Should I terrace this slope?

Hello! I am a newly registered user in this forum, though I've been already checking it from time to time.

I thought of asking the community for help (though I'm still somehow unsure of whether this is the appropiate forum to ask for this specific information) on whether I should terrace or not a new piece of land that I'm starting with, after renting it this past month. It's 2000m2 (a little less than half an acre), and it's located in Asturias, Spain. The wheather is often rainy here, and, as you see in the images, the terrain does have a more than perceptible slope. I've been thinking, thus, of terracing it to prevent erosion, but nevertheless I'm still quite unsure of the extent of terracing needed, or if it's truly needed at all. Evidently, of course, I wish to be careful to prevent the soil from depleting, but since I've seen practically all gardeners in the region growing things in even worse slopes, I begin to doubt whether it's truly necessary.

If so, I was thinking of making bench terraces, cutting and filling, and holding them with turf walls. As the slope is not that bad, I've even thought of making just two really wide ones, with turf walls. Do you think this is enough, friends, or will it need more work still?

Thanks to all beforehand!

Oh, and by the way: the nearest part that appears in the first two photographs, from the newly planted hedges up to a little elevation at the left side of the terrain, is not actually land I plan on using to grow vegetables. I planned to work a little with the terrain there (as it coincidentally has the steepest sloping) and put some chickens, only planting a Sunburst cherry tree in the lowest area to contain the soil a little with its roots.

Miguel,

Bienaviedo.  What are you planning to do with the slope?  What tillage methods will you be using?  How often will it be worked?  Most importantly how often will the soil be bare?  

The slope is not too step that it would need terraces, as long as the ground has a cover and a root net in it.  From the pictures it does not appear you have an erosion problem.  It will continue to be stable as long as the soil is not left uncovered.  However, if you are going to use traditional tillage practices; you will need to terrace.  Once to soil is turned and the plant roots are cut, you will move soil with every rain.

How much rain does the land receive per year?  How much does it rain in a day?  If the rainfall is light and evenly spaced, one might be able to pacify the drainage with swales.

The short answer is no, with appropriate techniques you will be fine with no terraces.  If you are plowing and turning frequently, you will wish for terraces.

As to the extent of the terraces, what size equipment will you be using?  Hand tillage, walking tractor, larger....?  Terracing seems like a lot of work and expense.  Less so, if you make multiple small terraces.  I would suggest a terrace wide enough for one or two passes of the equipment and then a undisturbed strip, permanently planted with a heavy deep rooting plant.   That way less earth movement and less ground disturbance.  Landslides are no fun.  

Hello, Jack! Thanks for your reply.

I plan to turn it into a vegetable garden for personal consumption, starting with a few crops for this year and progressively 'reclaiming' more land for crops until I reach the chicken's grass limits. In order to do this, I had in mind John Seymour's methods of deep bedding, and thus planned to section the terrain into smaller squares, dig deeply in each to loosen the soil well (see the attached image, although the part in which these ditches are filled with the soil dug up from the contiguous ditch is missing) and then just aireate that soil yearly with a pitchfork, again as John Seymour recommends.

After that, I plan to have it planted year-round, as in winter I will grow green manure on any unused patches of tilled land. And, of course, I plan to plant the crop rows cutting horizontally across the slope, to detain more the flow of water during rainfalls, which, by the way, are pretty common during the whole year (the area receives between 1000 and 1300 l/m2 yearly, or roughly between 24.5 to 32 gal/ft2). The place has an oceanic climate, Cfb in Koppen's classification.

If I do end up having to terrace the ground, I will have to do it mostly myself (perhaps a few friends will come and help) as I'm on a very tight budget, and would resemble those of the second attached image (excuse the bad resolution). I've leveled a little bit of the soil before, in order to put the foundations for a shed, and it's not that hard when it has rained recently. Of course, having to do that accross a first extension of 400 or so square meters will prove an absolute challenge, of which I will either get out with some real muscles or a nice wooden coffin to rest in.

Let's see!

Hi Miguel, from your climate analogue farther to the east!

From the looks of your photos, I would guess that you don't have slopes over 10 or 12 degrees. So I think terracing might be overkill, unless you just really want to do it. Of course, once you break the soil open, you need to worry about erosion and keeping it covered.

I'm a no-dig fan, so I personally would sheet mulch on contour without disturbing the soil. When I sheet mulch on a slope, I make the downhill side much thicker (even though in a year it will flatten out). Also I may drive in a few short stakes on the downhill side if I'm foreseeing any slippage problems. Since it's grass at the moment, your soil is likely to be very bacterially dominated, which is not bad for annual crops, but you might want to work on increasing the presence of beneficial fungi in the soil to balance it out. If you've been lurking for a while, maybe you already know about Dr. Redhawk's Soil Series? There's some fantastic information there.

Charles Dowding in the UK, similar climate to ours, has an even easier method for turning grass areas into new vegetable beds: Lay on a thick layer of manure and/or finished compost, cover for 6 months with old carpet, waste sheep's wool or black plastic, and then uncover, and just plant directly into it. He claims there's rarely any need to "loosen" the soil below if you do it this way (my experience also), and you have the advantage of leaving the soil biology intact so that your plants can take advantage of it, rather than destroying most of it by tilling and then having to re-establish it.

Just some ideas, what ever you do, happy gardening! Glad to have a Cfb climate buddy here on permies!

