Food forest on a steep slope

Hello everyone,

I was looking for some guidance on planning my food forest orchard on a small plot of land that's quite steep (an average of 40° throughout the piece of land).

I've been debating for a while whether or not any earthworks are neccessary in the first place. Given this area will always be planted (with trees, shrubs and perennial herbs) and there won't be any soil movement that will happen after afterwards, I don't really see any kind of soil erosion happening. Currently and for the past centuries this has been a hay field/grazing land (never been tilled from what I know, and/or definitely not in the past 50 years). There is quite a nice biodiversity of grasses, most of which have incredibly dense and deep root systems so they have a major role on keeping the soil in place and preventing erosion (grasses which I will keep, and either mow for hay—by hand or with a two wheel tractor at most—or graze with small animals). The soil is mostly comprised of clay. All of the points I listed here weigh on the side of "not doing any kind of earthwork", so let's see the other side of the story now.

What makes me consider earthworks in the first place is that I would definitely slow down water. Where I live water isn't really an issue since I get about 1400-1500mm of rain yearly (evenly spread for the most part), and a clay-heavy soil is practically always moist. The caveat here is that part of these 1400mm of water are under the form of snow. The problem with snow on a slope is that it slowly slides. I'm not worries about avalanches, but as snow slides, it does move everything that it finds on its way (this includes mulch and organic matter that I would put around the plants, but it also includes the plants themselves which will eventually get tilted downwards). I'm not talking about finding the trees flat on the ground next spring, but they will definitely get a few degrees of tilt (until they adapt and build the necessary support fibers and roots to hold up the pressure from the snow). Then there is also the fact that even if I'm not able to see full blown soil erosion, water undergrownd follows gravity and will still take nutrients with it, which I'd like to avoid.

The kind of earthwork I've been considering (if anything) is a gentle terracing which will only impact the contour lines where the fruit trees and other perennials will be planted, and not a "full blown staircase" (with retaining walls or equvalents) so to speak. If this ends up being the final decision, I intend to plant both the flat area of the terrace with my main trees and shrubs, as well as the downside edge with smaller shrubs and periennials in order to lock it in and keep it in place properly (this would also increase my growing area).

(In the previous paragraph I mentioned that I intend to plant in lines following contour, though I'm also open to the idea of adopting the more natural approach of planting "randomly")

Any kind of imput or feedback will be highly appreciated 🙏

Hi Franscesco,
Welcome to Permies!

I do not have experience with that sort of earthworks, but I believe that is too steep for something like a swale. Which leaves either planting it as is, or else a full on terrace. It would be a lot of work, but if you are going to be planting a food forest where you will be walking along harvesting things... I think you might appreciate the flatter areas down the road. I know it would be a lot of work.

You might find this of interest:

Sepp Holzer's Terraces and Raised Beds movie

https://permies.com/wiki/179366/videos/Sepp-Holzer-Terraces-Raised-Beds

Thank you for your response Matt and Anne!

I will definitely look into the Sepp Holzer resource.

Full on terraces really aren't an option, especially due to the scale of the plot of land I'm working with. Getting there with machinary is also not the easiest thing, and to be completely honest I don't see it as a good investment of money or time (again, for the size and purpose of the orchard). Full on terraces could actually become an inconvenience since I intend to graze animals or let chickens free range in between, which could make moving animals more challenging.

I'm aware that swales aren't suited, and in fact, my idea of terraces is quite different. I would love to post a drawing which could better explain it, but I'm new on this forum and still haven't figured out how 🙈

I will try my best with text: my plan is to leave the walkways/areas in between the tree lines as they are right now (steep slope). The reasoning for this goes back to what I mentioned in my first paragraph mainly, and given I'll only be working by hand tools I don't really see it as an issue (all the contrary if anything, it's good for my fitness haha). The areas where I'd create a "flat" surfact is only where the trees will be planted, so it would be quite narrow (50-100cm). A layback lounger chair would probably be the most similar example that would illustrate what I have in mind. There I intend to keep planted with perennials both the flat surface as well as the front drop and possibly the back drop (or let the grasses take care of that side).

