Terrace with heavy compaction

Hi,
I am designing a mixed orchard and the terrace (1500 m2) where I'd like to plant the trees is heavily compacted.

The compaction was originally generated by tilling machinery, since it was a cereal field for many years. In the last few years though, compaction has worsened because the terrace was used a repository of dirt mounds and big rocks, brought back and forth by heavy duty trucks (10 tons or bigger) and a wheeled backhoe (while a house was being built).
The surface is so compacted that almost no rain gets absorbed and what water remains on top, it quickly dries out once the sun shines again.

Since it is the closest available place to the house site (a very good zone 2, distance wise) and it is already protected by a fence, I think I'd like to have a go at loosen this soil, and start building the soil straight afterwards. Also there aren't other good terraces within the site and it has water access already.

In order to go fast (which doesn't mean necessarily good!) I see that one possible strategy is to use the backhoe again, this time to dig the soil down to a depth that can be good for optimal tree rooting, breaking the compaction all through.
We are talking about a silty-clay (top layer), clay soil (bottom layer) with no topsoil. Seems like a tough site indeed.

I am wondering if anyone has experience with a similar situation and wants to share it. Especially the "post-backhoe" soil building part but also comment about the soil moving part.

My idea regarding to the soil building is, once the soils has been mechanically loosened:
1) incorporate biochar (not sure how much though) to the loosened soil + rock powder (like basalt). Soil type is quite alkaline here with high levels of CaCO3 but not saline.
2) spreading compost all along (how much though?)
3) broadcast and grow cover crops with deep tap roots/green manures, for at least two years
4) have chickens graze the cover crop and fertilize the terrace by creating paddocks and run the chickens either unprotected or with a chicken tractor (dome type)

Can't think of more useful things I could do, maybe using compost teas, but I guess this should be done after the first cover crop is established, so the roots can be inoculated with beneficial microorganisms.

[Update] I re-read that mulching could be another strategy...but I am just wondering where to include it in the above sequence, and if it is not better to grow cover crops first (unless the soil has to remain bare for a long period)

hau Antonio, The site you describe is very similar to a field that we turned into a fledgling Pecan Orchard around 18 years ago so I'll go through what we did there, it should be similar to what you need to think about doing.

Compaction from farm machinery can go deep, as deep as 10 to 15 feet and there could be a layering effect where there are zones of only slight to no compaction so that you end up with several horizons in the soil.
The best thing to do when going for a one time tillage (more wipes out the microbiome) and you know you're dealing with compaction, is to use a subsoiler, this digs in deep and lifts the soil, breaking the soil without turning it over.
This also allows more to infiltrate, so if you were to spread a thick layer of compost then pull the subsoiler through that area, you would be making channels for the organic materials to seep down into.
While this might not sound like it works, I can assure you that it will do wonderful things such as break up the compaction (even though you would possibly add some from the tractor tires along with the weight of the tractor).
Getting those channels opened up deep into the soil by lifting instead of turning it over keeps the microorganisms you want, protected from the UV rays of the sun. (the primary killer of microorganisms)
Getting the organic matter as deep as the subsoiler will allow means better water retention, more air infiltration and so better moisture content and by default more nutrients available to any plant growing in that space.
By not turning over the soil, when you make biological organism additions, they will be able to stick around and thrive, so that they become reproducing wonders and that means even more nutrients available for your plants.
Mushroom slurries and compost teas that have been aerated for at least 24 hours will install superior microbiome components that will only help speed up the processes of remediation so that your soil is always improving to the point of equilibrium of the microbiome organisms and the minerals (nutrients).

Redhawk

on the re-read I see I missed your question about how much to use.  Compost: I like to put down a minimum of 12 inches if I'm going to use a tractor implement to work it into the soil (I don't use a "digger" such as a back hoe, I use either a disc or subsoiler.
If you are going to use the back hoe, go ahead and work the soil but have the compost in place first so it is turned into the soil you dig up and turn over.
When you expose deep soil, you are most likely killing off the organisms of the microbiome, these will have to be replenished or you just made dirt! Only adding compost does not mean you have replenished the micro organisms.
Compost that is not bone dry is best, I even spray water on the compost after I have spread it, when I am going to be turning it into the soil, this prevents wind loss and the additional moisture means the compost will stay where I put it while I work it into the soil.
If you have Char or already activated bio-char, put it in-between two passes of compost, this way it will work into the soil better and you won't have any loss of particles. Bio char should be spread at 1 lb. per sq. ft. for a minimum and 5 lb. per sq. ft. would put you near the original Terra Preta levels found in the amazon.

