Humic Substances for Farming

Humic Substances in Biological

Article Submitted to Acres USA magazine

Agricultural Systems

Introduction

by Gary Zimmer

Author of The Biological Farmer & President, Midwestern Bio-Ag

Organic matter, compost, humus, humates, humic acid, and fulvic acid are all related to, and

parts of, decaying plant materials. It’s food for soil life and a storehouse for minerals, energy and water.

These organic materials are mediums for certain organisms to grow on.

The biological/organic farming system is based on balanced minerals and lots of soil life in terms of

diversity and volume.

So where do humic substances fit in farming systems? The objective of this article is to clarify

some of the confusion about humic substances, update and review the scientific research and provide

guidelines for use of the many different humic materials being marketed.

Research is proving what farmers have long known to be true: humic substances stimulate plant

roots, stimulate soil life (mostly fungal populations), chelate minerals (holding them for future use by

plants), improve absorption of minerals for root and plant use, and improve the effectiveness of

herbicides.

In the first section of this paper I’ll explain the different humic products available and how they

presently are being used. The last section is a scientific review completed by Lawrence Mayhew, working

in Product Development for Midwestern Bio-Ag.

Humates

Humate is a common term used to describe dry mined carbonaceous materials found in areas

where coal is mined. They are correctly called Leonardites or oxidized Lignites. For many years the most

commonly used humic product was a black liquid extract called humic acid. Humic acid is obtained by

mixing a strong base liquid material like sodium hydroxide or more commonly potassium hydroxide with a

dry humate material. The black humic acid material (not really an acid because of the base extraction has

a pH of 9+), usually a 6% or 12% solution, was most commonly mixed with fertilizers, used in transplant

solutions mixed with liquid nitrogen sources or mixed with herbicides. Because of its high pH you had to

be careful because it would cause the liquid mix to jell, or precipitate out. Mixing it with phosphorus

materials was a real problem in many situations.

Besides, mixing it in transplant solutions (where it is highly diluted and didn’t give many problems)

my favorite place to use humic acid is mixing it with liquid nitrogen sources. It gives an organic material

for the nitrogen to hook to, therefore reducing the leaching and loss of nitrogen and buffering the solution

for more effective and efficient use. A rate of 1-3 gallons/acre, depending on nitrogen needs (which can

be reduced with humic acid use) seems to work best from my observations.

Fulvic acid, another extraction from the dry humates, is truly an acid. It is an acid extraction and

has a pH near 3.0. It can be mixed with any liquid compound without difficulty. It is a part of the original

material but quite different from the humic acid. My favorite place to use it is in liquid fertilizer mixes to

buffer the soluble fertilizer, chelate it and improve its uptake by the plants. Another area of common use is

mixed with herbicides, besides acidifying the tank mix which helps the effectiveness of the herbicide, it

again also chelates and improves the intake of the chemical. Application rates are from one quart to one

gallon/acre, depending on the crop, and on the amount and type of fertilizer and chemicals used.

Now if you have extracted part of the original humic substance (humic acid) with a base, then

another part (fulvic acid) with acid, what you have left is a large molecule called humin, the ‘sponge’ as it

is known because it holds and absorbs things.

My belief in agriculture is that, where ever possible, don’t take parts or pieces, but use the whole

compound. Sometimes the parts we leave behind have some real benefits like the calcium, trace

elements and rare earths remaining when the fertilizer industry extracts phosphorus from rock

phosphates. The same is true for the minerals, vitamins, hormones and other unknown compounds left

behind when cytokinins are extracted from kelp. Where ever possible, why not use the whole?

As for humic substances, in the last few years micronized compounds with added suspending

agents have been showing up in the marketplace. This is the original humic material ground really fine.

It’s an expensive process and not fool proof, as precipitation of materials and spray nozzle plugging has

occurred, but the idea makes sense. This material can be used anywhere humic and fulvic acids are

used. Not being the same as them because of the base or acid treatment, but having the same materials

in them.

In my biological farming experience, after a lot of observations and testing, dry fertilizer mixes

give more flexibility and are better buys. Plus, you can balance the soluble to slow release materials.

Liquid fertilizers are water soluble, can leach, tie up in the soil, cause short term nutrient imbalances, and

don’t provide nutrients over the plant’s life. They have their place as a pop-up to get the crop out of the

ground or as a foliar to give a boost, but not as a complete fertilizer program.

So humic substances and dry fertilizers, how can they work together? I’ve tried bulk spreading

dry humates on soils. They’re dusty, hard to handle and I struggled to find any measurable results.

It makes sense to add humic substances to fertilizer materials to provide carbon, a buffering,

chelating agent, and some microbe foods. Using the original raw material is providing the most benefits

for the dollar. Yet, handling that black dusty humic material seemed unworkable for most fertilizer

blenders.

In Australia, farmers and consultants are blending humates with natural phosphates, calcium,

sulfur and trace mineral materials, inoculates with beneficial organisms, adding molasses, and brewing

the batch: just like making compost. The natural humic material has a low pH, large nutrient holding

capacity and feeds microbes. The results looked good and the process makes sense.

However, the problem is still handling. You certainly can’t put it down the row as a crop fertilizer.

The secret to fertilizing is a balance of nutrients, the concentration putting them where and when needed

and the recovery throughout the growing season.

Pelletizing

To overcome these problems, we at Midwestern Bio-Ag started pelletizing the humic materials,

and mixing them with calcium sources and rock phosphates.. It’s not an easy process and because of the

nature of the material, it’s hard to keep it in a hard pellet form.

During early attempts, something surprising occurred. When a pile of humic substances is premixed

with rock phosphates and allowed to sit for a period of time, the measurable soluble phosphorus

content went up! A reaction occurred; the moist low pH humic materials released activating the rock

phosphate (the same thing that was happening in the brew piles in Australia). The beneficial results in the

field have really been noticeable!

Humic materials from my experiences belong mixed with fertilizers. Not only can humic materials

buffer fertilizers, but also chelate, holding nutrients for longer plant use.

Our next step in pairing humic materials with buffers is to make up homogenized trace mineral

mixes using sulfate trace minerals paired with humic substances. This should also chelate the mineral for

more efficient and long term use.

In our effort to help farmers, consultants, and agricultural researchers to better understand humic

substances, Lawrence Mayhew, Midwestern Bio-Ag’s product development specialist, did an extensive

review of current scientific research about the material. Research gives us clues and ideas in this field of

agriculture, then we need to evaluate this research as to where it fits and how it can be best utilized.

The updated scientific study that follows will, I hope, give you a better understanding and

clarification of what humic substances are, and are not, and what researchers have seen and measured.


Humic Substances as Agronomic Inputs in Biological

Agricultural Systems: a Review

by Lawrence Mayhew

Background

Humankind has realized for thousands of years that dark-colored soils with high humus content

are more fertile than light-colored soils. It has long been recognized that humic substances have many

beneficial effects on soils and consequently on plant growth (Mulller-Wegener, 1988). Anywhere on the

globe where there is soil or water associated with organic matter, humic substances are present. They

are the brownish tint often seen in natural streams, the darkness of dark soils and the dark brown color of

weathered lignite coal.

Humic substances are the most widely distributed organic products of biosynthesis on the face of

the earth (Tan, 2003), exceeding the amount of carbon contained in all living organisms by approximately

one order of magnitude (Steinberg, 2003).

Soil organic matter is defined as the total of all naturally occurring organic (carbon based)

substances that are found in soils, which have come from living things. The process of changing from

recognizable bits and pieces of plants (or animals) to an amorphous, “rotted” dark mass is called humification.

Humus is defined as the organic matter in soil that is a mixture of partially and totally

humified substances. Most humic substances come from the natural process of decaying plant matter.

(Hayes, 1998) Humic substances make up about 80% of the soil organic matter in dark soils. (Schnitzer,

1986)

Humic substances in soils are the dark brown, fully decomposed (humified) remains of plant or

animal organic matter. They are the most chemically active compounds in soils (Tan, 2003) with cation

and anion exchange capacities far exceeding clays. They are long lasting critical components of natural

soil systems, persisting for hundreds to thousands of years, which can be destroyed in less than fifty

years by some agricultural practices.

The interest surrounding the use of humic substances comes forth from the necessity to

understand an essential component of the most complex ecosystem on the globe…soils! The global

movement away from chemical to biological agriculture is encouraging some of the best minds in the

scientific world to solve the great mystery of how these substances operate in the environment.

As information-age agriculture moves towards biological methods, the world is compelled to

reconsider the post World War II paradigm of indiscriminate use of high-energy input, high solubility, and

toxic chemical resources. (Nardi, et al, 1996) Natural humic substances are destroyed by conventional

practices, but can be replaced by proper management practices.

Humic substances are the most widely distributed products of biosynthesis on the face of the

earth (Tan, 2003). Besides soils, they can be found in varying concentrations in a number of different

sources: rivers, lakes, oceans, compost, sediments, soils, peat bogs and soft coal.

As the use of humic substances in agriculture grows, the number of vendors of humic products is

also growing. Historically, the typical supplier has been a small, privately owned operation located where

the materials can be easily removed with basic equipment. Because humic substances are typically

associated with coal deposits, large coal mining companies are beginning to realize that the market for

these materials may be attractive.

