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8 forms of capital active hope agroecology agroforestry alder buckthorn Amazon anxiety apples arthritis back yard beans Bec Hellouin beech tree bees beneficial berries biochar biodigester biodiversity blackberries blackthorn book review brain brassica cage budget build building campesino capital card deck Celtic festivals change changes chemical-free chickens christmas circular clay pot cleansers cleansing milks climate change climate emergency climate grief climate solutions climbers climbing cob comfrey community compost compost teas connection consciousness conservation container cooking coppice coppicing cordial cosmology courgettes crafts crisis crop protection Cross Quarter Festival cultural emergence culture cycles degraded design diary diversity DIY do it yourself dryland earth care Earth's energy ecoculture economics ecopoetry ecosystem ecosystem restoration camps ecosystems edges edible edible flowers education efficiency elder elderflowers elements elixir energy equinox ethics face mask fair shares Fairtrade farming feedback feminine ferns figs film firewood flower essence flowers food food forest food garden footbath forage foraging forest garden forest gardening forests fruit fruit leather fruit trees fungi future future care gardening garlic gift economy gin Give Nature a voice Glennie Kindred global poverty glut grapes greenhouse grief groundcover grow grow food grow your own growing guilds habitat habits handcream harvest harvests hawthorn hazel hazelnut healing shrubs healing trees health healthy soil heart health hedgerow hedging herbal herbal remedies herbal teas herbalist herbs holistic holistic planned grazing home homeless homemade wine homestead hope Hugelkultur humanure hummus hungry gap IBC tanks Imbolc incense increase yields Indigenous inexpensive influence inspiration International Womens Day jam keyline kitchen garden lacto-fermentation Lammas land landscape landscapes life lifestyle limeflowers livelihood livestock living labs logs lotion low cost low-impact Lush Spring Prize macerations Mangwende Orphan Care Trust market garden market gardening marmalade marshmallow mass heater meadowsweet medicinal microbes microfarm mimic mindset mitigation money moringa Mother Earth mulch multifunctional mushrooms native plants natural natural building natural fertiliser natural skincare natural swimming pool nature nature connection nitrogen no dig no waste no-dig November nutrition nuts observe oca October off-grid oil cleansing orchard orchards organic organic gardening outdoor shower oven oxymel oyster pallets pasture-fed patterns people people care peoplecare perennials permaculture permaculture design permaculture magazine award permaculutre permayouth pesto pests philippines pine tree pips pizza oven plant profile plants pollinators pollution polyculture polycultures preserving principles propagating protection pruning prunings psycho-spiritual awareness psychospiritual transformation rainforest rainwater raspberries recipe recipes reduce reed beds regeneration regenerative regenerative agriculture relative location relative matter remedy renewable renewable energy resources restoration reuse revolution rhythms rootstock rootstocks roundhouse roundwood runner beans sage salad salve Samhain schools Scotland scotts pine seasonal seasons seeds selfcare Sepp Holzer september septic tanks sewage treatment shade sheet mulching shrubs skincare sloes slugs small solutions small-scale smallholding social justice soil health solar solutions sowing spiritual spring squash stacking functions stock-free straw straw bale summer sustainable Sweet Bay syntropic systems temperate terraces thistles thrutopia timber timber framing tincture tonic toolkit tools transformation trees upcycle urban veg garden vegan veganic vermicomposting vinegar walnuts waste water water cleansing watering weeds wellbeing wetland wild edges wild food wild garlic wildflower wildlife wine recipes wings winter winter greens winter salads wood stove woodburner woodland woodland management woodlands worms yarrow year-round food yield young people youth zai pits zone 00 zoning

Topics

8 forms of capital active hope agroecology agroforestry alder buckthorn Amazon anxiety apples arthritis back yard beans Bec Hellouin beech tree bees beneficial berries biochar biodigester biodiversity blackberries blackthorn book review brain brassica cage budget build building campesino capital card deck Celtic festivals change changes chemical-free chickens christmas circular clay pot cleansers cleansing milks climate change climate emergency climate grief climate solutions climbers climbing cob comfrey community compost compost teas connection consciousness conservation container cooking coppice coppicing cordial cosmology courgettes crafts crisis crop protection Cross Quarter Festival cultural emergence culture cycles degraded design diary diversity DIY do it yourself dryland earth care Earth's energy ecoculture economics ecopoetry ecosystem ecosystem restoration camps ecosystems edges edible edible flowers education efficiency elder elderflowers elements elixir energy equinox ethics face mask fair shares Fairtrade farming feedback feminine ferns figs film firewood flower essence flowers food food forest food garden footbath forage foraging forest garden forest gardening forests fruit fruit leather fruit trees fungi future future care gardening garlic gift economy gin Give Nature a voice Glennie Kindred global poverty glut grapes greenhouse grief groundcover grow grow food grow your own growing guilds habitat habits handcream harvest harvests hawthorn hazel hazelnut healing shrubs healing trees health healthy soil heart health hedgerow hedging herbal herbal remedies herbal teas herbalist herbs holistic holistic planned grazing home homeless homemade wine homestead hope Hugelkultur humanure hummus hungry gap IBC tanks Imbolc incense increase yields Indigenous inexpensive influence inspiration International Womens Day jam keyline kitchen garden lacto-fermentation Lammas land landscape landscapes life lifestyle limeflowers livelihood livestock living labs logs lotion low cost low-impact Lush Spring Prize macerations Mangwende Orphan Care Trust market garden market gardening marmalade marshmallow mass heater meadowsweet medicinal microbes microfarm mimic mindset mitigation money moringa Mother Earth mulch multifunctional mushrooms native plants natural natural building natural fertiliser natural skincare natural swimming pool nature nature connection nitrogen no dig no waste no-dig November nutrition nuts observe oca October off-grid oil cleansing orchard orchards organic organic gardening outdoor shower oven oxymel oyster pallets pasture-fed patterns people people care peoplecare perennials permaculture permaculture design permaculture magazine award permaculutre permayouth pesto pests philippines pine tree pips pizza oven plant profile plants pollinators pollution polyculture polycultures preserving principles propagating protection pruning prunings psycho-spiritual awareness psychospiritual transformation rainforest rainwater raspberries recipe recipes reduce reed beds regeneration regenerative regenerative agriculture relative location relative matter remedy renewable renewable energy resources restoration reuse revolution rhythms rootstock rootstocks roundhouse roundwood runner beans sage salad salve Samhain schools Scotland scotts pine seasonal seasons seeds selfcare Sepp Holzer september septic tanks sewage treatment shade sheet mulching shrubs skincare sloes slugs small solutions small-scale smallholding social justice soil health solar solutions sowing spiritual spring squash stacking functions stock-free straw straw bale summer sustainable Sweet Bay syntropic systems temperate terraces thistles thrutopia timber timber framing tincture tonic toolkit tools transformation trees upcycle urban veg garden vegan veganic vermicomposting vinegar walnuts waste water water cleansing watering weeds wellbeing wetland wild edges wild food wild garlic wildflower wildlife wine recipes wings winter winter greens winter salads wood stove woodburner woodland woodland management woodlands worms yarrow year-round food yield young people youth zai pits zone 00 zoning