By doing a work in of compost, any compost you then use for mulch makes things so much better because there is already a population of compost loving bacteria, fungi and the other microorganisms present.

Good cover crops are not mono crops, use as many different types of cover plants that you can, this diversity will build better diversity in the soil when you chop and drop.
Chicken grazing the land is never a bad thing and you get all that scratching (works organics into the soil), pooping (manure is manure and that is good stuff).

Gypsum is almost a miracle substance when trying to address compaction, as it breaks down it breaks up the compaction, with little effect on the pH instantly, it is more of a long term buffer for pH.

Redhawk

Hi Bryant,
many thanks for sharing your experience.

I was planning on using a backhoe because I feel that the subsoiler won't be able to break deep enough given the degree of compaction.
Also, I considered that in such a compacted soil, with no topsoil at all (on top!) ... and without having done any soil test to check for the existence of microbiology, I feel that not many interesting microbes may still live there, so turning the different soil (or subsoil) layers wouldn't have much of a detrimental effect, that is it can't be worse than how it is now.
So these have been my assumptions, but I may be wrong on assuming that turning the different layers over, even in this case, might still not be worse than not doing it.

Many thanks for suggesting quantities of compost and biochar.

When you expose deep soil, you are most likely killing off the organisms of the microbiome, these will have to be replenished or you just made dirt! Only adding compost does not mean you have replenished the micro organisms.  

I am not sure I understand the sense this statement, are you just intending to state that in order to make sure I replenish the microorganisms ONLY adding compost is not enough?

If you have Char or already activated bio-char, put it in-between two passes of compost,  

Two passes of compost....can you please explain this sentence in more detail? Do you mean that if I put 12 inches of compost overall, in order to do two passes with the machine I first spread 6 inches then do the backhoe business, then spread the biochar, incorporate that (by hand with a rake for example?), then spread the remaining 6 inches and come again with the backhoe?

Gypsum is almost a miracle substance when trying to address compaction, as it breaks down it breaks up the compaction, with little effect on the pH instantly, it is more of a long term buffer for pH.  

Does it matter that the soil is already between pH 8.1 and pH 8.3 and that it has high levels of Ca and CaCO3? What about also the soil being somewhat silty (as for the effect of gypsum)?
And what amount would it be advisable to spread to obtain the effect you explain? (I have seen this being done in heavy clay soils, in Australia for example, but have never seen this done here in where I live) Mollison (Designer's Manual) suggests a few handful / m2....would still be a good metrics to use?

Regards

I unwittingly bought a former Christmas tree farm. I did not use Dr RedHawks method on the initial area and did basically exactly what he is referring to on the new area ( I used 12” of wood chips subsoiled to 28”). Based on his expert recommendation with what I had on hand.

We had 1.5” or 37mm of rain yesterday and the areas I completed in November had basically no runoff-at all. The areas I did not complete are totally swamped.

The ideal would be to subsoil to the depth of compaction but it’s just not feasible generally and without something preventing recompaction it will tend to recur. Organic matter at depth without roots opening channels for oxygen will be anoxic and growth inhibiting. The main idea is to store water in the ground, get roots established to depth to provide both oxygen and hydraulic pressure to reduce recompaction.

I can’t speak to bio char as I haven’t made enough to validate its use in this situation but I suspect Dr Redhawk is a field leader in this stuff. Gypsum is a sulfate and as such it tends to buffer the formation of more stable nearly limestone aggregate. In my place with high aluminum it prevents formation of dense aluminum-silicate aggregates with the moisture effectively pressed out, and with it most of the CEC ions.

I’m doing cycles of chickens and deep rooted annuals in the original area, but is suspect a deep subsoiling with organic seeds would have gotten me there years earlier.

