Green beans in Farmstead World — crop in the game, and what it is on a real farm.
Green beans are the unripe pods of the common bean, a legume whose roots work with soil bacteria to fix nitrogen from the air.
A snap-bean harvest is mostly water and tender pods, so it draws lightly on nitrogen and potash — but pods are a phosphorus-hungry crop to fill, which is why a bean field is a good place to work phosphorus down.
A short history
Green beans are the young pods of the common bean, Phaseolus vulgaris, domesticated in Mesoamerica and carried around the world in the centuries after European contact. Breeders later selected stringless pods that snap cleanly, which is why the market class is called snap beans.
How it is grown
Beans are warm-season legumes: the seed germinates only in warm soil and the crop is killed by frost. Growers often inoculate seed with rhizobia so the roots nodulate and fix nitrogen, and they pick the pods young, while the seed inside is still small and the pod is tender.
Processing and uses
Snap beans are eaten fresh, frozen, or canned, and the freezing and canning trade takes the largest share of the crop. Because pods are picked before the seed fills, the harvest carries less nitrogen and potash off the field than a dry bean crop would — but the phosphorus in the pick still leaves with it.
Rhizobia bacteria living in nodules on legume roots turn nitrogen from the air into ammonia — fertilizer the plant gets from its tenants in exchange for sugars. (microbewiki.kenyon.edu)
The air is full of nitrogen, yet plants can't use it as it is: two atoms locked by a triple bond, which specialized microbes break at ordinary temperature and pressure. (ncbi.nlm.nih.gov)
Nitrogenase, the enzyme that fixes nitrogen, is damaged by oxygen, so legume nodules use an oxygen-binding protein called leghemoglobin to ferry oxygen to the bacteria while shielding the enzyme. (ncbi.nlm.nih.gov)
A clover or alfalfa stand can let farmers cut the nitrogen rate for the corn that follows by roughly 50 to 100 pounds per acre. (practicalfarmers.org)
A good stand of red clover can supply the corn that follows with roughly 60 to 120 pounds of nitrogen per acre, depending on the stand and when it is killed. (nmsp.cals.cornell.edu)
Peanuts aren't nuts — they're legumes whose pods form underground: after a flower self-pollinates, a 'peg' grows down into the soil and the pod starts developing there in the dark. (lsuagcenter.com)