I need an explanation on soil health: Beneficial Fungus, Microbes, How they feed,

[Guest]

humates, humus, whatever - I need a general overview or description of how to maintain all of that good stuff and what the parts of a good organic soil are in specifics and how it all works together.

Does anyone have a good link or resource on this? Thanks.

 

[minds_I]

Here you go.



http://faq.gardenweb.com/faq/lists/organic/2002114848008095.html


minds_I

 

[- ezra -]

Here is a good text on Micorrhizae. -


"What is Mycorrhiza?

A symbiotic relationship between plant roots and certain soil fungi has been known for the past 100 years, but only within the past 20 years has research focused on the cultivation of mycorrhizal fungi as an aid in crop productivity. Only in the past 10 years has the research revealed the vast importance the fungi hold to both plant and soil. And only in the last couple of years has that research benefited the home gardener.

Mycorrhiza (plural: mycorrhizae) is the term applied to a symbiotic fungus-plant association. The term is often mistakenly applied to the various fungal species involves, rather than to the association itself. The fungi involved are more appropriately called mycorrhizal fungi.

Over 95% of all plant species characteristically form mycorrhizae, unless the association in inhibited. In the plant world, the mycorrhizal condition is the rule, not the exception. However, in contemporary agriculture and horticulture, micorrhizae are generally repressed by cultural practices such as soil fumigation, tilling, and chemical fertilization.

There are four types of mycorrhizae:

Ericaceous, commonly found in heather, rhododendron and blueberries;
Orchidaceous, found in orchids;
Ectomycorrhiza, found in many woody plants, particularly forest tress, typified by mushrooms and a mycelial net in the soil;
Endomycorrhiza, found in a vast number of herbaceous and woody plants.
Endomycorrhiza, more commonly referred to as arbuscular mycorrhiza (AM), or by its older term vesicular-abuscular mycorrhiza (VAM), is the object of discussion here, as it is the association most commonly found in roses.

The fungi that form AM are all classified in the order Glomales. I did not find a report of the number of species within Glomales, but I did find a study of a North Carolina field that supported 30-40 plant species and 37 AM fungal species, of which 16 were most common.

AM fungi are not host-specific, i.e., any fungal species can infect many different plant species. However, once a plant is colonized, one species tends to become dominant on that plant. In this way, many plants in a bed or field may be colonized by different fungi, even though the plants in the bed may be the same. For this reason, most mycorrhizal inoculates contain as many as a dozen different fungal species.

Mycorrhiza benefits both the host plant and the invading fungus in a symbiotic relationship. The host plant supplies the fungus with carbon compounds in the form of sugars and amino acids. The fungus supplies the host with increased uptake of nitrogen, phosphorous, trace minerals and water. The fungus is especially valuable for its effectiveness in supplying phosphorous. The plant uses the nutrients to increase photosynthesis, which produces more sugars to replace those transferred to the fungus.

The fungus also has a mutual relationship with the soil biota. Some of the carbon supplied by the host is transferred to the soil where it feeds soil bacteria. Additional carbon goes to fungal growth, which eventually dies or breaks off, also feeding soil bacteria. The soil bacteria in turn break down organic matter to a point where the fungus can absorb it, or carry nutrients directly into the plant through the fungus. Some studies have found this relationship to be so close that when fungus spores form, bacteria spores are already in them, ready to germinate when the fungal spores germinate.

Let’s take a closer look at how the micorrhizae work.



AM and the plant host

When the fungus first invades the host, it grows between the outer cortical cells of the root. It soon penetrates the cell walls and grows within the cells. Although the fungus penetrates the cell through the wall, it does not invade the wall itself or the cell membrane. As the fungus grows within the cell, the cell’s membrane envelopes it, creating a new compartment filled with a material of high molecular complexity. This space prevents direct contact between the host and fungal cyctoplasms and provides a medium for nutrient exchange between host and fungus. Within this compartment, the fungus produces a highly branched hyphae, called an arbuscule (meaning "little tree") with a high surface area for nutrient transfer.

The arbuscules survive for less than 15 days. As the arbuscules die, the fungus forms thin-walled, lipid-filled structures, called vesicles, in the spaces between cells. These are thought to be storage areas, although in some species, the vesicles also provide a site for spore production. More often, spores are formed outside the root in hyphal swellings. It is from these structures that the term "vesicular-arbuscular micorrhiza" derives.

Of course, the root continues to grow, providing more cells for colonization. Old cells are sloughed off as the root grows, and the cells and dead arbuscules contribute to the soil’s organic matter.

