Custom Biologicals, Inc.

TECHNICAL DISCUSSION #5

Accelerated Soil Bio-Rejuvenation

Today, more than 70 chemical elements and dozens of different minerals are mined and produced from more than 100 different deposit types and geographic environments.  Most of the mining techniques available completely destroy, or nearly destroy the natural environment of the mine site.  As the mining sites mature, and the deposits are completely exhausted, mining companies and governments alike are looking for quick, low cost solutions to restore the land to its original condition, or, more likely, convert the land into a productive resource, such as farms or plantations. 

Unfortunately, the soil conditions left behind form the mining are less than ideal.  The extracted and/or processed soil does not contain the necessary organic material, nutrients, or microorganisms required to support plant life.  In some cases, the soil is polluted by chemicals or has been subject to extreme pH adjustments that must be remediated before the soil is to be used.

Custom Biologicals, Inc. has developed a new agricultural system designed to rejuvenate soil that has been rendered non-fertile due to fire, mining, floods, or other environmental problems.

 

The non-fertile soil in question usually does not contain enough organic material to support immediate growth of plants or even microorganisms.  To make the situation worse, the area is usually too large to economically add organic material such as compost, manure, or other waste organic material.

In most non-fertile soils, the soil microorganisms have been destroyed, removed, or not allowed to grow by environmental conditions and can quickly be reestablished with a proprietary bioaugmentation method developed by Custom Biologicals, Inc.  Once the population of soil bacteria and fungi has been reestablished, indigenous plant life can be introduced quickly to prevent the further difficulties of soil erosion by water and wind.

Background

BACTERIA

Bacteria are very small, prokaryotic organisms – generally 4/100,000 of an inch wide (1 µm) and somewhat longer in length.  But what bacteria lack in size, they make up for in numbers.  A gram of fertile soil generally contains between 100 million and 1 billion bacteria. That is as much biological mass as five cows per hectare (two cows per acre).

Soil bacteria and fungi fall into five functional groups.  Most are decomposers that consume simple carbon compounds, such as root exudates and fresh plant litter.  By this process, bacteria convert energy in soil organic matter into forms useful to the rest of the organisms in the soil.  Decomposers are especially important in immobilizing, or retaining, nutrients in their cells, thus preventing the loss of nutrients, such as nitrogen and phosphate, from the soil.  However these organisms are of little help in initiating growth with non-fertile soil that does not contain adequate nutrients.

A second group of bacteria are the mutualists that form partnerships with plants.  The most well known are the nitrogen-fixing bacteria.  Nitrogen-fixing bacteria form symbiotic associations with the roots of legumes like clover and lupine, and trees such as alder and locust.  Visible nodules are created where bacteria infect a growing root hair.  The plant supplies simple carbon compounds to the bacteria, and the bacteria convert nitrogen (N2) from air into a form the plant host can use.  When leaves or roots from the host plant decompose, soil nitrogen increases in the surrounding area.

The third group of bacteria is the pathogens.  Bacterial pathogens include Xymomonas and Erwinia species, and species of Agrobacterium that cause gall formation in plants.

A fourth group of bacteria, called lithotrophs and/or chemoautotrophs, obtain energy from compounds of nitrogen, sulfur, iron or hydrogen instead of from carbon compounds. Some of these species are important to nitrogen cycling and degradation of pollutants.

A fifth group of bacteria (and the most important to reclamation of non fertile soil) utilizes light energy, as they are photosynthetic organisms. These organisms are especially important in the rejuvenation of non-fertile soil, as they do not rely on preexisting carbon sources for energy or carbon.  In addition to using light energy, they use carbon dioxide from the air for their carbon source and they fix nitrogen. So they are ideal to initiate growth in non-fertile soil.

FUNGI

Fungi are microscopic cells that usually grow as long threads or strands called hyphae, which push their way between soil particles, roots, and rocks. Hyphae are usually only several thousandths of an inch (a few micrometers) in diameter.  Single hyphae can span in length from a few cells to many yards.  A few fungi, such as yeast, are single cells.  Hyphae sometimes group into masses called mycelium or thick, cord-like “rhizomorphs” that look like roots.

Fungi perform important services related to water dynamics, nutrient cycling, and disease suppression. Along with bacteria, fungi are important as decomposers in the soil food web.  They convert hard-to-digest organic material into forms that other organisms can use.  Fungal hyphae physically bind soil particles together, creating stable aggregates that help increase water infiltration and soil water holding capacity.

 

Soil fungi can be grouped into three general functional groups based on how they get their energy. Decomposers – saprophytic fungi – convert dead organic material into fungal biomass, carbon dioxide (CO2), and small molecules, such as organic acids. These fungi generally use complex substrates, such as the cellulose and lignin, in wood, and are essential in decomposing the carbon ring structures in some pollutants.  Like bacteria, fungi are important for immobilizing, or retaining, nutrients in the soil.  In addition, many of the secondary metabolites of fungi are organic acids, so they help increase the accumulation of humic-acid rich organic matter that is resistant to degradation and may stay in the soil for hundreds of years.