There are a number of theories that attempt to explain how coal is converted to humic matter. All

of them agree that “younger” deposits of organic matter have lower concentrations of humic acid (Tan,

2003). The concentration of humic substances in the converted coal can be as high as 80% by weight.

Although humic substances can be found in every scoop of soil and almost every drop of water

on the earth, no one has succeeded in the last 200 years at describing their structure. (Steelink, 1999)

Behaving more like chameleons, humic substances rapidly rearrange their molecular structure as the

surrounding conditions change (Tombacz and Rice, 1999).

The worldwide usage of humic substances is extensive (Fataftah, et al, 2001) The benefits of

humic substances in agricultural soils is well established (MacCarthy, 2003), especially in soils with low

organic matter. (Chen and Aviad, 1990) They are an integral part of all ecosystems and play an important

role in global cycling of nutrients and carbon (MacCarthy, 2003).

Humic substances are extremely versatile. They provide a concentrated and economical form of

organic matter that can replace humus depletion caused by conventional fertilization methods as well as

being used in biological programs. (Burdick, 1965) The addition of humic substances to soils, including

calcareous soils, can stimulate growth beyond the effects of mineral nutrients alone. (Chen, et al, 1999)

Humification

Humification is the natural process of changing organic matter, such as leaves, into humic

substances by geo-microbiological mechanisms. Compost is an intermediate product consisting of humic

substances and partially decomposed organic matter. As the conversion process continues, different

chemicals dominate at different points in time (Ziechmann, et al, 2000). Complete conversion to humic

substances will eventually occur.

Unlike most other natural biosynthetic processes, humification occurs in a complex, chaotic

“open” system where there is no “closed” control of the process by enzymes, cell structures, membranes

or cellular transport systems. With the infinite variety of plant materials that exist in nature and with the

infinite access to chemical radicals, humification should produce humic substances that are infinitely

variable. (Ziechmann, et al, 2000) It would seem impossible to find two humic molecules with the same

structure.

Confusion and Non-Standardization

Humic substances have been a matter of scientific controversy for over 200 years. They are

incredibly complex colloidal supermixtures (MacCarthy, 2001) that have never been separated into pure

components. (Steelink, 1999; MacCarthy, 2001) Inconsistent use of terminology and the previous lack of

standard materials for comparison purposes have compromised the ability to translate the sparse amount

of scientific knowledge to practical applications in soil environments. Traditionally, humic substances have

been defined by their solubility in aqueous (water) solution at arbitrary pH levels and molecular weights.

The use of numerous names to describe commercially available humic materials has contributed

to the confusion. Humates, humic acid, Leonardite, brown coal, lignite, slack lignite, oxidized lignite,

weathered lignite, humalite, fulvic acid, fulvates, ulmic acid, humic shale, carbonaceous shale, colloidal

minerals, humin, concentrated humus, soil organic matter, peat, humus acid, humus coal and dead

organic matter are some of the terms that are used to describe and/or market humic substances.

Non-standardization and confusion is not limited to humic substances. For example, many labs

are using soil tests that may not accurately determine soil organic matter content due to

oversimplification. There are numerous tests for soil organic matter (Tabatabai, 1996), but there is no

standardized test protocol for all soils. Some of the tests for soil organic matter have to be interpreted with

much caution (Magdoff, 1996). Additionally, conventional analyses do not predict possible adverse

interactions of trace elements (Olness et al, 2002).

In the past, some scientists have added to the confusion surrounding humic substances by

refusing to study the materials, calling them “dirt” (Tan, 2003), thus putting a drag on the flow of scientific

knowledge and the study of their beneficial effects on soil and plants (Stevenson, 1994).

The establishment of standard reference material by the International Humic Substances Society

http://www.ihss.gatech.edu/ has helped to remedy some of the communication problems. The society is

composed of scientists from all over the world who are striving to understand the structures and functions

of humic substances. The north-central United States contact is Dr. Alan E. Olness, USDA-ARS, North

Central Soil Conservation Research Laboratory, Morris, MN 56267, 320-589-3411 x131.

The Benefits of Humic Substances

While the complete structure of humic substances has eluded scientists, their effects on

everything from apples to zucchini have been extensively studied.

Humic substances are renowned for their ability to:

  • chelate soil nutrients
  • improve nutrient uptake, especially phosphorous, sulfur and nitrogen
  • reduce the need for nitrogen fertilization
  • remove toxins from both soils and animals
  • stimulate soil biological activity
  • solubilize minerals
  • improve soil structure
  • act as a storehouse of N, P, S, and Zn (Frank and Roeth, 1996)
  • improve water holding capacity for better drought resistance and reduction in water usage (

Russo and Berlyn, 1990),

Extensive research on the stimulatory effects of humic substances has been conducted by the

USDA-ARS soil lab in Minneapolis (Clapp et al, 2001; Chen et al, 2001; Chen et al, 1999) and worldwide

(Karr, 2001). Most of the research conducted in Eastern Europe on improving nitrogen utilization has not

been translated into English (Clapp et al, 2001).

Depending on the form of fertilizer applied, nitrogen may become a structural component of

humic substances as a stable organic material, preventing it from leaching through the soil. (Haworth,

1971; Stevenson, 1982; Haynes and Swift, 1990; Kelly and Stevenson,1996) In their natural state, humic

substances contain anywhere from 1% to 5% nitrogen.

Despite the fact that all humic substances posses the abilities describe above, regardless of their

origin or molecular weight (Wershaw, 2000; MacCarthy, 2001, p.24), many vendors of humic substances

engage in a bit of “chest beating” when making claims about their products based on arbitrary definitions

of “humic acid” and “fulvic acid” content. (Fataftah, et al, 2001)

Nitrogen Management

Other effects of humic substances include increased CEC (cation exchange capacity),

stabilization of soil structure (Piccolo et al, 1999) and the reduction of nitrogen and phosphorus fertilizers.

(Day, et al, 2000; Fataftah, et al, 2001) The importance of humic substances on the fertility of soils and

the stabilization of nitrogen has been well documented (Thorn, 2000; Kelly and Stevenson, 1996; Nardi,

et al, 1996). One study done by a science team from West Texas A&M University and the USDA-ARS

(Shi et al, 2001) demonstrated the potential of humic substances in reducing ammonia emissions from

feed lots.

If there are sufficient humic substances present, up to 35% of the soluble nitrogen applied to soils

as fertilizers can be retained in the soil in organic forms at the end of the first growing season (Stevenson

and Xin-Tao He, 1990), thus converting the N to a stable, yet bioavailable form.

The ecological impact of nitrogen applied to turf grass is increasingly coming under the

scrutiny of the public sector and the federal government. Because of this pressure, humic substances

have become the most commonly used organic materials in golf course turf management (Clapp et al,

1998). After 45 years of research, C. Edward Clapp of the USDA-ARS, Department of Soil, Water &

Climate in Minneapolis, Minnesota is recommending humic substances be used to prevent nitrogen

leaching on golf courses (Clapp, 2001).

An exhaustive review of the scientific literature has revealed very little regarding the practical

application of humic substances in agriculture. There are numerous references to a large body of

research in Russia that has not been translated into English. A recent reference (Steinberg, 2003) states

that most of the information is buried as internal reports within universities.

Pelletized Leonardite

One of the biggest obstacles to using humic products is the dustiness of the dry materials,

making them almost impossible to handle. Liquid “humates” are easier to handle, but they their use is

restricted to foliar application at very low concentrations. Because of extremely low application rates, they

have no effect on soils. The water soluble derivatives from alkali extractions are only compatible with high

pH liquids and they are expensive. Pelletizing humic substances improves their handling and allows them

to be blended with fertilizer “in the row” where they can do the most good.

A team of scientists with the US Bureau of Mines, University of North Dakota combined

standard NPK fertilizer with Leonardite into a pelleted form (Cooley et al, 1967). Although the

addition of Leonardite lowered the soluble analysis for N, P, & K to 10-10-5, thus lowering the

relative amount of applied fertilizer, the pelleted Leonardite combination (10-10-5 L) was effective

on barley, potatoes and sugar beats.

Barley Test

Fertilizer Tissue Analysis Nitrate ppm Total N % Plants / row Yield

bu / acere

16-20-6 1275 4.4 68 47.3

15-22-5 945 4.8 84 47.6

10-10-5 L 1025 4.7 96 53.5

There was over a 12% increase in yield in the barley test a plot despite the fact that the

Leonardite treated crops had relatively low nitrate nitrogen. The significant yield advantage was attributed

to increase tillering.

Potato Test

Fertilizer Tissue Analysis Yield Nitrate ppm Total N % Specific Gravity C Wt. Bu/acre

16-16-8 820 4.7 1.095 162 270

10-10-5 L 1600 5.2 1.096 134 224

The potato tests plots reveal how a 95% increase in plant tissue uptake of nitrogen was possible

while 35% less nitrogen was applied with the Leonardite fertilizer combination.

