What's The Deal with Syntropic Agroforestry?

[agroventuresperu]

At first glance, it sounds like one of those "hey I've got the magic beans to make your landscape extremely productive even if Aluminum saturation is 90% and every nutrient is deficient in your soil" approaches.

The guy who coined the approach, Ernst Gotsch, seems to be a pretty intelligent person, although I get sleepy watching his presentations, and have to muck through his diatribes about the usual environmentalist gripes in order to glean a few nuggets of gold. What's missing is the hard data. Or perhaps it's not presented well and I haven't found it yet with my less-than-extensive internet searches. Most everything seems anecdotal, although it looks like a good approach to regenerative agriculture as far as I can tell.

Okay he started with a desertified piece of land with "soil pH from 3.7 to 4.5" in northeastern Brazil. What was the aluminum saturation? What was the CEC? Which species did he use in the areas that were pH 3.7? Did anyone conduct a geological assay of the soil using Inductively Coupled Plasma - Optical Emission Spectrometry? What elements were deficient?? Were any of these elements imported to the landscape in the form of amendments, fertilizers, manures, mulches, etc? Was any liming ever done during the reforestation process? What was the average annual precipitation of the area?

Hard to believe that a property that was a total desert with soil so poor that farmers "couldn't even produce a pineapple", was able to be converted into a thriving rainforest ecosystem without any irrigation nor inputs besides seeds and hard work - but that appears to be the insinuation. I guess if it took the guy thirty years to get to that point, it makes more sense. But I imagine the better part of the first decade saw little to no production, which wouldn't be practical for most people lacking a swiss bank account.

How does pruning tall trees effectively mine subsoil of elements? I can understand that, but what if those elements aren't there in the first place? Surely healthy populations of microorganisms can access unavailable nutrients, but I don't believe they have the ability to add elements that aren't in the soil profile or parent materials in the first place. If I'm wrong, someone please tell me there's a microorganism capable of the alchemy necessary to start adding gold to my soil. Now that would solve some of my problems. I have a lot of questions about this approach, which sounds like it's being marketed as a silver bullet solution.

[agroventuresperu]

For the uninitiated, here's probably the most watched video on the topic:
https://www.youtube.com/watch?v=gSPNRu4ZPvE

[1rainman]

Its like weeds they grow on poor soil then rot and replenish it. Brazilian pepper tree in Florida grow like weeds in soil with few nutrients and over time the leaves rot and create top soil. I guess they pull nitrogen out of the air and I don't know how they get micronutrients. Just really big root systems that can scrape small quantities together i guess.

[Galatians522]

I am only generally familiar with these systems, but here are a few observations from common agricultural knowledge. Clay is actually pretty fertile soil. It mainly lacks nitrogen. About 10% of the world's nitrogen is fixed from the atmosphere by lightning. Organic matter mineralizes back to nitrogen and other components through biological processes over time. For every 1% increase in soil orgnic matter content, nitrogen inputs can be reduced by 10% according to recommendations I have read from the University of Nebraska. Logically, building up organic matter will supply the missing ingredient in a clay soil. Organic matter also improves water retention and infiltration and can absorb harmful elements like aluminum (similar to how activated charcoal absorbs odors in your fridge). Shade also reduces transpiration. I think those factors account for most of the benefits in the system.

[booeyschewy]

I live pretty close to Ernest’s farm. Degradation is real here and it’s pretty easy for them to destroy land temporarily. Calling it a desert is an exaggeration. Not sure how much rain he gets as I’m closer to the coast but our averages are 2000+mm and he has to be near that. The Atlantic forest regenerates without any intervention in many parts of Brazil so Ernest accelerated this process only. If you leave pasture alone it will become forest in about 5-10 years. The other component of regeneration is microbes making nutrients available in soil that otherwise wouldn’t be. Increased rotting biomass contributes to this.

