Nitrogen fixation - a deep dive (From 4)

Then it was time for that right now the last post in the plunge about kvävefixerare forest garden, which is about how we can practically choose the best plants. Before that, however, I would recommend anyone who has read this series to also take a look at the many comments that have been received on the previous interventions, they are highly readable!

What is it that characterizes a good (vedartad) kvävefixerare? From what has emerged in the literature, I think that it is important to:

  • The plant bloom in early spring, to take advantage as much as possible of the incident sunlight during the spring and early summer.
  • The plant has a high growth rate. The more leaf mass produced, the more sugar can be supplied with the bacteria, resulting in yet more growth and even more nitrogen bound. To it must kvävefixerarna having high production capacity have plenty of water.
  • growth is fully vinterhärdig To reduce the risk of frost damage, that would jeopardize next year's leaf mass production.

With these criteria in mind, we can, for example, emphasize the honey locust (Gleditsia triacanthos) from List of nitrogen-fixing trees and shrubs. It turns out very late in the spring and miss an important part of the incoming sunlight. Japanese and Korean silver bush (Elaeagnus multiflora and IS. umbellata) are undecided in zone IV and north, because they can easily freeze cold winters. Last winter was reported freezings although the cultivation zone III IS. umbellata. Further south, these are very useful, and the silver deciduous shrubs are described in the literature as some of the best kvävefixerarna, Thanks to its easily soluble nitrogen that quickly becomes available for other plants and soil organisms [4].

Honey locust (Gleditsia triacanthos) is a beautiful and large tree with edible fear and impressive tags, but kvävefixerare can not be recommended in our latitudes.

Even porcelain and American porcelain (Myrica gale and M. pensylvanica) I deleted from the list. They may have their place in very wet soil, but their growth rate in the better locations are so low that they do not do much good, and rather can be replaced by other kvävefixerare.

How did the US myrtle (Myrica pensylvanica) when it was fairly newly planted 2014 and it has not happened much growth since then.

After this thinning list becomes rather shortened, which in a way is good, because it reduces the choices and make it less complex to choose appropriate kvävefixerare. At the same time it shows that it is well worth taking a closer look at the herbaceous kvävefixerarna and examine what contribution they can make to the overall nitrogen budget. This investigation is ongoing and I hope to show results for the forest garden nitrogen budget later this year.

 Scientific nameSwedish nameResistanceNitrogen Fixation Ability *Note
TreeAlnus glutinosaEuropean alderSun Vhigh
Alnus incanaGrey alderZon VIImediumSending suckers and are a pain in the warmer cultivation zones. Should only be used in Zone VI and VII.
Robinia pseudoacaciaRobiniaZon IIImedium
ShrubsColutea arborescensBlåsärtZon IIIcreations data
Caragana arborescensSibirisk ärtbuskeZon VIIImedium
Cytisus scopariusHarrisZon IIIhigh
Elaeagnus changedSilverbuskeZon VIImedium
Elaeagnus multifloraJapansk silverbuskeZon III ?highFirst in zone I-III
Elaeagnus umbellataKorean silver shrubsZon IV ?mediumFirst in zone I-III
Genista tinctoriaFärgginstSun Vcreations data
Hippophae rhamnoidesHavtornZon YOUmedium
Shepherdia argenteaBisonbuske / BuffelbuskeSun Vmedium

*according to [9]

This whole series is a result of the literature study in our research project entitled "Limitations and opportunities for forest gardening in Swedish climate" funded by the Royal Forest- and the Academy of Agriculture and is expected to be completed in spring 2018. More results we will post here on the blog ahead.

References

[4] Roggy, J.C., A. Moiroud, R. flew, and A.M. domains, Estimating N transfers between N2~-fixing actinorhizal species and the non-N2~-fixing Prunus avium under partially controlled conditions. BIOLOGY AND FERTILITY OF SOILS, 39: p. 312-319, 2004.

[9] USDA. Plants Database, Advanced Search and Download. 2017. https://plants.usda.gov/adv_search.html, Retrieved 2017.

10 thoughts on “Nitrogen fixation - a deep dive (From 4)”

  • Interesting in this context is of course also nitrogen-fixerarnas value as food plants by themselves.

    • Missing from the list Alnus glutinosa, alder which in my opinion have many advantages over gray alder. Shoots not suckers (!) , is much older and bigger (if you like), strongly virkesproduktion. Anything less hardy of course, but the zone 6 sufficient for most?

  • Silver Bush also shoots suckers so it is lovely to. It's something I personally can not stand the.

    • According hearsay and according Stångbys product catalog projecting Elaeagnus commtata (usual) suckers, but not Elaeagnus angustifolia (smalbladig). Do not know if it's true.

  • Taaaack for this series came the moment when I write essay on forest garden and design a small suggestion (“Sustainable school garden – a design proposal with forest garden modeled”). Good scientific references in the series of articles that I have read also!

  • I have had trouble finding Silver Bushes with varietal names. But today I finally found a dealer in Germany (deaflora.de) who had many different kinds of Elaeagnus umbellata. Now waiting with bated breath 4 various shrubs that will hopefully withstand some southern Swedish winter.

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