jumpincactus
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This I found to be an awesome article. Hope some find the theories and data useful. I know I did.
To come to a rudimentary understanding of how organic or natural growing really works, one must cast off previous miscomprehensions from the chemical model, that when we fertilize or add compost or other organic matter, we are feeding plants. This is not the case. With true organics one is feeding the microorganisms in the soil which convert organic nutrients into a form which can be assimilated by the roots of plants. According to studies, there are only a very few plant species capable of absorbing only a very few organic nutrients. Most plants are only capable of absorbing inorganic nutrients which are made that way by microbes which live at the root to soil interface, the rhizosphere. So the idea which you have, that you are feeding your plants when they appear to need nitrogen and you feed an organic fertilizer deemed high in nitrogen, is bogus. You are feeding the microbes which feed the plants.
Chemical fertilizers, mostly derived from petroleum are inorganic and can be absorbed by the roots of plants, however they are pollutants, which can cause a die off of and population change of soil microbes [** see addendum below], build up unused residues which run into the water table and, in my opinion, create harmful tissue changes in the plants which humans consume as food and medicine. In addition, I believe, the use of chemical fertilizers promote the incidence of plant pathogens like powdery mildew, erwinia, fusarium, pythium, etc. The grower can end up in a vicious spiraling downward fall as they use one chemical after another to control the effects brought on by the others.
The plant is no passive player in the natural growing game of survival but is the master conductor of this delicately balanced orchestra. The plant receives energy from above the soil in the form of light. This photosynthesis results in the plant’s internal production of carbon. It utilizes this carbon to create and reinforce tissue as it grows, so it is a very valuable commodity. As we all know the plant also requires a form of nitrogen (N) and other macro and micro-nutrients which it receives through the root system. As already stated this N must be in a form which the plant can directly uptake and use, usually a form of ammonia (N). Research has shown that when a plant needs to uptake N from the soil it sends out some of its precious carbon through it’s root system as a feed for bacteria and *archaea which live in the rhizosphere. [* Archaea are prokaryotes indiscernible from bacteria except through specialized testing; usually DNA] There are more complexities involved, such as, that certain plant types attract certain bacteria/archaea types but that is beyond the scope of this portrayal. When the bacterial/archaea population has increased in response to the carbons excreted by the roots, protozoa and bacterial feeding nematodes are attracted to the region, ‘hatch out’ from cysts and eggs respectively and in the case of protozoa multiply rapidly. Protozoa consist of flagellates, amoebae and ciliates. Some protozoa can multiply (divide) every 2 to 4 hours so their numbers can increase in short order. The protozoa and nematodes consume the bacteria/archaea and release, as waste, the ammonia (N) which the roots can then absorb. The multiplication rate of the bacteria/archaea increases in response to this predation and so on. This has been called the microbial loop. Protozoa are particularly good providers as their ‘digestive system’ only utilizes about 30% of the nutrients consumed meaning that roughly 70% is released as the waste which the roots crave. This factor, combined with their short generational time makes them real feeding machines. Undoubtedly there are micronutrients also processed and absorbed in this cycle. There are still many mysteries which research has yet to unfold or are not yet known to this author.
This is not the end. The concert continues. The bacteria/archaea also consume the ammonia (N) which is now bioavailable to them, so are in competition with the plant for these nutrients. Because of this, if there are no predators or insufficient numbers to consume the bacteria/archaea they could potentially lock up the N. When the plant is growing it is in a vegetative state and requires a large load of available nitrogen (N) so it is advantageous for it to continue this release of carbon and maintain a balance of bacteria/archaea and protozoa, while uptaking just the right amounts of nutrients. Don’t get me wrong. There are other players in this orchestra, either playing subdued roles or waiting their turn to play. There are higher order animals like mites, other microarthropods and worms. There are various forms of fungi, most of which are degraders but some of which are mycorrhizal. These all have roles in breaking down organic matter into a form which can then be mineralized by the plant’s bacteria/archaea team or delivered directly to the roots.