Sugar Beet Test

Yield

Fertilizer Seedling

Emergence Tons / acre Sucrose

%

Sucrose

lbs. / acre

5-45-5 175 8.873 17.0 3010

10-10-5 L 140 10.925 15.9 3474

Sugar beets treated with the fertilizer- Leonardite combination yielded 23% more tonnage per

acre and 15% more sugar per acre.

Despite the fact that the above report from the US Bureau of Mines concentrated primarily on

yield, which is typical of conventional NPK fertilization programs, the report underscores how humic

substances can improve nitrogen utilization and impact overall crop quality by increasing the efficiency of

fertilizers. Additionally, the reduction in nitrogen usage demonstrates the environmental significance of

using humic substances blended directly with fertilizers.

Carbon Cycling

The carbon held in soil humic substances is so stable it may be retained in soils for thousands of

years, depending on conditions. (Miller and Gardiner, 1998) The shear complexity of these materials may

explain why they are not broken down by microbial action for thousands of years. (Schnitzer and Khan,

1972) It is possible that the surfaces of humic substances are unrecognizable by microbes. (Orlov et al,

1994).

Conventional fertilizers rapidly age soil components, resulting in acidification of soils (Burdick,

1965; Barak, 1999) and by dissolving the humic materials with soluble nitrogen. Urea is so effective at

dissolving humic substances, it is used in some laboratory extraction procedures. (Pokorna et al, 1999) A

typical Iowa soil under conventional agricultural management retains its carbon for as little as 90 years.

(Miller and Gardiner, 1998)

The negative effects of high soil acidity have been extensively researched. “Liming”, which is the

use of dolomitic limestone (calcium magnesium carbonate) improves soil productivity by providing cations

of calcium (Ca2+) and magnesium (Mg+) The carbonate ions raise the pH by combining with the excessive

hydrogen protons.

The ability of humic substances to complex with cations, such as calcium, is decreased as the

bulk pH of soils goes down (more acid) due to aggregation of the humic molecules. The aggregation

reduces the exposure of functional groups, cutting off the access of nutrients to the molecules. (Liu and

Huang, 1999) Functional groups attached to carbon chains are primarily responsible for the biochemical

characteristics of organic compounds.

Humic Acid, Fulvic Acid and Humin

The traditionally accepted definition of humic acid, fulvic acid and humin is much like defining

common table salt as “the remaining solids left over from the evaporation of seawater”. One would say

that the remaining material after evaporation is operationally defined instead of calling it what it really is;

sea salt, a mixture of numerous minerals along with sodium chloride. Common table salt, by the way,

contains sodium chloride along with other chemical additives, such as sodium alumino-silicate, to help it

flow out of a salt shaker.

About 200 years ago, the names humic acid, fulvic acid and humin were used to describe what

workers believed to be three distinct fractions of humic substances. The three fractions were separated

from various materials by using “classical” extraction techniques with aqueous (water) solutions.

(Schnitzer, 1999) First, the humic material was treated with a strong alkali (base), then an acid was

added. The acid caused a coagulated black sludge-like material to precipitate out of solution. They

named the precipitate “humic acid”.

The remaining mixture that survived the base/acid treatment consisted of an acidic liquid and a

solid. The liquid was named “fulvic acid” and the solid which was unaffected by the treatments was

named “humin”. Despite the fact that manufacturers use variations of these operations, which don’t

necessarily duplicate the process described above, the names humic acid, fulvic acid and humin persist.

Potassium hydroxide is the typical alkali used by manufacturers to extract “humic acid” from

Leonardite. Since the remaining liquid solution is very alkaline, in the range of 8 to 12 pH, it is

incompatible with acids. Here lies some of the confusion, “humic acid” synthesized by this operation is not

an acid. Because it can also be described as the product of adding acid to an alkaline solution, it is a

“salt”. Therefore, the word “humate” may be more appropriate.

Some manufacturers follow the traditional method described above by treating the alkaline extract

with acid, precipitating out the “humic acid” portion, leaving behind the so called “fulvic acid” fraction in

solution. The fulvic fraction is acidic with a distinctive yellowish tint. Note, however, that the operation is

vague. There is no definite pH at which the precipitate and acid are separated.

As various fractions of humic substances are soluble in a wide pH range, it makes sense that

some fractions must be soluble at neutral pH. Some manufacturers treat humic materials with water,

extracting the water-soluble fraction, calling that fraction either fulvic acid or “colloidal minerals”, which are

promoted in the human neutraceutical markets. Fulvic acid can be operationally defined as “ the fraction

of humic substances that is soluble in water under all pH conditions (MacCarthy, 2003).Humic Acid, Fulvic

Acid and Marketing

The marketing of humic substances is interesting in that there is a lack of standardized analysis

within the industry for fulvic acid and humic acid. For example, if liquidized humic materials are subjected

to analysis, it is difficult to determine what the analysis reveals because of the infinite number of reassociations

of free radicals that are possible during the extraction process. Some scientists argue that

the reaction products are substances created by alkali treatment as complex degradation products,

stripped of many of the original functional groups and recombined into an indescribable material (Pokorna

et al, 2001). This may seem to be a nit pick, but some scientists like to argue about it.

The humin fraction gets very little attention. It may seem to be somewhat inert but it has been

described as acting like a sponge, soaking up nutrients (Karr, 2002). Hayes and Graham (2000) report

the composition of humin to be the same as humic acid and fulvic acid. They say that humin may be a

humic substance in association with mineral oxides or hydroxides (from the reaction). Alternatively, humin

may be coated with hydrocarbons or lipids (fats) that were stripped during the reaction, making them

insoluble to aqueous solvents. Nobody really knows for sure.

Some people thing that fulvic acid is more biologically active than humic acid because of its

smaller molecular size. There is some truth in these representations as there is evidence that the lower

molecular weight fractions have the ability to cross plant membranes and improve permeability of cell

walls. It is true that fulvic acids have a higher “total acidity” than humic acids (Tan, 1986), however the

chemical reactivity and chelating ability of humic acids is equal to or greater than fulvic acid (Tan, 2003)

making them very bioactive substances. The humic acid fraction may be more effective than fulvic acid at

solubilizing extremely stable aluminum and iron phosphates (Lobartini et al, 1998).

13Carbon Nuclear Magnetic Resonance and Mass Spectrometric Analyses have revealed that the

main structural features of humic acid, fulvic acid and humin are nearly identical. To scientists who study

humic substances, the names have no meaning chemically (Wershaw, 2000; Schnitzer, 1999). Some

scientists say that humic substances from different sources are essentially the same. (Pokorna et al,

1999; Cook and Langford, 1999;Gajdosova, 2000)

Reported variations in plant response to different sources of humic substances are rare. In one

case reviewed by Chen and Aviad (1990), the young age of the humic materials were suspect, because

humification is a time dependant process. As the material ages, more bioactive ingredients become

incorporated into the humic complex (Ziechmann et al, 2000). Old age is good.

Wet Chemistry vs. Complex Geobiological Systems

The lower molecular weight (the mass of a substance expressed in gram equivalents of its atomic

mass) of fulvic acid is sometimes said to account for its greater biological availability. That is somewhat

correct (Chen and Aviad, 1990), but very vague because the industry has not agreed on standardized

molecular weights for fulvic acid. Defining humic acid, fulvic acid and humin by their molecular weights is

a controversial concept.

Some wet chemistry techniques can be used to characterize different humic materials. For

example, the carbon / oxygen ratio is used by some to determine the presence of functional groups.

There may be some merit to this as functional groups are high in oxygen content. The difficulty with wet

chemistry techniques is that it rarely mimics the real environment in which these materials are expected to

perform.

Humic substances change their structure depending on pH and the type of metals present. (Kolla,

1998; Piccolo et al, 2000) High pH (or the presence of multivalent ions, such as calcium Ca2+) makes

humic substances open up their long chain polymers and low pH makes them close. In the presence of

toxic metals, humic substances remove the metals from the surrounding environment by forming insoluble

aggregated spheres around them (Liu and Huang, 1999).

Humic substances are “polymer-like” molecules that demonstrate self-organization. (Hayes, 1998;

Cook and Langford, 1999; Piccolo, et al, 2000) The bi-layers formed by humic substances to surround

otherwise insoluble minerals (Tombacz and Rice, 1999) are reminiscent of the way all living things utilize

biochemical reactions to carry on life in general. The self-organized (micellular) colloidal phases act like

biological molecules in cellular systems, showing a strong resemblance to the biological mechanisms of

living membranes, as described in college text books, such as Voet and Voet, 1995. Humic substances

are more like living creatures than chemical entities, but they don’t reproduce.

Slight changes in pH will actually cause the humic polymers to fracture, breaking up the original

molecules. (Tombacz and Rice, 1999, Piccolo, et al, 2000) The fractured molecules are then free to

associate with numerous other free radicals, metals or impurities. Humic substances are made up of

hundreds of different molecules of many different sizes (polydispersity) with many ways to orient

themselves by twisting, bending, compressing and expanding (conformational changes). They are held

together very loosely by weak forces (Piccolo, et al, 2000) in a colloidal state.