A weird question: how hard is it for you to walk on the slope? I am terracing mine, it slopes a lot like that, but I have health issues, and hard time on slopes, I'd rather go down, then walk level, rather than be sloped when I walk the whole time. Plants will grow fine on a slope, it's more you that is the deciding factor.

If you do decide to terrace it, I'd suggest doing it by digging a trench and using that to make a pile on your downhill side. Less work to move it that way. More like swales than terraces. If you get a lot of rain, that might drown your plants though, depending on how much water runs off vs how much soaks in.

Welcome to permies! An excellent first post! :D

Swales work something like a terrace with the additional benefit of capturing rainwater and sinking it into the soil.  If you make them wide, they work great as a terrace and they'll hold thousands of gallons of water that would otherwise run off your property.  There are a zillion threads on this site about how to layout and dig swales, the benefits of swales, etc.  

You might start with laying out a single swale on contour with a A-frame, and see how it works with your garden plans.  If it were me, I'd dig the first swale down toward the bottom of your hill, and then plant a row of fruit trees below the swale.  The water captured by the swale will soak in and provide moisture to the tree roots below.  If you like the look, feel and function of that, you can continue up the slope and lay out your next one.

Here are a couple of videos that show how swales work, and how they function somewhat like a terrace.   This first one is Geoff Lawton.  Pay attention to what he talks about regarding "rise to run" ratio.  That's key if you want a swale to function as a terrace.



This is just a general video about what a swale does, and some footage of a guy digging one.



Here's a dude building his swale with a little tractor.  




Best of luck.

Marco Banks wrote:You might start with laying out a single swale on contour with a A-frame, and see how it works with your garden plans.  If it were me, I'd dig the first swale down toward the bottom of your hill, and then plant a row of fruit trees below the swale.  The water captured by the swale will soak in and provide moisture to the tree roots below.  If you like the look, feel and function of that, you can continue up the slope and lay out your next one.

Yes! I was thinking of something like that at first: planting a long line of berry bushes (blackcurrants mainly, but also blueberries and thornless blackberries) at the base of the field, as I prefer them over fruit trees for concerns of their shade later affecting the growth of nearby vegetable patches (...though perhaps I could maintain them small and very well pruned?). But now I shall do a swale in contour, also, which should fixate the soil much better.

As you see in the image I took from Google Earth (I really like this image-attaching thing, everything is explained better with graphic support!), the slope is not continuous, though, but much steeper as you approach the street. It makes something of an obtusangle triangle, but with an inclined base, as if it were a first very steep slope that cuts directly into a much less steeper one. As you see in the first of all my attached images in this thread, I already planted a Leylandii hedge along that steeper slope, thinking of both using it to contain the soil with its roots and charmed by its relatively low price. In consequence, I was thinking also of cutting into the base of that 'first' slope, where the hedges are planted, and making a swale to also be useful as a path, hoping that the Leylandii's roots will hold the slope. And I planned to do this second swale because:

Pearl Sutton wrote:A weird question: how hard is it for you to walk on the slope? I am terracing mine, it slopes a lot like that, but I have health issues, and hard time on slopes, I'd rather go down, then walk level, rather than be sloped when I walk the whole time. Plants will grow fine on a slope, it's more you that is the deciding factor.

Because yes, it's kind of annoying to walk along a slope all the time; particularly when you are carrying heavy or voluminous things from one extent of the terrain to the other. My only concern is whether if I dig this near-the-top-of-the-slope swale, it may eventually produce a landslide. But near that part the soil is more clay-ish, and this gives me some moderate tranquility as to its capacity to hold its position.
Thanks for your compliment on my post, Pearl, by the way!

Dave de Basque wrote:Hi Miguel, from your climate analogue farther to the east!

From the looks of your photos, I would guess that you don't have slopes over 10 or 12 degrees. So I think terracing might be overkill, unless you just really want to do it. Of course, once you break the soil open, you need to worry about erosion and keeping it covered.

I'm a no-dig fan, so I personally would sheet mulch on contour without disturbing the soil. When I sheet mulch on a slope, I make the downhill side much thicker (even though in a year it will flatten out). Also I may drive in a few short stakes on the downhill side if I'm foreseeing any slippage problems. Since it's grass at the moment, your soil is likely to be very bacterially dominated, which is not bad for annual crops, but you might want to work on increasing the presence of beneficial fungi in the soil to balance it out. If you've been lurking for a while, maybe you already know about Dr. Redhawk's Soil Series? There's some fantastic information there.

Hello, Dave, and thanks for all the incredibly valuable resources! I'd like to do the sheet mulching strategy at least in part of the land, but just a couple of hundred square meters of this requires already a massive amount of mulch, and my resources are limited (as even lumbermills want to charge you for giving you their sawdust). Same for the manure idea, since apparently even poo is sold, or if it's not sold then transportation is hard and not provided, which means very expensive third persons, the transport companies, need to be hired. I do plan to bring in manure, of course, but if I mix it with the existing soil I maybe need only half or less than half of what I would need if I wanted to plant directly on it. Still, I shall keep these plans in mind for later stages, as they may very well come in handy if I start to experience difficulties with more conventional methods!

I'm also greatly pleased of having a fellow Spain-based, Cfb climate colleague in here! Maybe I'll hit you up later to get your plant nursery, seed provider and other similar services' information.