Holzer terraces problem

Hi everyone,

We finally put in our much desired Holzer terraces about 2 weeks ago and planted it with grasses, brassicas and chicory for quick and rigorous root development and are almost ready to put in our fruit trees.

However, after a 24 hour, battering rain 4 days ago, we've started to sweat a bit... Parts of the terraces slipped and landed on the terrace below. Sepp never mentioned anything about this in his course so I'm slightly lost about what to do and prevent the whole thing from coming down...

In the attached pictures you can see how far it is now and what could happen.

Does anybody have any advice for us on how to stop this?

Mega thanks,

Pascal

2nd picture

without a retaining wall, my only suggestion is to get some deep rooted plants in there, quick!

probably not very helpful... sorry.  I see soil slumps happen in our area along ditches and steep hillsides where there are not many trees.  Our 6 month rainy season adds a lot of weight to the clay loam.  If the slump gets bad, I've seen where people have brought in medium sized (6-12") rocks to put in the area to help stabilize it.  deep rooted plants would seem easier and better in the long run.

Is your soil clay based?  Do you expect more rain in the next few weeks?

swales like this need to planted right away. get some fast growing, nitrogen fixing pioneer species in there.

I'm not educated enough about frost in NSW, you'd know if you got it, but I would run a quick youtube on vetiver grass. You need something that will go 2 meter's down and looking at the photos you don't have any forest in between your terraces. For some reason they appear really close together for that degree of slope, but I do know picture's can distort the landscape.  If you don't want to end up having to retain the wall at a high cost, I would really really see if vetiver is viable in your bio region.

I do appreciate your enthusiasm for sepp's methods, but I've also seen him mention on several occasion's that he had criteria to prevent landslide on his own landscape, and each was different depending on soil's, waterfowl and incline. Your original statement's seem to imply, I took sepp's course why didn't his method's work.

I have a fair bit of terracing in my future working with limestone steep slope "karst cartography" and I DO remember in every sepp video I watched he mentioned starting from the bottom up so that in case of landslide the lower slopes can catch the debris which for the moment it looks like you've done.

I hope the vetiver grass is applicable to your location, you need rapid stitches in your soil fast. Are your terraces excessively tilted back towards the hill? This is another factor I know sepp speaks of in regard to water management on terraces with excessive water to never have that done to them, for the retainment of that much water will swell the earth and send it downhill. 

Terraces are not Swales or they'd be called swales.

I meant to include this link in my post last night:
http://frank.mtsu.edu/~cdharris/GEOL100/erosion/slump.htm

this kind of thing even happens to the professionals

I wonder if you uprooted the trees that where in place before and implemented them in your terraces?

Normally terraces are built by manual labor. You bring in cuttings, branches, all kind of woody material and then loosen up the soil above with a pickaxe. Then you move the rubbel down hill in your brush pile. You plant nitrogen fixing legumes to loosen up the soil. And when you got your desired broadness you use stones, trees, shrubs, etc, to hold the soil in place. The woody material holds the soil in place until your perennials have been established. By doing that your terrace gets broader year after year. Obviously you start on top of the hill working your way down.

When building terraces with heavy machinery experience is required. It's not your fault. The transmitted point of view that doing terraces that way is easy is wrong and dangerous.


You have to do something now! You need drainage and you have to cover the soil to stop erosion immediatley. Deep rooted annuals are WRONG here, they will loosen up your soil and create erosion. You need bamboo. Shallow rooted perennials. Trees will help in the long run. Stones are a good. Heavy mulch is good until the shallow rooted perennials are established.

I would plant a mix of rye/clover/vetch. Good shallow and deep(er) rooted grasses/legumes to help the slopes remain intact.

Seems much of your seeds are just germinating ...
Hope the roots get going before more rains come
seems drainage is important now as Darkness said ,
".. gravity thou art a heartless bitch ..." Newton ohh wait no that was Sheldon...

Grow grass grow...

unfortunately it appears you have weakened your entire hillside and may have some serious problems if you don't get some deep roots into it soon.

there are a lot of edible (ornamental type) perennial plants that would work quickly to send deep roots out..like malva, hollyhock, horseradish, comfrey, dayllilies, rhubarb, etc.

if you were close enough I would be happy to share jerusalem artichoke and horseradish roots with you but it would be too much for me to dig and send them..also could share some other plants if you are near enough to help dig them..I'm just too busy to do it all and mail them. I'm in Central Michigan..PM me if you want to come by and get some

The next rain can come tomorrow and I would not rely on plants alone. but rather cover the unplanted area with old carpet hay or whatever you can find. Plants need time to develop roots and cannot hold the earth tomorrow.