Any change in solution pH, concentration or the presence of metal ions, especially calcium ions,

will cause huge changes in the physical make up of the humic molecules. Even slight changes cause the

molecules to change in orders of magnitude (Tombacz and Rice, 1999). Rapid changes in molecular

structures are not peculiar to just humic substances. Water molecules change their structure

10,000,000,000,000 times a second. (Voet and Voet, 1995) Although water is an extremely simple

molecule, the determination of its structure at any given instant is still somewhat unknown. The amazing

complexity of humic substances may forever keep their structures a secret.

Fulvic Acid

The primary reason why there is so much confusion about humic substances is the fact that the

some procedures used to describe them are based on “classical” aqueous extraction. If minerals are

present in the parent material, they become complexed by humic substances. This allows more humic

and non-humic material to be solubilized during extraction (Ozdoba, et al, 2001) by breaking down ion

bridges that would normally hold the molecules together in higher purity materials. Unless the supernatant

is separated by special procedures (such as passing over a XAD-8 resin) to isolate the fulvic portion, the

extracted substances may contain anything from amino acids, proteins, sugars or fatty acids in addition to

the fulvic acid (Hayes and Graham, 2000).

In biological molecules, it is an established fact that the presence of functional groups, such as

carboxyl, phenol, quinone and hydroxyl groups are responsible for the activity of these molecules. There

is some evidence that there are more functional groups in fulvic than humic acid. The effectiveness of

fulvic extracts may be influenced by the way they are synthesized during chemical processing. The fulvic

fraction of humic substances is undoubtedly a beneficial part of oxidized lignites.

Analysis of Humic Substances: In Search of a Standard

It is important to know the Cation Exchange Capacity (CEC) since these materials are renowned

for that characteristic. It should be in the range of 100 to 200 (on a dry matter basis) as analyzed by the

ammonium saturation method. Low pH is very important because the acidity initiates the dissolution of

rock minerals. Low pH may be a broad indicator for open sites for chelating or complexing reactions to

take place and an indicator of the relative concentration of functional groups. A pH of about 3.8 is

acceptable. An ash content over 10% is not unusual, indicating the degree of association with clay

minerals or other contaminants (Ozdoba, et al, 2001). CEC, pH and ash analysis can be performed by

many laboratories.

A large percentage of manufacturers are using the services of A&L Western Agricultural

Laboratories, Inc. to determine the quality of their humic substances. A&L offers two methodologies for

humic substance analysis; the California Department of Food and Agriculture method (CDFA) and the

A&L Western Method. The CDFA Method is a quantitative analysis of humic acid. This method reports

the acid insoluble fraction of humic material. The analysis is reported on an “as received” basis (includes

moisture). The result can be mathematically converted to a dry matter basis report.

The CDFA method is based on the operational definition of humic acid. This technique, however,

only uses a portion of the methodology described by the International Humic Substances Society (IHSS)

method, which analyzes both humic acid and fulvic acid fractions. The Standard Methods for Soil Analysis

of the Soil Science Society of America, Madison, Wisconsin (Swift, 1996) states that the IHSS method is

broadly accepted and it can be performed in most laboratories. The CDFA method is a compromise

because the fulvic fractions are completely ignored. The fulvic fraction is actually discarded during the

process!

The A&L Western Method is a qualitative analysis, which may report all of the alkaline soluble

humic materials in a sample. It consistently reports a higher percentage of “humic acid” than the CDFA

method. It cannot be converted to a “dry basis”. The A&L Western Method may mimic some of the

industrial process used to extract humic matter from oxidized lignite. However the base extraction method

cannot discretely remove unwanted materials nor can it prevent the extracted materials from recombining

with free radicals or contaminants. Therefor, the A&L Method more than likely includes non-humic

materials as well as humic substances.

One person who has some experience analyzing oxidized lignites is Richard Lamar of EarthFax

Engineering, Midvale, UT 84047, (435-787-2743), a soil reclamation, civil, geotechnical and

environmental engineering firm, just to name a few. His lab is set up to analyze humic substances using

techniques that are similar the IHSS protocols. It’s a bit pricey, but Richard says he can get the price

down in the future if there are sufficient requests for the service. He seems to understand the industry.

Geochemical Analysis

Silicon, iron and aluminum are among the most abundant elements in the earth’s crust and the

most common minerals associated with humic substances. (Liu and Huang, 2000) Finding a humic

substance low in contaminants is challenging, but not impossible. Since humic substances are composed

mostly of carbon, a high carbon content can be used as a crude measure. Loss On Ignition (LOI) is less

reliable, but may be used to confirm the presence of carbon because organic material is burned off during

this high temperature procedure.

Geo-chemical analysis (table 1) for total carbon, organic carbon, and metal contaminants can be

done by an ISO accredited lab, such as Acme Analytical Laboratories, 852 Hastings Street, Vancouver,

British Columbia, V6A 1RS, phone 604-253-3158. The Group 4A and 4B whole rock geochemical

analysis includes all major elements, 43 trace elements and toxic metals.

Examples of geochemical analysis (Tables 1 and 2) and humic acid analysis (Table 3) of oxidized

lignite, Leonardite and humic shale from nine different mine sites in North America are presented. Aside

from the consistent report for pH and sodium, the results demonstrate how there can be variations in

CEC, metals, ash, carbon, sulfur, minerals and humic content in the various sources. The report for

sodium is intriguing because there are many claims that oxidized lignites of fresh water origin are

supposed to be lower in sodium than those derived from ancient sea bottoms.

Humic Substances Enhance Nutrient Bioavailability

Studies of the direct and indirect effects of humic substances on plant growth have repeatedly

shown positive effects on plant biomass as long as there is sufficient mineral nutrition. Stimulation of root

growth is generally more apparent than stimulation of shoot growth. (Chen and Aviad, 1990; Nardi, et al,

1996; Abad et al, 1991)

For many years, the stimulatory effects of humic substances were attributed to hormone-like

activity because the action of humic substances was similar to auxins, cytokinins and absisic acid. This is

no longer the case (Clapp et al, 2001). The stimulatory effects of humic substances have been directly

correlated with enhanced uptake of macronutrients, such as nitrogen, phosphorus, sulfur (Chen and

Aviad, 1990) and micronutrients, i.e. Fe, Zn, Cu and Mn. (Chen et al, 1999).

Humic substances enhance the uptake of minerals through the stimulation of microbiological

activity. (Albuzio et al, 1994; Figliolia et al, 1994; Visser, 1995; Nardi, et al, 1996; Paciolla, et al, 1998:

Day et al, 2000) Humic substances actually coat mineral surfaces with a membrane-like bi-layer, which

aids in the solubilization of otherwise insoluble compounds (Tombacz and Rice,, 1999) by dissolving,

complexing and chelating the dissolved nutrients.

The bioavailability of nutrients released from rock minerals by biological activity is enhanced in

the presence of humic substances. (Chen and Aviad, 1990) Geo-microbiologists have reported that

organic acids generated by microbial activity directly influence the rate of dissolution (release of nutrients)

from rock minerals (Barker et al, 1997; Welch et al, 2002).

The implications of this research are astonishing. While conventional farmers are faced with the

mandated reduction of soluble fertilizers, sustainable, biological and organic farmers can take advantage

of the microbiological release of nutrients from insoluble minerals while the humic substances stabilize

and improve the bioavailability of the minerals that are in soil solution.

Calcium

Humic substances are becoming renowned throughout the world for their importance in

agriculture (Fataftah, et al, 200; Tan, 2003), especially their ability to chelate nutrient minerals (Chen et al,

2001) and increase root mass (Amarasiriwardena et al, 2000; MacCarthy, et al, 1990; Chen and Aviad,

1990). The benefits to soils and plants are extensive and correlate well with the benefits of humus,

organic matter and calcium.

It seems reasonable to conclude that humic substances saturated with unwanted cations and

heavy metal contaminants may lower bioavailability and the efficacy of the product. Therefor, it must be

important to seek out a high grade uncontaminated source. Since there are many sites on a humic

molecule for acceptance of cations (Tan, 1986), it seems reasonable that calcium in combination with

humic substances should make a powerful combination.

Many of the benefits of calcium overlap with the benefits of humic substances. Also, the low pH of

humic substances along with their biological stimulation and chelating capacity combined with the right

dry calcium source may perform as well as, if not better than, chelated liquid products and calcium

chloride (Tan, 2003). Furthermore, because humic substances are known to complex both cations and

anions (Huang and Violante, 1986; Mortland, 1986) creating a synergistic effect (Clapp et al, 2001), the

combined benefits should be greater than the individual ingredients.

