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How would I determine which plants fix which nutrients into soil? Any resources?
I'm very on board with the concept of permaculture, and while I understand the concepts I don't have a good intuition for which plants fix which nutrients. For example suppose I grow basil in my herb garden.
How do I figure out which nutrients it will eventually deplete? How do I figure out a good buddy crop(s) to replenish those nutrients?
Any permaculturists out there that can point me in the right direction?
I don't think it's really helpful to get down into the micro scale as you're suggesting when it comes to nutrients and I don't think the data is necessarily there to support it. Like let's say tomatoes deplete more calcium than cucumbers do (I don't think this is true, but for the sake of argument). What fixes calcium into the soil? I don't know of any plants that make calcium more available in the soil. What can make it more available is supplementing with available forms (fishmeal for example), and ensuring the pH is on the more acidic side.
In other words the solution to lack of nutrients in a permaculture setting isn't companion planting, but to compost everything and use that compost to enrich your soil, slowly, over time. For the first few years using a good organic fertilizer should kickstart the process. Humans have been using animal poop as compost for thousands of years; if you don't have animals with poop you can fertilize with, you may need to continue to supplement with fertilizer.
While companion planting isn't really the answer to nutrient imbalance, it IS the best answer to a question you didn't ask - pest control. Sweet Alyssum attracts predatory wasps that kill tomato hornworm caterpillars. Basil deters thrips. Nasturtiums are a "trap plant" for beetles and slugs that otherwise would be munching down on your cabbages. There's tons of information out there on what to plant with what, so I won't reiterate it all here, although I did find this video entertaining as well as informative. Basically the tl;dr is intersperse all of your plantings together, don't do a huge pile of tomatoes with nothing else around it, but mix in flowers and herbs all throughout your garden to ensure a vibrant and healthy bed.
I think the biggest think to think about is to have a good combination of plants that extract nitrogen, and plants that introduce nitrogen. Nitrogen is usually the main problem in all of human history. So much so that several cultures suffered famines due to nitrogen depletion. Once cyclical farming was introduced (have corn one season and potatos the next one) people could grow food continually.
What I do is I try to ask my local store for "nitrogen enriching" plants to combine with my other plants to make sure there is a balance.
Interesting, I assumed there was more to it than just nitrogen.
AFAIK there aren't any nutrients beyond nitrogen that can be fixed into soil by plants. All the nutrients necessary would have to be introduced by fertilizer or dissolved in water. Nitrogen is the exception because it is a gas, so readily available in the atmosphere for fixation.
The main 3 nutrients are Nitrogen (N), Phosphorus (P), and Potassium (K). If you have ever seen a fertilizer that has three numbers on it, such as 3-3-3 or 10-0-5, those are referring to the amount/percentage of N-P-K in the fertilizer. Other elements, such as iron and calcium, are necessary for proper plant growth and survival, but NPK are used in much higher quantities and more easily depleted.
Nitrogen (N) is mainly used to produce foliage and helps makes the leaves green. If there isn't enough N in the soil then the plant will produce less leaves and the leaves that are grown may look yellow, which produces less energy from photosynthesis. Leafy plants, like corn/grasses, leafy greens, and bananas, will need more N than other plants.
Phosphorus (P) helps with root development and blooming. If there isn't enough P in the soil then the plant will have fewer flowers/fruits, and the roots will be weaker/fewer in number further restricting nutrient uptake. Root vegetables, like potatoes, would use more P than corn, as they are using the P to build roots to store energy/nutrients, that we then harvest. Plants that produce fruits, such as tomatoes or apples, need P to produce blooms which leads to growing fruit.
Potassium (K) helps the plant grow stronger. A plant with low K will be weaker and can fall over or break easier.
As far as I know, the main plants that can add any of those back to the soil naturally, and without you needing to amend soil yourself, are legumes (beans/peas) and clover. Legumes/clover have a symbiotic relationship with nitrogen-fixing bacteria, which take atmospheric Nitrogen (N2, unusable by plants), and turn it into something they can process. This is why farmers will alternate between corn and soybeans. Plant corn one year and use up N, next year plant soybeans to naturally add N, and then do corn the next year.
As long as you amend your soil with compost it should be really easy to prevent your nutrients from depleting. One super easy plant to use for composting is comfrey. It is known as a mining plant. It sends down really deep taproots, pulling up different minerals/elements that would otherwise be inaccessible to most plants. You grow the comfrey, cut leaves from it, and then compost the leaves or you can shred the leaves at the base of plants where they will decompose. It is super easy to grow and bees absolutely love the flowers (blooms from May to frost in Zone 5b). Just make sure to get a sterile variety (I grow the Bocking 14 variety), otherwise it will spread like crazy.
If you’re in the US, you can check if your state’s agricultural extension agency has a way to interact with experts. Some of those ag extension agencies provide great advice for landscaping and garden design and maintenance. I got some great help from mine (in MD) on picking out specific plants for permaculture and edible landscaping, for example.
Edit: permaculture, edible landscaping and native landscaping plants. They’re often big on that last one.
I'm Canadian
Yes, and how to go about this is what I'm asking
I don't know an awful lot about permaculture (I don't have a garden so I just read about it in wishful thinking kind of mode) but this article might be a good place to start. It links to a spreadsheet which has a lot of info, though interpreting it for your own needs might require a bit of heavy lifting.
I'm still a beginner at some of this, so keep that in mind. But I don't think Permaculture is about taking any plant you want, finding a companion, and expecting it to grow perfectly. It's more about figuring out plants that do well together in your conditions. So you might not find a perfect companion that will balance out what basil depletes. But you might find a series of plants that produce mulch and compost that will help you with your annual garden. Or you might find some natives or imported plants that do well in your conditions that are similar enough to basil to satisfy that need.
One tool that your title suggests you're looking for is this awesome cover crop tool: https://midwestcovercrops.org/covercroptool/
It might not work perfectly for your area--you might need to look elsewhere for information about when to plant and to ensure the plants are suitable for you--but it should give you an idea about your goals and what you could plant.
Also, have a look at the Balkan Ecology Project, particularly their "Biomass Belt," a garden whose purpose is primarily to produce biomass for mulch and compost so as to feed other gardens.
As for figuring out what nutrients particular plants need, you really just need to research that particular plant. I can't quite tell what your gardening knowledge level is (so forgive me if you're more advanced), but I know that when I first started with gardening, I just wanted to plant everything. I didn't have time to learn about each plant's needs because I wanted to grow as much as possible. There's nothing wrong with this, but I didn't have much success. Getting beyond the beginner level is all about doing research on each plant, growing it with successes and failures, and figuring out how to do it right. I'm not sure exactly what basil needs in particular...I'm still in the beginner phase myself with many plants, especially annuals!