I am quite interested in the possibilities of developing and managing vegetable gardens without
digging the soil, or to significantly reduce the disturbance of the soil.
I still manage a few of the family scale gardens and some of the other growing spaces
with digging or regular cultivation, but more of the gardens have shifted
to a no-dig, or reduced tillage method. The main No-Till approach I have used
involves simply placing compost on the surface of the soil, a method I have been using for the
No-Dig family scale garden for a while, where the soil has never been cultivated or turned.
In other growing spaces we have shifted to using a similar approach of applying all the
compost and fertility to the surface of the soil, after an initial cultivation or deep digging,
a method that we when establishing the new polytunnel this year, which was mostly successful.
But I have wanted to try out other methods of no-till or no-dig establishing growing spaces,
using different materials to cover the ground to suppress the existing vegetation,
and to provide the organic matter and fertility that is useful for building
the soil and growing great crops of vegetables. And we are currently working to create a large
No-Till trial area where we are using 5 different methods of establishing
a vegetable garden without disturbing the soil underneath, to see how they compare.
I have been wanting to establish this side by side comparison of different
No-Till methods for a few years, but haven’t had the capacity or made the time to set it
up and manage it properly until now. The site for this No-Till trial is
in the Black Plot beside the large polytunnel that we put up last year,
and is part of the slow but gradual development of this intermediate scale growing space.
This area of ground had been cultivated in the past, but has been fallow for a few years,
with a wide variety of grasses and other vegetation on it,
including a few pernicious weeds such as scutch grass and a bit of bindweed.
The alkaline topsoil in this space is not very fertile, and it is relatively fairly free
draining, with a fair amount of rocks in it, but I have found it can grow good vegetables,
once enough fertility is added. I was planning on going over the entire
site with a broad fork to loosen the soil a bit, but I decided to leave all the soil undisturbed,
to see how the different methods are able to develop the soil profile over the next few years.
I roughly chopped back the grass and vegetation, and spread some concentrated amendments on the
surface of the soil, including seaweed dust, sulphur and and chicken manure pellets.
These are the usual amendments that we like to add, to boost some of the major nutrients
and to supply some minor and trace elements that can be in short supply in this soil.
Then the ground was covered with overlapping layers of cardboard.
It would have been good to add several layers of cardboard, to reduce the chance that the weeds
would get through, but the supplies that we had collected over the year ended up not being enough.
The 20m long site was then divided into 5, with each of the 4m long
sections to be further developed using a different approach and mix of materials.
And we set out the site so that there could be four long beds within the roughly 5m width
of the space, so that each of the 20m long beds covered all 5 variations of No-Till.
In the first section I decided to use the method of establishing a growing space by simply adding
more topsoil on top of a layer of cardboard or newspapers placed over the existing vegetation.
This can be a useful way to start a garden if you have access to good quality topsoil from
somewhere, and is similar to what happens when you build a raised bed, as it can suppress the
existing vegetation, provide a much deeper layer of soil for the plants to grow in,
and we can even start growing right away. I figured the best soil to use in my context
would be the topsoil from underneath the composting area, as we had good
results using this topsoil by itself in the potato grow bag trial this past year.
This soil has been gradually amended and improved over the years with lots of nutrients and organic
matter leaching down through the compost above, or brought down by the worms and other soil biology.
So we have been digging out this enriched topsoil, sieving it to remove some of the stones,
and hauling it over to the No-Till Trial area, and filling the hole we dug with
less fertile topsoil from another pile. We plan to continue to add more of this
good quality topsoil over the next few months as we clear the older compost piles, and I plan to
build up a layer of about 15cm or 6 inches deep, over the roughly 18m2 area of this first section.
Once the 30 wheelbarrow loads of soil are in place and levelled, we will top up each of the 4 growing
beds with another wheelbarrow load of municipal compost, and add wood chips to the paths.
This top dressing will serve as a mulch to help reduce evaporation, and will help to suppress
the germination of some of the dormant weed seeds that are probably in the soil,
and we plan to continue to add this additional layer of
compost and woodchip each year to continue to build the fertility.
Although there was lots of digging to move the soil, the existing soil in the growing
area remains untouched, and the beds will not be turned or disturbed once they are established.
I figured this combination of amendments on the existing vegetation, cardboard, a thick layer
of fertile soil then finished with compost and woodchip on top, will work well to suppress the
existing vegetation, and provide a deeper and more fertile topsoil to grow a good crop of vegetables.