In theory, the enhanced benefits should result in greater:

  • biological release of nutrients from otherwise insoluble minerals (Tan, 1986; Chen and Aviad, 1990;

Banfield and Hamers, 1997; Barker et al, 1997)

  • root growth, (Chen and Aviad, 1990, Chen et al, 2001)
  • nutrient uptake from the larger root mass (Kapulnik, 1996)
  • respiration (Nardi, et al, 1996; Marschner; 1999, Chen et al, 2001)
  • photosynthesis (Marschner, 1999, Chen et al, 2001)
  • mineral bioavailability and stabilization (Banfield and Hamers, 1997)
  • nitrogen stabilization and fertilizer efficiency (Fenn, et al, 1995; Clapp, 2001)
  • disease resistance (Marschner, 1999)

Indeed, recent research has demonstrated how the combination of dry calcium with oxidize lignite

performed as well as calcium chloride and EDTA, a popular synthetic chelating agent. (Pare’, et al, 2001)

The Effect of Humic Substances on Rock Phosphates

The ability of humic substances to solubilize and complex with natural minerals, such as rock

phosphates, is well documented (Chen, et al, 1999; Burdick, 1965: Banfield and Hamers, 1997;

Schnitzer, 1986: Martinez et al, 1984; Tan, 1986). The bioavailability of nutrients released from rock

minerals by microbiological activity is enhanced in the presence of humic substances (Chen and Aviad,

1990).

Humic substances can improve the effectiveness of rock phosphates by causing the release of

(PO4 )3- anions and (Ca)2+ cations from hardly-soluble rock minerals (Sinha, 1971; Lobartini et al, 1994)

because of high total acidity (Tan, 1986), ability to complex and chelate the resulting solutions (Tan,

1986; Chen, et al, 1999; Clapp, et al, 1999) and stimulate microbial metabolism (Albuzio et al, 1994;

Figliolia et al, 1994; Nardi, et al, 1996; Paciolla, et al, 1998: Day et al, 2000;Chen et al, 1999; Visser,

1985).

Natural Leonardite or oxidized lignite is a complex supermixture of high and low molecular weight

humic substances The lower molecular weight constituents (fulvic acids) are primarily responsible for the

solubilization of phosphate minerals (Levesque and Schnitzer, 1967; Weir and Soper, 1963). Just like the

fulvic acid fractions, the higher molecular weight components (humic acids) also engage in solubilizing

minerals, have a high capacity for stimulating biological activity and greater potential for chelation (Tan,

2003). In natural soil systems, the two components may act synergistically by complementing each other.

Humic substances also chelate iron, zinc, copper and complex with many other trace elements

(Clapp, 2001).Elements typically found in natural phosphate minerals, such as zinc and copper, are

known to suppress pathogens and encourage the growth of beneficial organisms (Duffy and Defago,

1999).

These phenomena have environmental implications as well because the solubilization of rock

phosphates by humic substances can reduce the need for industrial acidification of rock phosphate used

for the production of phosphatic fertilizers. Industrial production of phosphate fertilizers is extremely

inefficient and creates enormous waste piles that are burdened with contaminants. Additionally, 60 to

80% of all highly soluble phosphate fertilizer applied to soils is lost to the environment (Griffin et al, 2003).

Colloidal humic substances are part of natural soils and help retain nutrients in the soil system

through soil stabilization (Piccolo et al, 1999) and the stabilization of nitrogen (Day, et al, 2000).

Furthermore, the complexing action keeps the minerals in solution instead of precipitating (locking up)

with soil iron, aluminum (Tan, 1986; Banfield and Hamers, 1997; Schnitzer, 1986) and rare earth

elements (Banfield and Hamers, 1997).


Applying Theory to Practice

 

Silicon, iron and aluminum are among the most abundant elements in the earth’s crust and themost common minerals associated with humic substances. (Liu and Huang, 2000) Finding a humicsubstance low in contaminants is challenging, but not impossible. Since humic substances are composedmostly of carbon, a high carbon content can be used as a crude measure. Loss On Ignition (LOI) is lessreliable, but may be used to confirm the presence of carbon because organic material is burned off duringthis high temperature procedure. Geo-chemical analysis (table 1) for total carbon, organic carbon, and metal contaminants can bedone by an ISO accredited lab, such as Acme Analytical Laboratories, 852 Hastings Street, Vancouver,British Columbia, V6A 1RS, phone 604-253-3158. The Group 4A and 4B whole rock geochemicalanalysis includes all major elements, 43 trace elements and toxic metals. Examples of geochemical analysis (Tables 1 and 2) and humic acid analysis (Table 3) of oxidizedlignite, Leonardite and humic shale from nine different mine sites in North America are presented. Asidefrom the consistent report for pH and sodium, the results demonstrate how there can be variations inCEC, metals, ash, carbon, sulfur, minerals and humic content in the various sources. The report forsodium is intriguing because there are many claims that oxidized lignites of fresh water origin aresupposed to be lower in sodium than those derived from ancient sea bottoms. Humic Substances Enhance Nutrient BioavailabilityStudies of the direct and indirect effects of humic substances on plant growth have repeatedlyshown positive effects on plant biomass as long as there is sufficient mineral nutrition. Stimulation of rootgrowth is generally more apparent than stimulation of shoot growth. (Chen and Aviad, 1990; Nardi, et al,1996; Abad et al, 1991) For many years, the stimulatory effects of humic substances were attributed to hormone-likeactivity because the action of humic substances was similar to auxins, cytokinins and absisic acid. This isno longer the case (Clapp et al, 2001). The stimulatory effects of humic substances have been directlycorrelated with enhanced uptake of macronutrients, such as nitrogen, phosphorus, sulfur (Chen andAviad, 1990) and micronutrients, i.e. Fe, Zn, Cu and Mn. (Chen et al, 1999). Humic substances enhance the uptake of minerals through the stimulation of microbiologicalactivity. (Albuzio et al, 1994; Figliolia et al, 1994; Visser, 1995; Nardi, et al, 1996; Paciolla, et al, 1998:Day et al, 2000) Humic substances actually coat mineral surfaces with a membrane-like bi-layer, whichaids in the solubilization of otherwise insoluble compounds (Tombacz and Rice,, 1999) by dissolving,complexing and chelating the dissolved nutrients. The bioavailability of nutrients released from rock minerals by biological activity is enhanced inthe presence of humic substances. (Chen and Aviad, 1990) Geo-microbiologists have reported thatorganic acids generated by microbial activity directly influence the rate of dissolution (release of nutrients)from rock minerals (Barker et al, 1997; Welch et al, 2002).The implications of this research are astonishing. While conventional farmers are faced with themandated reduction of soluble fertilizers, sustainable, biological and organic farmers can take advantageof the microbiological release of nutrients from insoluble minerals while the humic substances stabilizeand improve the bioavailability of the minerals that are in soil solution.CalciumHumic substances are becoming renowned throughout the world for their importance inagriculture (Fataftah, et al, 200; Tan, 2003), especially their ability to chelate nutrient minerals (Chen et al,2001) and increase root mass (Amarasiriwardena et al, 2000; MacCarthy, et al, 1990; Chen and Aviad,1990). The benefits to soils and plants are extensive and correlate well with the benefits of humus,organic matter and calcium. It seems reasonable to conclude that humic substances saturated with unwanted cations andheavy metal contaminants may lower bioavailability and the efficacy of the product. Therefor, it must beimportant to seek out a high grade uncontaminated source. Since there are many sites on a humicmolecule for acceptance of cations (Tan, 1986), it seems reasonable that calcium in combination withhumic substances should make a powerful combination. Many of the benefits of calcium overlap with the benefits of humic substances. Also, the low pH ofhumic substances along with their biological stimulation and chelating capacity combined with the right

