View Full Version : Soil food Web, part 1
01-24-2006, 08:04 PM
& THE SOIL FOOD WEB
Copyright May 1975 © Revised in 2003
Originally written by Michael Martin Melendrez in 1974
Updated by Michael M. and Dr. Michael Karr, Ph.D. ARCPACS Cert. Prof. Soil Scientist
With Water becoming more and more of an issue in the Western United States, Landscapes are increasingly being targeted as one of the main culprits of water waste. The problem lies with the absolute necessity of shade and greenscapes in our Southwestern High Desert Cites. Gravel is simply not a viable answer for converting or creating low water landscapes as the main criteria of function is lost. Who wants to sit in a gravel yard on a typical hot, sunny summer day? The construction of shade structures cannot replace the cooling benefit of trees over the same square footage. The second problem lies with our historical use of fertilizers to help prop up the health of our Trees and other landscape materials. You will learn by reading this paper that fertilizers result in growing all plants Hydroponically or with water. In other words, the only way to keep fertilizers available to plants is to keep the nutrients in a soil solution of water with the soil always well hydrated. This contradicts what happens in nature and how plants acquire nutrients in a natural Soil Food Web Cycle. You cannot convert to lower water usage in a landscape and continue to use Fertilizers at the same time. Please read on and learn how the Natural Process of Nature works and how we can help you build a truly 'Ecologically Sound Landscape.'
Why We Need a Soil Food Web
Plants depend on beneficial soil organisms to help them obtain nutrients and water from the soil, to prevent nutrient losses, to protect them from pathogens, and to degrade compounds that could inhibit growth. Each class or type of microorganism plays unique roles in these processes. Soil organisms create a living, dynamic system that can do all these things, but must be managed properly for best plant growth.
A spoonful of healthy soil contains millions of beneficial microscopic organisms of various kinds that perform vital "functions" in the root zone that can bring plants to health, if soil conditions are managed in ways that allow the microbes to live and work. These organisms include beneficial species of bacteria, fungi, protozoa, microarthopods and nematodes that never cause disease or become pests.
Why We Need a Soil Food Web continued
In healthy soil ecosystems, while nutrient cycling and productivity increases, nutrient loss is minimized. What makes this possible is the complexity of the soil foodweb. The greater the interaction of decomposers, their predators, and the predators of those predators the more tightly nutrients cycle from stable forms in soils to plants, and back again (Coleman et al, 1985; 1992).
Effects of Pesticides, Herbicides and Fertilizers
Pesticides, which include plant killers (herbicides), bug killers (insecticides), fungi killers (fungicides) and bacteria killers (bactericides) also kill related and often beneficial organisms. While each application may impact only a few species, the cumulative effect of multiple and repeated pesticide applications is a reduction in the numbers and diversity of soil organisms.
Fertilizers do not kill many soil organisms directly. The effect of high levels of nutrients from fertilizers is that the plant is less likely to form beneficial associations with soil organisms like mycorrhizae and rhizobium. Since the plant is less able to obtain water and nutrients without their help, it becomes dependent on continuously high levels of nutrients and water. The plants are less able to tolerate water stress or low nutrient levels. Thus the landscape suffers unless both are continually applied.
Organic fertilizers, like composts and manure, have nutrients stored in the organic matter. The beneficial microorganisms are fed as the nutrients are slowly released to plants. Adding inorganic fertilizers supplies nutrients but does not feed microorganisms. The microorganisms decline in numbers and, since they aren't there in sufficient numbers to release nutrients stored in organic matter, the plants become even more dependent on repeated applications of fertilizer nutrients.
And if you don't have many beneficials then you are left with relatively high numbers of pathogens, because only the plants are present for them to feed on!
To correct this problem you need to inoculate the soil with the beneficials to make sure they are there, and then put back the food in those systems to grow and maintain these organisms.
What Happens to Soil Nutrients Without a Functioning Food Web
When we add fertilizers containing N, some of the fertilizer will dissolve and diffuse directly to the roots and be taken up, helping the plant to grow. Much of the excess N is in danger of being leached away. Without large numbers of soil organisms that can "capture" excess N, retention in the soil doesn't happen and the nutrients can be leached into the groundwater. Other nutrients, like phosphorus, iron, manganese, zinc & copper, are rapidly converted into insoluble (less available) forms.
The solution? Protect the nutrients and cycle them! Apply the microbes that make up the food web and feed them. In return they will retain and cycle plant nutrients. And they will also do a great deal more.
What Happens to Plants Without a Functioning Soil Food Web
Disease organisms are not suppressed; and therefore multiply and threaten plants. The loss of symbiosis with soil microorganisms results in reduced ability to take up water and nutrients. Not only are plant growth adversely affected but resistance to temperature and moisture stress is reduced as well.
The lasting solution…
Restore the health of the soil ecosystem, the soil foodweb.
A highly populated and balanced soil foodweb will:
1. Create humus by decomposing organic matter
2. Improve soil structure by binding particles together and creating microaggregates
3. Protect roots from diseases and parasites
4. Retain nitrogen and other plant nutrients
5. Slowly release retained nutrients to the plant
6. Produce enzymes and hormones that help plants grow and resist stress
7. Decompose pollutants that enter your soil
To do all this, the following types of organisms need to be present in sufficient numbers:
Soil organisms which capture nutrients before they are lost.
The soil bacteria and fungi form the first level of organisms - the consumers of organic matter and leftover nutrients. Nitrate nitrogen and some other nutrients can leach out and be lost unless they can be held in soils until the plant needs them. When bacteria and fungi multiply they gather up free nitrogen from the soil and convert it to protein in their bodies. Nitrogen in this form cannot be leached away or be lost as a gas.
