Stratification: Oh God, What IS This?
Stratification I find to be the most confusing tenet of syntropic agriculture. For one thing, it’s still being fine-tuned by the creator of syntropic agriculture, Ernest Gosh. The actual inventor of the agricultural system that we are talking about isn’t completely sure how it works. For another thing, this tenet of syntropics deals with plant niches, which are still not fully understood.[1] So yeah, this should be a super fun section, full of exact scientific knowledge with nothing left up in the air. But as it says in the header, “let’s grow together” so I will do my very best to tell you everything I know, and we can learn the rest as a team.
When we grow, both as plants and as people, we must be aware of the level of competition in our lives. Now, for people, sometimes competition can be a good thing: it pushes us to do better, become motivated, put in our best effort, ect. But for plants (and most other creatures on Earth) intense competition can be a detriment. Plants are not competing the same way humans do, for first place in a swim meet, or the department bonus at the end of the year. Plants, when they compete, are competing for their lives. In every environment, there are finite amounts of resources. There is finite sunlight (confused about how this could be true? Think about taking a walk through a sunny field as compared to a walk in a shady forest), water, and soil nutrients. When plants have to compete for these resources, it stunts the growth and development of plants. As you can imagine, when you are trying to grow mass amounts of food for a human population, plant competition could be seriously detrimental. In syntropic farms, it is the manager’s job to figure out how to plant a variety of plants without making them compete for resources.
The key framework that managers and farmers use to avoid competition between plants is called stratification. Stratification, the third tenet of syntropic agriculture, focuses primarily on sunlight as a resource. Before I start to talk about stratification (I’m getting there! I promise) I want to briefly address why sunlight is the main consideration for syntropic farmers. Why not soil nutrients? Why not water?
Plant species have an amazing ability to pull nutrients from the soil through their roots. As I have talked about previously, one of the main goals of syntropics is to nurture and support healthy soil. The best part about this? Plants do it on their own. The coolest part about this? We don’t really know how![2] The current best guess is the plants do this through root exudates, which is basically root juice. Plants give off this root juice through their (you guessed it) roots, and it somehow influences the healthy microbes around them to help stop harmful microbes from growing. How this information gets communicated to the microbial networks, scientists are currently not sure.[3] Philosophers also don’t know. I asked one to make sure I covered my bases. Despite not understanding how, scientists are in wide agreement that plants, left alone, will largely make the soil that is best for them and their specific nutrient needs.[4][5]There is some evidence that biological pest controls, such as fungi that kill bugs, can impact the microbes in the soil. But they do so in a positive way! In one recent study, scientists found that introducing one specific fungus species Metarhizium, not only helps with pest control, but also increased the number of plant-growth bacteria in the soil.[6] One specific one that increased was a type of nitrogen fixing bacteria, which is very important for plants.
Essentially, this means that if farmers are fostering a positive soil environment, which they can do by following the tenets of syntropic agriculture, then they really don’t have to worry all that much about competition for soil nutrients. Farmers also control the amount of water plants receive through irrigation techniques, so plants shouldn’t have to compete for water. I suppose plants could still be drowned by water if there is a huge rainstorm or flood, but acts of nature are largely beyond the control of any one farmer or farm. I say “largely” because I don’t know everything that exists and if some weather-warping witch runs a small farm in Nebraska, I certainly don’t want to offend her. You’re valid, witch. But generally speaking, syntropic farmers shouldn’t worry about soil nutrients or water. That only leaves one thing that plants could compete over: sunlight.
And now, at long last, we are at stratification. Stratification is a system used by syntropic farmers to make sure that every crop planted gets the right amount of light for that crop. Some crops need a lot more light than others, and a large part of the challenge in arranging syntropic rows is making sure that every crop has adequate light. Stratification separates plants into five different categories, or strata, based on sunlight needs.
1. Emergent plants, which need constant or near-constant sunlight
2. High plants, which need a lot of sunlight, but less sun than emergent
3. Medium plants, which need occasional sunlight
4. Low plants, which only need some sunlight or scattered sunlight
5. Ground cover plants, which need the least amount of sunlight
Now, emergent plants are also normally quite tall, because they are reaching up towards the sun. Practically, this means that you can’t plant an emergent plant next to a high plant, because the emergent plant will block out all of the sun for the high plant. However, you could plant an emergent plant with a low plant, because the sunlight filtering through the emergent plant would be enough for the low plant. In this scenario, the emergent would actually shield the low plant from getting too much sun, so they work together really well. The same relationship works for high plants and medium plants.
So how do we know which plants are which? The answer to this question, as with so many other questions, can be found by studying the natural environment. For example, you will often find blueberry bushes growing at the edge of forests. This would imply that blueberries seem to thrive in medium to low light conditions because the tall trees of the forest would block out some light. Blueberries then, are likely a medium-low plant, and would not do well in the baking sun. Classifying plants as emergent, high, medium, low, or ground cover is way more complicated than I would like, as the light needs of the same plant could change based on the environment it is in. For example, in Australia, raspberries are a low-level plant, but Australia gets more powerful UV rays than New England.[7][8] In New England, raspberry plants grow best in a median level of light. Also, there is no database for this system of strata classification because syntropics is a relatively new way of farming. To me, the difficultly of placing plants into strata is one of the highest barriers to implementing syntropic agriculture. To properly identify a plant’s strata, one must have an intimate knowledge of not only the conditions a crop prefers but the conditions it prefers in the environment that it is in. That’s a tall order. I do not fit the bill, and I think I would be hard-pressed to find anybody who does.