When the plant receives its signal from the upper world, above the soil, that it is time to switch gears and produce flowers and or fruit, its nutrient requirement changes. Although the mechanics are not well known to this author, studies indicate that the plant then increases the uptake of the ammonia (N) (bioavailable nitrogen) and reduces or stops excreting the carbon which feeds the bacteria/archaea. This effectively starves the bacteria/archaea which will react by dying or becoming dormant. This of course results in a similar reaction by the protozoa and bacterial feeding nematode population. The mycorrhizal fungi previously mentioned is then triggered into increased growth and production. Studies have indicated that the transference of bioavailable phosphorus and potassium to the roots occur mainly as a function of arbuscular mycorrhizal fungal hyphae in symbiotic relationship with the roots of the plant. The fungal hyphae (microscopic strands) grow right into the root cells and exchange nutrients. In exchange for carbon, once again released by the plant, the fungal hyphae delivers the required bioavailable nutrients to the root system. The fungal structure derives these nutrients from organic matter and food sources in the soil, some naturally processed by the other players as previously mentioned. It is my hypothesis that the form of carbon released to stimulate the mycorrhizal activity is of a varied molecular structure from that released to promote the bacteria/archaea population previously discussed, however I have no direct data to substantiate this. There are often different types of bacteria which accompany mycorrhizal fungi, adhering to the fungal hyphae in a symbiotic relationship. It is thought that these bacterial species function to exchange nutrients with the fungi as well as to protect the fungal hyphae from consumption by other microbes and even contribute to the protection of the plant from pathogenic fungi. There are other types of mycorrhizal fungi (ectomycorrhizal) which encapsulate roots rather than entering them but these are mostly associated with trees in the temperate and boreal regions.
So you see it is quite a complex arrangement which the plant conducts or controls and there are many facets which yet remain a mystery.
References:
Protozoa and plant growth: 2003;
the microbial loop in soil revisited; Michael Bonkowski;
Rhizosphere Ecology Group, Institut für Zoologie, Technische Universität Darmstadt,
Darmstadt, Germany
Soil microbial loop and nutrient uptake by plants: a test
using a coupled C:N model of plant–microbial interactions
Xavier Raynaud Jean-Christophe Lata
Paul W. Leadley
Plant Soil
DOI 10.1007/s11104-006-9003-9
The mycorrhiza helper bacteria revisited; 2007 P. Frey-Klett, J. Garbaye and M. Tarkka
Interactions Arbres/Micro-organismes, Champenoux, France;
UFZ-Department of Soil Ecology, Helmholz Centre for Environmental
Research, Halle, Germany
Modern Soil Microbiology; 2nd edition 2007 - Chapter 6 - Protozoa and Other Protista in Soil
Marianne Clarholm, Michael Bonkowski, and Bryan Griffiths
Soil protozoa: an under-researched microbial group gaining momentum
Marianne Clarholm
Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences (SLU), Box 7026, S-750 07 Uppsala, Sweden
Soil Biology & Biochemistry 37 (2005) 811–817
SOIL BIOTA, SOIL SYSTEMS, AND PROCESSES
David C. Coleman
University of Georgia
http://www.microbeorganics.com/#Living_Soil
To come to a rudimentary understanding of how organic or natural growing really works, one must cast off previous miscomprehensions from the chemical model, that when we fertilize or add compost or other organic matter, we are feeding plants. This is not the case. With true organics one is feeding the microorganisms in the soil which convert organic nutrients into a form which can be assimilated by the roots of plants. According to studies, there are only a very few plant species capable of absorbing only a very few organic nutrients. Most plants are only capable of absorbing inorganic nutrients which are made that way by microbes which live at the root to soil interface, the rhizosphere. So the idea which you have, that you are feeding your plants when they appear to need nitrogen and you feed an organic fertilizer deemed high in nitrogen, is bogus. You are feeding the microbes which feed the plants.
Chemical fertilizers, mostly derived from petroleum are inorganic and can be absorbed by the roots of plants, however they are pollutants, which can cause a die off of and population change of soil microbes [** see addendum below], build up unused residues which run into the water table and, in my opinion, create harmful tissue changes in the plants which humans consume as food and medicine. In addition, I believe, the use of chemical fertilizers promote the incidence of plant pathogens like powdery mildew, erwinia, fusarium, pythium, etc. The grower can end up in a vicious spiraling downward fall as they use one chemical after another to control the effects brought on by the others.
The plant is no passive player in the natural growing game of survival but is the master conductor of this delicately balanced orchestra. The plant receives energy from above the soil in the form of light. This photosynthesis results in the plant’s internal production of carbon. It utilizes this carbon to create and reinforce tissue as it grows, so it is a very valuable commodity. As we all know the plant also requires a form of nitrogen (N) and other macro and micro-nutrients which it receives through the root system. As already stated this N must be in a form which the plant can directly uptake and use, usually a form of ammonia (N). Research has shown that when a plant needs to uptake N from the soil it sends out some of its precious carbon through it’s root system as a feed for bacteria and *archaea which live in the rhizosphere. [* Archaea are prokaryotes indiscernible from bacteria except through specialized testing; usually DNA] There are more complexities involved, such as, that certain plant types attract certain bacteria/archaea types but that is beyond the scope of this portrayal. When the bacterial/archaea population has increased in response to the carbons excreted by the roots, protozoa and bacterial feeding nematodes are attracted to the region, ‘hatch out’ from cysts and eggs respectively and in the case of protozoa multiply rapidly. Protozoa consist of flagellates, amoebae and ciliates. Some protozoa can multiply (divide) every 2 to 4 hours so their numbers can increase in short order. The protozoa and nematodes consume the bacteria/archaea and release, as waste, the ammonia (N) which the roots can then absorb. The multiplication rate of the bacteria/archaea increases in response to this predation and so on. This has been called the microbial loop. Protozoa are particularly good providers as their ‘digestive system’ only utilizes about 30% of the nutrients consumed meaning that roughly 70% is released as the waste which the roots crave. This factor, combined with their short generational time makes them real feeding machines. Undoubtedly there are micronutrients also processed and absorbed in this cycle. There are still many mysteries which research has yet to unfold or are not yet known to this author.