Meanwhile, outside the root, the fungus has been growing hyphae that reach out beyond the root hairs as far as several millimeters, creating an extensive hyphal network enhancing absorption of water and nutrients. For nutrients with low soil mobility, such as phosphorous, zinc and copper, a narrow depletion zone quickly develops around the root. The fungal hyphae quickly bridge this zone to reach new sources of nutrients. Other nutrients transferred by the fungus include nitrogen, potassium, sulfur, magnesium and iron.

The fungus has another tool at its disposal for accessing the elusive phosphorous. Phosphorous is sometimes tied up by metal-hydroxides in the soil and is inaccessible to the root. The hyphae release organic acids such as oxalate that can replace phosphorous bound by metal-hydroxide surfaces, dissolve those surfaces, or prevent the precipitation of metal phosphates. The hyphae are also smaller than root hairs and can grow into smaller soil pores. In these ways, micorrhizal fungi are extremely efficient at retrieving phosphorous from low-phosphorous soils.



AM and the soil

The role of AM hyphae in the soil is less well understood. Most research has focused on the benefits to the host plant. We do know that the exuded organic acids tend to clump soil, improving soil texture, that the soil surrounding the hyphae contains a high concentration of soil microbes, and that the hyphae are an important source of carbon for soil biota. However, some researchers believe there may be a closer relationship between the fungus and soil bacteria.

It has been commonly believed that plant roots take in nutrients as atoms or small molecules through cation and anion exchange with the surrounding soil. The plant then combines the ions with sugars produced by photosynthesis to create longchain molecules, which are the building blocks for various parts and functions of the plant. Chemical fertilizers are based on this form of plant nutrient processing. Organic fertilization assumes that soil biota break down the organic matter into basic nutrients so the plant root can take them up.

Robert Linderman, with the USDA’s Horticultural Crops Research Laboratory at Oregon State University, suggests that the soil bacteria work with micorrhizal fungi to provide nutrients in an entirely different form. Humic acids, one of the most common components of compost and other decaying matter, are composed of longchain molecules. These molecules by themselves cannot pass into the root and through cell walls, but the fungi can. The bacteria can pick up these larger molecules and use the fungal hyphae as highways into and through the root system and into the arbuscules within the cells. The plant may then be able to transfer the longchain molecules with the arbuscules.

Linderman suggests that the plant may find it easier to modify the longchain molecules than to construct new ones from ions and sugars. At this point, a great deal of research has focused on the role of bacteria in fixing nitrogen in legume roots, but little has been done to explore other bacterial roles in roots and micorrhizae.

We know that the nutrient content of compost is fairly low, and have assumed that improved growth in soil amended with compost comes from the compost’s assistance in maintaining a steady moisture level in the soil. Bacterial ferrying of humic acids could better explain growth differences between plants grown in compost-enriched and chemically fertilized soils.

For more information on this theory, review Lon Rombough’s "The Web of Life -- All Toether Now" in Growing Edge, Nov/Dec 1997. (This was the third in a series of articles on micorrhizae, beginning in Winter 96/97; Growing Edge is published in Portland OR, http://www.growingedge.com.)"

 

[Protostele]

http://www.maximumyield.com/past-issues-about-hydroponic-gardening.php

Here are the past issues of Maximum Yield magazine which are chock full of articles on the subjects you are looking for. An example of what you can find is pasted below.

Protostele

Organics, A Growing Market - Humic and Fulvic Acid
By Luis Bartolo

In this issue we are going to talk about humic and fulvic acid and the role they play in the organic and horticultural market. Nowadays both humic and fulvic acids are being used by a lot of growers (organic as well as hydro growers) for their benefits. We hope you will enjoy this article and derive the necessary useful information from it.

Historic background of humic acids

What is Humic acid?

Humic acid is that fraction of humic substances that is not soluble in water under acid condition (below pH 2) but soluble at a greater pH. It is the collective name for the acid radical found in humic matter.

Liquid humic acid is a suspension, based on potassium-humates, which can be applied successfully in many areas of plant production as a plant growth stimulant and soil conditioner. The origin: through extraction the potassium humates are isolated from leanardite and are dissolved in water. This produces an aqueous suspension with a high content of humic acids, potassium, iron and a large number of trace elements ready for uptake by plants.

The Role of Humic Acids

Horticultural/Organic growers have recognized the value of regular additions of organic matter to the soil since prehistoric times. However, the chemistry and function of the organic matter has been a subject of controversy since men began their postulating about it in the I8th century. Until the time of Liebig, it was supposed that humus was used directly by plants, but after Liebig, it shows plant growth depends upon inorganic compounds. Many soil scientists hold the view that organic matter is useful for fertility only as it is broken down with the release of its constituent nutrient elements into inorganic forms.

