WILLISTON, N.D. -- North Dakota farmers from the early 1980s probably remember "leonardite" being marketed a soil amendment. It's still being manufactured in the North Dakota and there are those who swear by it and others not convinced.
Jay Goos, a North Dakota State University soil scientist, says manufacturers treat the leonardite with a "base" to dissolve it. These solutions are called humates. These might be more beneficial in sandier soils of the world, but not anywhere he can think of in North Dakota.
In the end, GeoResources got its leonardite from land leased from the U.S. Bureau of Land Management, about three miles from the plant. The lignite vein is about 10 to 15 feet below the topsoil. In the spring of 2005, the plant had a fire. Just prior to the fire, the plant was producing some 50 to 75 tons a month.
Humic acid is a group of powerful natural substances that are very complex and impossible to replicate synthetically. All humic acid products are derived from leonardite deposits that have formed over millions of years, yet the humic acids have not broken down or leached out into the water table, because they are extremely insoluble and inactive in their natural state.
One problem with leonardite ore, (insoluble humic acids), is they are very low in chemical and biological activity. For leonardites to provide a response to a plant or provide benefit to the soil, the fulvic and humic acids must be activated through chemical process.
Once raw source leonardites are converted into water soluble humates through specific chemical reactions, all the humic and fulvic components are biologically active and play important roles in plant and soil health. The goal of carbon inputs is to promote soil microbial diversity.
In July, the Williston Herald was introduced to Leonardite at the NDSU Williston Research Extension Center Dryland Crop Tour. Since then, we've explored what leonardite is all about and how the Williston-based company, Leonardite Products, mines, processes, dries and prepares it for transportation across the nation the world.
Leonardite Products has the Stoney Creek Mine that is located a few miles east of town. The mined leonardite is found 20 feet below the ground's surface within three layers that are located between layers of clay.
Through the use of excavators, the top soil, subsoil and overburden is removed and set to the side so that a loader can remove the clay and extract the leonardite. The mined product is then hauled to the processing plant at Leonardite Products for drying, milling and processing before shipping across the U.S. as well as international destinations.
Using leonardite will not bring back missing nutrients from the soil, hence why it is not considered a fertilizer, but it will help a crop's ability to absorb nutrients; resulting in faster growth, healthier plants and higher yields.
Leonardite is a coallike substance, similar in structure and composition to lignitic coal and believed to be derived from lignitic coal by the process of natural oxidation. Leonardite is little known outside lignite-producing areas and has been developed commercially only tn a minor extent. The higher oxygen content and less compact structure of leonardite, compared with lignite, make it undesirable as a fuel but indicate that it has potential as a source of chemicals and for other nonfuel uses. It is a convenient source of humic acids. The United States has a large natural reserve of leonardite; furthermore, it can be produced in the laboratory under controlled conditions.
The significant elemental difference between leonardite and lignite is the oxygen content (leonardite, 28-29 percent; lignite, 19-20 percent). The higher oxygen content of leonardite is due entirely to a larger number of carboxylic acid groups. This fact explains the 17-fold increase in alkali solubility of leonardite. Spectral studies indicate that the material is mixed salts of humic acids.
Interest in the use of low-rank fuel reserves in the United States has directed attention to certain side products, of which leonardite is a major item in the lignite field. Frequent requests for information regarding this little-known material led to the preparation of this report, in which are assembled, in convenient form for interested parties, the small amount of available data and results of current investigations. Limited commercial development of leonardite has been a reality for several years, but details of development have been the exclusive property of the companies involved, and the potential of the material has not been widely known. The information contained in this report, although meager, may indicate new uses or prompt further investigation; if so, this report will have served good purpose.