Bacteria - the "Cows" of the soil.
Total bacterial numbers range between 5 million and 500 million per teaspoon of soil in agricultural soils, and between 20 million and 2 billion in forest soils and highly productive garden soils.
Soil bacteria are like cows in soil. They tackle the easy to decompose materials, like green yard waste and manure. These materials contain most of the nutrients. These organisms need a lot of nitrogen, and they grab it quickly (more quickly then plants!) so they often go after some of the residual nitrogen from fertilizers, if present.
They retain nutrients like N, P and S. in the soil as bacterial biomass. Productive garden soil should contain more bacteria than any other kind of organism. Bacterial waste products that cannot be broken down any further become soil humus (humic substances)
Fungi - The Goats of the Soil
A single teaspoon of healthy soil can contain up to 40 miles of fungal hyphae! The soil fungi consume the tougher, hard to decompose materials, like straw, pine needles, bark and wood. The nutrients from these types of organic matter are not lost by leaching or other processes, but are incorporated into the fungal biomass.
Just like bacteria, fungal waste products and materials that cannot be broken down any further become soil humus.
01-24-2006, 08:06 PM
Nitrogen Retention and Organic Fertilizers
Nitrate is the most mobile (leacheable) form of nitrogen, followed by ammonium. Chemical fertilizers contain nitrogen in these forms. Even the N in urea is quickly converted to ammonium-N by the urease enzyme, which is naturally present in soils. The least mobile form is organic nitrogen in biomass and inside microbes. One advantage of organic fertilizers is that most of the nitrogen and other nutrients are bound as part of the biomass. Then, when microbes decompose the biomass, most of the N is incorporated into microbial biomass.
At this level nitrogen and other nutrients are "tied up" from loss by leaching (in bacterial and fungal biomass), but also are tied up away from plants. If there were no predators of the bacteria and fungi, the plants would not be able to get at that nitrogen. Fortunately, the soil foodweb contains the predator trophic level.
The Second Level
Organisms That Recycle Plant Nutrients
Once nutrients have been retained by bacteria and fungi, other kinds of soil organisms can be encouraged that feed on the bacteria and fungi. These predator organisms form the second level of the soil foodweb They include protozoa, beneficial nematodes, and microarthropods. As these organisms feed on the bacteria and fungi, the excess nitrogen and other nutrients are metabolized and released back into the soil, at gradual rates that supplies plants with a steady diet of nutrients all season.
There are from 100 to 100,000 protozoa per teaspoon of soil. The numbers vary widely among soils, but the more the better. Protozoa -- flagellates, ciliates and amoebae, one-celled, highly mobile organisms that feed on bacteria and on each other. As protozoans eat bacteria, N and other nutrients are released, and are now available for plants to absorb. This is the primary source of mineralized N on grass and garden soils.
Nematodes - Good & Bad.
A healthy soil has from 5 to 500 beneficial nematodes per teaspoon of soil. Nematodes in soil range in length from about 0.25 to 5.5 mm (1/4 inch) long. A bacterial-feeding nematode consumes about 100 bacteria per day, and a fungal-feeding nematode consumes about 80 feet of hyphae length per day. Nematodes need less nitrogen and other nutrients than the bacteria and fungi, so the excess is released as they feed, making these nutrients available for plant growth. Well-made compost that has been cured for long periods under optimum conditions contains beneficial nematodes.
Nematodes that are pests feed on plant roots, often carrying in diseases too. However, a healthy soil has predator nematodes and microarthropods that eat these nematode pests. In addition, fungi trap nematodes then dissolve them for consumption. In addition, by having healthy colonies of bacteria and fungi that surround root systems, this makes it more difficult for root feeding nematodes to find the roots and attack them.
A teaspoon of soil has several species of microarthropods. These organisms have several functions. They feed on fungi, releasing the excess nutrients locked inside the fungi. They also feed on nematodes, most importantly the plant-feeding nematodes. Microarthropods also chew the fresh (but dead!) organic material - leaves, stems and roots, into smaller pieces, making it easier for bacteria and fungi to decompose. In addition arthropods carry around an inoculum of bacteria and fungi that they apply to plant material as they chew on them!
The Top of the Soil Food Web
There are even higher-level predators, such as millipedes, centipedes and earthworms! These keep the nematodes and protozoa from exploding in population and over-eating the fungi and bacteria. The net effect to plants is a slow, sustained release of nutrients, with little danger of losses by leaching.
The insects and earthworms are preyed upon by rodents and birds, and these in turn may be eaten by mammal predators like foxes and raccoons -- for a total of six trophic levels, all starting from plant-produced organic matter!
SPECIAL SOIL ORGANISMS
Earthworms will not colonize soils to any significant degree unless sufficient organic matter is present, because they digest the organic material present in the soil they eat. Earthworms create channels for water, air and plant roots as they tunnel through the soil. They also release much of the nutrients locked into the organic matter they eat. Many pesticides and the salt effect from heavy fertilizer additions kill earthworms.
Mutualist bacteria and fungi can be critically important for plants. For example, the nitrogen-fixing bacterium on legume plants. The plants feed the bacteria that inhabit the roots, and the bacteria capture atmospheric nitrogen and convert it to plant usable forms. In fact, the whole landscape ecosystem benefits when the high-N organic matter of legumes is decomposed, and the N is later released.
Studies have also shown that if soil nitrogen levels are high, due to chemical fertilizer additions, the plants will not form the symbiotic association with N-fixing bacteria. Because of this, they become dependent on regular nitrogen fertilization to grow.