Antonio Scotti wrote:Hi Bryant,
many thanks for sharing your experience.

I was planning on using a backhoe because I feel that the subsoiler won't be able to break deep enough given the degree of compaction.
Also, I considered that in such a compacted soil, with no topsoil at all (on top!) ... and without having done any soil test to check for the existence of microbiology, I feel that not many interesting microbes may still live there, so turning the different soil (or subsoil) layers wouldn't have much of a detrimental effect, that is it can't be worse than how it is now.
So these have been my assumptions, but I may be wrong on assuming that turning the different layers over, even in this case, might still not be worse than not doing it.

Many thanks for suggesting quantities of compost and biochar.

When you expose deep soil, you are most likely killing off the organisms of the microbiome, these will have to be replenished or you just made dirt! Only adding compost does not mean you have replenished the micro organisms.  

I am not sure I understand the sense this statement, are you just intending to state that in order to make sure I replenish the microorganisms ONLY adding compost is not enough?

 When you turn soil over the soil and organisms are treated to a solar ray barrage that kills the microorganisms (extreme sun burn)

If you have Char or already activated bio-char, put it in-between two passes of compost, Two passes of compost....can you please explain this sentence in more detail? Do you mean that if I put 12 inches of compost overall, in order to do two passes with the machine I first spread 6 inches then do the backhoe business, then spread the biochar, incorporate that (by hand with a rake for example?), then spread the remaining 6 inches and come again with the backhoe?

 I lay down about two inches of compost, spread my char at about 1 inch thickness then cover that layer with an 8 to 10 inch layer of compost. If I already have plants growing I reduce the second layer of compost to around 3 inches thickness, this is so the roots won't have oxygen deprivation.

Gypsum is almost a miracle substance when trying to address compaction, as it breaks down it breaks up the compaction, with little effect on the pH instantly, it is more of a long term buffer for pH.  
Does it matter that the soil is already between pH 8.1 and pH 8.3 and that it has high levels of Ca and CaCO3? What about also the soil being somewhat silty (as for the effect of gypsum)?
And what amount would it be advisable to spread to obtain the effect you explain? (I have seen this being done in heavy clay soils, in Australia for example, but have never seen this done here in where I live) Mollison (Designer's Manual) suggests a few handful / m2....would still be a good metrics to use?

There are a few great things about Gypsum used as a soil amendment; 1. slow release of ions means a fairly steady supply of ions for reactions taking place from the actions of the bacteria and fungi when they are making their food.  2. very slight adjustments in the pH so unlike the normal commercial products, you get small adjustment over a long period of time.  3.Many concerns about very high mineral concentrations become moot points when the microbiome is very active and has high numbers, the microorganisms do a lot of buffering actions simply by them doing what they do to feed themselves.

Redhawk

Again, thank you Bryant for your answers.

So, now it is clear to me how to lay the compost and biochar.

I still have some doubts about the use of gypsum. From what I read around gypsum is very good for soils that have high Na content but for soils that have a very high Ca content (4500+ ppm in my case) is it ok to add more calcium, even if in the form sulphate?

In case I do use gypsum, should I just lay it on top of the compost or is it better to lay it as the first layer, in contact with the soil and in what quantity?

After looking at how much might the biochar cost (I figured out we might need as much as 38 m3, to have 1 inch spread on top of the surface) we might end up not using it....I also considered producing the biochar ourselves but  I reckon that it might take a big amount of work and time before we produce 38 m3.

As for the compost that I should use, do you have any recommendations? I am looking around for compost resellers (that produce compost from cattle operations manure, mixed with vegetable biomass, mainly wood stuff I reckon),  and what I am finding is that some of them have pH ranging between 6 & 8.5, others even a bit higher, quite a large range, and a C/R ratio between 8 & 19,9, not really ideal it seems, as the ideal balanced compost should have a C/R ratio around 25-30 isn't it? So it seems more bent towards the N.

