every last scrap of biomass on the south sides of the trees, shielding them from as much of that direct sunlight as we can.  Over time, as those branches and such breakdown, they become something of a terrace on the downhill side of the trees, making picking and pruning easier.

6.  Vetiver grass is a great way to build natural terraces.  Using an A-frame like you would when laying out a swale, you plant the grass plugs on contour.  We planted ours about 10 inches apart, which worked great.  As it grew in, it clumped together in an almost continuous "fence" of grass.  Laying sticks up against the clumps of vetiver on the uphill side, and back-filling mulch up against the grass, it began to create a level terrace on the uphill side of the grass.  3 years later, it's clearly working to make a terrace.

We have done pretty much what is pictured in Judiths post and it is working well. Our slope is much steeper though. Closer to 60 degrees and some spots are easily 80 degrees. Its not possible to walk directly up. Ours is facing a lake and gets incredibly hot during the summer even here in Alaska. Our elevation rise is about 100 feet from the lakeshore to the upper gardens and there is on average, summer and winter, 15f degree higher temp at the top. I can ripen tomatoes in the upper beds made of rock and I cannot in the lower beds. So far the stone terraces are holding up very well. The most important thing I learned when making them is to have a solid and flat foundation, which entails a lot of work with a pick and shovel. Then I backfill as a Hugel bed with as much rotting seaweed, wood, brush and salmon carcasses as I can fit. And a good layer of sifted soil, lake muck and glacial silt. Things grow wonderfully.

Marco, thanks for sharing your experience, a lot of useful information!

Figs are native here and we have some in pots. Monkeys(Japanese macaques) would happily harvest them for us. I have seen monkeys running from people's fields with armfuls of figs, must have been growing out of the fence. We are wrestling with what to do about fencing, and might have to fence the whole area. There is a lot of pressure from monkeys, deer, and boar.

Avocados are another great suggestion. We are right on the edge climate-wise for avocados. We have some in pots, and we will see if they make it through the winter. It sounds like from your experience they might be happy on our south facing slopes.

Marco Banks wrote:Over time, as those branches and such breakdown, they become something of a terrace on the downhill side of the trees, making picking and pruning easier.

6.  Vetiver grass is a great way to build natural terraces.  Using an A-frame like you would when laying out a swale, you plant the grass plugs on contour.  We planted ours about 10 inches apart, which worked great.  As it grew in, it clumped together in an almost continuous "fence" of grass.  Laying sticks up against the clumps of vetiver on the uphill side, and back-filling mulch up against the grass, it began to create a level terrace on the uphill side of the grass.  3 years later, it's clearly working to make a terrace.

I've been trying to convince people that this would work! Thanks for the real life example! Will look into vetiver grass.



Chris, Thanks for sharing your very steep experience! 15 degrees F is a big difference. Now I'm curious to record the temperature difference for our slopes this winter.