This is not the end. The concert continues. The bacteria/archaea also consume the ammonia (N) which is now bioavailable to them, so are in competition with the plant for these nutrients. Because of this, if there are no predators or insufficient numbers to consume the bacteria/archaea they could potentially lock up the N. When the plant is growing it is in a vegetative state and requires a large load of available nitrogen (N) so it is advantageous for it to continue this release of carbon and maintain a balance of bacteria/archaea and protozoa, while uptaking just the right amounts of nutrients. Don’t get me wrong. There are other players in this orchestra, either playing subdued roles or waiting their turn to play. There are higher order animals like mites, other microarthropods and worms. There are various forms of fungi, most of which are degraders but some of which are mycorrhizal. These all have roles in breaking down organic matter into a form which can then be mineralized by the plant’s bacteria/archaea team or delivered directly to the roots.
When the plant receives its signal from the upper world, above the soil, that it is time to switch gears and produce flowers and or fruit, its nutrient requirement changes. Although the mechanics are not well known to this author, studies indicate that the plant then increases the uptake of the ammonia (N) (bioavailable nitrogen) and reduces or stops excreting the carbon which feeds the bacteria/archaea. This effectively starves the bacteria/archaea which will react by dying or becoming dormant. This of course results in a similar reaction by the protozoa and bacterial feeding nematode population. The mycorrhizal fungi previously mentioned is then triggered into increased growth and production. Studies have indicated that the transference of bioavailable phosphorus and potassium to the roots occur mainly as a function of arbuscular mycorrhizal fungal hyphae in symbiotic relationship with the roots of the plant. The fungal hyphae (microscopic strands) grow right into the root cells and exchange nutrients. In exchange for carbon, once again released by the plant, the fungal hyphae delivers the required bioavailable nutrients to the root system. The fungal structure derives these nutrients from organic matter and food sources in the soil, some naturally processed by the other players as previously mentioned. It is my hypothesis that the form of carbon released to stimulate the mycorrhizal activity is of a varied molecular structure from that released to promote the bacteria/archaea population previously discussed, however I have no direct data to substantiate this. There are often different types of bacteria which accompany mycorrhizal fungi, adhering to the fungal hyphae in a symbiotic relationship. It is thought that these bacterial species function to exchange nutrients with the fungi as well as to protect the fungal hyphae from consumption by other microbes and even contribute to the protection of the plant from pathogenic fungi. There are other types of mycorrhizal fungi (ectomycorrhizal) which encapsulate roots rather than entering them but these are mostly associated with trees in the temperate and boreal regions.
So you see it is quite a complex arrangement which the plant conducts or controls and there are many facets which yet remain a mystery.
References:
Protozoa and plant growth: 2003;
the microbial loop in soil revisited; Michael Bonkowski;
Rhizosphere Ecology Group, Institut für Zoologie, Technische Universität Darmstadt,
Darmstadt, Germany
Soil microbial loop and nutrient uptake by plants: a test
using a coupled C:N model of plant–microbial interactions
Xavier Raynaud Jean-Christophe Lata
Paul W. Leadley
Plant Soil
DOI 10.1007/s11104-006-9003-9
The mycorrhiza helper bacteria revisited; 2007 P. Frey-Klett, J. Garbaye and M. Tarkka
Interactions Arbres/Micro-organismes, Champenoux, France;
UFZ-Department of Soil Ecology, Helmholz Centre for Environmental
Research, Halle, Germany
Modern Soil Microbiology; 2nd edition 2007 - Chapter 6 - Protozoa and Other Protista in Soil
Marianne Clarholm, Michael Bonkowski, and Bryan Griffiths
Soil protozoa: an under-researched microbial group gaining momentum
Marianne Clarholm
Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences (SLU), Box 7026, S-750 07 Uppsala, Sweden
Soil Biology & Biochemistry 37 (2005) 811–817
SOIL BIOTA, SOIL SYSTEMS, AND PROCESSES
David C. Coleman
University of Georgia
http://www.microbeorganics.com/#Living_Soil