The other point about the compost type, is that at this point I need to reduce the soil compaction and grow green manures, the trees will get planted in the best scenario in 1,5- 2 years time, so does it matter the type of compost to use now with this in sight (more bent towards bacteria communities than towards fungi communities, such as the types I am finding around here)? I say this because if I want to initially grow cover crops a bacterial dominated soil will be fine but if I then want to grow trees I should probably have a fungi dominates soil ...although some kind of grasses will be grown as well between tree lines eventually, to maintain the soil covered and active (and also to serve as chicken forage areas). On the other hand if I use a more fungi dominated compost initially, this may not be as good to favor the cover crops....any comments on this?

The last point I would like to make is about the incorporation of compost in the soil. Since my objective is to have a deep soil decompaction, which I would be addressing with a backhoe, most probably part of this compost might also end up also quite deep if we excavate deeper that 1m (3 feet +), and I am wondering if this would be appropriate.

Also I figured out that in order not to mix soil horizons when using the backhoe bucket, this latter could be carefully placed in the ground then removed without actually digging a hole and then putting the (sub)soil back in the hole. I guess this can also work for having the compost slide in while the earth breaks, but also in this case part of the compost might end up deep down....

When you read about using gypsum, most likely you are reading data reported as chemistry, which leaves out the biological factors since chemistry is only about minerals and their ions along with compounds created with those.
We have found that soils that have a high concentration of the organisms of the soil microbiome, the issues generally reported by chemists in soil tests don't really come to pass, instead we find that plants, through the use of their exudates and electrical signals activate great numbers of the microorganisms and those organisms function to created ions where needed or they remove ions where there is an over abundance. When the microorganisms are removing ions, they not only change the pH of the soil next to the roots but they also form stable compounds with those ions, effectively removing them from the equation.

I blend the gypsum into my compost as it is decomposing, that way much of the breaking down into microscopic particles is done by the biome for me, I do crush solids like gypsum prior to incorporating but I don't worry if there are pea sized hunks left, those will provide some soil structure component and they also serve as a "pantry" for the microorganisms.

Bio Char has become more of a Buzz word in the gardening world over the last 10 years, more about trying for Terra Preta than for immediate benefit to the soil. The real problems come from today's user trying to achieve the results that were discovered after 500+ years of incorporation in the soils.
I believe that adding char is good for our soils, but I do not expect to see the same results as we find in the Amazon areas of Terra Preta. When we charge char, we are artificially getting our fresh char to a point recognizable as the char found in the Terra Preta, but is it really? we do not at this point in time know for certain.
If you have it available, use it by all means  but do not beat your self up because you don't have the funds to purchase a commercially produced bio char and don't worry a lot about making your own. We have time on our side as land owners, we can make additions every year, and when we have a written down agenda, we have a road map that we can follow to get to our desired end results. It just might not happen in a five year period, or it might happen over night (if you won a lottery that paid huge for instance).

Instead of looking for a "finished product" go for 1. well rotted manures, 2. top quality top soil, 3.Compost that had the initial components tested for residual contaminates or where they used components known to come from non contaminated soils where no sprays were used for the last 10 years.
Or make your own, it might set your time table back but it far better to wait a year than to hurry into composting and find out later that you contaminated your growing beds by adding bad compost or other materials.

Decompaction can be done by mechanical means, or it can be done by organic means, both work, the latter takes a bit longer than the former. Decide what is acceptable to your time table and if you can push back some parts of that time table. Then you simply do what you need to do so you are on track.
One other thing about decompaction, while digging and turning soils does relieve compaction (to a point) there is also the possibility of creating compaction while you are trying to remove compaction, this is dependent on both the methods being used and the components of the amendments being used.
The main caveat of de compaction is that how deep you go only counts if roots can't penetrate that compaction, most of the time, well growing plants with deep roots will penetrate compaction that isn't to the level of something like a parking lot or road way. If some water will soak in, there isn't so much compaction as to be necessary for mechanical correction prior to starting seeds. (many grasses will, when allowed, grow roots up to 20 feet deep)

If you can't get but enough good quality compost to cover 100 m sq. it is better to decide which 100 m sq. you are going to do this time over trying to spread questionable materials and later finding that you killed everything you planted due to using contaminated materials.