Mutualists – the mycorrhizal fungi – colonize plant roots. In exchange for carbon from the plant, mycorrhizal fungi help solubolize phosphorus and bring soil nutrients (phosphorus, nitrogen, micronutrients, and perhaps water) to the plant.  One major group of mycorrhizae, the ectomycorrhizae (Figure 3), grows on the surface layers of the roots and is commonly associated with trees.  The second major group of mycorrhizae is the endomycorrhizae that grow within the root cells and are commonly associated with grasses, row crops, vegetables, and shrubs.  Arbuscular mycorrhizal (AM) fungi (Figure 4) are a type of endomycorrhizal fungi. Ericoid mycorrhizal fungi can by either ecto- or endomycorrhizal.

The third group of fungi, pathogens or parasites, cause reduced production or death when they colonize roots and other organisms.  Root-pathogenic fungi, such as Verticillium, Pythium, and Rhizoctonia, cause major economic losses in agriculture each year.  Many fungi help control diseases. For example, nematode-trapping fungi that parasitize disease-causing nematodes, and fungi that feed on insects may be useful as biocontrol agents.

Of all the fungi available, the genus Trichoderma, is the best suited for soil bioaugmentation and reclamation. They are ubiquitous fungi and are among the most common saphrophtic organisms that can be isolated from the soil.   
These beneficial microorganisms facilitate plant and bacterial growth in a number of ways including the breakdown and transfer of nutrients, competition with pathogenic organisms, and even the degradation of toxic organic chemicals such as hydrocarbons and fungicides.

The Trichoderma are known as early colonizers of root systems and directly promote plant growth by increasing the beneficial microbial activity in the rhizosphere, which is defined as an intense zone of stimulated microbial activity around the roots.  They are naturally present in fertile soil but their population can be greatly increased by adding selected strains of laboratory grown organisms to non-fertile soil.  Currently they are widely used in bioaugmentation programs as growth stimulating agents as the artificially added organisms quickly occupy an ecological niche on the roots and greatly increase the root mass and plant health for a season long effect.

Plant growth stimulation by Trichoderma is quite complex and is probably effected by a variety of interactions.   It has been attributed to several biochemical factors including supplying essential nutrients such as nitrogen, phosphorus, calcium, copper, molybdenum, magnesium, zinc, iron, and very importantly a source of water.

One plausible contributing factor is that Trichoderma have been shown to have the ability to solubilize Manganese contained in MnO2.   Manganese is a microelement required for several physiological functions of plants including photosynthesis and is thought to play a major role in both growth and disease resistance.   It is available to plants only in its chemically reduced form (Mn+2) whereas the oxidized form (Mn+4) is essentially insoluble.  The solubilization of Mn+4 by Trichoderma was shown to occur without being correlated to pH changes and did not require a deficiency of Mn+2.


Reestablishing soil fertility

       
Before plants can become established on fresh sediments or non-fertile soil, the bacterial community must first be established starting with photosynthetic bacteria. These microorganisms fix atmospheric nitrogen and carbon, produce organic matter, and immobilize enough nitrogen and other nutrients to initiate nitrogen cycling processes in the young soil.  Then the other added bacteria and fungi become established and early successional plant species can grow.

As the plant community is established, different types of organic matter enter the soil and change the type of food available to bacteria.  In turn, the altered bacterial community changes soil structure and the environment

Bacteria from four of the five groups perform important services related to water dynamics, nutrient cycling, and disease suppression. Some bacteria affect water movement by producing substances that help bind soil particles into small aggregates (those with diameters of 1/10,000-1/100 of an inch or 2-200µm). Stable aggregates improve water infiltration and the soil’s water-holding ability.

Treatment and Product (Custom ASR)
Concentrated solutions of Soil bacteria containing:
            1.         Two photosynthetic species

            2.         Five species of Bacillus

            3.         Three species of Arthrobacter

            4.         Two species of Trichoderma

Product can be sprayed or misted onto soil using aircraft (crop dusting) or heavy spray equipment.  It is recommended that an initial application be made with a combined product containing the photosynthetic bacteria, Bacillus species, Arthrobacter species, and Trichoderma listed above.   A secondary product application of some, or all of these organisms may be necessary.  Soil samples will be analyzed after 60 days to determine populations.

After 30 days, an indigenous grass seed, or other beneficial plant seed can be added.  Legumes or forages such as peanuts or alfalfa work symbiotically with the nitrogen-fixing bacteria introduced.  As the microorganisms are restored, the greatest threat is now soil erosion due to water and wind.  Establishing a layer of plant material will dramatically reduce this danger.  

Farming can begin after 90 days and the soil will continue to improve from the accelerated soil bio-rejuvenation for years to come!