dry calcium source may perform as well as, if not better than, chelated liquid products and calciumchloride (Tan, 2003). Furthermore, because humic substances are known to complex both cations andanions (Huang and Violante, 1986; Mortland, 1986) creating a synergistic effect (Clapp et al, 2001), thecombined benefits should be greater than the individual ingredients.In theory, the enhanced benefits should result in greater:•biological release of nutrients from otherwise insoluble minerals (Tan, 1986; Chen and Aviad, 1990;Banfield and Hamers, 1997; Barker et al, 1997)•root growth, (Chen and Aviad, 1990, Chen et al, 2001)•nutrient uptake from the larger root mass (Kapulnik, 1996)•respiration (Nardi, et al, 1996; Marschner; 1999, Chen et al, 2001)•photosynthesis (Marschner, 1999, Chen et al, 2001)•mineral bioavailability and stabilization (Banfield and Hamers, 1997)•nitrogen stabilization and fertilizer efficiency (Fenn, et al, 1995; Clapp, 2001)•disease resistance (Marschner, 1999)Indeed, recent research has demonstrated how the combination of dry calcium with oxidize ligniteperformed as well as calcium chloride and EDTA, a popular synthetic chelating agent. (Pare’, et al, 2001) The Effect of Humic Substances on Rock PhosphatesThe ability of humic substances to solubilize and complex with natural minerals, such as rockphosphates, is well documented (Chen, et al, 1999; Burdick, 1965: Banfield and Hamers, 1997;Schnitzer, 1986: Martinez et al, 1984; Tan, 1986). The bioavailability of nutrients released from rockminerals by microbiological activity is enhanced in the presence of humic substances (Chen and Aviad,1990).Humic substances can improve the effectiveness of rock phosphates by causing the release of(PO4 )3- anions and (Ca)2+ cations from hardly-soluble rock minerals (Sinha, 1971; Lobartini et al, 1994)because of high total acidity (Tan, 1986), ability to complex and chelate the resulting solutions (Tan,1986; Chen, et al, 1999; Clapp, et al, 1999) and stimulate microbial metabolism (Albuzio et al, 1994;Figliolia et al, 1994; Nardi, et al, 1996; Paciolla, et al, 1998: Day et al, 2000;Chen et al, 1999; Visser,1985). Natural Leonardite or oxidized lignite is a complex supermixture of high and low molecular weighthumic substances The lower molecular weight constituents (fulvic acids) are primarily responsible for thesolubilization of phosphate minerals (Levesque and Schnitzer, 1967; Weir and Soper, 1963). Just like thefulvic acid fractions, the higher molecular weight components (humic acids) also engage in solubilizingminerals, have a high capacity for stimulating biological activity and greater potential for chelation (Tan,2003). In natural soil systems, the two components may act synergistically by complementing each other.Humic substances also chelate iron, zinc, copper and complex with many other trace elements(Clapp, 2001).Elements typically found in natural phosphate minerals, such as zinc and copper, areknown to suppress pathogens and encourage the growth of beneficial organisms (Duffy and Defago,1999).These phenomena have environmental implications as well because the solubilization of rockphosphates by humic substances can reduce the need for industrial acidification of rock phosphate usedfor the production of phosphatic fertilizers. Industrial production of phosphate fertilizers is extremelyinefficient and creates enormous waste piles that are burdened with contaminants. Additionally, 60 to80% of all highly soluble phosphate fertilizer applied to soils is lost to the environment (Griffin et al, 2003).Colloidal humic substances are part of natural soils and help retain nutrients in the soil systemthrough soil stabilization (Piccolo et al, 1999) and the stabilization of nitrogen (Day, et al, 2000).Furthermore, the complexing action keeps the minerals in solution instead of precipitating (locking up)with soil iron, aluminum (Tan, 1986; Banfield and Hamers, 1997; Schnitzer, 1986) and rare earthelements (Banfield and Hamers, 1997).Applying Theory to Practice

Because of their ability to improve fertilizer efficiency, humic substances are best utilized as partof a total fertility program blended into the fertilizer. Programs that include rotations, green manures,cover crops, livestock manure and compost are the best methods to derive the full effect of humicsubstances. However, the most effective form, dry Leonardite or oxidized lignite, is an extremely dustymaterial.In order to improve the handling of the dusty material and to take advantage of the benefitsderived from whole, natural material, Midwestern Bio-Ag has succeeded in pelletizing Leonardite withvarious combinations of calcium products. The results of field trials conducted by customers areconsistent with the reports in the scientific literature of the effectiveness of blended products.The release of nutrients from insoluble minerals has been confirmed also. By combining rockphosphate with Leonardite (oxidized lignite), the available phosphate analysis (AOAC, 1999) can increasefrom near zero to over 10%. When considering that the total P2O5 content of the rock phosphate was20%, that means that over 50% of the total phosphorus was released from the rock. The releasedminerals may exist in a chelated form, providing an environmentally safe bioavailable form of calcium andphosphorus while avoiding the industrial pollution, energy waste and ground water contamination createdby highly soluble phosphate fertilizers.Summary and DiscussionHumic substances are formed by a process called humification. The humification process ischaotic, with innumerable reactions occurring under countless conditions. The process occurs overgeological time, therefore younger deposits of humic materials generally have lower concentrations ofhumic acid.Humic substances are critical components of water and soil ecosystems, which are essential tosoil genesis and the global cycling of carbon and nutrients. The interactions among microbes, clays andminerals are dependent upon humic substances. The vast agronomic and environmental importance ofthese materials is just beginning to be appreciated. Distinction based on molecular mass (weight) or the quantity of functional groups and fulvic acidcontent are useless if here is no agreement regarding the methods used to evaluate the materials. Thequality of natural humic materials can be assessed by pH, CEC, total carbon, total organic carbon, andassociation with calcium, silicon, sulfur, iron, aluminum and toxic contaminants. The concentration ofhumic acid and fulvic acid can be analyzed by some labs because standard reference materials andprocedures for the extraction and analysis of humic substances are available from the International HumicSubstances Society. The agronomic effectiveness of humic materials may be influenced by the presence of metalsassociated with the natural ores. Because humic substances are powerful complexing and chelatingentities, association with silicon, aluminum or iron (typically found in clays) may influence the materials insoil systems. Research based on the agronomic effectiveness of humic materials (oxidized lignites) fromdifferent sources has not been performed. ConclusionThe conventional tools of chemistry cannot be applied to these materials to explain why they workin complex soil ecosystems. They have all the qualities of humus in a compact convenient package.Although the microscopic detail and structure of humic substances is currently not achievable, theirbeneficial properties are evident. The ecological and plant nutritional benefits provide sufficientjustification for using these extraordinarily complex Eco-minerals. If the supply side of the industry so chooses, a set of standards could be adopted by some kind ofprofessional society or trade group representing the industry. An independent laboratory could monitorthe standards. Some of the best and brightest professionals in the industry are working toward that goal. Standardization of materials may also provide a basis for acceptance by state fertilizer regulators.Anyone in the supply industry should seriously consider joining the International Humic SubstancesSociety (IHSS) to communicate the industry’s needs to the scientific community. Besides, scientists needto be reminded sometimes that there are many good people who can benefit from their knowledge. Thatknowledge needs to be communicated to everyone, not just other scientists.

For the consumer, there is an endless variety of applications for humic substances, both asagronomic inputs and as human health aids. Humic substances are part of an environmental engineer’stoolbox for the bio-remediation of toxic contaminants. Humic substances are possibly the most versatilenatural substances ever known.

Analysis of Weathered LignitesTable 1Geochemical Analysis LocationSiO2Al2O3Fe2O3MgONa2OCaOTOT/CLOIAsh SulfurCEC %%%%%%%%%%pHdrybasisNorth Dakota6.71.81.21.00.423.94485182.223.8159North Dakota5.31.80.81.00.476.64280163.273.8111North Dakota7.62.31.31.20.263.44683130.44.2196North Dakota3.41.40.91.10.313.5518990.44.2126Canada6.42.60.50.20.411.64588361.003.8127Texas26.98.61.60.40.160.63860371.004.178North Dakota6.83.42.51.20.313.44382151.683.7181New Mexico17.97.90.80.20.261.13270320.63.584New Mexico11.96.10.40.10.090.35180200.53.572Utah24.56.02.70.40.221.14163422.333.692Single analysis, not a databaseTable 2Table 3Contaminants Humic Acid PbAsCdHgSeNorth Dakota55%ppmppmppmppbppmNorth Dakota54%North Dakota640.11346North Dakota65%North Dakota5650.38941North Dakota35%North Dakota450.12523Canada70%North Dakota8210.41282North Dakota70%Canada620.1211New Mexico57%Texas1810.1803New Mexico30%North Dakota1810.11283Utah4%New Mexico2620.3583New Mexico1310.10.63CDFA Method, dry basisUtah1230.60.22Single analysis, not a databaseSingle analysis, not a database

ReferencesAbad, Manuel, et al, 1991. Effects of Humic Substances from Different Sources on Growth and NutrientContent of cucumber Plants. In Humic Substances in the Aquatic and Terrestrial Environment,Proceedings from the International Symposium Linkoping, Sweden, 1989, Springer-Verlag, pp. 391-396Albuzio, A. Concheri, G. Nardi, S. and Dell’Agnola, G., 1994. Effect of Humic Fractions of DifferentMolecular Size on the Development of Oat Seedlings Grown in Varied Nutritional Conditions. In: HumicSubstances in the Global Environment and Implications on Human Health. Edited by N. Senesi and T.M.Miano. Instituto di Chimica Agraria Universita degli Studi-Bari, Bari, Italy. Elsevier Science B.V. pp. 199-204.Amarasiriwardena,D., et al, 2000. Flow Field-Flow Fractionation-Inductively Coupled Plasma-MassSpectrometry: A Versatile Approach for Characterization of Trace Metals Complexed to Soil-DerivedHumid Acids. In: Humic Substances, Versatile Components of Plants, Soil and Water, E.A. Ghabbour, ed.Royal Society of Chemistry, 2000 p. 215.AOAC, 1999. Official methods of analysis, 16th ed., 5th revision, Vol. I. Association of Official AnalyticalChemists, Arlington, VA.Banfield, J.F. and Hamers, R.J., 1997. Processes at Minerals and Surfaces with Relevance toMicroorganisms and Prebiotic Synthesis. In: J.F. Banfield and K.H. Nealson (eds.), Geomicrobiology:Interactions Between Microbes and Minerals, Reviews in Mineralogy, Vol. 35. Mineralogical Society ofAmerica, Washington, D.C. pp.81-122.Barak, P., et. al., 1997. Effects of long-term soil acidification due to agricultural inputs in Wisconsin. Plantand Soil 197:61-69.Barker, W.W., Welch, S.A., and Banfield, J.F., 1997. Biogeochemical Weathering of Silicate Minerals. In:J.F. Banfield and K.H. Nealson (eds.), Geomicrobiology: Interactions Between Microbes and Minerals,Reviews in Mineralogy, Vol. 35. Mineralogical Society of America, Washington, D.C. pp.81-122.Berthelin, J., Munier-Lamy, C. and Leyval, C., 1995. Effect of Microorganisms on Mobility of Heavy Metalsin Soils. In: P.M. Huang, J. Berthelin, J.-M. Bollag, W.B. McGill and A.L. Page (eds.), EnvironmentalImpact of Soil Component Interactions. CRC Lewis, Boca Raton, Florida. pp. 3-5.Burdick, E.M., 1965. Commercial Humates for Agriculture and the Fertizer Industry. Economic Botany,Vol. 19, no.2:152-156.Chen, Y. and Aviad, T., 1990. Effects of Humic Substance on Plant Growth. In MacCarthy, C.E. Clapp,R.L. Malcolm, and P.R. Bloom (eds.), Humic Substances in soil and Crop Sciences: Selected Readings.Soil Sci. Society of America, Madison, Wisconsin. pp. 161-186.Chen, Y., Clapp, C.E., Magen, H. and Cline, V.W., 1999. Stimulation of Plant Growth by HumicSubstances: Effects on Iron Availability. In: Ghabbour, E.A. and Davies, G. (eds.), Understanding HumicSubstances: Advanced Methods, Properties and Applications. Royal Society of Chemistry, Cambridge,UK.. pp. 255-263.Chen, Y., Magen, H., and Clapp, C.E., 2001. Plant Growth Stimulation by Humic Substances and TheirComplexes with Iron. Proceedings of the International Fertilizer Society Symposium, Lisbon, March 2001. Clapp, C.E., 2001. An Organic Matter Trail: Polysaccharides to Waste Management to Nitrogen/Carbon toHumic Substances. In E.A. Ghabbour and G. Davies (eds.), Humic Substances: Structures, Models andFunctions. Royal Society of Chemistry, Cambridge, UK. pp.3-17.