Nitrogen Fixing Plants and Microbes

Nitrogen is essential in plant growth and nitrogen-fixing plants are hugely beneficial in any ecosystem. Paul Alfrey explains the two main groups of microbes plants use when nitrogen-fixing, Frankia and Rhizobium.

Nitrogen is an essential nutrient for plant growth and development and although around 78% of the earth’s atmosphere is nitrogen, plants cannot utilise this. Plants instead depend upon combined or fixed forms of nitrogen, such as ammonia and nitrate. Currently the majority of this nitrogen is provided to cropping systems in the form of industrially produced nitrogen fertilizers. Use of these fertilizers has led to worldwide ecological problems, such as the formation of coastal dead zones, and requires a high energy input to produce. Biological nitrogen fixation, on the other hand, offers a natural means of providing nitrogen for plants.

Biological nitrogen fixation is an important component of organic gardening/farming, forest gardening and other agro-eco practices. Through a partnership with micro-organisms in their roots, some plants can turn atmospheric nitrogen into nitrogen fertilizers useful to themselves but also becoming available to their neighbors over time through root die back, leaf fall, and chop and drop pruning. These are known as the nitrogen fixing plants.

This is a mutually beneficial relationship with the plant providing carbohydrates obtained from photosynthesis to the microorganism and in exchange for these carbon sources, the microbes provide fixed nitrogen to the host plant.

While it does not replace the need to bring in other nutrients depleted by harvests such as phosphorus and calcium, nitrogen fixation provides a valuable biological source of an essential fertilizer.

There are two main groups of microbes that plants associate with in order to utilise the atmospheric nitrogen to fuel growth. They are Frankia and Rhizobium.

Frankia

Many plants partner with micro-organisms called Frankia, a group of Actinobacteria. These plants are known as the actinorhizal nitrogen fixers.

Actinorhizal plants are found in many ecosystems including alpine, xeric, chapparal, forest, glacial till, riparian, coastal dune, and arctic tundra environments and can be found in the following plant families:
Betulaceae, the birch family
Myricaceae, the bayberry family
Casuarinaceae, the Austraian ‘pines’
Elaeagnaceae, the oleasters
Rosaceae, the rose family
Rhamnaceae, the buckthorn family.

These plants tend to thrive in nitrogen-poor environments and are often the pioneer species in plant communities playing an important role in plant succession.

Rhizobium

By far the most important nitrogen-fixing symbiotic associations are the relationships between legumes (plants in the family Fabaceae) and Rhizobium and Bradyrhizobium bacteria. These plants are commonly used in agricultural systems such as alfalfa, beans, clover, cowpeas, lupines, peanut, soybean, and vetches.

The Rhizobium or Bradyrhizobium bacteria colonize the host plant’s root system and cause the roots to form nodules to house the bacteria. The bacteria then begin to fix the nitrogen required by the plant. Access to the fixed nitrogen allows the plant to produce leaves fortified with nitrogen that can be recycled throughout the plant. This allows the plant to increase photosynthetic capacity, which in turn yields nitrogen-rich seed.

We are growing a range of nitrogen fixing plants at our bio-nursery. Visit www.balkep.org/plant-profiles.html for more information. If you would like to purchase some plants for your garden please send us an email to [email protected]. We deliver to anywhere in Europe.

This post orginally appeared at http://balkanecologyproject.blogspot.co.uk/2014/05/nitrogen-fixing-plants.html

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Further Resources

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Compost Teas and Biofertilisers

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Compost Teas for the Organic Grower
by Eric Fisher

About the Author

Paul runs the Balkan Ecology Project in Bulgaria with his wife Sophie Roberts and their two boys Dylan and Archie.