Tom Mann

I think an intelligent discussion deserves to be had about the wisdom of burning in metal drums. I saw a post on the biochar facebook group about it and it started a real flame war.

If you've ever walked around old junk yards there's virtually nothing will grow in them but weed patches. This just a casual observation and could be biased of course. And there are certainly other kinds of run off and compaction to be expected in a junkyard. Completely anecdotal but certainly got me thinking.

I think the most obvious question is whether such small amounts one might think would be released through heat/oxidation and finding its way into the charcoal are worth considering in the first place. But on the other hand there's a considerable list of things that applied in small amounts are known to disrupt the mycorrhizal structure of soil. And a burn barrel is not isolated but emits smoke and how much of that smoke may contain iron and other metals.

So the amount being small isn't something that ought to be written off entirely. Many people made the point that iron and other metals are in soil naturally. But I think the difference here is it is already within the existing mycorrhizal/mineral structure in a natural form.

Is it such a stretch to think even a small film of metal particles can be detrimental to fungus and bacteria? Out of curiousity I just searched for iron + antibacterial and at least one study says this:

Do Iron Oxide Nanoparticles Have Significant Antibacterial Properties?... At present, multiple studies have been published that show the antimicrobial effect of IONPs against Gram-negative and Gram-positive bacteria and fungi.

https://pmc.ncbi.nlm.nih.gov/articles/PMC8300809/

Well, any variety of metals will interfere with life processes, that is for certain. Its why quarries become environmental dead zones when various metals enter the soil and water.

But what really got me thinking was that many people quench their biochar in a burn barrel. The rapid water/temperature plummeting could very well become a slurry of small rust and various particles from the barrel itself which has now coated your charcoal which is itself very binding to whatever is around it.

Anyway, my intent isn't to be alarmist by any means. I am also not a chemist. People have been using barrels for a while now. And maybe after a long enough time frame it becomes a moot issue. I am just saying if you are really trying to maximize the microbial/fungal life, charcoal that is potentially covered in some kind of metal particles might hinder the overall objective there.

I'm not quite following everything you say here, but it seems to me you have a mistaken idea of how swales work. Swales are rather shallow, and they slow down water rather than accelerate it. Another counterintuitive fact is that on almost flat ground, you'll get way more bang for your buck with swales: the same amount of construction effort (volume of earth moved) holds back many more liters of water.

My mistake - rather ditches accelerate water out of an area which ultimately exacerbates the problem of compacted soil by stripping top soil after rain by creating rapid flowing water.

At least in examples I've seen, swales in permaculture context use zig-zag/contouring shapes over sloping terrain which makes a lot of sense - but that may be cognitive bias which might only appreciate water flowing over the surface. The properties of how water/earth interact below ground is less obvious.

I've seen examples in arid regions digging out holes to prevent water run off. Not so much in wetter regions as in northern Europe.

If you asked what the attached photo was I suspect many people would guess it was a retention pond of some sort. What I find intriguing is where are found on quite flat terrain, it runs contrary to how we typically think of how water works after it rains. I think most people might be resistant to the idea of digging a large square swale where a garden or pasture might run a risk of turning into a flood zone.

Perhaps they would operate as a kind of flood plain and crops were kept on the slope in certain seasons. I think more likely is the permeability of the earth was so excellent they acted more as underground reservoirs and never create problematic amounts of standing water. I think ground cover and a well developed hedge would make the earth quite permeable and effective at absorbing excess water.

Jeff Lindsey wrote:Based on time frames, I'd doubt that it the result of plowing deformation because that much lockstep plowing would result in significant top soil loss.

Water retention, wind breaks, and mixed crop planting. One water hungry, wind shy crop in the hollow, one sun loving, probably nitrogen fixing crop on the slopes.  Probably with some 3 sisters style synergy, based on the known caloric efficiency of  Celtic horticulture.  Also increases the surface area of the farmland, more plants in less room.

The ease of expansion of the farming grid and the boundary marking system also makes a lot of sense to me.

I doubt it was a case of just one reason.

Neat idea.
Thanks for brining it to our attention.

As far as I know, plowing with implements really began in earnest when grain-cultures like the Romans expanded into these northern places. Metallurgy would have been quite basic and the necessary labor and large populations to sustain a grain-based culture would not have existed in these small settlements. The grain-based systems have left a kind of psychological mark on every other type of farming. If grains can be grown in huge fields, why not make it the default method for all growing. It may be in fact be the case that cultivated plants are not meant to be grown on flat ground but rather on sloping ground, it's just the fact its easier to plow over flat surfaces that led to the habit of planting this way.