Clapp, C.E., Liu, R., Cline, V.W., Chen, Y. and Hayes, M.H.B., 1998. Humic Substances for EnhancingTurfgrass Growth. In: G. Davies and E.A. Ghabbour (eds.), Humic Substances: Structures, Properties andUses. Royal Society of Chemistry, Cambridge, UK. pp, 227-233.Clapp, C.E., Chen, Y., Hayes, M.H.B., and Cheng, H.H., 2001. Plant Growth Promoting Activity of HumicSubstances. In: R.S. Swift and K.M. Spark (Eds.), Understanding Organic matter in Soils, Sediments andWaters. Proceedings of the 9th International Conference of the International Humic Substances Society,Adelaide, Australia, 21st-25th September 1998, IHSS St Paul, Minnesota.Cook, R.L. and Langford, C.H., 1999. A Biogeopolymeric View of Humic Substances with Application toParamagnetic Metal Effects on 13C NMR. In: Ghabbour, E.A. and Davies, G. (eds.), Understanding HumicSubstances: Advanced Methods, Properties and Applications. Royal Society of Chemistry, Cambridge,UK.. pp. 31-48.Cooley, A.M., Douglas, G., Rasmussen, W.H., Rasmussen, J.J. and Theis, J., 1967. Leonardite inFertilizer. In: Information Circular 8471, Bureau of Mines, United States Department of the Interior, pp.158-164.Day, K.S., Thornton, R. and Kreeft, H., 2000. Humic Acid Products for Improved Phosphorus FertilizerManagement. In Humic Substances, Versatile Components of Plants, Soil and Water, E.A. Ghabbour, ed.Royal Society of Chemistry, pp.321-325Fataftah, A.K. et al, 2001. A Comparative Evaluation of Known Liquid Humic Acid Analysis Methods. InE.A. Ghabbour and G. Davies (eds.), Humic Substances: Structures, Models and Functions. RoyalSociety of Chemistry, Cambridge, UK. pp.337-342.Feagley, S.E. and Fenn, L.B., 1998. Using Soluble Calcium to Stimulate Plant Growth. Texas AgriculturalExtension Service, Texas A&M University System, Publication L-5212, 9-98.Fenn, L.B., Hasanein, and Burks, 1995, Calcium-Ammonium Effects on Growth and Yield of SmallGrains. Agronomy Journal 87:1041-1046.Figliolia, A. Benedetti, A. Izza, C. Indiati, R. Rea, E. Alianiello, F. Canali, S. Biondi, F.A. Pierandrei, FMoretti, R. (1994). Effects of fertilization with humic acids on soil and plant metabolism: a multidisciplinaryapproach. In Humic Substances in the Global Environment and Implications on Human Health. N. Senesiand T.M. Miano,eds. Instituto di Chimica Agraria Universita degli Studi-Bari, Bari, Italy. Elsevier ScienceB.V. pp. 579-584Frank, K.D. and Roeth, F.W., 1996. Using Soil Organic Matter to Help Make Fertilizer and PesticideRecommendations. In: Soil Organic Matter: Analysis and Interpretation. Soil Science Society of AmericaSpecial Publication No. 46, p. 33.Gajdosova, D. et al, 2000. Mass Spectrometry and Capillary Electrophoresis Analysis of Coal-DerivedHumic Acids Produced from Oxyhumolite. A Comparison Study. In: E.A. Ghabbour and G. Davies (eds.),Humic Substances: Versatile Components of Plants, Soil and Water. Royal Society of Chemistry,Cambridge, UK.. pp. 287-298.Ghabbour, E.A., et al, 1998. Adsorption of a Plant and a Soil Derived Humic Acid on the Common ClayKaolinite. In: G. Davies and E.A. Ghabbour (eds.), Humic Substances: Structures, Properties and Uses.Royal Society of Chemistry, Cambridge, UK..Griffin, T.S., Honeycutt, C.W. and He, Z., 2003. Changes in Soil Phosphorus from Manure Application.Soil Science Society of America Journal 67:645-653

Hayes, M.H.B., 1998. Humic Substances: Progress Towards More Realistic Concepts of Structures. In:G. Davies and E.A. Ghabbour (eds.), Humic Substances: Structures, Properties and Uses. Royal Societyof Chemistry, Cambridge, UK.. pp. 1-25.Hayes, M.H.B. and Graham, C.L., 2000. Procedures for the Isolation and Fractionation of HumicSubstances. In: E.A. Ghabbour and G. Davies (eds.), Humic Substances: Versatile Components ofPlants, Soil and Water. Royal Society of Chemistry, Cambridge, UK.. p106.Haynes, R.Y. and Swift, R.S., 1990. Journal of Soil Science, 41 1990 p.73Haworth, R.D. The Chemical Nature of humic acid. Soil Science. 1971, 111:71-79.Huang, P.M., 2002. Foreseeable Impacts of Soil Mineral-Organic Component-Microorganism Interactionson Society: Ecosystem Health. In: A. Violante, P.M. Huang, J.-M. Bollag and L. Gianfreda (eds.), SoilMineral-Organic Matter-Microorganism Interactions and Ecosystem Health. Elsevier, Boston.Huang, P.M. and Violante, A., 1986. Influence of Organic Acids on Crystallization and Surface Propertiesof Precipitation Products of Aluminum. In: P.M. Huang and M. Schnitzer, (eds.), Interactions of SoilMinerals with Natural Organics and Microbes. Soil Science Society of America, Special Publication No.17, Madison, Wisconsin.Inskeep, W.P. and Silvertooth, J.C., 1988. Inhibition of Hydroxyapatite Precipitation in the Presence ofFulvic, Humic and Tannic Acids. Soil Science Society of America Journal 52:941-946.Jungk, A.O., 1996. Dynamics of Nutrient Movement at the Soil-Root Interface. In Y. Waisel, U. Kafkafiand A. Eshel (eds.), Plant Roots, The Hidden Half. 2nd ed. Marcel Dekker, Inc., New York. pp. 529-556.Kapulinik, Y. 1996. Plant Growth Promotion by Rhizosphere Bacteria. In Y. Waisel, U. Kafkafi and A.Eshel (eds.), Plant Roots The Hidden Half. 2nd ed. p. 769-770. Marcel Dekker, Inc., New YorkKarr, M., 2001. Oxidized Lignites and Extracts from Oxidized Lignites in Agriculture. Unpublished.Available from M. Karr, ARCPACS Cer. Prof. Soil. Sci., 10 Davis St, Monte Vista, CO 81144.Kelly, K. R., and Stevenson, F.J., 1996. Organic Forms of N in Soil. In: Humic Substances in TerrestrialEcosystems, Edited by A. Piccolo. pp. 407-427Kolla, S., et al, 1998. Humic Acid as a Substrate for Alkylation. In: G. Davies and E.A. Ghabbour (eds),Humic Substances: Structures, Properties and Uses. Royal Society of Chemistry, Cambridge, UK.. pp.216-224.Leyval, C. and Joner, E.J., 2001. Bioavailability of Heavy Metals in the Mycorrhizosphere. In: G.R.Gobran, W.W. Wenzel and E.Lombi (eds.), Trace Elements in the Rhizosphere. CRC Press, Boca Raton,Florida. p. 165Lobartini, J.C., Tan, K.H. and Pape, C., 1994. The Nature of Humic Acid-Apatite Interaction Products andTheir Availability to Plant Growth. Commun. Soil Sci. Plant Anal., 25(13&14): 2355-2369Lobartini, J.C., Tan, K.H. and Pape, C., 1998. Dissolution of Aluminum and Iron Phosphate by HumicAcids. Commun. Soil Sci. Anal., 29(5&6), 535-544.Liu, C. and P.M. Huang, 1999. Atomic Force Microscopy of pH, Ionic strength and Cadmium Effects onSurface Features of Humic Acid. In: Ghabbour, E.A. and Davies, G. (eds.), Understanding HumicSubstances: Advanced Methods, Properties and Applications. Royal Society of Chemistry, Cambridge,UK.. pp. 87-128.