But we will move on from that slightly depressing thought, and go instead to a happy, rosy world in which we do have all of the correct information about our crops’ strata. How do we know how much of each type of strata to plant? I like to think about the strata as a broken five-tiered fountain. The rain that falls is the sunlight, flowing down through each of the five strata. The tier that catches the rain first has to, by default, be the smallest because the water would overflow and then move down to the next tier, just like sunlight would do. The tallest tier represents emergent strata. The number of emergent strata that you plant has to be small enough to allow light to go down to the rest of the plans, just as the small top tier of the fountain fills up and then overflows. The next tier would be the high strata plants, the next the medium strata, then the low strata, and finally ground cover plants, which would be the bottom of the fountain, absorbing all of the water that made it down the other four tiers. Just as the size of fountain tiers needs to allow water to trickle down and fill the rest of the fountain, plant strata need to be in a ratio that allows sunlight to trickle down and support each crop.
The exact percentage ratios may change, but Ernest Goshe, the creator of syntropy, recommends that you start with 20% emergent, 40% high, 60% medium, 80% low, and 100% ground cover. This adds up to more than 100%, but it’s designed to. The percentages are not in relation to each, but rather the overall amount of space that it is possible for the crops to be planted in. For example, if you were planting an emergent crop, and had 100 acres to do so, only you should actually only plant 20 acres of the emergent crop, which is 20% of the “available” space. In syntropic agriculture, different crops are planted in and around each other — remember the initial idea that syntropic farms should look like forests, not farmland. The 80 acres that are not being planted with emergent crops may seem like an empty space, but keep in mind that the emergent crops will be spread out among the farm, and other crops planted around them.
On the other side of the spectrum, ground cover should take up all the space available to it and should be planted at a ratio of 100%. Ground cover is essential to the workings of a syntropic farm (for a remind why see here), and it also does not block out sunlight for any other crop below it. It receives as much sunlight as possible, kind of like the pool at the bottom of the fountain. The other strata, high, medium, and low, operate in the same way as emergent does, with varying levels of planting depending on the strata. It could also be the case that these strata-planting ratios need to change given the specific environment the syntropic farm is in. Right now, all of the recognized syntropic farms are in tropical climates, namely Brazil and Australia, but as the method spreads to more temperate zones, it may need to change. Stratification is complex and still in development, but I have given you all I currently understand about it. If I understand more later, I promise you’ll be the first to know.
With an appreciation of soil bioengineering,
Ajah
[1] Silvertown, Jonathan. “Plant Coexistence and the Niche.” Trends in Ecology & Evolution 19, no. 11 (2004): 605–611.doi:https://doi.org/10.1016/j.tree.2004.09.003. http://www.sciencedirect.com/science/article/pii/S0169534704002630.
[2] Jacoby, Richard, Manuela Peukert, Antonella Succurro, Anna Koprivova, and Stanislav Kopriva. “The Role of Soil Microorganisms in Plant Mineral Nutrition-Current Knowledge and Future Directions.” Frontiers in Plant Science 8, (2017): 1617. doi:10.3389/fpls.2017.01617. https://pubmed.ncbi.nlm.nih.gov/28974956 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5610682/.
[3] Jacoby, Richard, Manuela Peukert, Antonella Succurro, Anna Koprivova, and Stanislav Kopriva. “The Role of Soil Microorganisms in Plant Mineral Nutrition-Current Knowledge and Future Directions.” Frontiers in Plant Science 8, (2017): 1617. doi:10.3389/fpls.2017.01617. https://pubmed.ncbi.nlm.nih.gov/28974956 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5610682/.
[4] Lei, Haiying, Ake Liu, Qinwen Hou, Qingsong Zhao, Jia Guo, and Zhijun Wang. “Diversity Patterns of Soil Microbial Communities in the Sophora Flavescens Rhizosphere in Response to Continuous Monocropping.” BMC Microbiology 20, no. 1 (2020): 272. doi:10.1186/s12866–020–01956–8. https://pubmed.ncbi.nlm.nih.gov/32867674 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7457492/.Top of FormBottom of Form
[5] Cavalieri, Andrea, Frederik Bak, Adriana Garcia-Lemos, Jacob Weiner, Mette Haubjerg Nicolaisen, and Ole Nybroe. “Effects of Intra- and Interspecific Plant Density on Rhizosphere Bacterial Communities.” Frontiers in Microbiology 11, (2020): 1045. doi:10.3389/fmicb.2020.01045. https://pubmed.ncbi.nlm.nih.gov/32528445 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7264394/.
[6] Barelli, Larissa, Alison S. Waller, Scott W. Behie, and Michael J. Bidochka. “Plant Microbiome Analysis After Metarhizium Amendment Reveals Increases in Abundance of Plant Growth-Promoting Organisms and Maintenance of Disease-Suppressive Soil.” PloS One 15, no. 4 (2020): e0231150. doi:10.1371/journal.pone.0231150.
https://pubmed.ncbi.nlm.nih.gov/32275687 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7147777/.
[7] Pers. Comm. Neil Hawes. October 20th, 2019.
[8] “From Australia to Brazil: Sun Worshippers Beware.” Bulletin of the World Health Organization 87, no. 8 (2009): 574–575. doi:10.2471/blt.09.030809. https://pubmed.ncbi.nlm.nih.gov/19705004 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2733274/.