Rick Alexander wrote:Great post! Love this kind of stuff. I strongly believe that ancient civilizations were much more advanced and sophisticated in terms of living in harmony with nature, and retained the notion that their very survival was contingent upon them stewarding and regenerating natural ecosystem.

I also believe they had a much deeper understanding of water itself, a knowledge that only began to resurface in modernity with people like Viktor Schauberger. The concept of living water, and looking at everything in nature as cycles.

In permacukture, we all know the concept of succession and how natural plant death can lead to conditions perfect for the growth of a different, possibly more desirable species.

The ancients used this knowledge accross every domain of life. Very impressive people's lived back then.

Thank you for brining up Victor Schrauberger here. One of the thoughts I had was wouldn't these fields be prone to flooding? Large swales are fixtures in every modern day pastures and fields given rain will cause flooding. But holistically managed grazers report standing water no longer being an issue, rather, the deep roots create storage for water underground and natural reservoirs filling up and swales becoming unnecessary.

I've often seen earth works in the permie-sphere used mainly in managing elevation in sloping land. But these Celtic fields are found throughout in low-lying/flat regions like the Netherlands. One might start to consider that managed correctly, earthworks in flat zones slow the flow of water stop run-off and perhaps have some type of energizing effect on water as it percolates into the earth like Victor Schrauberger talks about. Could a sloping/hedge in these pool-shaped fields paradoxically manage water better than merely flat surfaces? Draining into swales accelerates water velocity taking with it the top soil. The undulating land being sort of a energizing effect where water circulates throughout the ground/plant complex rather than laying stagnant after a large rain event or sloping away creating a knock-on effect on later cycles of plant growth.

Kenneth Elwell wrote:Tom Mann, something from growing up in New England in the U.S.A. is the prevalence of stone walls. I didn't notice mention of the berms containing stone, but stone fences around paddocks and pounds for livestock are quite common here, and field/property boundaries are lined with stones removed to make plowing or mowing possible. In the days before machinery, and even with draft animals, the distance one would consider moving stones would be as short as practical. And in the absence of stone or trees for windbreaks or fences, mounds might have sufficed, or reduced the materials needed.

I think there is something quite important to consider with regards to the 'human scale' of these fields. The remnants of bronze age livestock - like soay sheep and dexter cattle - show they need not have large scale pastures we're familiar with today. In my humble opinion homesteaders or plain old hobby farmers that aim to mimic modern farming techniques get in over their head quite quickly for the reason the amount of labor and inputs do not scale downward.

There are a couple threads on here with regards to hedge laying to sort of recreate these types of systems. Using rather basic tools and a bit of sweat one could begin their own Celtic field if they start out with smaller animals and 'leap frog' their way through brush with dead hedges. I've seen many a youtube video of the upstart grazer using machinery to clear paddocks to more or less mimic the appearance of lately developed grazing lands that we're more familiar with. Granted it all depends on one's goals and context but I think for the permaculture/lean startup mentality one might be better served looking toward our distant ancestors.

Burra Maluca wrote:I grew up in Wales and somewhere along the way I learned that livestock should not hear the church bells (traditionally rung on Sundays, though some were every two weeks or monthly) twice from the same paddock.

So I wonder if these small enclosures were some form of rotational grazing?

I think if we look at the few ancient forests scattered through Europe we see can start to picture the genesis of these systems. Imagine encountering dense forest, you might begin by clearing a portion and heaping the brush to create a basic corral. Small groups would overtime create a honeycomb of paddocks to rotate their herds through while offering protection against predation and weather. It may have been the real origin of the earthen mounds, perhaps they're a product of accumulated earth protected from wind and rain events against the relative compaction in the paddock.

This appears to be a well preserved example from the island of Gotland. One imagines the importance of extensive hedges against the cold weather.  

The small field near Uggårde (Rone sn) on SO Gotland has the same shape as over 2000 years ago! The large field system ("Celtic fields") of the Bronze and earliest Iron Ages lives on here in the late arable land. Just next door are former fields of the same type.

https://x.com/connelid/status/1038458264223211520

This image shows the contrast between the small Celtric plots, perhaps left alone over the years for grazing purposes, with the large smooth uniform plots tilled with modern methods. To the west the round burial mounds can be seen.

Jeremy VanGelder wrote:To my eyes those look like the rather haphazard fields that Europeans have usually used for farming. They often have a wall or hedge between fields. And plowing can compact soils.

