I’m constantly looking for better ways, more local solutions, and more efficient solutions, to building soil, high brix food, and the ecology around me.
Several years ago, I discovered information about something called ‘ramial wood chip’ or ‘rwc’ as it is commonly called. Ramial wood refers to the part of the tree that is 7cm in diameter and less, including all the tips and bark. To make ramial wood chip these small branches are cut and chipped during winter when trees are dormant. Ramial wood is quite different to the trunk and larger branches which are much higher in carbon.
The best trees to use are deciduous, dormant hardwoods, and best to not include more than 20% evergreen wood. Willow, poplar, maple and alders are all regarded as hardwoods. hardwoods are defined as deciduous trees rather than evergreen trees!
Using the tips and smaller branches means there is a carbon nitrogen ratio of between 30/1 and 70/1, and all the minerals required for plant growth in balanced form. This means that the soil food web is able to digest the ramial woodchip unlocking mineral energy to grow the next crop.
I spent some time searching out as much information as I could on the internet and it seemed that the value and uses of ramial wood chip have been known for centuries, and there are people today finding ways to use it to great advantage in many different situations.
In particular I came to understand that ramial wood is basically ideal food for many microbes, especially fungi, who break it down and in the process release all the mineral energy required for building healthy cells back into the earth, perfect for our fruit trees and vegetables to take up, and use in their growth process.
Here at Kōanga we immediately saw the value that using ramial wood chip could hold in our forest garden. We have a 1 hectare forest garden containing many heritage fruit trees in very poor sandy pumice soils, and the trees were not doing well, with a lot of disease and poor growth. Buying the fertiliser we required to remedy the situation was beyond our means so we saw growing and making ramial wood chip as being a perfect solution. We had already planted many forest garden support trees that we could use to make ramiaL wood chip over several years and it was time to begin coppicing and pruning many of these, so we began 2 years ago mulching the heavy feeding fruit trees in our forest garden with ramial woodchip as fast as possible. Within six months we saw dramatic changes for the better, with fungi coming up all over the forest floor, and far greater tree growth, fruit set and tree health, and this is continuing to improve all the time.
Our greatest challenge was selecting and obtaining a chipper that met our needs. We identified a Hansa C13 as being the best for our purposes. Hansa are a NZ company and generously supported us by giving us a chipper. This was very important as we had been quoted $5,000 for 1 years fertiliser and the chipper enables us to build ecological health for our heritage fruit tree collection. Chippers are not cheap pieces of equipment but incredibly useful and one option for gardeners is to buy a chipper with friends to share the cost which is what Gail and John have done up in Hokianga.
We’ll come back to the growing of ramial wood chip and forest gardening a little later…
I had not been expecting to find solutions to building our vege garden soils in local regenerative and super-efficient ways using ramial woodchip
The information I found recommended placing 2.5cm of ramial woodchip on vege beds in the Autumn, then forking into the top 5cm and planting a leguminous crop into the bed, ready to plant your vegetables in Spring
I was already hooked, I could see this rwc system could potentially revolutionise local food production, creating the possibility for many small scale local food producers to grow food without having to buy fertiliser or even bring in anything in from outside their gardens….. so long as we surrounded our gardens with a forest garden, producing not only the rwc required to feed the beds, but also bringing in the insects and birds required to reconnect the broken phosphate cycles, bringing the phosphate back over time to our garden soils.
I made the decision to start small and do lots of testing.
The first step was to get a Reams soil test done before adding the rwc, and again in Spring when I pulled out the lupins before planting with garlic, onions and greens, all heavy feeders
When pulling out the lupins it became obvious that the bed was very full of white mycelium, which was connecting the lupin roots and the ramial wood chips. The bed had become a connected mat of mycelium, rwc, soil and lupin roots.