Free-living Nitrogen Fixers
Free-living nitrogen fixers, like blue-green algae, and several species of bacteria, can capture atmospheric nitrogen and convert it into plant-usable forms. For the support of the bacteria a good source of organic matter in the soils is needed. This support may come indirectly from plant root secretions. Regular organic matter additions to soils will also help maintain these populations.
Vesicular-arbuscular mycorrhizal (VAM) fungi are very important for most plants because they help plants scavenge for water and nutrients in the soil. Studies have shown, so far, that over 90% of all plant species form a symbiotic association with mycorrhizae in natural soils. After the mycorrhizae "infect" the plant roots, the plants feed the mycorrhizae. The mycorrhizae benefit plants by sending mycelial threads far out into the soil, penetrating the spaces too small for plant roots. These threads capture water and plant nutrients that were not available to plant roots. The greater nutrients use efficiency that result means that fertilization requirements go way down. In addition, your plants can tolerate drought a lot better if they are mycorrhizal, because mycorrhizae also bring in water.
A number of studies have indicated that the lack of mycorrhizae fungi can result in poor plant growth, due to the reduced ability to survive under nutrient and water stress conditions. In situations where soil degradation has been severe, it may not be possible to maintain a successful planting of several plant species without mycorrhizal inoculation.
Studies have also shown that if soil nutrient levels are very high, due to regular chemical fertilizer additions, the plants will not form the symbiotic association with VAM fungi. Because of this, they become dependent on regular and frequent watering and fertilization to continue living and growing.
The presence of at least 1 to 5 spores per gram of soil is adequate for most planted areas. When the number of spores falls below one per gram, then inoculation of VAM spores generally results in positive effects. Earth Magic & Terra Pro contains live spores of several species of mycorrhizae.
A new and even more exciting discovery in recent years is the real soil builder – Glomalin. When plants are Mycorrhizal, production of Glomalin in the soil occurs. Sara F. Wright, a soil scientist with the USDA’s Sustainable Agricultural Systems Laboratory in Beltsville, Md., discovered glomalin in 1996 and named the substance after Glomales, the taxonomic order of the fungi that produce the sticky protein.
The Glomus genus of Mycorrhiza fungi living on plant roots, use the plants carbon to produce glomalin. As the roots grow, glomalin sloughs off into the soil where it acts as a "super glue," helping sand, silt and clay particles stick to each other and to the organic matter that brings soil to life. It is glomalin that helps give good soil its feel, as smooth clumps of the glued-together particles and organic matter flow through an experienced gardener's or farmer's hands.
01-24-2006, 08:07 PM
How Soil Organisms, Control Root Diseases and Parasitic Nematodes.
A healthy soil that contains a broad diversity of microbial types contains species that kill, inhibit or suppress the kinds of fungi and bacteria that cause root rots and the species of nematodes that attack roots.
Up to one-third of the plant's carbon flows down below ground and is pumped into the soil through the roots. These root exudates are the food resources for soil microbes near the root surface: sugars, proteins, carbohydrates. Through this process, each plant is attracting the right kinds of microbes to colonize the area right around the root system. These microorganisms will produce enzymes and growth hormones, and protect the plant against pathogens.
In a healthy soil, there should be at least 100 million organisms per gram of soil. But in the zone close to the root, the plant can support up to a trillion organisms per gram -- which creates what scientists call a "rhizosphere" of soil organisms in a symbiotic relationship with the plant.
Mycorrhizal fungi play in important role in disease suppression. These fungi wrap its mesh of hyphae around the root system, so root-feeding nematodes can't penetrate the network. In addition, mycorrhizal fungi secrete compounds that are antibiotic and inhibitory to many pathogenic microbes.
Organisms That Build Soil Structure
Good soil structure allows for water, mineral nutrients and air to move to the plants easily. Both bacteria and fungi improve soil structure. Bacteria produce glues that attach to soil colloidal surfaces, causing the small particles to stick together. Fungi grow hyphae strands around soil particles and groups of soil particles, binding them together into what are called microaggregates. Soils high in microaggregates have a loose, crumbly structure - like earthworm casts. In the spaces between the "clumps" of soil particles, water and air can penetrate, and plant roots grow down between the clumps.
Organisms That Build Soil Structure continued
In addition, larger organisms like nematodes, earthworms, millipedes and other arthropods create passages for air, water and roots as they push through the soil. But these organisms are sensitive and easily disturbed by pesticides and heavy fertilizer additions.
Organisms That Decompose Toxic Compounds
These are primarily the bacteria and fungi at the first trophic level. However, most require regular organic materials to eat along with the toxic compounds. This process is called co-oxidation. It's a bit like eating salad dressing (toxic compounds) along with the salad (organic materials). The dressing is consumed along with the salad, but we rarely eat the salad dressing all by itself! So you have to have both the organisms and a good food supply available for the organisms present in order for them to decompose the toxic compounds.
Organisms That Produce Plant-Growth-Promoting Hormones and Enzymes
All plants depend on the presence of certain species of soil microorganisms in the root zone to produce various hormones and other chemical "signals" that stimulate growth and development. The plant growing in healthy soil will exude food for these microorganisms, and the microbes in return secrete enzymes and growth hormones not made by the plant itself.
How to Keep the Soil Foodweb Healthy
Bacterial numbers are maintained by mixing high-N, easily digestible plant material into the soil. But the bacteria eat this material rapidly, so additions are required every year. This includes manure, compost, grass clippings (a mulching mower does this on the fly), etc.
