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Thread: Nitrogen fixation

  1. #1 Nitrogen fixation 
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    Do I undestend it correct that fixing Nitrogen from air requires
    in any case more energy than fixing it from soil or fertilizers?
    And therefore any plant which is growing with help of Nitrogen-
    fixing bacteriums will grow slower than plant which uses abundant
    mineral nitrogen-containing fertilizers?
    Or there could be some legumes which are able to fix Nitrogen from
    air almost without energy spending?


    Antislavery
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  3. #2  
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    I'm not sure what you're getting at here, but nitrogen fixing legume plants are killed by soils which are too rich in nitrogen - from any source. That's the mechanism underlying those feed&weed mixtures for grasses. You apply the mix, which is basically urea with a few other bits and pieces, and it kills the unwanted clovers in your grass, lawn, golf course or whatever.

    So whether anyone thinks the process is slow or inefficient is beside the point. The plant won't grow at all unless it's in a position where it can use those nitrogen processing soil enzymes to produce the nodules in the root system and end up producing the seeds - highly desirable, extremely nutritious beans and peas - ready for the next generation.


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  4. #3  
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    I meant comparison of different plans one of which fix nitrogen from
    air and others from fertilizers.Will the second group have advantage
    in speed of growth?Because to fix nitrogen from air a plant should
    spend more energy and have energy looses?
    Antislavery
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  5. #4  
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    Nitrogen fixing plants have no option - regardless of any impact this method might have on some abstract notion of 'efficiency'. As for fertilising soil by this method, it can work really well.

    One option is the 'three sisters' method. Three Sisters (agriculture) - Wikipedia, the free encyclopedia Grow these three crops together. one lot of water does for all the root systems, the nitrogen fixed by the beans fertilises the (quite greedy) corn and pumpkins, the large pumpkin leaves shade the soil and stabilise the moisture and temperature for the benefit of all 3 plants.

    They're all ripe and ready at the end of the season. Pick the lot. Put them all in storage and you're set for the winter.

    And it's obviously easily adapted to orchards and other perennial plantings. You just interplant the rows with groundcovers, small shrubs or coppiced trees and put down the nitrogen rich slash to fertilise and stabilise the soil for the cropping plants.

    The other option is green manuring. This is also cost free in terms of time, water and fertiliser. The soil should be given a break from repeated plantings of the same crop. If you put in a nitrogen fixing legume in the off growing season, you enhance the fertility by fixing the nitrogen. You also stabilise the soil and prevent erosion by wind or rain by not leaving the soil exposed and 'crowd out' weeds which might colonise the vacant soil. And the moisture holding capacity of the soil is improved for future seasons by the remnants of the green manure crop being dug in or merely left to decay back into the soil.

    There are modern versions like the CSIRO's 'clever clover' system. With this you just put the spring plantings straight through the dying seasonal clover. No weeds, wonderful soil. The perennial clovers and lucerne are probably better suited to an orchard or similar permanent planting.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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  6. #5  
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    I read that some scientists discussed possibility to create wheat which is
    capable fix nitrogen from air like beans.For example it could be done
    with help of genetic engineering.But later those works lagged because
    they came to conclusion that nitrogen fixation from air is energy intensive
    process and (as I assume) will slow down growth of wheat.But I not in
    course of those works exactly.The question is: if we could ultimately bread
    all plants nitrogen fixing like beans and completely eliminate need for
    nitrogen contained fertilizers.
    Antislavery
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  7. #6  
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    completely eliminate need for nitrogen contained fertilizers.
    Well, we're going to have to work out something to replace oil-based fertilisers. Long before we run out of it, oil will become far too expensive for widespread use on cropland.

    Getting started now on replenishing or enhancing soils - perhaps with bio-char mixtures in the terra preta style Terra preta - Wikipedia, the free encyclopedia - sounds like a pretty good idea to me. Certainly a whole lot more sensible than depleting them and having to constantly top up with irreplaceable fossil materials.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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  8. #7  
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    Certainly a whole lot more sensible than depleting them and having to constantly top up with irreplaceable fossil materials.
    Replaceable in a few million years
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