Polycultures

~namlur-foprus

The benefits of polycultures boils down to two principles: Interaction and niche occupation.

Interaction is when the activity of any element in a system (over space or time) changes the context for another element of the system. Grass exudes sugars into the soil, fungi grow on thsoe sugars, critters eat the fungi, other fungi populate the corpses of those critters, bacteria break down the fungi populating the corpse, that bacteria is sucked up by the plants during the rhizophagy cycle which helps the plant build more biomass to capture more sun to exude more sugar and we're back at square one. This process of recycling energy and resources between things occupying similar space and time can also be a negative; fortunately, most associations in nature are neutral or positive. There are a few negative ones (consider juglone from black walnut as a good example of allelopathy (a negative interaction)) but coevolved species may have certain immunity to these (there are plenty of things you can grow alongside black walnut).

Niche occupation is about capturing every possible resource and recycling as much energy as possible, this is the reason the explosive diversity of well made slow compost rich in not only fungi by volume, but fungi species, is so powerful.For more on that, search Johnson-Su Bioreactor. When very possible niche is occupied, the amount of resources and energy being recycled through a system is maximized, which increases the availability of that resource and energy for any element in the system. If you have a fungi that is good at unlocking phosphorous into a plant available form, then you have increased the bioavailable phosphorous to all elements similarly occupying space and time, which in turn may result in superior growth, increasing the availability of inputs that fungi requires, and now we're back to positive interactions.

How do you take advantage of these two principles in repeatable patterns to benefit your ability to capture energy and resources, and transform them into yields that you value?

Mixed cover crops - Maximize your soil building and biomass creation

The goal of cover crops is to maintain life in the soil around the year, not just during the growing season. Fallowing is a bad idea and should be avoided. A cover crop of a grass before planting a field of corn doesn't make a lot of sense, as you are creating more competition for scarce resources, and being a mnonoculture, you're not providing a diversity of interactions to rebuild those scarce resources. One lifeform's waste is another lifeform's food, that means you need enough lifeforms everyone has some poop from someone else to eat. That simple.

Cover crops utility explodes alongside their diversity as they provide more types of food for life at all scales (from bacteria that form relationships with only a certain species, to yielding habitat and food for birds or spiders). A 50 species cocktail of everything you can find is far superior to growing clover and rye when you're not growing cash crops, every niche has a chance to be occupied, and this is a strategy that is particularly robust to changing weather conditions.

A dry year is not a problem when you have a few species that will thrive in dryer soil, a hot year is not a problem when you have a few species that will thrive in the heat. The objective of a diverse cover crop is not the HR-approved static diversity where each field must perfectly match the ratio of seeds sown; the objective is that whatever can find a niche will occupy it, because the more life in any field, the more sunlight being captured, is more soil being built for when your cash crops go in. If you're raising livestock on pasture, the added benefit of a well selected cover crop mix is that you can provide diverse nutrition to your animals; this includes certain herbs that may have immune boosting and protective effects to help your friends and employees (the livestock) live healthier; and, as we know, a healthy animal has healthy meat for market. Combining the reduced selectivity of herd grazed frequently rotated cattle with a diverse feed selection improves weight gain, as well as animal health; no surprise that the more we mimic nature, the closer we get to nature's outstanding results.

Every year your cover crops should look different, in different microclimates, they should look different, that's system level adaptation, and that's the goal - maximum sunlight capture means everything downstream from light (all life) has more to work with overall.

Layers

Anyone familiar with permaculture has likely heard of food forests, which are based on niche occupation in volumetric space, not just area space (a 'flat field' thinking) as a field of crops (although mixed fields begin to resemble micro-forests in their own right), as well as over significantly greater time spans (consider that some trees may live for centuries). In other more normal people words, they use trees. The general break up is big trees, smaller trees, shrubs, herbs, ground covers, roots, and vines. I think it is worth adding edible fungi in there too; there are other layers in scale and depth that effect the overall success of the food forest, but if we're focusing on the things we can seed and that produce direct yields, the 8 (7 layers + fungi) above are the most relevant.

The issue of sunlight in layers becomes very important, it is about creating and controlling the right amount of shade for each layer further down, as well as creating good microclimates for certain species. If you have a sun loving species under a tree, it may be best to place it towards the equator side to maximize the light it gets. If you have a herb layer species that needs huge amounts of sunlight, you will need to create a clearing with enough light for it to thrive. Plants grown in well planned layers may appear to require less light than grown alone, this is due to the massive number of positive interactions in microclimate and soil life happening that is invisble to us, sometimes you can achieve a 1 + 1 = 3 because the interaction between subsystems creates a whole greater than the sum of the parts.