Letting litter accumulate on the soil’s surface or by adding low-N fibrous organic materials, like mulch, straw, brown leaves, etc can maintain fungi.
Do not apply pesticides or synthetic fertilizers. The former kills soil organisms and the latter breaks the relationship between plants and soil organisms.
Soil Secrets, LLC
( 505) 866-SOIL Email: SOILSECRETS@AOL.COM
Los Lunas, New Mexico 87031
01-24-2006, 08:08 PM
PLANT FOOD FOR HEALTHIER PLANTS & IMPROVED YIELDS
Plants obtain nutrients for their biosynthetic processes in the form of carbon dioxide, water, nitrate, phosphate, and ionic forms of potassium, calcium, and other essential elements. Nitrogen generally enters the roots as nitrate and becomes assimilated by the plant’s bio-chemistry into organic compounds. Accordingly, nitrate can be classified as a "natural" plant nutrient or can it?.
In a natural system, nitrate in the soil is derived from the gradual breakdown of humus, the dark, complex, polymeric material that gives the soil its "tilth." Nitrogen is integrally bound to the carbon atoms that make up the organic structure of humus, which is itself the end product of a complex chain of events that carries nitrogen into the soil. The main path of entry begins with the deposition of organic nitrogenous compounds on the soil in the form of animal feces and urine and the dead remains of animals and plants. These largely organic materials are subjected to hydrolytic and oxidative degradation by decay microorganisms, yielding organic low-molecular-weight products that support the growth of soil microbial flora. These processes finally yield a mass of microbial cells, which on their death, together with some other remains, become humus. The other source of soil nitrogen is nitrogen-fixation, which also delivers the element to the soil system in organic form. Thus, in a natural soil system, untouched by human technology, nitrogen enters into the system in organic combination with carbon, largely as the nutrient for microorganisms that eventually produce humus.
Farmers who wish to add nitrogen fertilizer to the soil to support crop nutrition have two main alternatives. Nitrogen can be added in a natural, organic form - as plant residues, manure, sewage, food wastes, or for that matter, in the form of any nitrogenous organic compound that can be metabolized by the soil’s microbial flora and thereby yield humus. In the alternative, nitrogen can be added in an inorganic form, such as nitrate or ammonia.
Soil is an integrated system and there is a vast difference in the outcomes of the two methods. Because nutrient uptake is a working-requiring process, it must be driven by the root’s oxygen-dependent energetic metabolism. Humus is much more than a store of nutrients; is also the chief source of the soil’s porosity, hence of its oxygen content, and therefore of the efficiency with which nutrients, such as nitrate, are taken up by the crop.
The critical difference between the alternative means of supplying nitrogen fertilizer is that the organic form leads to the production of humus, while the inorganic form does not. The use of synthetic urea as a fertilizer provides an informative test of this distinction. Urea is, of course, an authentic organic compound and is, in fact, an ordinary constituent of a clearly natural source of nitrogen-urine. The scientific agronomist may often cite the organic farmer’s objection to pure urea as a fertilizer - it is a fairly common one in modern agriculture - as evidence of the irrational basis of organic farming. But is it?
While urea is, indeed, an organic compound, it will not support the bacterial growth that is essential for the formation of humus. When urea is metabolized, the products are ammonia and carbon dioxide. Thus, urea yields carbon in a form that will not support the oxidative metabolism of soil bacteria. To accomplish that, carbon must be in the reduced state, combined with hydrogen as it is failing to support the growth of soil bacteria, and therefore the formation of humus, it does not quality as an "organic fertilizer."
The intensive use of inorganic nitrogen fertilizer (or urea) may so overload a humus-depleted soil with nitrate as to cause it to leach into surface waters when nitrate levels may readily exceed public heath standards. Leached nitrate also wastes expensive fertilizer synthesized from an increasingly diminished supply of natural gas. Apart from any other possible and yet to be established virtues, the use of organic fertilizer (as defined above) avoids these difficulties and holds the promise of restoring the natural source of soil fertility - humus. While it remains to be seen whether food grown in such naturally fertile soil contributes distinctively to the health of people, the practice can, it seems to me, contribute significantly to the health of the soil and the economy.
Dr. Barry Commoner
Director, Center for the Biology of Natural Systems.
Vol. 10, No. 4
01-24-2006, 08:13 PM
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Quotes from Understanding the Soil Processes
Most of us will agree that the soil is the major natural resource available to mankind. Yet it is and has been abused by us to the point of self destruction. Many past civilizations have perished due to their abuse of the soil (like Mesopotamia and the Mayan civilization).
Why didn't anyone stop the destruction? The soil destruction process takes time and the changes in each generation are "small" so no one cared-and most of us still don't.
The soil in which we plant crops today has been self perpetuating for millions of years without man's help. It will continue to do so if we do not disturb its natural cycle.
In the soil there are nutrients and trace elements both of which plants require for growth. They are essential.
Soil moves continually in a natural cycle aided by oxygen, water, minerals and decomposing animal and plant matter. These elements create life in the soil, which is ongoing if not disturbed. We speak of healthy soil if it works well and nutrients continue to be available to the plant.
Good soil consists of 93% mineral and 7% bio organic substances. The bio organic parts are 85% humus,10% roots, and 5% edaphon.
Edaphon is itself a "world" of life and consists of microbes, fungi, bacteria, earthworms, micro fauna, and macro fanuna as follows:
· The Edaphon consists of:
· fungi/algae .........................40%
· Macrofauna........................ 5%
· micro/mesofauna............... 3%
Some of the nutrients get lost naturally through leaching continually wet weather, melting snow, flooding or through denitrification. Also each cultivated plant takes nutrients from the soil, as soon as the crops are harvested.