Hi Francesco and welcome to Permies! It sounds like you've got a great project there. Without understanding your climate more it is difficult to be really constructive, but I'll share my experiences planting trees on a slope. I'm on the Isle of Skye and I have very shallow soil over solid rock, but luckily have almost constant rain, so at present am not short of water. My slope is probably generally a bit less than yours, probably mostly 10-15%, although I have a couple of escarpments which are more like 80%. I laid out trackways to access most of the area and then footpaths developed over 'lines of desire' over time. My trees were mainly planted for future coppicing, so were fairly evenly spaced initially. I did try and plant sort of on contour, but they aren't really in lines and I have done virtually no earthworks - just a ditch to intercept runoff springs and pond, and widening a sheeptrack down the steep escarpment to make an easier path. I'm pretty sure that the trees themselves have increased the amount of water that the land holds however. At any rate, the runoff springs that come out after persistent rain are less frequent now than they used to be before the trees grew. If you are planting your trees in lines on contour, then the trees themselves will act as sort of swales, slowing the water down.

Thank you Nancy!

I've thought about it for the past few days/weeks and came to the conclusion of avoiding earthworks alltogether. At the end of the day the benefits and the work required aren't really matching.

Loved the point on the trees themselves retaining water! Makes total sense to me, and at the end of the day, we have our garden just below where the trees will go, so any nutrient loss will end up there.

As far as the snow pushing the trees goes, I guess we'll just give them some support for the first few years until they get established (a couple of people that live nearby have been doing this and it seems to be doing its job).

The final plan is to plant them on contour lines and leave the slope as is.

Francesco,

I recently spent a lot of time considering this same scenario, as I was presented with an opportunity to buy 50 hectares of land in Costa Rica for a very attractive price because it was almost all 45 degree slope to a river valley.  I ended up walking away when I discovered it also fell into a protected primary forest zone and was heavily regulated by the State.  

But I will share some permaculture thoughts with you that I worked through in my own process.  

Silvopasture and agro forestry are two methods in permaculture that drive fertility and enhance food forests.  They also allow for multiple functions to stack on the same ground and become symbiotic, increasing productivity  and nutrient density.   Both of these systems revolve around grazing animals inside an area of trees.  Rotational grazing among the trees tend to get the best results and allow the most control to keep plants and animals in the ideal 'growth zone' of development.  The biggest drawback is the need to fence and contain the animals to allow proper rest to the land during the rotation.

My solution was to utilize a hedge material like willow or hazel that could be used as an understory or 'bush zone' plant that could be woven into a fence or hedge along contour.  Using sheep and goats as the grazing tool, the herd could be be moved to each new strip and contained for the needed period of time.  Sheep and goats are good on slope and easier on the land than say cattle or horses.  They would be able to graze up the slope to the 'back' of the upper hedge and down to the 'front of the lower boundary.  As this system matured, my thoughts were they would allow some normal erosion of the up slope which would be stabilized by the roots of the upper hedge and wear a walking path near the lower hedge which would  eventually berm up around the base of the lower hedge, thus allowing the animals to slowly shape the terrace as the system matured.  It would also allow for a water brake/collection berm much like a swale but no uphill ditch other than the walking path of the animals.  No machinery on a steep incline, no earthwork engineering, just animals doing what they do with the help of strategic husbandry by maintaining the hedge.

this system would take a few years of growth and training before it could be fully loaded with grazers.  It could be accelerated if one was willing to use electric wire or other fencing.   One might want to use cut branches on the ground at the base of the downhill hedge to allow a natural earthwork to further stabilize the slope and shape your terrace.  I have noticed in most pastures and in hedging videos animals wear a path about half a meter from the perimeter boundary that sits lower than the hedgerow, naturally berming the pasture.  Animals tend to follow a contour when transversion a slope, as it makes a more natural gate.  Planting a hedgerow on a contour gives them 'rail to follow' and a nice berm on contour.  I have yet to put this in practice as my land is 2% at its steepest; but may provide some thoughts to ponder for those with steeper slopes.