It was also obvious that the mycelium had totally changed the nature of the soil, because the matt of mycelium was so thick and strong it was holding air in the soil, rather than the soil becoming compacted, and from that moment I didn’t feel there was any need to do any aeration at all in any beds that had had ramial wc forked into the top 5cm of the beds in Autumn.
My garden became a no dig garden pretty much overnight!!!, something I was not expecting (I mean anybody can simply stop digging and say they have a no dig garden, but to have a no dig garden that is maintaining soil aeration and soil building and growing nutrient dense is something special).
The Spring soil test showed a 10% jump in humus levels and a raised and more balanced mineral profile. I grew my garlic and onions and lettuce to a brix of 12 in that bed following the lupins, with no added compost or fertiliser. That would not have happened pre rwc, the soil was very sandy.
I was excited about that because ramial woodchip is something we can all grow and make, or access, and if that enables us to build soil so fast whilst adding balanced minerals it could make regenerative local food production a real possibility
Since then I have been trialling ways to use it that integrates well with the food I like to eat and my garden plan.
I noticed in the garden that every bed I applied rwc to in the Autumn automatically became a no dig bed from then on. I simply did not need to do any aeration at all when I replanted beds. The fungi was apparently holding the air in the soil, right down deeper than the top 5cm.
I developed a method of applying compost to the surface of beds being planted, in the late Summer Autumn for Winter crops and that has worked well, and in the Spring, when I didn’t want to leave compost on the surface in the hot sun, I mulched it with comfrey in the case of the tomatoes, and in the case of the peppers, pumpkins, and climbing beans I put on ramial wood chip as a mulch only, planning to fork it in, in Autumn before planting lupins. So I have been adding compost and planting straight into the beds.
Over 2 years I have watched what is happening, and developed a system of adding ramial wood chip to all Summer crops, where that is easy to do, i.e. on 1 bed of dry beans I plant every summer, 1 bed of tomatoes I plant every year, and my 3 pumpkin beds, plus my 5 beds of flour corn, totalling 10 beds out of a total of 20 that I mulched after composting and planting the crops in Spring.
All the other Spring planted crops did not suit being mulched, so I left it until Autumn to apply and dig in the ramial wood chip. The garden is 200 sq m or 20 beds, so there were 10 beds where the Autumn procedure has become to simply fork in the ramial wood chip that was already applied as mulch in Spring, and then apply ramial wood chip to all other beds possible in Autumn.
It turned out that I had 4 beds each Autumn that did not suit to apply ramial wood chip because the crops I was planting were not legumes and would not like growing with ramial wood chip freshly dug in. It turned out that those beds were my 3 beds of Winter heavy feeders , brassicas, endive lettuce etc, and the other bed was my carrots and beetroot and root crops bed .
Because we are rotating all sections of the garden each season though, there were only 4 beds in the whole garden that were not getting ramial wood chip every year, and those beds could have it incorporated every two years. I figured I could just add more compost to those beds anyway, so I wasn’t concerned about that.
So I could only see positive effects in the garden in terms of soil health, soil tests results, crop health (with the exception of tomatoes) and super noticeable increased crop production. My beds were producing far more than previously.
Tomatoes are a vegetable that prefer a less fungal and more bacterial environment so I now mulch in Spring after composting the bed that had rwc the previous Autumn, with deep comfrey and alfalfa mulch, which I add to each month until the end of January.
The tomatoes did not like being mulched with ramial wood chip, but on the other extreme end, the garlic and onions loved being planted into the newly forked in ramial wood chip in the Autumn, even though they are not legume crops. I did it by mistake the first time, and couldn’t believe how well they did.
Another interesting thing I noticed is that the weeds have totally changed. Obviously the beds are growing weeds that prefer a more fungal environment, but overall far less weeds over Summer, way less weeding, but over Winter a weed that was not that obvious previously, became far more prevalent.