The substantial task of the farmer is to take care of returning nutrients taken from the soil through harvesting. The conventional farmer is using water soluble, mostly salty chemical fertilizers.
In contrast, the bio-organic farmer uses organic matter in the form of crop residues, and other wastes, and /or compost and BTR, in order to take of soil life, its proliferation and stimulation to highest effectivity.
With this treatment and approach, the bio farming system should bring out the following: Stronger nutrient accumulation and nitrogen fixation. Availability of soil nutrients to plants.
The natural life cycle of out fields must be kept functional through the addition of organic matter after the residues from the previous crop have been depleted in order to build new Bio-Organo-Mineral nutrition for our next crop. This action connot be replaced with the water soluble salts or overdoses of chemical fertilizer which destroy soil life, not build it.
During the growing season, as the plants fix carbon dioxide by photosyntheses, about 10-25% of this fixed carbon,finds its way back to the soil through the roots (root exudates) this is even if all residues including roots are removed. This is very important in bio-organic farming.
The production of humus is a complex process. In general cyclic substances like phenol groups and also other like organic acids and vitamins (humus is also related to crude oil) are polymerized with help of enzymes,like phenol oxidase. These cyclic compounds are both from plant parts(like lignin) and are also produced by the microorganisms. Mostly fungi, actinomycetes (Streptomycets) seem to be responsible for humus formation. Aspergillus, Pisolithus, Rhizoctonia, Streptomycets are only but a few examples of microorganisms actually capable of synthesizing cyclic(aromatic) compounds and form them into humus from non-cyclic materials.
It is impossible for man to produce stable humus synthetically. Man can properly cultivate the field, supply organic matter and so encourage the development of stable humus in the soil. Soil with stable humus must always be protected to maintain the fertility and productivity of the soil.
The production and maintenance of stable humus in the soil should be the primary goal of every farmer. Good stewardship of the land is necessary to protect and maintain mankinds most important asset, fertile soil.
For nearly one hundred years soil science in most schools of higher learning (especially in agricultural colleges) has been primarily concerned with the physical and mechanical aspects of soil structure. Biological thinking has become a major concern only in the last few years.
The new approach considers not only the physical properties and mineral structure of the soil,but also the process by which organic matter is transformed into humus by microorganisms.
Humification, the transformation of organic matter into humus, is a fascinating process. Organic materials such as manure or field wastes ,when disked into the upper three to six inches of topsoil, will undergo several changes. The humification process involves first catabolism , then anabolism. These are not truly correct terms as they are usually used for same functions within living organisms, but we may consider soil as one living organism.
The first stage in the break down process is important to be started by fungi, these make the debris "pre-digested" for many animals in the macro and mesofauna. Many of these animals lack needed enzymes for the start of the decomposition process (springtails, millipeds, earthworms, etc.) The debris is fragmented into smaller parts and chemical changes occur in breaking up of cellulose, chitin, etc.
Most plant parts already contain fungi within(seed,leafs,stems all are inhabited by fungi): these are going to start the decomposition process. Many fungi residing within seeds are known and seeds (or plant parts )carry only certain fungi, that will actually start the decomposition process (sometimes they also carry pathogens.)
If bacteria start the decompostion process instead of fungi, this may happen because of several reasons, the one most common would be water logging (too moist), the process turns to putrefaction. During this stage toxic substances are produced (methane, formaldehyde, hydrogen sulfide, phosphine) which are harmful to soil and ****** the growth of plants.
Please do not misunderstand-bacteria and fungi are decomposing all at the same time,we mean predominance of one over the other not that the other is not involved at all.
The excrements of the neso and macrofauna are a very suitable medium for growth of bacteria, algae, and nematodes. These multiply rapidly and again draw the mesofauna, as it feeds on the bacteria. Many new animals are involved in this stage, some are the same as in the first decomposition.
Slowly the materials are broken into smaller parts, at the same time many are again combined and used for building hormones, enzymes, proteins for the rapidly multiplying microfuna. Antibiotics are produced to secure an area for growth, form other microorganisms.
Carbon dioxide is evolved back to the atmosphere and only about 20-30% of carbon originally found in the plant parts makes it to humic complexes.In case of carbohydrates as starting point the carbon percentage that makes it to humus is less than 20%. If the starting point is lignin, tannins, or other phenolic groupings (mostly found in wood and leaves) the percentage may reach 75%.
Mineralization is the process of freeing minerals from organic molecules (carbon bonds). During humification there are two possible end products for atoms within the starting molecules. Minerals may either be build up stable humus or be in free form, carbon either tied within humus or evolve in form of carbon dioxide. The following is a summarizing table where atoms end up after humification:
All minerals within organic compounds
80% freed up and 20% in humus
Carbon from carbohydrates
80% evolves as carbon dioxide and 20% goes to humus formation.
Carbon from lignin, aromatic type amino acids (tyrosine, tryptophan...) and like compounds (fats, hydrocarbons like waxes,...)
25% evolves as carbon dioxide and 75% goes to humus formation
will remain to 50% in humic form.
The micro, meso, and macrofauna is so closely interwoven that one could say, if areas have small amounts of earthworms, beetles, etc. the microbial population will be small.
01-24-2006, 08:15 PM
The second half of soil metabolism-anabolism now begins, starting with the synthesis of soil plasma. It is in this process of plasmolysis that the catabolized organic matter becomes plasma building material for new plant life. This is the least understood of all the processes that go on in the soil.
Soil plasma is the liquid portion of the soil. It contains proteins, salts, degraded organic compounds and water. It is like the liquid part of the blood which, although without corpuscles , is much more than water.
