How to plan and build terraces?

Ronin49(5a Ontario)November 14, 2005

Does anyone have a link or reference to straightforward instructions on how to design and build terracing - the functional, low-cost type?

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joel_bc(z6 BC)

I've made a link to a PDF/HTML doc that describes the process. You have to scroll down into the document a ways. Pretty brief, simple instructions.

I helped some people make a terraced vegetable garden when I was a lad. I'm sure we used some process similar to what is described in the article, though I've forgotten the exact details. I remember I enjoyed it, though.

Joel

    Bookmark   November 15, 2005 at 10:05AM
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Ronin49(5a Ontario)

Thanks for the reply, Joel, but I can't seem to find the link?

    Bookmark   November 15, 2005 at 9:20PM
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joel_bc(z6 BC)

Not sure what I did wrong yesterday! Apology for the deficiency. The link should appear.

J.

Here is a link that might be useful: Terracing a garden

    Bookmark   November 16, 2005 at 9:48AM
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joel_bc(z6 BC)

Whoops!

I just tested that link I provided this morning... Unfortunately, it only gets you to my Google search-results page! LOL...

But all is not lost. When you are on that page, scroll down to:

HGA-00237-Gard-SE

Hit this page. (It gives you a PDF or HTML choice, so choose PDF if you have software that will open that type of file.)

It's a twisty road to this doc, it may seem, but you can get there...

    Bookmark   November 16, 2005 at 10:03AM
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Ronin49(5a Ontario)

Got it. Thank you very much.

    Bookmark   November 16, 2005 at 10:42AM
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yelenick(z5 CO)

Terrace Construction Outline and Description:
(see also: Mollison, Bill. Permaculture: A Designers Manual. Tagari Publications. 1988)

Exceptions to suitability of land to terracing arised when we:
-Attempt to terrace in unstable soils or sediments;
-Risk hydraulic pressures on hill slopes from impounded or infiltrated water;
-Create terraces that are unstable at the bund or wall face;
-Extend terracing as annual crop over too large a proportion of the landscape, and so lose leaf or tree nutrient input to crop; and
-Make very large series of terraces in high rainfall areas, so that run-off is concentrated.

With a useful assessment of the above factors in mind, we can gain long-term production from short series of polycultural terraces (wet and dry crops), with stable bunds (either rock-walled or a 1:3 slope). Trees, on bunds and between, above, and below terrace series, should form 40-60% of the total landscape plan, and both soils and installed water inlets and outlets should permit safe and controllable irrigation.

The great benefits of terraces are these:
-Very easy crop access on slopes;
-Easily controlled and effective irrigation procedures;
-Minimal soil loss due to overland water flow, or to slope cultivation; and
-A potential gain in silts or nutrients in irrigation or run-off waters and from leaf fall.

As with dams, terracing is most effective where slopes are least, as earth moves versus area of cropland developed becomes impractical or inefficient as slopes steepen. At about 30° slope, but preferably at 10-18°, terracing becomes worthwhile.

Terrace construction always begins on the lowest terrace level, with the removal and stockpiling of topsoil over the whole area of the lower terraces, and proceeds uphill as each terrace is made, so that the topsoil of the next highest level is cleared on to the preceding lower terrace. Stockpiled soil at the lowest terrace is finally carted or lifted to the last of the series uphill.

Every Terrace system is ideally designed to allow perennial bund and terrace wall plants, specifically for wall stability and green manure crop.

As for the extent and series size in a terrace system it is wise to limit both on the basis of:
-Heavy rainfall (hence expected run-off) in tropics; and
-Expected rainfall harvest in arid areas, where total terrace areas should not exceed one-twentieth of the catchment harvested, and where perennial or adapted crop (never water-demanding crop) should form the selected species.

Thus, all terrace systems should aim to occupy no more than 30% of tropical or 5% of dryland areas, and in the tropics tree crop should be developed to maintain fertility of the terrace areas. Water catchment areas should be developed to do the same for arid areas, so that run-off brings leaf mulch to terraced slopes.

In humid cool or tropical areas, wet terraces (10-20% of all terrace areas) can be devoted to a fish-plant polyculture, giving yields of fish, shellfish, and water plant products. Yields of protein from water cultures can exceed all land-based systems if managed at the same levels of husbandry and care.

Wherever people occupy very steep sites (slopes of 20° or more), especially in areas of high rainfall, it is preferable to abandon broad terracing for a series of 4-6 narrow production terraces, each series carefully drained to spill excess rain down permanently vegetated slopes.

Thus, by ridging the terrace tips, mulching paths, and staggering path spills in short series, we can get the advantages of terrace on quite steep slopes without risking erosion and soil loss. Needless to say, machines are inappropriate for such construction, and steep slope terracing of this nature is always hand-cut.

    Bookmark   December 6, 2005 at 3:17PM
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huisjen(z5 ME)

I used to have a (really bad) job, building retaining walls out of busted up old sidewalks. If you can get this type of material, which is sometimes free for the hauling, then you can build a retaining wall fairly simply. Grade the soil under your first course of "rock" so that the wall will slope back into the hillside slightly. Make the base at least half as thick (back into the hillside) as the wall is going to be tall. Make sure to avoid aligning joints vertically. The courses can get smaller as you go up, so that on top, the final course is only six or eight inches thick. Plant xeric stuff appropriate to your climate in the cracks.

Simple is not necessarily easy though. This is work. I've done some for myself occasionally, but I'd hate to be doing it day in and day out again. Wear a weight lifters belt. Pace yourself.

Dan

    Bookmark   December 6, 2005 at 5:21PM
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