Roots of plants that go deep (alfalfa (Lucerne)) and other deep rooting nitrogen fixing plants are the normal way to remove compaction. When we use the one time tilling and then utilize those deep rooting plants, we get double or triple the results of simply plowing up the soil.

Most of the people I have helped in the past, didn't understand that what I was guiding them to do was for the long term instead of the short term. It is easy to want everything Right Now! But the really successful gardener or farmer is planning 10 years ahead or more (if they are smart about their soil).

Redhawk

Dear Bryant,

Most of the people I have helped in the past, didn't understand that what I was guiding them to do was for the long term instead of the short term. It is easy to want everything Right Now! But the really successful gardener or farmer is planning 10 years ahead or more (if they are smart about their soil).  

I totally subscribe this point, and I would actually wait for as much as necessary, but the people who asked for my help want to try anyway..and I might tell them to find some other advisor if they are not willing to wait for securing long term result, but...yeah decided to help them anyway and to this end I'm trying to hold them back as much as I can, so that some more wise decisions a least can be made.

So from your explanation about the gypsum: should I gather that it is not very important if the Ca content is high because when plants will be growing there, the microbiology will buffer any Ca excesses?
I also gather that I can lay the gypsum on top of the compost layer before the decompaction starts. so it will get mixed in.

Still not sure how much gypsum should I aim for. Mollison suggests 30 t/Ha, would it be safe to assume such a figure?

You suggest to use good, not pollluted compost. What are the parameters of a good compost according to your experience (apart from what you mention already)? So that I can check the company specs and make some informed decision before buying any.
And also if it matters that that compost can be on the alkaline side seen that the soil is already alkaline.

hau Antonio.  I add gypsum to my compost heaps as I build them, I also tend to compost animal parts in heaps that I set up specifically for that purpose.
The problem with trying to follow "suggested amounts" from anyone is that they are working either from their own experience on their own land or they are using math to make a calculation for quantity needed.
There is a real problem when we try to do this, Those "suggested amounts" are not specific to your situation which means they very probably will not be exact. They might get lucky and be in the ball park, but ball parks are pretty large, what if you are working on a smaller or larger area?

If the land is already alkaline, perhaps you would be better off waiting to make any gypsum addition, if any at all. Most plants aren't super finicky about growing conditions except for the extremes.
when I consult I take 4 samples per 100 m2 and after checking the actual soil profile I may combine these 4 samples or I may not combine them, it is very much dependent on; 1. what the profile looks like visually, 2. what the profile looks like chemically and 3. what microorganisms are already present and the quantities of those present organisms. For me the most important thing is the biology of the soil, how much bacteria, fungi and other organisms are there to start with has far reaching effects on what grows in that soil.
I might simply add compost that is free of any pesticide, herbicide residues and I want to know for certain that these contaminates are not present, since they can literally kill off the microbiome we really want living and growing in our soils.

Many well known horticulturist will tell you that soil in the pH range of 6.4 to 6.8 is what you want to grow your plants in.
While that is a good "norm" to shoot for, most all plants also do quite well in the pH range of 7.1 to 7.8, so as long as you aren't growing Acid lovers you can consider the range 6.4 to 7.8 as great for growing food plants.
What we really are looking for is ionic exchange, which means we can't be at 7.0 where no Ions are available to the microbiome. (the microbiome will change a 7.0 soil to something slightly to one side or the other so they can break down the minerals they use for food).

Compost and compost teas are generally the best place to start improvement of most soils, after that comes the one time tilling used to add organic matter which is almost always missing in compacted soil.
This might be a good way to start the process, or it might not fit with the desires of the client should they be looking for some "instant results". You need to know what they expect and how soon they want those results, they might be wishing for the elusive "pipe dream" results.
Don't get me wrong, we can, with fairly large amounts of money, provide great results in less than 3 months, but most folks don't have that sort of cash to put into their soil all at once.

I still do not recommend using a back hoe to relieve compaction, if you want a swimming pool or a pond or a road bed ditch, that is the right implement, for soil improvement, it is more like taking an aircraft carrier into a small stream, you are most likely going to do more damage than good.