Global - ..had another look at the pics -
Seems the water came from the top of the slope
Maybe from the house too - So have a good look around
Try to see from where and stop the flow or divert it
until the Vegetation has stabilized the slope.

I don't know if the original poster is still actively seeking a solution or out on the land trying to revise the slope with a dozer.

I'll repeat the cry for vetiver grass, I know it wasn't your dream to have a grass retaining wall, but where not looking at a deep rooted in 10 years ground cover. Most of the plant's everyone is mentioning are deep rooted plants nutrient transporting plants or decompacting tap rooted plants. Comfrey will go a meter with a root one day left in position for 10 years in loose soil, but those are "swale" solution's.  This is a terrace solution so please check out the vetiver link, I don't know why people dont know about it, I was shocked when i realize it was the same as the essential oil I give my dog's sometimes.

http://www.floridavetiver.com/

Saybian - I never saw roots like that before - and NOT invasive !
My vote is for Vetiver Grass now!
Thanks for that one.

looks like the low points on your terraces are in the wrong spot and the excess rain caused the erosion. ive been down this road when i first started terracing the land. you should have the low points on the end of the terrace, sort of like a spillway to a damn. that runs to the terrace below and so on. any extra rain can be diverted to a pond at the bottom. if you have the low points mid terrace the water that builds up will ALWAYS move to that spot.

this can even happen with a good annual ground cover. perennial plant roots hold better but take longer to establish.

From the pictures of Holzer's terraces it looks like he makes them at a definite slant, not level like a swale, so the excess water will continue to travel downhill without overflowing the terraces.

if its too steep of an angle off level it will cause erosion. to simply fix this problem for the original poster, they just have to either add a lip on the edge, or slant the terrace upwards just a few inches on the outer edge sort of like a swale but very minimal. and create somewhere for the excess water to get from terrace to terrace. in asia they sometimes build special areas out of rock on each terrace so it wont erode as it passes down. then it waterfalls down to the terrace below onto a rock to prevent erosion and floods the next terrace in the case of rice farming. you can also use bamboo and replace it every few years. lots of ways to solve a simple problem.

anyways you just need to create a place for excess water to travel. or give it a place to stay and soak in the soil.

when you get a living root system holding it in place, if you dont have anywhere for the water to go it will still cause problems and slipping. just so you know.

Found this by accident - Erosion Control Products.
I like the Burlap the most - Planting through it may be a challenge.
http://www.mutualindustries.com/html/erosion.html

This comment is particularly relevant to the discussion:

Saybian Morgan wrote:
I do appreciate your enthusiasm for sepp's methods, but I've also seen him mention on several occasion's that he had criteria to prevent landslide on his own landscape, and each was different depending on soil's, waterfowl and incline. Your original statement's seem to imply, I took sepp's course why didn't his method's work.

I have a fair bit of terracing in my future working with limestone steep slope "karst cartography" and I DO remember in every sepp video I watched he mentioned starting from the bottom up so that in case of landslide the lower slopes can catch the debris which for the moment it looks like you've done.

I hope the vetiver grass is applicable to your location, you need rapid stitches in your soil fast. Are your terraces excessively tilted back towards the hill? This is another factor I know sepp speaks of in regard to water management on terraces with excessive water to never have that done to them, for the retainment of that much water will swell the earth and send it downhill. 

Terraces are not Swales or they'd be called swales.

Thanks susan I appreciate your awareness, earthworks is no place for inspirational attacks and I know about struggling with bouts of fervent enthusiasm without sufficient trepidation.
I got to borrow an excavator for a day once and tried to dig as many holes as the 1 day allowed and my ability to use an excavator with no training permitted. The only reason I didn't end up digging into a gas line which I later found out existed was because the excavator would tip when I swung the arm.
It's been awhile since that original post and I hope the original poster has had more happy little accidents than sad little failures. Life has limited me to what I can do with a shovel before and since the day with that excavator and I've learn so much about what can and can't be anticipated in the micro I'm not afraid for the day when I can get back to the macro. But I sure do expose bare soil without a seed mix already laid out anymore, and I sure wouldn't get into an excavator without a truck full of bamboo on hand.