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Anyone considered growing cover crops /green manure'?

young codgeryoung codger Posts: 543
in Plants
I was reading up on this subject to see what farmers grow, and then plough back in to the soil.

From a farmers perspective, the gov article seems to say that there are benefits. While the plants are growing, they take nitrogen from the air, and it is transferred to the soil. The additional benefit of course is the decomposing plant material.

I was pondering the idea of growing some types of produce over winter, to simply use for composting material. The question I asked myself was this

"Is it possible that a crop produced solely for this purpose, could add more nutrients to my composting  interest than it actually takes from the soil while growing".

As I have an area of the garden that I don' use, it seems to make sense. Apparently brassicas are a good choice for this sort of thing. Over winter may be a time to try.
https://www.gov.uk/guidance/use-cover-crops-or-green-manure#about-cover-crops-and-green-manure

What do others think?



Posts

  • philippasmith2philippasmith2 Posts: 3,742
    I suppose it depends on the size of the area and why it isn't in use as part of the garden ?  Not being funny just wondering whether or not it could be put to more permanent use - wildlife habitat perhaps ?
    Growing cover crops, for whatever reason, would certainly be preferable to leaving bare ground if that is what you have at present.
    Maybe @Dovefromabove could advise on the ins and outs of it ?
  • young codgeryoung codger Posts: 543
    Thank you for your reply,

    "Is it possible that a crop produced solely for this purpose, could add more nutrients to my composting  interest than it actually takes from the soil while growing"?
  • Lizzie27Lizzie27 Posts: 12,494
    @young codger, I don't know, you'd need a soil scientist to answer that I think. 
    We did sow a green manure one year in one of our veg beds (we don't use any of them for winter veg) as an experiment. Don't remember if we came to any useful conclusion and now just cover them all with cardboard over the winter months.
    North East Somerset - Clay soil over limestone
  • Lizzie27Lizzie27 Posts: 12,494
    On second thoughts, Charles Dowding might have some ideas on that if you've got any of his books.
    North East Somerset - Clay soil over limestone
  • barry islandbarry island Posts: 1,847
    I tried growing tares sown late summer to over winter they didn't grow as thickly as I had hoped to shade weeds out, they needed digging in before they flowered in the spring and then they add a chemical to the soil as they start to decompose which prevents other plant seeds from germinating so I couldn't use the soil for a month after digging them in. I used the green manure method for a couple of seasons but gave up as it didn't suit my needs. As for growing crops to compost I have plenty of weeds/vegetable waste to fill my composters.
  • robairdmacraignilrobairdmacraignil Posts: 782
    The plants that take nitrogen from the air include legumes that have a bacteria associated with the roots in nodules that fix the nitrogen gas in a form that the plants can use. The plant provides food for these bacteria and benefits from the nitrogen being available for improved growth and the relationship is a classic example of symbiosis where both organisms benefit each another. Clover is an example of a plant that does this and peas and beans would also be common crops that employ this type of growth. These types of plant are specifically better as green manures as the nitrogen they build up in the plant tissue can come from the air and so would not have been in the soil without that crop being grown.

    Heavy rain can wash nutrients out of soil if it is not protected by plants so even non nitrogen fixers can be used as a green manure as they will lower the amount of nutrients eroded out of the soil and lost to future plants to be grown there. The green manure will take nutrient from the soil as it grows but all of these should go into your compost and are not lost as might happen if the ground was bare. Brassicas are good for overwinter green manures because they can often grow strongly in colder conditions than other options.
    If you are talking about creating an area just to continually produce material for compost then maybe Comfrey might be worth considering. It is dormant over winter but the deep roots take nutrients from parts of the soil that shallower rooted crop plants can't get to. I have it combined with clover and birds foot trefoil which also is a nitrogen fixer and these soil improving plants also provide good flowers for pollinators.

    Happy gardening!
    https://www.youtube.com/user/sustainableveg/videos
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