Soil plasma is that substance in the soil that can spin catabolized remnants of former life into vital threads that are woven together into the fabric of new life through the processes of anabolism.
In the anabolism process the plasma is transformed into stabel humus. This plasma also contains the decomposed cell walls of organic residues and has become a spongy, gelatinous substance that bonds the surface of the clay crystals together. In this manner, clusters of clay crystals form aggregates that are resistant to being broken apart. This gives the soil the ideal structure farmers refer to as tilth. The combination of plasma and clay forms what is known as stable humus.
The presence of stable humus allows air, water and essential mineral nutrients to be held in the aggregates. The chemical nutrients are in the form of ions-atoms carring positive or negative electrical charges . In science, they are referred to as swarm ions.
The spongier the soil the more pores or open spaces are within it. Like Swiss cheese reduced to an infinitesimal scale, each of these holes or pores has an inner surface that is coated with plasma. The greater the porosity of the soil the more capacity it has to accumulate and hold air, water and nutrients and prevent them from being washed away.
Consequently, we can imagine that a loss of this porosity with all its inner surfaces represents a catastrophe to the soil. With the loss of stable humus, the mineral particles of the soil come together almost like concrete. The porosity is lost and with it the ability of the soil to retain air, water and nutrients. As this capacity diminishes , the fertility of the soil is reduced and productivity declines.
When we have stable humus,we have all the ideal conditions we are seeking for our soils. We have the inner protected porosity, the glued together clay crystals coated with plasma containing the decomposed organic matter holding air, water and chemical nutrients-swarm ions.
In this ideal environment the third phase of stable humus, plant feeder roots develop. It is here the dormant power and original resource of soil fertility comes to life. This is the secret of rebuilding the energy and fertility of "Mother Earth".
Here the living matter, which was originally buried in the soil to decay, celebrates the birth of new life; the re-births of organic matter for germinating and growing plants
Stable humus, the so desired, ideal stage of fertile soil, could be considered the connectiong link or connector of life. Here decomposition ends the last stage of death:and new life begins. Through this process,we can understand the fertility of the soil depends on the ability of Nature to create living,organic order from inorganic disorder.
Many farmers are imprisoned in a way of thinking that is only concerned with levels of chemical fertilizers and must be re-educated to begin considering the biological processes occurring within the soil. Balanced soil fertility is a condition which cannot be measured by chemical or physical tests. The farmer who strives to maintain the bio-organo-mineral complex in correct balance in his fields can achieve the hightest agricultural production levels as a result of these biological processes.
Today's popular chemical tests of soil do not tell anything about the decisive life processes. They are merely a yardstick of the mineral content of the soil and do not help farmers in knowing how to treat the fields for future productivity and healthy corps. The whole process misses the basic point that the true purpose of agriculture is to recycle life to capture the life factor from decomposing organic material and channel it into new growing plants. It is only by doing this that vital healthier life can be maintained in plant, animal and man.
When the farmer decides to begin a biologically balanced fertility program, soil analyses show minimal values of nutrient reserves and indicate that large amount of fertilizers should be applied to meet the needs of the crop. However, after a few years of successful biological farming, analyses can show high residual levels of available nutrients, although the farmer has not used any chemical fertilizers during that time.
The absurdity of conventional chemical thinking is revealed in the mistaken notion that larger quantities of nutrients will continue to result from the aid of chemical fertilizers. But the truth is ,that by the activity of microbes, the nutrients are biologically enriched, accumulate in the pores of the soil aggregates as swarm ions, and will become available to the growing plants. The farmer who implements the balanced fertility program can achieve needed levels of nutrients in the soil in a less expensive way, can achieve the highest possible yields, and a higher quality harvest. By using the wrong fertilizers, excessive chemicals and heavy machinery we are destroying our soil, our filds, our farms and our future.
Plants supplied with this kind of nutrient require less water. This assures the biological farmer a significant saving of water in the production of crops, an especially important consideration in arid zones and in dry seasons elsewhere.
We cannot outwit Nature. Nature does not allow a wasting or loss of living matter in the restless process of mineralization the procedure for impregnating the soil solution with the mineral elements required for plant growth. In the final stage of decomposition the remmants of plasma still contain the essential elements of the life processes. These remnants are then transformed into soil plasma in the process of producing stable humus.
Stable humus is the crucial center, the focal point of the life cycle. Adhering to farming practices that assure the production of stable humus thus becomes the farmer's main objective.
01-24-2006, 08:15 PM
V. soil fertility
Over 130 years ago (1855) Justus von Liebig's discovery that plants are fed by water soluble substances started a revolution in agriculture.
However this revolution went in a different direction far from the original thinking of von Liebig.
Von Liebig's discovery reads:
"Plants take up water soluble nutrients"
This discoveries became internationally understood, but unfortunately, a single word has been added to the Liebig statement and his sentence and the meaning changed as follows:
"Plants take up water soluble nutrients only"
There is a great difference between his original statement and his interpretation by the addition of the single word "only".
The single addition changed the truth of his discovery. First to recognize the important misunderstanding was von Liebig himself. However, the huge agro-chemical industry built their fort based on the word "only".
Science neglected his best discoveries and findings which are as follows:
1. Man must regard nature as one unit, a whole and everything that occurs in nature works together as knots in a net
2. Diseases of plants are diseases of the soil.
3. We must treat the prime origin of the disease, not the symptom
It is important to understand that if the soil is living and healthy, the plants will be strong and healthy with natural resistance against disease. This opinion is the basic pillar of organic biological farming.