The ideal would be to build compost heaps on top of the areas you want to improve and let all that organic material decompose in place, then all you have to do is wait for the compost materials to finish the decomposition cycle, the soil under those heaps will be loose and rich with organic matter as well as having a good microbiome with all the good organisms we want to see in our soil. This, however, takes time, the one thing it seems your client doesn't want to do, that means money expenditures for already finished compost to make teas to spray from as well as finished compost to work into the soil via pulling a sub soil plow through so you aren't setting the land up for recompacting from the heavy equipment being used. Also, you need to get at least 10 yards per acre of compost worked into the soil down to around 1.5m. Placing organic matter deeper than that isn't going to mean a deeper microbiome, just organic matter that will sit there like a rock.

Good luck with this project.

Redhawk

Hi Bryant,
again thanks for sharing your experience with me (all actually).
I may have given the impression that these folks I am collaborating with may want a result in no time at all, and indeed they would if that was possible.
I think what they would prefer is not to wait 5 more years before planting anything edible, and of course it is taking some effort on my side to explain why sometimes this can be the case, and little by little I am educating them on this. So all your suggestions are applicable somehow.
I would rather use a subsoiler instead than a backhoe, but the soil there is really hard and I fear it may not be able to penetrate very much.

Anyway now I am much more aware of the possibilities thanks to this exchange. Hope I can figure out the best course of action.

If you desire, I can lay out a plan for you that will take one year and then plants will take off like they were supercharged.
In my world, all you have to do is ask.  (if you can, show them my soil series, I think that will really help them get a grasp)

Redhawk

Hi Bryant,
well what can I say, yes of course I'd love to see a specific plan done by you. Of course I can show these folks your soil series, although that might be a bit beyond their capacity I reckon, but I can select specific parts related to their case.
What would you need from me?
As mentioned in my initial post, I have 1,5/2-year horizon to minimally condition that soil. Given that spring is already at the door here, I reckon that if nothing fails, we should be able to start planting in fall/winter 2021

Are Straw Bales available in the area? if so we can have a crop this year while conditioning the soil at the same time. Bales generally can last two years tops, then they have broken down into compost.

Straw bales work best for; tomatoes, peppers, broccoli, lettuces, peas, beans, etc. As long as you don't try root vegetables you will have good success growing vegetables and those bales will begin seeping high quality liquid humus into the soil below, tomatoes will put roots down into the soil through the bales too.
This works so well for me that I always start a new bed with bales for the first year, that way I get some produce and I improve the soil in the area I will be using as a garden bed at the same time.
Bales work very well and really all you have to do is get them started correctly and then it is add water when needed, the bales hold water for us for about a week.
To start the bales after you have set them where you want to have a garden bed I like to use spent coffee grounds and some compost that contains manure.
I set my bales in the shape of the bed, then I use a stick that is around 3 or 4 cm diameter and sharpened on one end to poke holes down into the bales (set so the straw ends are open on the top of the bale).
Once I have these holes done I place the coffee grounds and compost down into them, filling till the holes are full, next is watering the bales, we are setting controlled rotting into motion so we want the bales saturated with water as much as is possible.
When the bales are "dressed" with the compost/coffee grounds and soaking wet, you do nothing until the next day when you water them once again.
I usually water bales for 3 days in a row then I can wait a day or two before I go through another 3 day watering cycle, this goes on for three weeks. Once that is completed the inside of the bales should be heating nicely, at which point you can set transplant plants into place but you can't seed them yet.
To direct seed a bale you first have to cut a trench down the center then you need to add compost and soil so you have something to plant the seeds in that will keep those seeds in place.

From that point on all you do is water when needed and if you find the plants need more food, simply add some compost tea or organic fertilizer. You can use compost teas and mushroom slurries on bales so you are growing in a good microbiome and that microbiome will seep down into the soil below, getting the soil ready to be a garden bed without much work at all. (this method can be started as late as mid summer so you have the bales ready for a fall garden planting).