I will say there’s lots of hype around syntropic stuff which is innovative and interesting hype aside. Two big weaknesses I see are labor and commercialization. Ernest did everything manually. Much of the techniques require either expensive machinery often not accessible to small or medium farmers outside the us and Europe or plentiful cheap labor which is also less and less likely in many rural areas. The other weakness is if you plant a crazy amount of crops you often can’t sell most of it if supply chains don’t exist where you are. These issues are surmountable but worth mentioning because in my limited experience most syntropic projects are noncommercial, small scale, or done by independently wealthy people. There are some medium scale things happening in Brazil but it’s all initial stages, funded, and pending the test of time.

[agroventuresperu]

I live pretty close to Ernest’s farm. Degradation is real here and it’s pretty easy for them to destroy land temporarily. Calling it a desert is an exaggeration. Not sure how much rain he gets as I’m closer to the coast but our averages are 2000+mm and he has to be near that. The Atlantic forest regenerates without any intervention in many parts of Brazil so Ernest accelerated this process only. If you leave pasture alone it will become forest in about 5-10 years. The other component of regeneration is microbes making nutrients available in soil that otherwise wouldn’t be. Increased rotting biomass contributes to this.

I will say there’s lots of hype around syntropic stuff which is innovative and interesting hype aside. Two big weaknesses I see are labor and commercialization. Ernest did everything manually. Much of the techniques require either expensive machinery often not accessible to small or medium farmers outside the us and Europe or plentiful cheap labor which is also less and less likely in many rural areas. The other weakness is if you plant a crazy amount of crops you often can’t sell most of it if supply chains don’t exist where you are. These issues are surmountable but worth mentioning because in my limited experience most syntropic projects are noncommercial, small scale, or done by independently wealthy people. There are some medium scale things happening in Brazil but it’s all initial stages, funded, and pending the test of time.

Well thanks for giving me better insight into the context. Do you happen to know what soils are like there? Is aluminum saturation common there? We tested our subsoil here on one part of the property and it measured 80% aluminum saturation. Many plants struggle to grow in that. Even Cassava struggles there.

What would you say are the most noteworthy factors that Ernst was able to overcome? Why is his approach so touted, when you could just sit back and nature would do the same thing at about the same rate?

I just wish syntropic agroforestry were more scientific. It all sounds so theoretical to me. For example, if I get lazy and cut a Eucalyptus or Schizolobium or whatever at head height instead of getting an extension ladder and cutting at 5m height is that so much worse? How did he come up with that level of specificity? Anyway, on this steep, rugged landscape I'm not wandering around 10 hectares with an extension ladder to prune thousands of pioneer trees. Not happening.

Why is Syntropic Agroforestry so poorly documented? It doesn't even seem like there are any books on it. I'm just trying to scrap together pieces here and there (mostly from youtube videos) to try and comprehend it better.

[booeyschewy]

Not sure about the soils there. Ours are aluminum heavy but less than yours it seems. Gypsum goes a long way!

I think the deal is the holy grail of no inputs and regeneration of forest. The devil is in the details though. People will say there's no witches broom fungus in syntropic farms and no infestations. This is not true. The one famous case of a commercial syntropic farm I know of with decades of experience is billed as being zero input and the like, but actually they use manure and the like like everyone else, as well as large teams of labor from people who pay to take classes. It does show that you can restore soil by accelerating regeneration and labor alone which is a feat. In terms of commercial farming though labor and selling those products is a massive question.

They cite some studies but I've never found them. In Brazil there's lots of research on SAFs (agroforestry systems) particularly for coffee, cacao, and açaí if you read Portuguese.

Ernest is very into old school life in terms of doing everything manually, oral history etc. He never wrote anything. The followers skew to the philosophical side so that compounds it. It's all very new. We're talking since the 90s only and Ernest cultivates just 5ha these days and never seems to have tried to sustain a commercial operation. A sober view would be that it's just a pocket of the broader agroforestry world which is getting worked out.