Fertilizer facilities prospered and became firmly established as the bass of a huge, new agro-industry.
Ammonia taken up by plants is utilized directly, but nitrates have to be converted to ammonia within the plant to be utilized. In addition the production of ammonia from nitrates within plants is only on a as needed basis; therefore if soil is high in nitrates that are taken up by the plant in higher amounts than needed they will not be formed into ammonia, but will sty in nitrate form and this is toxic to animals ( carcinogenic compounds may be easily created under certain cooking conditions.)
Liebig actually discovered that plants take up solutes, these are dissolved substances. Well dissolved substances is a very broad statement, it does not mean in water only. Many things can be dissolved in substances other than water yet are not water soluble. The actual meaning of solutes in the biological sense is that the molecules are in fluid state, independent of each other, there may or may not be other substances present (solubilizing agents , like water) The word dissolved means broken up into molecules, or ions in salts. This is what the agro-chemical changed "Only ions are taken up" But ions are not the only solutes, nor does the wording solutes necessarily imply a solubilizing agents(like water) is present. The molecules only have to be disassociated to be solutes.
Good soil is a world of working microbes. One gram of soil can contain over ten million bacteria. "Around the roots of a healthy growing plant a dense coating of microbes may contain a population of from 100 to 200 billion microbes. The life span of a single microbe in this environment is approximately one half hour.
Microbes live in colonies and are very mobile. In their rapid life cycle from creation to death they develop tremendous metabolic activity and steadily improve the structure of the soil.
Some microbes excrete antibiotics. They metabolize phosphorus and iron bonds which are difficult to dilute efficiently without this microbial activity. The earthy odor of the soil is due to them. They create two thirds of the soil carbons, attack cellulose and mineralize nutrients.
We have another important grouping of life in the soil. These are mites, nematodes, centipeds,worms,and insects. All preying on or eating plant and animal residues, eating each other, producing dung and other excrements. As death they leave important waste. They work on stages in the formation of humus in the soil.
01-24-2006, 08:23 PM
wow thats a lot of info
01-24-2006, 08:35 PM
01-24-2006, 08:42 PM
For those that read all of this, notice the one constant factor that everybody says must be present to have a good healthy soil.
If you are not applying humus or creating humus with the products you buy and apply, you are not restoreing a healthy soil.
Healthy Soil = minerals, air, water, and HUMUS
The microbes cant live without humus and fertilizer destroyes humus. Simply adding microbes to a humusless soil is just killing microbes
02-07-2006, 08:16 PM
Muddstopper, great work! What you have posted here is awesome.:waving:
02-09-2006, 12:00 PM
keep it coming, this is good stuff brother. I'm working with a lawn this afternoon that is new construction. The guy who installed it put 1/4 inch of dirt on top of a foot of hard clay and threw some seed down. I'm tempted to truck in real soil and start from scratch, but there isnt that kind of budget for the job so several seasons of humus building will have to suffice. And pray for a wet season.
What kind of install person does this kind of work? As long as its green when the buyer signs the mortgage, that's all they care about. The hard part is taking over a lawn like this when it's deep green and new going into a hot summer, and convincing the owners you're doing everything you can but its still going to take a hit. I brought a six inch chunk of turf from a healthy property and showed the owner what it looked like next to a slice of his 1/4 dirt on clay. So far it's the only way I've found to show a customer what real soil is supposed to look like.
It's an uphill battle when the guy across the street just dumps a bunch of chemicals on the grass and it greens right up. But fighting downhill is boring.
02-10-2006, 07:22 PM
A good source of tapes on organics
Mineral Nutrient Depletion in US Farm and Range Soils
02-10-2006, 07:46 PM
Humates and Humic Acid
Humate materials: their effects and use as soil amendments
By T.A. Obreza, R. G. Webb and R. H. Biggs
Humate materials are widely distributed organic carbon containing compounds found in soils, fresh water, and oceans. These substances are formed from the biological and chemical breakdown of animal and plant life, and make up approximately 75 percent of the organic matter that exists in most mineral soils. Humates play a direct role in determining the production potential of a soil.
The importance of organic matter in soil is not a recent discovery. Soil fertility in early agricultural systems was based on the recycling of organic wastes, and the addition of decomposed organic materials improved plant growth. The rise in popularity and use of mineral fertilizers enabled growers to directly supply plant nutrients to the soil, and rapid growth in agricultural productivity occurred. As a consequence, the importance of soil organic matter was somewhat neglected. In Florida, organic matter should be considered as very important due to the sandy nature of the soil. In soils void of significant quantities of clay minerals and organic matter, the addition of humates can have an impact on soil fertility which may be noticeable in the form of improved plant growth.
Effects on Soil Fertility. Native soil humic substances enhance plant growth both directly and indirectly. Physically, they promote good soil structure and increase the water holding capacity of the soil. Biologically, they affect the activities of microorganisms. Chemically, they serve as an adsorption and retention complex for inorganic plant nutrients. Nutritionally, they are sources of nitrogen, phosphorus, and sulfur for plants and microorganisms. All of these effects increase the productivity of the soil.
Commercially-available humic substances added to the soil do not directly contribute significant quantities of nutrients to plants in modern agriculture at the rates normally applied. However, indirect effects of these materials on soil fertility can be significant. Micronutrients, especially iron, may be made more available to plants in the presence of humates. Inorganic iron compounds are very unstable in soil and tend to become insoluble and unavailable, especially in calcareous soils. Humate compounds can incorporate iron into chelated complexes, maintaining its availability to plants, although still in insoluble form.