Redhawk

(this method works so well, others I have helped set up have thought we were doing magic)

Dear Bryant,
thanks so much for sharing this method, I know about starting veggies in strawbales already, from my previous permaculture training but have never actually tried it myself and I think it is a great way to both grow veggies and create topsoil.
If I manage to get my hands on organic strawbales I'll definitely give it a go
Kind regards

Here is a short YouTube video that explains compaction and soil structure in clayey soil.



This may help with understanding the role of cover crop plants in building a good soil structure. I would suggest using many deep-rooted kinds of grass and perhaps a few annuals like daikon radishes which can punch their roots down into compacted soil. Once they have gone to seed, just leave them in place to add carbon and as a store of slow-release nitrogen. Using grasses will take at least one or two growing seasons to show improvements. Plant the grass seed as soon as the compost is installed. Try to time all this so seasonal rains will come soon after you plant, or else plant long enough after the rain so that the soil isn't waterlogged.

The advice from Redhawk is also very useful and may speed up the process considerably. He knows a lot more about this stuff than I do. If you do use mechanical methods, try to use a tractor with either track or with oversized tires that will spread out the tractor's weight and reduce the mechanical compaction.

Thanks Mark!
I am planning to use many type of grasses at once, some of them are NFs, others have strong tap roots like mustard and sanfoin (which is also a NF), others are grasses that can also work as chicken food. What I'm wondering is if I mix all the seeds together and spread the seeds by hand (or by some other means), could it be possible that some of the grasses will actually suppress some others (among the same ones that I have sawed)?
How can I avoid this? I guess it may have to do with the seeding density....any thoughts on this?

Antonio Scotti wrote:Thanks Mark!
I am planning to use many type of grasses at once, some of them are NFs, others have strong tap roots like mustard and sanfoin (which is also a NF), others are grasses that can also work as chicken food. What I'm wondering is if I mix all the seeds together and spread the seeds by hand (or by some other means), could it be possible that some of the grasses will actually suppress some others (among the same ones that I have sawed)?
How can I avoid this? I guess it may have to do with the seeding density....any thoughts on this?

From what I've learned from my Master Gardener friend, who has been studying the planting of native seeds for wildland restoration, you just mix all the seeds into some soil and broadcast them over the land, preferably just before an expected rainfall.  Seeds have evolved to lie dormant until the right conditions come along for germination. Since most of these grasses have evolved to grow together, almost any mixture of grasses should be mutually beneficial as an initial cover crop (don't select known antagonistic varieties to start with, especially with your added annuals). You might try lightly raking the seeds in to hide them from birds and rodents.

In his book, "Sowing Seeds in the Desert", Masanobu Fukuoka describes a recipe (with some specific spices to ward off rodents) for coating the seeds in a clay slurry first to protect them from getting eaten before they have a chance to sprout. He also recommends just broadcasting the seeds (even from an airplane for large areas). Since you will probably be planting into compost, the seeds should have not problems getting started. After all, Mother Nature has been doing this for millions of years! For larger quantities, he uses a small cement mixer to make the slurry.

Good luck with your project. Please post your progress and results. I'm always looking to learn more from the experiences of others.

Hi all
I have an update on the original post. We are into doing the loosening of the terrace ground.

I eventually proceeded with using the backhoe. I tried to hammer a piece of rebar into this soil just to check how deep down I could drive it to, and realized that it wouldn't go any deeper than 10 cm (3+ inches?) Even the backhoe is having quite a hard time loosening at a higher depth sometimes. We have found very compacted (almost rock hard but easily breackble with the machine) clay blocks in spots, not everywhere thankfully.

We have bought 160 m3 of mature compost with 55% of organic matter, which would account for some a 15 cm high layer of compost on top of the terrace ground.
In order for the operation to be more cost effective, the machine operator suggested that he excavates the first 30 cm of soil first (there was no soil as such anyway) and mix it with the equivalent quantity of compost so 2 buckets of soil mixed with 1 bucket of compost in the top part in a place where it would be easy to do so. Plus we are adding some biochar, not very much to be honest (only 4 m3) also only into this higher layer.
Then he would loosen deeper down (he reached 1.4 meters deep is some spots), rearrange this subsoil and then cover this with the mix of top soil (or rather top dirt) and compost + biochar.