The power of layers is that you can mix and match to your circumstance, if you live in the tropics, it may be better to have several further subdivisions of large trees from truly massive canopy trees down to small coffee trees; if you live in an arid climate, you may only be able to support a limited collection of woody species in your system; the point of layers is to stretch your thinking from time in seasons and space in area to time in centuries and space in volume.

Companions and guilds

Companion plants, or guilds of companion plants is an intentional design strategy of observing the interaction between plants and arranging them to maximize the positive interactions. Leaving a garden go a bit feral for long enough will naturally lead to the formation of guilds and companions, but if your gardening style is more manicured and controlled, you might enjoy playing tetris with your species.

There is a good list on wikipedia of companion plants, and a few resources on guilds; but guilds complexity lends them towards being context dependent, which means you will need to begin to experiment with what works in your context specifically. The most well known guild is the three sisters of beans, squash, and corn. The squash provides ground cover (nice cool shady soil, reduces erosion by slowing water, reduces evaporation etc) and protection from some animals due to it's small thorns, the corn provides a trellis up which runner beans can be grown. This same format can be extended in many ways, experiment with different cucurbits, different tall fast growing species (sunflowers are an aesthetic alternative to corn), and different climbing species. People mention the nitrogen fixing capability of the beans in this situation; but when you allow legumes to fruit they use most of the nitrogen locked up by their bacterial root nodule friends, maybe there's more to nitrogen in the soil than the limited amount we can measure when we take it back to the lab eh?

Agroforestry Strategies

Food forests - Succession planning is important here, you may start by planting annuals and a few small saplings, but 15 years later, you are likely to have less of a garden and more of a large orchard of fruit and nut trees. I would encourage anyone with space they are unsure of how to best utilize to begin ramming as many seeds from as many species with yields they value into the ground, and let your context decide how your food forest looks. Food forests with wild animals or livestock integration represent the peak of polycultural design, and you will observe that they are an anologue to a species-selected wilderness if you were to have the space and time to let it develop. Control is most easily exerted by selecting out, not selecting in. This means cutting a tree down once it gets too old and yield tapers off (great, more space for annuals until it's replacement grows back), and thinning undesirable or inferior species. The system that you are optimizing is the forest, not any particular tree. Regular introduction of outside species helps avoid developing over selected communities within the forest, and if you don't like them - select them out. Food forests produce a lot of woody debris as they mature, so you will be richly rewarded for learning to use saprotrophic fungi to compost your woody debris into edible mushrooms. Chop and drop style composting also becomes an option as your soil explodes with life in the growing forest, which is a great low effort way to keep plants at whatever stage of growth you want them to be.

Silvopasture - Growing your pasture between trees is almost always a better idea than open pasture, especially in environments that are prone to powerful weather events. You will need to protect the trees from livestock for the first few years of their life, but once they are large enough, they will provide: Shade(pasture yield with the right shade % for your context is higher than with 0% shade in almost every environment), fodder (potentially), erosion control (wind or water), improved soil health, habitat for biodiversity, firewood, timber (if you manage them, your cattle pasture can also yield furniture grade timber), and of course: aesthetics. If in doubt, the mighty oak normally has a species suited to your context that will provide a wealth of positive interactions. Depending on your livestock, your trees can be a good source of supplemental feed - consider the spanish dehesa systems.

Windbreaks - Using trees to diffuse harsh winds can be especially important in arid climates to reduce erosion and humidity loss. These trees can be selected to stack functions by also providing yields such as fruits, nuts, or timber. Alley cropping - Delineating alleys of shorter lived crops between rows of trees, this is a lower investment strategy for crop farmers to begin reaping the benefits of trees in their systems, whilst being a great financial diversification of income streams, and if arranged correctly, provide many of the benefits of windbreaks.

Summary

Hopefully that's convinced you, even a bit, that you should be (where possible) getting rid of the monocultures; they take more inputs, utilize fewer resources, compete for more of the same resources, and produce far fewer positive externalities. If you have mechanized crop harvesting, you may have to separate your crops into beds or alleys, and rotate them through time instead of have them diverse in both space and time. If you're a home gardener, I hope you will consider letting go of the idea of perfect straight lines, rows of soldiers, and bare soil under your roses type thinking. If you're ever in doubt, a mulberry tree if you've a lot of space, or some clover as ground cover in the garden beds. Grassholes are for assholes, plant some flowers; the bees will thank you. References

This list is short, inadequate, and hastily put together (just like this post):

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