Now that I have been trialling using ramial wood chip over 3 years, I can see I love it, and it has huge potential. I can also see that if it is not easily available cheaply, which it isn’t for all of us, then it is possible we could grow our own. We have begun to work out how much area will it take to grow enough ramial wood chip for each sq m of garden we apply it to.
How much we need will depend on how often it needs to be applied. Our soil is pumice sand and I have added it 3 years in a row now and I can easily see that there might come a time when I would not need to do it so often.. and after 3 applications annually, it feels that right now is that point in my garden. After having watched the change and growth of my soil, I feel as though I could make good decisions around how often to apply it.
A European practitioner says he only does it every 6 years, and that is all he does to maintain soil fertility. Without doing years more research I’m going to plan on planting enough trees that can be coppiced to achieve applying rwc to all of my beds every four years , so that I apply rwc to ¼ of the garden each Spring or Autumn depending on the crops. As well as using rwc to feed the microbes in my soil I’m going to continue making compost, as well as using my chicken/Autumn leaf compost, as well as the vermicast we make.
My vege garden is surrounded by a forest garden and so I now need to ensure there is enough rwc produced from my forest garden to enable me to add 2.5cm into the top 5cm of 50sqm of garden bed each year. That means I need 1.25cu m of rwc each year, and based on some intelligent guessing based on research on the internet plus the results we are getting in our trials (we will publish them as we feel we have patterns) it will mean we need to plant approx 6 alnus glutinosa and approx. 20 Egyptian willows for coppicing each year to supply that rwc. These trees would take up approx. the same area as the garden
I can imagine that there might come a time in the future when there might be no need at all to be growing compost crops to make compost to feed my soil, if I find the ramial wood chip is doing that well, and I don’t actually need the compost, we’ll see. I also wonder just how good the ramial woodchip will be at continuing to raise calcium and phosphate levels , the two biggest challenges for most of us, and in the meantime I’m going to also continue to make compost under my chickens using Autumn leaves a in order to continue raising the phosphate levels in a local regenerative way.
There are still many questions for me.. Even if we have balanced minerals in the ramial, what if we began with badly unbalanced minerals, ie nowhere near enough available calcium or phosphate then we may need to add these in other ways at least initially, or can we use ramial alone to build our soil to grow high brix crops
I began using the ramial after 8 years of Bio intensive practice in that garden, using biological fertiliser based on Reams tests, so my beds were already pretty good. If I began with rwc only, what would have happened? I’m trialling that now, so I will report as that trial progresses.
We have been growing and chipping alders and willow and measuring the output of rwc per sq m of tree grown, and it is clear that the area involved to grow enough wood chips to apply 2.5cm to every sq m of garden bed depends on many factors like
- The tree species being used
- How close they are planted
- How often they are coppiced
- Conditions they are growing
It also seems clear that there are patterns that we’ll be able to see pretty soon, which we will share.
It seems obvious at this point that a diverse integrated set of strategies for building soil will be the best option, so adding the strategy of using rwc to those strategies already in place that feel good and appropriate for small scale gardens, could be the best option in terms of space needed, time taken, costs etc etc
Our rwc trials here include
- Alnus glutinosa (the only one that coppices well, we find )
- All of the willows we have that were selected by the research station at Akautere for biomass production ( all available on the kōanga forest garden support species shop right now)
- Poplars especially Kawa
- Maples
- Mulberries
- Chestnuts
- Oaks
All of these trees are called ‘deciduous hardwoods’ and all coppice, or pollard very well.
Maybe you can tell I’m excited by this whole topic, I promise I’ll keep in touch
I can see now that possibly the most powerful thing we could all do to be building life, creating REGENERATION and especially amazing soil and high BRIX vege is to be planting trees that can be coppiced year after year .
Come to a Kōanga Open Day, Guided Tour or Workshop to check out what we’re up to.
We will be completing our Kōanga Health and Healing Masterclass shortly and we are well down the track of filming our Forest Garden Masterclass so watch this space. You’ll all be able to see what I’m talking about when that is finished!