About two years ago I wrote a post where I celebrated the nitrogen-fixing plants as one of the keys to getting a step closer to the forest horticulture lofty goals of the self-creating fertility. In the same post I presented as a table with quite a variety kvävefixerare, ranked by their ability to capture the nitrogen from the air and make it available to other plants. Although I have not found any direct factual errors in the post, it has in the last months turned up a lot of questions about kvävefixerarnas proper role and possible limitations. It started when I was wondering how it actually works - what mechanisms underlie nitrogen fixation, how much nitrogen plants can capture, how much of it they can spread to their neighbors and how they do it? What factors influence their nitrogen-fixing ability? And how many kvävefixerare needed for them to make a difference? Unfortunately, it appears that there are no simple answers to these questions. Nitrogen fixation depends on numerous factors and is a surprisingly poorly studied phenomenon. In the following posts I still want to make an attempt to find answers to questions. Welcome to comply with the proper delving!
All nutrients are important, but the subject nitrogen (N) is perhaps the most important of them all. It needed to build amino acids that are the building blocks of all proteins, even those proteins called enzymes, which control virtually all biological processes in plants. In addition, we need to form chlorophyll, it helps to absorb other nutrients and stimulates growth both above and below ground. A plant suffers from lack of nitrogen is characterized by pale yellow leaves and poor growth.
The plants we call kvävefixerare, however, does not really bind nitrogen from the air themselves but collaborates with highly specialized bacteria that capture nitrogen from the air and convert it into a form that plants can absorb. These usually live in small bumps that sit on the outside of the roots. The best known nitrogen-fixing plants belonging to the family of legumes (Fabaceae). These cooperating with bacteria that either belong to the genus Rhizobium or the genus Bradyrhizobium . In addition to the countless legumes are the woodland garden grower interesting plants in other genera that have entered into a symbiosis with nitrogen-fixing bacteria of the genus Frankia, such as alder (Alnus glutinosa) and sea buckthorn (Hippophae rhamnoides). There are more types of nitrogen-fixing organisms, but they are not relevant to forest horticulturist .
Whatever microorganisms which capture nitrogen, it is always the enzyme nitrogenase that catalyzes the uppspjälkningen of atmospheric nitrogen molecules (N2) and converts them into ammonia (NH3). Enzymes are catalysts that chemical reactions that otherwise would not have been. We can think of them as the oven when baking bread. To water, flour and yeast to become bread, they need to be baked and it takes a lot of energy. In biological nitrogen fixation, this energy from the sun, whose light has been converted into energy through photosynthesis. This energy is used to break the enormously strong (triple)the bond between the two nitrogen atoms that form each kvävmolekyl. It is clever is that the nitrogenase enzyme remaining after the reaction has taken place - just as we can use the oven several times to make bread.
In nature there are only two processes that add new nitrogen to the terrestrial ecosystems: den ena, dominant process is the biological nitrogen fixation by bacteria. The second occurs during thunderstorms, When Lightning DEVICES enormous energy splits up atmospheric nitrogen molecules, which then combines with oxygen and nitrogen oxides are subsequently raining down and be absorbed by the vegetation. Everything else nitrogen circulating in the ecosystem is recycled nitrogen which once was picked out of the atmosphere by either bacteria or during thunderstorms. A lot disappears course also, either back to the atmosphere as a result of various degradation processes or by leaching into watercourses, so there is a continuous supply of nitrogen from the atmosphere to the biological systems to keep them running. In modern times, however, we have disrupted this system properly by both the combustion of fossil fuels (where the nitrogen compounds formed later raining down and provides nitrogen present in the atmosphere for millions of years ago) and by the excessive use of fertilizers manufactured by artificial and energy-consuming way fix nitrogen from the atmosphere. Man's conversion of atmospheric nitrogen currently exceeds all natural nitrogen fixation processes together .
Since we are in the forest gardening do not want to use chemical fertilizers are nitrogen fixation using plants very important to bring new nitrogen to the system. But how will the nitrogen available to plants actually? More on that in the next post.
 Brady, N.C. and R.R. Because, The nature and properties of soils. Upper Saddle River, N.J.: Prentice Hall, 2002.
 Santi, C., D. Bogusz, and C. Franche, Biological nitrogen fixation in non-legume plants. Annals of botany, 111(5): p. 743-67, 2013.
 Rock Power, J., W. Steffen, K. Noone, A. Persson, F.S. Chapin, E.F. Lambi, T.M. Lenton, M. Scheffer, C. Folke, H.J. Schellnhuber, B. Nykvist, IT. the White, T. Hughes, S. van der Leeuw, H. Rodhe, S. Sorlin, P.K. Snyder, R. Costanza, The. Svedin, M. Falkenmark, L. Karlberg, R.W. Corell, V.J. Fabry, J. Hansen, B. Walker, D. Liverman, K. Richardson, P. Crutzen, and J.A. Foley, A safe operating space for humanity. Nature, 461(7263): p. 472-475, 2009.