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I read that Goji berries fix 60lbs of nitrogen in the soil per acre, does this mean that one plant will put 60 lbs into the soil, or do i need many plants to do this?

black thumb
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  • The title of your post is asking a completely different question from the body. Do you want a definition of nitrogen fixation, or do you want to know how many goji plants you need to fix a given amount of nitrogen? – Niall C. Sep 07 '20 at 21:50
  • the question is completely about nitrogen fixing in the soil – black thumb Sep 07 '20 at 22:03
  • A quick web search suggests that for commercial growing you would plant about 600 bushes per acre, so each bush is going to fix about 1 1/2 ounces of nitrogen per year. 60 lb per acre is a low figure for plants grown specifically to fix nitrogen. – alephzero Sep 07 '20 at 22:12

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If you are thinking that planting lots of plants with nitrogen fixing roots will increase nitrogen levels in your soil while they are growing, they will not. They will increase nitrogen levels IF you turn them into the soil - as they degrade (no longer functioning or growing) they will then release the stored nitrogen, see here https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/nitrogen-nodules-and-nitrogen-fixing-plants.htm#:~:text=As%20these%20plants%20decompose%2C%20they,beneficial%20symbiotic%20relationship%20with%20bacteria.

Bamboo
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  • how do fruit trees, and bushes fix nitrogen into the soil then if they're not tilled into the soil? – black thumb Sep 07 '20 at 23:24
  • They don't - they hold onto it in their roots while they live,clover being a good exampleof that process. – Bamboo Sep 08 '20 at 11:46
  • Why don't they say that it's nitrogen building, not nitrogen fixing or something similar then? – black thumb Sep 08 '20 at 17:24
  • I just came across this article on nitrogen fixing trees from a reputable source: https://www.permaculturenews.org/2015/10/20/introducing-nitrogen-fixing-trees-natures-solution-to-curing-n2-deficiency/#:~:text=Trees%20with%20the%20capacity%20to,add%20it%20to%20the%20soil. – black thumb Sep 08 '20 at 17:30
  • But even in that article in reference to trees, it says soil enrichment with nitrogen occurs when the tree dies... whilst plants with nitrogen fixing nodules may have the effect of the soil avoiding serious nitrogen depletion while they live, the real nitrogen hit is achieved once the plant dies. That is why people plant cover crops in winter such as clover and till them into the ground the following spring,when the roots, as they die,release all the stored nitrogen. – Bamboo Sep 08 '20 at 18:42
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    What about bean plants, I have heard (not from reputable source) that they don't need fertilizing because they "inject" their own nitrogen into the soil... not true? – Jimmy Fix-it Sep 09 '20 at 04:34
  • @JimmyFix-it Not exactly; many beans (if not all) have nodules on their roots that hold nitrogen from the soil, so they can feed themselves when growing, in theory; chopping them down at the end of the season and leaving the roots in situ means the stored nitrogen will then be released back into the soil. – Bamboo Sep 09 '20 at 11:43
  • so this is wrong: https://www.youtube.com/watch?v=jFxz4kkNRew – black thumb Sep 09 '20 at 19:39