It did cost me a little bit to buy in the amendments and the municipal compost,
but these could have been replaced with free materials, and this method makes
really good use of the fertility that has been building up underneath the compost area.
Another option for establishing a new No-Till growing space is to cover the
ground with a lot of woodchip, which is often referred to as the Back to Eden method.
I got a load of ramial woodchip delivered a few years ago, which contained a lot of
smaller twigs and branches, that I set aside for trying out a method like this.
It is generally easier and recommended to let this woodchip decompose on the final growing space,
which can apparently take some time to really mature, but this stuff is already really well
decomposed in a separate pile, waiting for me to get around to doing this trial.
We had used some of this decomposed woodchip in the potato grow bag trial this past year,
and after amending it with a lot of general purpose organic fertiliser, we were able
to grow a good crop of potatoes in it. So I think it will work really well as
part of this No-Till trial, even though I haven’t followed the regular advice.
I decided to first add a layer of high quality compost on top of the cardboard and amendments,
to add some additional fertility, as well as bringing in a more diverse range of soil biology.
And then we placed about 20 wheelbarrow loads of the decomposed woodchip on top of the compost,
providing a layer more than 10cm or 4 inches deep. I decided to mix in some of the general purpose
fertiliser into the decomposed woodchip, to provide some of the nutrients that may be missing,
and to enable the material itself to serve as a more effective growing medium for the plants.
I plan to cover this whole section with a layer of fresh woodchip later in the winter,
to help reduce the evaporation, and to continue to add a new layer of this high
carbon organic matter each season to continue the process of decomposition.
And I expect the plants will do quite well in this first season with this modification of the
Return to Eden method, with the thick layer of decomposed woodchip, additional fertility
underneath and the undisturbed soil below. Apart from the fertility amendments,
I was able to get all the rest of the materials for free, but it would have been a lot less work,
and possibly a better trial if I was able to use fresh wood chips to start with.
Another method that I come across quite often is generally referred
to as the Ruth Stout method which involves covering the soil with a thick layer of hay.
Hay is widely available around here as an animal feed, and good quality hay contains a lot of
protein, and protein contains nitrogen which is what we are interested in when growing vegetables,
especially when it is balanced out with all of the carbon and other
nutrients was contained in the dried hay. I had bought about 20 bales of hay from a
local farmer earlier in the year, and stored it until I had a chance to start this trial,
but I didn’t cover it well enough and part of the bales got wet and started to decompose.
This would have been bad if I was using it for animal feed, but it was simply the start of
the decomposition process that will start to feed the soil which is what I wanted it for.
As with the other woodchip section of this No-Till trial, we added a thin layer of high
quality compost, on top of the cardboard and amendments, mainly to inoculate this hay and
soil below with a more diverse biology. The bales of hay easily separated out
into sections or flakes and we simply set these flakes side by side to cover the area,
overlapping the decomposed sections a bit. One layer of these flakes may have been
sufficient, but I had enough bales to cover the section with two layers, and I figured
that overlapping the gaps between the flakes would help to suppress any weeds that did get through.
We used about 16 bales of hay to cover the section, at a cost of €4 per bale,
though with a bit of searching I probably could have got some spoiled hay for free.
This produced a layer of compressed hay between 15 and 20cm or 6 and 8 inches deep,
and I don’t know how this will respond to the cool and wet winters and springs that we get.
It might become too wet and mushy underneath as it decomposes, and it will likely delay the
soil warming up in the spring, and possibly become a haven for slugs.
So although this method is quite easy, and uses materials that are widely available,
I am not sure if it is appropriate for this climate or context, but I think it is worth
including in this side by side trial, at least to see what issues might arise.
For the fourth section of this trial, I decided to use the method that has been
developed by Charles Dowding and others for a more temperate climate like this.
This involves simply covering the ground with cardboard and
a really thick layer of well decomposed compost.
It is the method I started using a few years ago to mange the No-Dig family scale garden,
and also used to establish the new polytunnel this past year.
My experience in these gardens and in the grow bag trials this year, is that this bulk
municipal compost that I get, and want to use in this trial, is not very rich, and probably
takes several seasons before it can really contribute to the strong growth of the plants.