A lot of this is only now being put together since the availability of LIDAR data where the many sites popping up across so many far-flung regions which, one of the main reasons I'm quite convinced they aren't haphazard. An isolated pocket or two is one thing but the widespread examples start to become very compelling. This little old site here I think provides an interesting summary of some of the theories about the fields: https://www.celtic-fields.com/index-e.htm

There's speculation the large banks are indeed from continuous ploughing, a theory also suggested for Lynchets, large ancient earthen berms of unknown origin found in the British isles where it is thought ploughing steep hillsides cause undulating formations after the hillside collapses (see attached picture). Perhaps evidence contrary of it being mere accident are 19th century maps showing apple orchards planted on some of these Lynchets - whether that is a mere coincidence is unknown. Nonetheless, it suggests it could be a remnant of an ancient agricultural practice involving extensive earthworks.

To me, the mere fact these are still observable thousands of years later itself suggests they served some useful purpose. When you consider their only tools to that end were shovels and perhaps draft animals with rudimentary metal implements, it becomes remarkable how extensive these really are. That site sums it up - "Where they occur, they are by far the largest prehistoric ground monuments!" To be mere accidents, they are very large accidents indeed.

Another thing, over the centuries the plots would change inevitably change hands. Why endlessly plow the same way because its previous tenant did? That is unless the new steward of said plot saw some utility in retaining the berms. This is a bit more plausible than thinking it was just done that way out of some rigid habitual inertia carried out over centuries and centuries.

The fact this same design can be found across so many varying settlements would be a remarkable if not miraculous coincidence of not just farming practices but of social order as well. The sheer length of time these earth works appear to have been made and in use requires for an immense amount of variables to remain rather static for a very long time. Rather than being a mere fluke, it was a very successful form of farming. Simply put, it was this success that allowed them to spread to far-flung corners of northern Europe in the first place. Such challenging climate variables required a rather robust and resilient system to succeed where others couldn't.

It therefore seems reasonable to assume a lot of thought and purpose went into everything they did to survive. The more you consider how remarkable it is, it could be considered part of a kind of 'civilizational mode' in itself. We seem to only grant that sort of title on ancient Egypt and Mesopotamia. I think this is merely because they left behind sophisticated monuments and writing. This agrarian civilization may have existed and been quite sophisticated in its own right. As such, it may have left behind these extensive earthworks of a very robust and successful farming method.

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I have some theories about what could be so special about the fields at a purely practical level. The way the fields are arranged in such large extensive grids rather than interspersed among different settlements/homesteads are the most obvious and I think a few things can be surmised here.

(This is all based on an assumption that this culture operated in a kind of egalitarian model. I think the .5 acre average size lends itself to the idea they were indeed operated by individual households.)

One, the berms being shared by neighboring fields mean each field shares 4 sides by the abutting field, thus attaching one's field to a neighboring field means one would only need to heap up a couple more berms to expand the grid rather than build up your own 4 sided berm from scratch. Secondly, soil amendments would spread quite charitably to one's neighbor during rain events creating a rather convenient mutual benefit which would otherwise become wasted runoff. If you clean your barn out and heaped dung to compost on the berm, each of your four neighboring gardens would equally reap the benefits of this added labor which would otherwise be wasted into surrounding wilds and vice versa. And would this undulating design create nutritional, heat and moisture banks that could over time create a fertile soil to allow for continuous farming over centuries?

A further benefit is fencing/hedges to keep wildlife/grazing animals out scales up nicely in this system. It is exponentially easier to fence in 100 garden plots at once than to do so individually. Add a dog or two to patrol and you have a very effective security system in place to prevent critters from raiding your fields - now imagine 100 individual homesteads attempting to do the same must each fend for themselves, massively compounding the net resources to achieve the same results. So many interesting implications here...

This is all speculation on my part but I'm also personally convinced they were designed intentionally and were effective on a number of practical levels. The possible benefits and purpose that went into such a design as well as further evidence of the intentionality behind the fields. Needless to say I find the mystery of the Celtic Fields compelling and maybe others might see this and maybe even experiment with this kind of berm structure. It's also entirely possible if not highly likely there's people still growing in the remnants of these plots in which case we might already have case studies to look at.

Lana Weldon wrote:Where in NW Europe? The British isles, Germany,  or Scandinavia?

Eino Kenttä wrote:Seems to be exclusively the Celtic area, so not really that very far north. Never heard of anything like it in Scandinavia...

This map shows some of the sites discovered. There may be more to be found as it is based on the known data from LIDAR (laser scans of elevation.)