food crops basics: legumes
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( image sources: Pollinator and Adam Jones on wikimedia )
legumes! If you’re veggie/vegan you probably know what I mean already because these bad boys are very very important for us in terms of proteins.
Common legumes folks may encounter at the store include peanuts, soy/edamame, chickpea/garbanzo bean, beans in general, lentils. Legumes can be eaten by humans directly, also used for oil (peanut/soy), or grown for animal feed (clover/alfalfa). Some were used more historically (e.g. gorse) than nowadays, which can cause problems with the plants spreading and taking over other habitats.
They are very important in a lot of diets worldwide. The dried pulses can be stored for a long time without having to worry about refrigeration and such.
There are some really great things that legumes do for us, of course, context dependent.
1 ) as mentioned earlier: Legumes are a very great source of protein for vegan/vegetarian/etc diets, so often they are integral for people who want to reduce their reliance on CAFOs (factory farms) or animal agriculture in general. However, soy & peanuts (& legumes more generally) are major allergens, with many people not being able to be in the same room where legumes were cooked. Combined with wheat (gluten e.g. seitan) being a major allergen, a lot of culinary creativity is required to navigate low/no-animal diets for many people as legumes are so central.
2 ) also (and why legumes are so protein-rich): Nitrogen fixation. Briefly, nitrogen is a very common element in the atmosphere & it is very important for life (proteins, DNA, you name it!), but the atmospheric nitrogen (dinitrogen) form isn’t something most organisms can use. Dinitrogen is two nitrogens bonded together very strongly and only a few life-forms can break it into something useable (ammonia).
Many legumes are important nitrogen fixers as their roots have little nodules on their roots that are like “houses” full of bacteria that can break the dinitrogen bond. So legumes can turn dinitrogen into useful forms, and when a legume plant dies, that nitrogen is now available to other things around it.
Here’s a picture of the nodules on Wisteria, a pretty flower:
common ways of using this nitrogen include crop rotation and intercropping.
For crop rotation, legumes and non-legumes are grown in a field in an alternating pattern (also including fallow times where the field isn’t used for crops). Often, dead legumes are left where they are, sometimes legumes are mixed into the soil while still green (“green manure”). This means that the nitrogen they contain is available to the non-legumes grown in that field. Sometimes, fallow fields and pastures can be used as nitrogen-fixers in this way, as clover and alfalfa are eaten by animals while also providing nitrogen fixing.
Intercropping is growing multiple different crops in the same area. Nitrogen-fixing legumes & non-fixing non-legumes are mixed. For example, growing soybean around coconut, as the plants don’t get in each others way (e.g. blocking light), and making more efficient use of the space between coconut trees1. Also, using “fertilizer trees”, which are often legumes, but are basically trees that fix nitrogen that are grown amongst crops for harvest like maize2.
now this nitrogen fixation thing is great but again has some caveats.
One concern is with allergens, beyond just mentioned in ( 1 ) above. Sometimes intercropping (etc) can contaminate other crops with allergens, so legume-intercropping may cause harm to people with allergies3, not 100% clear on the risks & strategies here but it is something I see often discussed in disability circles around intercropping (not just with legumes). Legume allergies can be incredibly severe & allergies in general are a growing concern (correlated often with pesticide exposure4, …so often poorer/farmworker families…?). so this aspect needs to be addressed robustly & specifically.
Another concern is with nitrogen pollution. Nitrogen is great because it makes life possible but sometimes that life is algae blooms. fertilizers of all kinds can get washed out of a field and into a river or lake or ocean or whatever, where they fertilize algae that can be toxic on its own, or can cause major problems when it dies off and leaves the water an oxygen-deprived death gunk. industrial-scale legume production can cause this, even without irresponsible fertilizer application4. Growing tons of soybeans without intercropping and/or crop rotation means there’s a lot of nitrogen to be washed away, and often these soybeans are grown for animal feed in CAFOs, but changing their end-use w/o changing the ways they are being grown isn’t going to fix the issue here.
overall though, Very Cool Guys and we know how to incorporate legume agriculture & legume-eating into our lifestyle very well! There is still work to be done re:allergies but that can also be mitigated by examining the overuse of pesticides that is implicated in the rise of allergies (& cancer). there is a lot of potential & legumes are worth discussing and seeing what people have tried over centuries of legume cultivation.
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thanks for reading!🪱🦀
This post is dedicated to the guy from high school who would get very mad if he saw beans.Hope you’re doing well, king. (he did not like the taste of beans, fair, which became a funny melodrama in-joke upon demanding beans get removed from his presence).
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1 ) Nuwarapaksha, T D., Udumann, S S., Dissanayaka, D M N S., Dissanayake, D K R P L., & Atapattu, A J. Coconut based multiple cropping systems: An analytical review in Sri Lankan coconut cultivations. Circular Agricultural Systems 2022, 2:8.
2 ) Ajayi, O C., Place, F., Akinnifesi, F K., & Sileshi, G. W. Agricultural success from Africa: the case of fertilizer tree systems in southern Africa (Malawi, Tanzania, Mozambique, Zambia and Zimbabwe). International Journal of Agricultural Sustainability 2011, 9(1):129-136.
3 ) Kiær, L. P., Weedon, O D., Bedoussac, L., Bickler, C., Finckh, M R., Haug, B., Ianetta, P P M., Raaphorst-Travaille, G., Weih, M., & Karley, A. J. Supply Chain Perspectives on Breeding for Legume–Cereal Intercrops. Frontiers in Plant Science 2022, 13.
4 ) Frances Moore Lappé and Joseph Collins, World Hunger: 10 Myths, 2015.