So I have taken the advice of other growers and placed a healthy 25mm or 1 inch thick
layer of high quality and biologically active compost at the base of the bed, on top of the
standard layer of cardboard and amendments. And with this section of the trial I kept
the beds separate from the paths, and used a wooden frame to help fill the
bed with another 125mm of municipal compost, bringing the total depth to 150mm or 6 inches.
To fill the 4 sections of beds, with a total area about 13m2,
this used up most of two large bags of municipal compost, which cost me about €150 total.
We then filled the paths with a rougher compost from a nearby pile and topped
this with a thick layer of woodchip. The dark compost on the surface of
the beds in this section of the trial will probably warm up the fastest in the spring,
and will possibly be the most successful at growing a wide range of different vegetables,
mainly because so much of the decomposition of all the organic matter is already mostly done.
For the fifth section of this No-Till trial I am using a deep litter mulch,
or the lasagne method that I learned about years ago through permaculture.
This method involves using a deep blanket of lots of un-decomposed organic material, layered in
with compost, cardboard and various amendments. While it can include a fair amount of compost
and other sources of fertility, it is also meant to supply a lot food for worms and
other decomposing organisms, that will work through all the material and in the process
hopefully develop excellent growing conditions, as well as smothering the existing vegetation.
I had tried using this method years ago when I was first developing the No-Dig garden,
but I didn’t do it very well, mainly because I didn’t use enough materials,
especially materials with enough fertility. And I ended up replacing this method,
with the approach of mulching with compost instead, partially because
it became a habitat for slugs, and that the thick layer of organic matter seemed to keep
the soil quite cool in the spring, delaying the crops and causing problems with growth.
But I have decided to try again, with a better mix of materials, to see how this
method can be improved to grow a good crop of vegetables in this cool maritime climate.
I started this section with a layer of the same amendments on the surface of the existing
vegetation, added a layer of partially decomposed rough compost, then the layer of cardboard.
On top of this I added more of the rough compost, the remaining bales of spoiled hay
which I loosened up, and a range of partially decomposed organic matter, including material
from a pile of mature grasses and vegetation that had dried out and not fully decomposed yet.
I had also added the remains of a pile of municipal compost from 2 years ago
and spread some nitrogen rich hair meal pellets over the full section,
to ensure there was enough nitrogen to balance out all of the carbon that we had added.
On top of this I decided to put another layer of cardboard, in case I had imported any weed
roots or seeds in all that diverse mix of materials that had been lying around.
And then we added a thin layer of high quality and biologically active compost
on top of the cardboard, and topped the whole bed with a thick layer of straw.
All these layers should be enough to smother the existing vegetation, and provide a wide mix of
food for the soil organisms and help develop the soil below, and includes a fair amount of
concentrated fertility to hopefully create very fertile growing conditions for the first season.
And it was great to be able to make use of so much material from poorly managed piles of
organic material we had collected over the years. I am not sure if this will work, but it will be
interesting to see how it compares with the other No-Till methods, as I think this deep
mulch of un-decomoosed material is probably more appropriate for a warmer climate.
I have been wanting to do this trial for a while, and it is great to finally get it started.
I think it would have been better to have started all of this a few months ago when it was warmer,
so it would give more time for things to develop and for more of the decomposition to occur,
before anything is planted next spring. I also suspect that some of the weeds with make
it through the overlapping layers of cardboard, and up through the rest of the material.
And we probably imported some pieces of scutch grass roots and the roots of other
pernicious weed in some of the woodchip and other compost, and these will need to be pulled out.
If there are a lot of weeds issues next spring, I plan to cover the entire area
with a tarp or ground cover fabric for a few months to kill them off.
So I am going to delay planting anything in these No-Till trial beds until at least
early summer next year, to make sure that all of the weed issues are taken care of,
and to give enough time for the useful biological processes to become really
developed in each of the 5 sections of this trial. And this will allow the material and the soil
underneath to warm up, and some sections will probably warm up a lot quicker than others,
and this might be one of the key factors that differentiates the 5 methods.
The first real test will be seeing how the plants grow in each of these section next
summer and into the autumn, and then to see how everything develops over the next few years.
Although each section has been started with an abundance of material, essentially front
loading a lot of the organic matter and fertility, I will need to figure out how
to manage each of these sections so that we can continue to get the best crops year after year.
I am really looking forward to seeing the differences of these approaches for establishing
a vegetable gardens in this climate without digging or tilling the soil below, and to figure
out how each of these methods can be adapted to be able to work better in this context and climate.