Stuff with more years behind it would be the communities in Tome-acu in the amazon which developed cooperatives and systems of agroforestry around acai, cacao, pupunha, cupuaucu, etc. There's others as well of course

[agroventuresperu]

Not sure about the soils there. Ours are aluminum heavy but less than yours it seems. Gypsum goes a long way!

I think the deal is the holy grail of no inputs and regeneration of forest. The devil is in the details though. People will say there's no witches broom fungus in syntropic farms and no infestations. This is not true. The one famous case of a commercial syntropic farm I know of with decades of experience is billed as being zero input and the like, but actually they use manure and the like like everyone else, as well as large teams of labor from people who pay to take classes. It does show that you can restore soil by accelerating regeneration and labor alone which is a feat. In terms of commercial farming though labor and selling those products is a massive question.

They cite some studies but I've never found them. In Brazil there's lots of research on SAFs (agroforestry systems) particularly for coffee, cacao, and açaí if you read Portuguese.

Ernest is very into old school life in terms of doing everything manually, oral history etc. He never wrote anything. The followers skew to the philosophical side so that compounds it. It's all very new. We're talking since the 90s only and Ernest cultivates just 5ha these days and never seems to have tried to sustain a commercial operation. A sober view would be that it's just a pocket of the broader agroforestry world which is getting worked out.

Stuff with more years behind it would be the communities in Tome-acu in the amazon which developed cooperatives and systems of agroforestry around acai, cacao, pupunha, cupuaucu, etc. There's others as well of course

You've got some very interesting insights about all that. All those claims sound a lot like permaculture. Permaculture is what inspired me. The founder of permaculture, on the other hand, documented his knowledge a lot better than Ernst. Mostly though permaculture has been co-opted by hippies with a lot of exaggerated claims, and it doesn't seem like there are many commercially successful examples there either. It feels a little cultish, and I also get a sense of that from the youtubers I've seen who are into syntropic agroforestry.

"It does show that you can restore soil by accelerating regeneration and labor alone which is a feat."
That's what interested me in learning more about it. I live in an area where it's not feasible to add a lot of product and mechanizing is probably impossible.  I wonder how long it would take to reduce subsoil Al3+ saturation of 80% to a more reasonable level like 40% without the addition of any liming agents. That Al saturation measurement at our place was taken two years after adding 1 ton per hectare of dolomite and weedwacking the area probably a total of 5 times (i.e. cycling the biomass 5 times). If we were able to till in another ton per hectare of dolomite to the subsoil, then it would probably get the levels pretty close to 40%. We are thinking of adding another ton to the top soon, but we have no way of tilling it in, and we probably shouldn't, because it would disturb the trees' roots. My understanding is that it will percolate to the subsoil over time and begin to correct that situation.

There is a liming effect of adding mulches, but it's not well-researched. I assume the weedwacking and leaf fall in our case is at least somewhat equivalent to the addition of mulches to the denuded croplands that were used in studies. I understand the disease-suppressive and nutrient-cycling/mining potential of soil biology as well, so that is why I am a believer in syntropic agroforesty. Just wish there were better resources to explain the justification for all the peculiar things that they do.

[booeyschewy]

Agree on all fronts. I think syntropic stuff is a wing of permaculture for sure and there’s similar dynamics there.

I learned all this stuff in Portuguese so might be off base. Dolomite is lime correct? Calcium basically. That corrects pH but for Al sat at depths you use gypsum (gesso?) which reaches profound soils. You likely know that just wanted to be sure because I didn’t!

There are machines that work on sloped terrain. Austria and italy make tractors such as the Antonio Carraro 5800. There’s also remote controlled mowers and the like. I expect this to expand soon. I’m in a similar scenario. I’ll prob do a mix of mountain tractors and remote stuff eventually. But at least where I am the soils are better it seems and respond well to cal and gypsum. We’re doing that at the same time as planting diverse biomass and will implement limited native tree lines say every 15m. In Brazil there’s some backlash developing to the use of grass in the inter-rows due to poor results and lots of work. Can’t find the studies but diverse biomass sources and non grass produce better soil and less odious weedwacking. Stuff like foraging peanut (?), crotalaria, feijão do porco and natives.

