Kvävefixerare – A compilation

We have learned much more about nitrogen fixation since this was published 2014 – Read this plunge first!

One of the key roles in the establishment of a forest garden is to provide the conditions for creating and maintaining their own fertility. In a previous post I wrote about Dynamic accumulators taking up minerals from deep soil layers and making them available to other plants. Although these minerals are essential for plant growth, is the nature of the rule the nutrient nitrogen is the limiting factor. In order to maintain a healthy growth of the plants in a forest garden, it is important to meet their needs for nitrogen, which primarily occurs through nitrogen-fixing plants. These plants symbiotic bacteria that has the ability to fix nitrogen from the atmosphere and can make it available for the plants in exchange of nutrients such as carbohydrates. The bacteria live in nodules attached to the roots of plants.

The nitrogen-fixing bacteria sits in nitrogen-fixing nodules on the plant roots.
The nitrogen-fixing bacteria sits in nitrogen-fixing nodules on the plant roots, that this alder (Alnus glutinosa).

The nitrogen fixed may be other, non-nitrogen-fixing plants benefit in several ways. During the growing season, it is mainly with the help of fungi that nitrogen is distributed in the forest garden. In a living soil, there are plenty of fungi with their hyphae (fine strands forming the fungal building blocks) connects various plant-root systems. The difference in concentration of nitrogen at different ends of hyphae allows the nitrogen automatically migrates from the nitrogen-fixing plants to those that do not have this ability, Thus from areas where there is plenty of nitrogen to areas where there is a lack of nitrogen. Because nitrogen is moved in the hyphae there is no risk of nitrogen leaching. The mushrooms also get nutrition in the form of carbohydrates from the plants thanks for the nitrogen they provide them with.

Nitrogen-fixing plants drop their leaves are often green, they do not need to withdraw nitrogen from the leaves of most other plants do, because they have a surplus of the important nutrient. Here is a leaf of Alder (Alnus glutinosa).
Nitrogen-fixing plants often release their leaves green, they do not need to withdraw nitrogen from the leaves of most other plants do, because they have a surplus of the important nutrient. Here is a leaf of Alder (Alnus glutinosa).

The nitrogen is also made available to other plants in the fall when the woody kvävefixerarna release their nitrogen-rich leaves and when the herbaceous kvävefixerarna dies down. This nitrogen runs slightly more likely to leach out and moreover it is not the fall nitrogen is needed most, but in the spring and early summer when the plant's growth occurs. A living soil with good interaction between microorganisms is thus indispensable for achieving the goal of self-maintaining fertility.

What plants are there for our climate that can help add nitrogen to the nutrient cycle in forest garden? The list below summarizes the Martin Gustafsson has made. It includes nitrogen-fixing tree, bushes, creepers, perennials, Bienne (perennial crops) and annuals (annual plants) with their names and where we have found the information even their nitrogen fixation ability. For woody plants also indicates resistance. The list includes such nitrogen-fixing plants that we find most useful in a forest garden context and of course there are many more kvävefixerare going to grow in Sweden. There are still some question marks remain and we are grateful for comments and additions!

 Scientific nameSwedish nameEnglish nameResistanceNitrogen Fixation Ability
TreeAlnus glutinosaEuropean alderCommon/European AlderZon IV/Vhigh
Gleditsia triacanthosHoney locustHoney LocustZon III (IV)
Gleditsia triacanthos 'Inermis'Honey locustHoney LocustZon IV
Robinia pseudoacaciaRobiniaBlack LocustZon IIImedium
ShrubsColutea arborescensBlåsärtBladder sennaZon IIIcreations data
Caragana arborescensSibirisk ärtbuskeSiberian Pea ShrubZon VIIImedium
Cytisus scopariusHarrisCommon broomZon IIIhigh
Elaeagnus multifloraJapansk silverbuskeGoumiZon III ?
Elaeagnus umbellataKorean silver shrubsAutumn OliveZon IV ?medium
Genista tinctoriaFärgginstDyer's greenweedSun V
Hippophae rhamnoidesHavtornSea BuckthornZon YOUmedium
Myrica galeFearsBog MyrtleZon YOUlow
Myrica pensylvanicaAmerican trackBayberryZon VII
Shepherdia argenteaBisonbuske / BuffelbuskeBuffaloberrySun Vmedium
TwistedAmerican apiosPotatisbönaGround NutLeast Sun IVmedium
Lathyrus latifoliusRosenvialEverlasting peaLeast Sun IV
Vicia pisiformisÄrtvickerPea VetchLeast Sun IV
PerennialsCLOVERWhite cloverWhite Cloverhigh
Trifolium pratenseRed cloverRed Clovermedium
Lotus corniculatusBitch ToothBird's Foot Trefoilmedium
Galega officinalisGetrutagoat's rue
Astragalus glycyphyllosSötvedelMilkvetch
Perennial LupinusGruslupinSundial
Trifolium mediumForest CloverZigzag Clover
Medicago sativaBlålucernAlfalfahigh
BienneMelilotus officinalisYellow melilotRibbet Melilotmedium
AnuellerTrifolium subterraneumSubklöverSub clovermedium
Lupinus angustifoliusBlålupinBlue Lupinhigh


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8 thoughts on “Kvävefixerare – A compilation”

  • I want to add gray alder that bind nitrogen as alder, but has the advantage that it thrives in a much larger part of the country.

    • Hi! Completely true that gray alder is hardy, but its drawback is that it sends out suckers and thus can easily take over a forest garden. Klibbalen shoot just ordinary shot and stays on so we place. Therefore, there Grail is not on the list.

    • Hi! First: thanks for table Philipp, very informative written!
      Subject alder: I still fairly limited knowledge about forest garden design, but thought I'd share with you my experience of alder in 60 old deciduous forest in a northern Aravin. Which I have not experienced that Grail shoot much suckers, or that it has taken over. Rather, it leaves room for other trees and shrubs (som asp, björk, hägg, raspberries, Currants). I would also guess that “Chop and drop” would work out in a northern forest garden situation on the Grail should happen to become invasive. An advantage of Grail – except that it is much hardier than alder in Norrland, is that it is relatively drought resistant and thus can be included for example to improve degraded soils with shallow root systems (old lawns on compacted soil, tex). Grail tolerates also pollarded, although it is a bit more sensitive than eg. alder and willow.
      Greetings January

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