MacCarthy, P., 2001. The Principles of Humic Substances: An Introduction to the First Principle. In E.A.Ghabbour and G. Davies (eds.), Humic Substances: Structures, Models and Functions. Royal Society ofChemistry, Cambridge, UK. pp.19-30.MacCarthy, P., 2003. Humic Substances: What We Know and What We Don’ Know. Symposium onNatural Organic Matter in Soils & Water, Iowa State University, Ames, Iowa, March 22, 2003.MacCarthy, P., C.E. Clapp, R.L. Malcolm, and P.R. Bloom, 1990. An Introduction to Soil HumicSubstances. In: MacCarthy, C.E. Clapp, R.L. Malcolm, and P.R. Bloom (eds.), Humic Substances in soiland Crop Sciences: Selected Readings. Soil Sci. Society of America, Madison, Wisconsin. pp. 1-12.Magdoff, F., 1996. Soil Organic Matter Fractions and Implications for Interpreting Organic Matter Tests.In: F. Magdoff, E. Hanlon, A. Tabatabai, (eds.), Soil Organic Matter: Analysis and Interpretation. SoilScience Society of America Special Publication No. 46, pp. 11-19.Marschner, H., 1999. Mineral Nutrition of Higher Plants. Academic Press, San Diego. Martinez, M.T., Romero, C and Gavilan, J.M., 1984. Solubilization of Phosphorus by Humic Acids fromLignite. Soil Science 138(4):257-261. Miller, R.W. and Gardiner, D.T., 1998. Soils in Our Environment. Eighth edition. Prentice Hall, New JerseyMortland, M.M, 1986. Mechanisms of Adsorption of Non-humic Organic Species by Clays. In: P.M. Huangand M. Schnitzer, (eds.), Interactions of Soil Minerals with Natural Organics and Microbes. Soil ScienceSociety of America, Special Publication No. 17, Madison, Wisconsin.Mulller-Wegener, U., Interaction of Humic Substances with Biota, In Humic Substances and Their Role inthe Environment, F.H. Frimmel and R.F. Christaman, (eds.). Interscience Publication, John Wiley & Sons1988 pp. 179-192Nardi, S., Condheri, G., and Dell’Agnola, G. Biological Activity of Humus. In: Humic Substances inTerrestrial Ecosystems, Edited by A. Piccolo, 1996, pp. 361-406.Orlov, D.S. Sadovnikova, L.K., Ammosova, J.M., Krasnyak, S. 1994. Roles of soil humic acids in thedetoxification of soil chemical pollutants and soil productivity. In Humic Substances in the GlobalEnvironment and Implications on Human Health. N. Senesi and T.M. Miano,eds. Instituto di ChimicaAgraria Universita degli Studi-Bari, Bari, Italy. Elsevier Science B.V. 1994 .p 681.Ozdoba, D.M., et al, 2001. Leonardite and Humified Organic Matter. In E.A. Ghabbour and G. Davies(eds.), Humic Substances: Structures, Models and Functions. Royal Society of Chemistry, Cambridge,UK. pp.310-313.Paciolla, M.D., et al, 1998. Generation of Free Radicals By Humic Acid: Implications for Biological Activity.In: G. Davies and E.A. Ghabbour (eds), Humic Substances: Structures, Properties and Uses. RoyalSociety of Chemistry, Cambridge, UK.. pp. 203-214.Pare’, T., et al, 2001. Response of Alfalfa to Calcium Lignite Fertilizer. In E.A. Ghabbour and G. Davies(eds.), Humic Substances: Structures, Models and Functions. Royal Society of Chemistry, Cambridge,UK. pp. 346-353.Piccolo, A. and Mbagwu, Hoe S.C., 1999. Role of Hydrophobic Components of Soil Organic Matter in SoilAggregate Stability. Soil Science Society of America Journal 63;1808-1810 , Madison, Wisconsin.Piccolo, A., Conte, P. and Cozzolino, A., 2000. Difference in High Performance Size ExclusionChromatography Between Humic Substances and Macromolecular Polymers. In: E.A. Ghabbour and G.Davies (eds.), Humic Substances: Versatile Components of Plants, Soil and Water. Royal Society ofChemistry, Cambridge, UK.. pp. 120-122.

Pokorna, L., Gajdosova, D. and Havel, J., 1999. Characterization of Humic Acids by Capillary ZoneElectrophoresis and Matrix Assisted Laser Desorption / Ionization Time-of-Flight Mass Spectrometry. In:Ghabbour, E.A. and Davies, G. (eds.), Understanding Humic Substances: Advanced Methods, Propertiesand Applications. Royal Society of Chemistry, Cambridge, UK.. pp. 107-119.Pokorna, L., Gajdosova, D., Mikeska, S., Homolac, P. and Havel J., 2001. The Stability of Humic Acids inAlkaline Media. In: : E.A. Ghabbour and G. Davies (eds.), Humic Substances: Structures, Models andFunctions. Royal Society of Chemistry, Cambridge, UK. pp. 133-149.Russo, R.O. and Berlyn, G.P., 1990. The Use of Organic Biostimulants to Help Low Input SustainableAgriculture. Journal of Sustainable Agriculture. Vol. 1(2):19-42.Schnitzer, M. 1986. Binding of Humic Substances by Soil Mineral Colloids. In P.M. Huang and M.Schnitzer (eds.), Interactions of Soil Minerals with Natural Organics and Microbes. Soil Science Society ofAmerica, Special Publication No. 17, Madison. pp. 77-101.Schnitzer, M., 1999. Forward. In: Ghabbour, E.A. and Davies, G. (eds.), Understanding HumicSubstances: Advanced Methods, Properties and Applications. Royal Society of Chemistry, Cambridge,UK.. p. vii.Schnitzer, M. and Khan, S.U., 1972. Humic Substances in the Environment. Marcel Dekker, New York.Schnitzer, M, Dinel, H., Pare’, T., Schulten, H.-R. and Ozdoba, D., 2001. Some Chemical andSpectroscopic Characteristics of Six Organic Ores. In: E.A. Ghabbour and G. Davies (eds.), HumicSubstances: Structures, Models and Functions. Royal Society of Chemistry, Cambridge, UK. pp. 315-342.Y. Shi, D.B. Parker, N.A. Cole, B.W. Auvermann, J.E. Mehlhorn. 2001. Surface Amendments to MinimizeAmmonia Emissions from Beef Cattle Feedlots. Transactions of the American Society of AgriculturalEngineers, Vol. 44(4):677-682. Seyedbagheri, M. and Torell, J.M., 2001. Effects of Humic Acids and Nitrogen Mineralization on CropProduction in Field Trials. In: E.A. Ghabbour and G. Davies (eds.), Humic Substances: Structures, Modelsand Functions. Royal Society of Chemistry, Cambridge, UK. pp. 355-359.Steelink, C., 1999. What is Humic Acid? A Perspective of the Past Forty Years. In: Ghabbour, E.A. andDavies, G. (eds.), Understanding Humic Substances: Advanced Methods, Properties and Applications.Royal Society of Chemistry, Cambridge, UK.. pp. 1-17.Steinberg, C.E.W., 2003.Ecology of Humic Substances in Freshwaters. Springer, New YorkStevenson, F.J., 1982. Humus Chemistry, Wiley Interscience Publications, New York.Stevenson, F.J., 1994. Humus Chemistry. Genesis, Composition, Reactions. Second Edition. John Wiley& Sons, New York.Stevenson, F.J. and Xin-Tau He, 1990. Nitrogen in Humic substances as Related to Soil Fertility. In:MacCarthy, C.E. Clapp, R.L. Malcolm, and P.R. Bloom (eds.), Humic Substances in soil and CropSciences: Selected Readings. Soil Sci. Society of America, Madison, Wisconsin. pp. 91-100.Swift, R.S., 1994. Organic Matter Characterization. In: D. L. Sparks et al (eds.), Methods of Soil Analysis,Part 3, Chemical Methods, Soil Sciences Society of America Book Series Number 5, Madison, Wisconsin.pp.1018-1020.Tabatabai, M. A., 1996. Soil Organic Matter Testing: An Overview. In: F. Magdoff, E.Hanlon, A.Tabatabai, (eds.), Soil Organic Matter: Analysis and Interpretation. Soil Science Society of AmericaSpecial Publication No. 46, pp. 1-9.