At the present time most soil scientists hold a more moderate view and at least recognize that humus influences soil fertility through its effect on the water-holding capacity of the soil. Also, since plants have been shown to absorb and translocate the complex organic molecules of systemic insecticides, they can no longer discredit the idea that plants may be able to absorb the soluble forms of humus.

What can Humic substances/acids do?

• Aid plant tissues requiring free oxygen for aerobic respiration, and thus provide metabolic energy to all higher plants.

• Combine with sunlight and photosynthesis to furnish metabolic energy.

• When used as a dilute solution for foliar spray, cause plants to experience a notable uptake of oxygen, thus increasing plant growth.

• Not only assist plant respiration, but also increase the production and productivity of microorganisms.

• Assist plant respiration; they can serve as hydrogen acceptors for various plant root storage tissue.

• Produce energy involving photosynthesis, enhancing this process which includes the biochemical manufacture of complex organic materials, especially carbohydrates from carbon dioxide, water, trace minerals, and inorganic salts, along with sunlight energy for chlorophyll production.

• Increase the chlorophyll content in plant leaves when the plant is provided with root nutrient or foliar spray.

• Directly influence the development of enzymes and the net enzyme synthesis.

• Contain auxins; auxins are involved in the chelating of iron for the plant, improving growth, health, and nutrient intensity of the plant, especially the development of the root system of the plant.

What is fulvic acid?

Fulvic Acid is the most plant-active of the Humic Acid compounds, offering physical, chemical and biological benefits. Natural buffering, chelating and extremely high ion-exchange properties make mineral elements easier for plants to absorb. This results in increased plant vitality, resistance to environmental stress and improved crop quality and yields.

Benefits of fulvic acids:

Fulvic acid is especially active in dissolving minerals and metals when solutions are in water. The metallic minerals simply dissolve into ionic form, and disappear into the fulvic structure becoming bio-chemically reactive and mobile. The fulvic acid actually transforms these minerals and metals into elaborate fulvic acid molecular complexes that have vastly different characteristics from their previous metallic mineral form. Fulvic acid is nature’s way of “chelating” metallic minerals, turning them into readily absorbable bio-available form. Fulvic acid also has the unique ability to weather and dissolve silica that it comes in contact with.

Fulvic acid enhances the availability of nutrients and makes them more readily absorbable, allowing minerals to regenerate and prolong time of essential nutrients. It prepares minerals to react with cells and allows minerals to inter-react with one another, breaking them down into the simplest ionic form, chelated by the fulvic acid electrolytes.

Fulvic acid readily complexes with minerals and metals, making them available to plant roots and easily absorbable through cell walls. It makes minerals such as iron, which are not usually very mobile, easily transported through plant structures. Fulvic acids dissolve and transpose vitamins, coenzymes, auxins, hormones, and natural antibiotics that are generally found throughout the soil, making them available.

These substances are effective in stimulating even more vigorous and healthy growth, producing certain bacteria, fungi, and actinomyceles in decomposing vegetation in the soil. It has been determined that all known vitamins can be present in healthy soil.

Plants manufacture many of their own vitamins, yet these from the soil further supplement the plant. Upon ingestion, animals and humans easily absorb these nutrients, due to the fact that they are in the perfect natural plant form as nature intended. Fulvic acid can often transport many times its weight in dissolved mineral elements.

Fulvic acid complexes have the ability to bio-react with one another, and also inter-react with cells to synthesize or transmute new mineral compounds. The transmutation of vegetal silica and magnesium to form calcium in animal and human bones is a typical example of new synthesis of minerals.

Fulvic acid has the ability to store complex vitamins in its structure, where they are presented to the cell in combination with complexed minerals. In this perfect, natural condition, they can be catalysed and utilized by the cell. In the absence of adequate trace minerals, vitamins are unable to perform their proper function.

It is apparent that there is very little that man-made intervention can do to aid or detract from Mother Nature’s complexities. We are of an age where profit and abundance may be the foremost motivation for farming of many plants, yet if you take the view that if it is not broke, do not fix it, you can see that everything is there for success in growing, all that is needed is the natural resources, a little faith and allowing the natural elements to do their magic. We can see the results still, as our ancestors did, maybe without the odd sacrifice of a cow, but the future is actually in our past in this respect. There is nothing scientists can do that will make better what is already a perfect blend once all the elements are present.

Until next time and think Organics …

 

[- ezra -]

Hey Protostele, there are some really good articles on the Maximum Yield site, I just copied 25 for my personal archive. Great post!

 

[Guest]

http://www.maximumyield.com/past-issues-about-hydroponic-gardening.php
Here are the past issues of Maximum Yield magazine which are chock full of articles on the subjects you are looking for. An example of what you can find is pasted below.

Protostele

Thanks I just spent more than an hour going throw every single issue and printed a hundred or two hundred pages. That was an amazing source thank you so much