Soil phosphates are often immobilized through reactions with iron and aluminum, which in turn may be complexed with organic matter. Chelating agents can break the iron or aluminum bonds between the phosphate and organic matter, releasing phosphate ions into solution. This dissolution is a process which occurs in soil in the presence of naturally-occurring humic substances or plant root exudates. The addition of humates may increase the rate of this process, thereby increasing the availability of phosphorus to plants.
Applied pesticides substantially interact with soil humic substances, but the reactions are complex. Some pesticides may be immobilized by humates and can practically disappear from the soil environment. In this case, humic substances can be very effective in removing excess pesticide from sandy soils very low in organic matter. The most common reaction between pesticides and humates is adsorption, followed by a release to the soil solution at a rate dependent on the chemical structure of the pesticide. Degradation of the pesticide will be determined in part by the rate of release. Humic substances may be used in this case to control the concentration of pesticide in the soil solution, and to avoid toxicity hazards. A third case involves the mobility of pesticides by humic material. Some groups of compounds can form complexes with humates, which can then be absorbed by plant roots.
Effects on Plants. Humic acids can have a direct positive effect on plant growth in a number of ways. They have been shown to stimulate seed germination of several varieties of crops. Both plant root and top growth have been stimulated by humates, but the effect is usually more prominent in the roots. A proliferation in root growth, resulting in an increased efficiency of the root system, is a likely cause of higher plant yields seen in response to humic acid treatment.
Humic matter has been shown to increase the uptake of nitrogen by plants, and to increase soil nitrogen utilization efficiency. It can also enhance the uptake of potassium, calcium, magnesium and phosphorus. Chlorosis in plants has been prevented or corrected by humate application, probably the result of the ability of humate to hold soil iron in a form which can be assimilated. This phenomenon can be particularly effective in alkaline, calcareous soils, which are normally deficient in available iron and low in organic matter content.
Effect of Management Practices on Soil Organic Matter. Cultivation of soils usually causes a decrease in the organic matter content. Rather than being completely destroyed, the organic matter in the soil tends to reach a new, lower equilibrium level. For most soils, a high level of organic matter is maintained only by grass species. Grass middles between citrus tree rows can help maintain higher organic matter in the portion of the citrus tree root zone that extends into them. However, the establishment of clean herbicide bands within three rows to facilitate harvesting and other operations may decrease the organic matter content in what is normally the major area of tree root concentration and fertilizer application.
Conventional sources of applied organic matter such as farm manures or crop residues are not normally used in a citrus grove situation due to lack of availability or prohibitive cost. The leaf and dead wood litter that is generated is not sufficient to maintain an organic matter content under the trees which is comparable to that under grass middles. Efforts to increase citrus grove soil organic matter content have been made by growing cover crops using species of Crotalaria or hairy indigo, but success was poor because the crops could not be sufficiently incorporated into the soil without damaging the tree root system.
Non-conventional Sources of Organic Matter: Humic substances. Humate products for agricultural use are produced through mineral sand mining and recovery operations. The end product contains a majority of organic material (concentrated humic acid) mixed with smaller amounts of mineral matter. It can be applied to soil to improve its fertility, especially in the zone of highest root activity. Humate concentrates provide many of the advantages of conventional organic matter sources over a long period with less handling problems, especially in situations where there is no feasible alternative to purchasing additional supplies of humus. They have been demonstrated to have favorable effects on tissue nutrient balance, fertilizer uptake, top and root growth, and crop yield and quality for a large variety of field, horticultural and ornamental plants. They have been most effective in soils with less than two percent organic matter.
The plant characteristic that the addition of humic substances has consistently enhanced more than any other is root length, especially on sandy soils. A preliminary study with the citrus trees potted in sand showed that after a period of one year, the root dry weight was increased when a humic acid material was added at the rate of one lb. per cubic yard of soil as compared to an untreated treatment. Tree top growth, vigor, and trunk cross-sectional area also increased in response to humate addition.
A field study with young citrus trees is currently underway to determine if the addition of humic acid can increase fruit yield. In this trial, the trunk cross-sectional area increase of newly-planted trees was greater for the first year of growth where 0.5-1.0 lb. of humate material per tree was applied at planting. These data are not conclusive, as much more research is needed to determine the long-term effects of humic acid addition to citrus trees, especially as they come into bearing.
REPRINTED FROM THE CITRUS INDUSTRY - OCTOBER 1989
The authors are Assistant Professor, (Soil Scientist), Southwest Florida Research and Education Center, Immokalee; former Research Scientist, and Professor, Fruit Crops Dept., Univ. of Florida Gainesville, respectively.
02-10-2006, 08:34 PM
A good video explaining humis 164mb requires windows media player
02-13-2006, 05:52 PM
Those comments are an over-simplification. Microbes do not solely depend upon humus as a carbon or nutrient source. Humus is the final product of microbial breakdown of organic materials. Humus is actually a very poor source of energy for soil microbes. Humus provides great increases in soil structure/physical properties as well as greatly increasing CEC levels. It does not, in and of itself, increase microbial populations as a food source. If you are culturing a microbially rich soil...humates will accumulate naturally.
02-13-2006, 08:13 PM
Those comments are an over-simplification. Microbes do not solely depend upon humus as a carbon or nutrient source. Humus is the final product of microbial breakdown of organic materials. Humus is actually a very poor source of energy for soil microbes. Humus provides great increases in soil structure/physical properties as well as greatly increasing CEC levels. It does not, in and of itself, increase microbial populations as a food source. If you are culturing a microbially rich soil...humates will accumulate naturally.
You will have to explain your over simplification comment. I dont get it.
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