The scarcity of information on leonardite is due partly to its limited use (less than 1 percent of the total annual output of lignite) and partly because it is not a distinct mineral. The stratigraphic occurrence of leonardite, its variable properties, and the ease with which normal lignite may be converted to material of similar properties by oxidation in the laboratory suggest that these deposits result from protracted weathering of lignite beds by atmospheric oxygen and/or ground waters under oxidizing conditions. Leonardite has been described as a precursor of lignite, gel like samples similar to dopplerite have occasionally been found. Pure pre lignitic material probably would not survive to duplicate the geologic position in which the larger masses of leonardite are found, but this possibility may not be entirely discounted. The question, however, is purely of academic interest. Leonardite has been limited to use as a dispersant and for viscosity control in oil-well drilling muds , as a stabilizer for ion-exchange resins in water treatment , and as a source of water-soluble brown stain for wood finishing. Experimental work has been conducted on its use as a soil conditioner and fertilizer, This use is dependent upon its adsorptive and moisture-retaining characteristics.
Bureau of Mines proximate and elemental analyses of three leonardite samples, given in table 1, indicate the similarity of materials from different locations. Comparable analyses of a typical lignite are included to demonstrate the close relation and probable origin of the leonardite. The example of North Dakota lignite and Leonardite were carefully collected column samples representative of the seams. The history of the Texas sample is unknown, but it appears to be a dried sample of run-of-mine coal. The greater nitrogen content of this material is further reflected in an appreciable increase in the amount of extractable waxes, indicating a canneloid antecedent in contrast to the humic precursors of the North Dakota samples. The excessive ash content of the Texas leonardite may be due largely to accidental inclusions; however, increased adsorptivity, resulting from more advanced weathering, could account for part of the inorganic constituents. The sample of oxidized lignite was prepared in a Bureau laboratory by oxidizing lignite in air at 150 C.
Solubility characteristics, chemical and spectral properties, and results of microscopic examination indicate that the leonardites are essentially salts of humic acids admixed with mineral matter such as gypsum, silica, and clay. The two North Dakota leonardite samples are being examined on a modest scale at the Grand Forks Lignite Research Laboratory as to the content and character of the humic acids. The humic acids have been variously defined but are perhaps best described by Oden as yellow-brown to black-brown substances of unknown constitution, formed in nature by decomposition of organic materials under atmospheric influence or in the laboratory by chemical action. They can split off hydrogen ions and form typical salts with strong bases and usually are insoluble in water, soluble in alkali, and reprecipitated by acid. Humic acids have received considerable attention, particularly the so-called regenerated humic acids obtained by oxidation of coals. It is generally conceded that the investigator is dealing with a collection of closely allied hydroxycarboxylic aromatic compounds, probably associated by hydrogen bonding and = representing species ranging in molecular weight from about 300 to as high as 4,000.
Leonardite represents a convenient and commercial source of regenerated humic acids produced under the mildest conditions. The investigation of these acids is a logical approach to coal-constitution studies and may indicate attractive features for increased commercial development of leonardite.
The initial investigations by the Bureau of Mines at Grand Forks were to determine the amounts of humic acids recoverable from leonardites, the factors influencing the amount recoverable, and the ash content of the recovered humic acids. Sodium hydroxide, sodium carbonate, or a mixture of sodium carbonate and lime were the most suitable reagents and had about equal effect. The percentages of humic acids recovered with these reagents were high and essentially equal. Yields were slightly lower with ammonium hydroxide. The concentration of the alkalis could be varied considerably without appreciably affecting the humic acid yield. When the ratio of water to leonardite was increased during extraction, the ash content of the recovered humic acids was lowered. Extraction temperatures had little effect on the yields of humic acids, although the yields increased slightly with alkali concentration of about 2.5 N at temperatures near the boiling point. Organic solvents were rather ineffective, unless the leonardites were first treated with acids. For example, later studies showed that the solubility of leonardite in acetone-water solution is directly proportional to the quantity of acid used in the pretreatment of the leonardite. The highest yields achieved with organic solvents were those in which a mixture of alcohol and benzene was used and indicated the presence of waxy material in the leonardites. 041b061a72