One of the things that I forgot to take into account was that by loosening and digging...the ground level would swell quite a bit....but that was inevitable I guess. The machine operator said that it might take 1 to 2 years before settling down again. But I guess the original grade would be lost..and it had been already lost after all the compaction that it has endured (as explained in a previous post) in the last couple of years.

Fortunately enough it isn't raining during this operation only quite strong winds at times.

Next stage after the loosening is over is sowing cover crops and green manures, also planning to protect the border of the site with vetiver grass, and add some of the pioneer native legume shrubs I had already planned to interplant with the fruit trees (in the future).

Antonio Scotti wrote:Hi all
... that by loosening and digging...the ground level would swell quite a bit....but that was inevitable I guess. The machine operator said that it might take 1 to 2 years before settling down again. But I guess the original grade would be lost..and it had been already lost after all the compaction that it has endured (as explained in a previous post) in the last couple of years. ...

It is good that you are mixing some compost in the lower depths of the compacted clay. That will aid in growing deeper roots. you want the plant roots from your perennial cover crops to penetrate as deeply as possible into the loosened clay so that it will be possible for the plants to exude carbon sugars to feed the microorganisms that actually grow the new soil at depth. You can even plant deep growing annuals (such as the daikon radish, and alfalfa) as your first cover crops. When these plants die, their roots will remain as carbon, or Soil Organic Matter (SOM). Later roots can follow these channels of dead roots to further break up the clay.

In your original post, I think you mentioned it was a terraced area? I would try to maintain a level surface. If that is not attainable for the entire area, try to include a berm or series of berms along the contours so that rainwater is not allowed to flow unimpeded down your slope. Some photographs would be good to show us what you are doing.

The rule of thumb is to slow, spread, and sink the water into the areas where you will eventually be planting. Get some ground cover plants seeded as soon as possible, preferably some with deep roots.

Keeping the top of the berm as level as possible is important or else any collected rainwater will just break out at the lowest spot and cause erosion problems. The idea is not to form a permanent pond, but merely allow the water time to soak in. That infiltration will happen more quickly if there are plants growing in the areas where the water temporarially collects.

Hoping for the great success of your project.

Hi Mark, the surface will be flat eventually, or as flat as possible. Unfortunately the machine operator couldn't finish the digging before the covid-19 pandemics hit our country.
I hope in the next few days the digging will be over.
I'll see if I can post a few photos later.

We did some sowing already, but not in the whole surface yet, because of the unfinished digging...let's hope that we can finish digging soon and can sow the rest of the seeds.

I was wondering if adding some basalt powder/dust might actually benefit the construction of this soil.
I have read other threads on permies.com where it is suggested that including rock dust is usually a good idea.
I don't have a specific soil test for this area, but I reckon it would be very similar to other terraces of the same property, that have all shown similar results, meaning high pH: 7.9 - 8.2, high in Ca
I wonder how much basalt should I consider spreading if ever.

Antonio Scotti wrote:
I don't have a specific soil test for this area, but I reckon it would be very similar to other terraces of the same property, that have all shown similar results, meaning high pH: 7.9 - 8.2, high in Ca
I wonder how much basalt should I consider spreading if ever.

I don't know about the basalt dust. However, putting lots of pine wood chips on the surface will help to hold moisture and soften the clay. Also, try planting daikon radishes (an annual), comfrey (a perennial), and other sacrificial (annuals) plants with deep taproots to help push organic material down into the clay. Talk to your local landscaping and tree-trimming companies, and see if they will dump the tree branches on your terrace. Rent a large commercial chipper (possibly from the tree trimmers) to chip the bigger branches to spread them all over the terrace to at least one foot (1/3 of a meter) depth. Do this after you have done the earth-shaping to get things level. The idea is to get the plants to do most of the soil building work for you!

Hi Mark, thanks..I am into this (what you suggest) right now....however just downloading any wood chips on top of the soil may not be beneficial since they can rob the little N that there may still is, for its decomposition. Rather I am trying to produce some BRF (Fragmented Ramial Wood) to put on top of the soil for better results..but covercorp and some biofertilizers + rock dust should start to get the microbiology going in the short term.