[agroventuresperu]

In English the term "lime" is often typically reserved for Calcium Carbonate only. Dolomite is a deposit that contains calcium carbonate and magnesium carbonate. We're lucky we have a good deposit of dolomite in our local area. I'd like to see those machines you speak of. Although I think we will have better results in the future doing Total Grazing with Cows and hair sheep. No sense to keep using machinery as the ongoing cost is high. We also need to be mindful of species selection. It would likely be an uphill battle growing avocados for example, whereas we could just plant something like cashew and enjoy high-productivity without any inputs.

I've read multiple sources that say well-managed tropical pastures (and silvopastures) sequester more carbon than native forest. A healthy improved pasture, with forage legumes and maintained with non-selective rotational grazing is probably the most effective approach to soil building. I would also argue that in the equatorial tropics, trees should be included in any pasture. There have now been studies showing that humus formation is several times more attributed to root exudates than from litter contributions to the O horizon. So it's actually better to not keep the grass constantly mowed, because the grass plants contribute more exudates once they have acheived full size and produced seed. When it comes to the growth of trees though, there is a valid debate though based on the argument of allelopathy. Most professional tree plantations, for instance, incorporate forage legumes as groundcover.

Gypsum is a zero on the calcium carbonate equivalence scale. Not a negative and not a positive. So neither acidity promoting nor alkalinizing.

Most of my thoughts about your points are based on the book, Properties and Management of Soils in the Tropics. The author of that book summarizes the benefits of gypsum as it relates to subsoil acidity, which sounds like it's a topic commonly confused. Here's what he says:
 

• Unlike lime, gypsum does not neutralize exchangeable Al3+
or increase pH.
• Gypsum reduces aluminum saturation, by adding
exchangeable Ca2+ to the ECEC.
• Gypsum eliminates calcium deficiency in the subsoil,
which is probably more important than subsoil aluminum toxicity in many Oxisols and Ultisols. Calcium must
be present in the soil around the root tips since it is not
translocated from the plant tops, as mentioned before.
• Gypsum increases the uptake of soil moisture from the
subsoil, preventing drought stress during dry spells in the
rainy season (veranicos in Brazil).
• The sulfate anions in gypsum form non-toxic insoluble
aluminum complexes, decreasing aluminum in the soil
solution and aluminum saturation in the subsoil as well.
• Nitrate ions not taken up by plants can rapidly leach
to the subsoil where they are captured by the anion
exchange capacity present in oxidic subsoils (see Chapter . Deep roots can capture this nitrate.
• Gypsum applications can decrease exchangeable Mg2+ in
the topsoil and move it downwards, necessitating dolomitic
lime on MgSO4 applications if the topsoil levels are low.
• Decreases in exchangeable K+ have happened occasionally
in fruit crops, but seldom in cereal crops, because crops
recycle leached potassium with their deep roots, promoted by gypsum, and add it to the soil surface as stover.
• Gypsum increases the sulfur content of forage, or cereal
stover that is used as forage, to the required level of 4 g S/kg
of dry mass (Chapter 15).
• The residual effects of gypsum surface applications can
last for at least 5 years in the subsoil.
• Crop yields often double, and the effects of more frequent
dry spells and rainfall variability, often attributed to climate change, are attenuated.
A summary of the effects is illustrated in Fig. 9.16. With no
gypsum, most of the roots were concentrated in the dry
topsoil. With the rate of 6 t/ha of gypsum, root distribution
with depth was more uniform, reaching 75 cm. Without
gypsum, nitrate “bulged” in the subsoil, no doubt due to
the anion exchange capacity of these subsoils. With gypsum,
the bulge disappeared because nitrate was taken up by the
maize roots. The best results occur when gypsum is applied
together with lime, preferably dolomitic.
Gypsum is now recommended for Oxisols, oxidic Ultisols
and acid, sandy Entisols and Inceptisols, which cover...