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posted by Fnord666 on Tuesday May 29 2018, @04:35AM   Printer-friendly
from the like-a-bad-penny dept.

Submitted via IRC for guy_

Plants, like all living things, need nitrogen to build amino acids and other essential biomolecules. Although nitrogen is the most abundant element in air, the molecular form of nitrogen found there is largely unreactive. To become useful to plants, that nitrogen must first be "fixed," or busted out of its molecular form and linked with hydrogen to make ammonia. The plants can then get at it by catalyzing reactions with ammonia.

But plants can't fix nitrogen. Bacteria can.

Some legumes and a few other plants have a symbiotic relationship with certain bacterial species. The plants build specialized structures on their roots called nodules to house and feed the bacteria, which in turn fix nitrogen for the plants and assure them a steady supply of ammonia. Only 10 families of plants have the ability to do this, and even within these families, most genera opt out. Ever since the symbiosis was discovered in 1888, plant geneticists have wondered: why? If you could ensure a steady supply of nitrogen for use, why wouldn't you?

A global consortium of geneticists sequenced and compared the genomes of 37 plants—some symbiotic, some not; some that build nodules, some not; some agriculturally relevant, some not—to try to find out what was going on. The group's genetic analysis of the conundrum was reported in Science.

Source: https://arstechnica.com/science/2018/05/plants-repeatedly-got-rid-of-their-ability-to-obtain-their-own-nitrogen/


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  • (Score: 1) by anubi on Tuesday May 29 2018, @10:09AM (1 child)

    by anubi (2828) on Tuesday May 29 2018, @10:09AM (#685516) Journal

    One thing I have where I live is "adobe" soil... stuff seems to set up like concrete. Really hard to dig in. Seems like even the earthworms can't work in it unless its been raining for several weeks.

    It seems that as I have been slowly increasing soil acidity, this seems to be breaking up, but so far I drop down two inches and again hit really hard soil.

    Think if I keep the soil above acidic, it will work its way down so my plants can get a decent rooting? My neighbor recently had a well-drilling outfit come over so he could plant an avocado tree, and he had the well driller sink him a hole to the water table with the intention that if he gets the tree to start its roots straight down, they won't fan so much right below the top, and leave his tree vulnerable to being blown over during Santa Ana wind conditions.

    I understand that alkali soil will lock up minerals as insoluble carbonates, but slightly acidic conditions will release the minerals, and will disintegrate the concrete-like structure that makes the soil so inpenetrable.

    I know I am a little off topic here, but its farming, and I think you probably have seen stuff like this. Me, I'm running on gut feeling about what to do. I'm ok on book learnin' but sorely lacking in field experience.

    --
    "Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
  • (Score: 3, Informative) by c0lo on Tuesday May 29 2018, @11:15AM

    by c0lo (156) Subscriber Badge on Tuesday May 29 2018, @11:15AM (#685531) Journal

    One thing I have where I live is "adobe" soil... stuff seems to set up like concrete. Really hard to dig in.

    Same experience with a plot I bought at countryside. About 100 years ago, it used to be eucalyptus forest, then transformed in a grazing plot, but without too many amendments. The base rock is mainly quartz and in my case the pH is already at 6.5.

    I understand that alkali soil will lock up minerals as insoluble carbonates, but slightly acidic conditions will release the minerals, and will disintegrate the concrete-like structure that makes the soil so inpenetrable.

    Without organic matter into the soil, the results will only go that much - see my case above.
    And not all salts will be soluble - e.g. hydrated calcium sulphate (gypsum) is very weakly soluble even if its presence will improve a bit the water penetration.
    As the pH improves, I'd suggest to try some green manure [wikipedia.org] cultures for a year or two - e.g. lucerne tends to develop deep roots (20 inches is not that unusual) and those will remain as organics in the soil for longer.
    This one [wikipedia.org] if you feel the need for some trees around

    I'm ok on book learnin' but sorely lacking in field experience.

    See what you can find here [uniteddiversity.coop] - this one is a classic [uniteddiversity.coop], this one [uniteddiversity.coop] as well even if a bit outdated (there are some more recent authors that went deeper). See other things to read in the same permaculture folder.

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford