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Humic acids play a vital role in soil fertility and plant nutrition. Plants grown on soils which contain adequate humin, humic acids (HAs), fulvic acids (FAs) are less subject to stress, are healthier, produce higher yields; and the nutritional quality of harvested foods and feeds are superior. The value of humic substances in soil fertility and plant nutrition relates to the many functions these complex organic compounds perform as a part of the life cycle on earth. The life/death cycle involves a recycling of the carbon containing structural components of plants and animals through the soil and air and back into the living plant.
What Are Humics, What Do They Do, and How Does That Benefit Me On The Farm?
Humics are a naturally occurring substance within soils. They result from the breakdown of organic matter and have been forming and reforming since the beginning of life on this planet. We know that they are vital for plant growth and for proper soil fertility. We know that they work to balance pH, increase cation exchange capacity, retain water within the soil profile, increase the quantity and quality of the hair-like feeder roots, and that they do all of this at much lower rates of application than traditional fertilisers. We know all of this based on years of research both domestically and abroad at the university and at the farm level. Even with all of that knowledge there is even more about humics which is still being discovered. According to Mr. Mir, one of the USA's foremost experts on humics and a research agronomist at the University of Idaho, “Humics are one of the most complex carbon-based molecules. We are only at the tip of the iceberg in discovering what this molecule is capable of doing.”
What the "organic" fertiliser industry doesn't want you to know about humates -
100 pounds per acre of humate replaces tons of the best compost or so called "organic" fertilisers like so called "soft rock phosphates". A liquid humic acid solution, really potassium humate, has the same effect or may be better than kelp extracts or fish emulsion type products at a fraction of the cost.
Below is collection of comments, research data, and excerpts from academic papers that will provide background on humic acids.
"Humate and Humic Acids for Agriculture Users Guide" by R.H.Faust Ph.D
Humates and humic acids are not fertilisers under the law, they do not replace fertilisers, they enhance them. - Humic acid research by Lee and Bartlett 1976 (Stimulation of Plant Growth by Humic Substances)
From the soil science Society of America Journal vol.40,#6 nov.Dec.1976. clearly showed a specific amount of humic acids that provided optimum plant growth. Lee and Bartlett also showed that algae were also stimulated but by larger amounts than corn needed (60 ppm). They showed that phosphate levels did come up when humic acids were used. In reality humic acids are required by cells just like N,P,K or zinc is required and at a specific amount above which no benefit was seen. When the fertiliser laws were first written when little was known about humic acid or even bio-chemistry in general, we have come a long way since then but the fertiliser laws and University recommendations are based on thinking from the turn of the century that sees soil as a "hydroponic media " that you add inorganic chemical salts to. These are the same people who recommended "not using " manure or compost because it didn"t have enough N,P, or K to be worth handling. All higher plants evolved in the presence of humic acids, they’re not really stimulants because they are needed for normal growth, plants in natural soils had humic acids. Only through tillage and row cropping do we destroy humic substances and need to replace them with the decomposition products of organic matter, that can be a large amount of compost to get the small amount of humic acids needed for normal corn growth; about 5 pounds in a million pounds of soil ( 5ppm) or about 10 pounds of humic acid per acre 8" deep. This may take 9-12 wet tons of a good compost…In spite of the published data humic acids are still not accepted as a requirment for plant growth like NPK, in fact the sale of "humic acids products" is banned in Iowa, one of our biggest corn growing states. The petro-chemical industry has been very effective at discrediting the need of humus, compost or humate for years and still is, the plants and microbes still respond all the same.
Use of Humates in Agriculture
- Introduction -
I have been working with humates for over 25 years and have seen the results of it's use on thousands of acres of crops and many livestock farms. I have been accumulating research and information on the subject and performing field and laboratory research on the subject for the same period of time. I developed a product called Humi-phos in 1973 which combined humates and ground rock phosphate in to a granular product. The humic acids release the phosphate in a dry state while mixed and even more in the soil. I have used humate and recommended humates to my clients on all kinds of crops from all the main crops grown in Montana and in Hawaii and literally everything in between. - Low molecular weight humic acids are what provides the effect on cells. These humic acids can be produced a number of ways including composting and mushroom production and natural humification of organic matter with the aid of certain funguses. Low molecular weight humic acids take time to form; this is why the advice in old gardening books was always for "well rotted" compost or cured/aged compost. Even well cured compost only has a few pounds of humic acid per ton which would then require 7-12 tons of compost per acre to get 35 pounds humic acid per total per acre. That amount would will provide the desired effect at the cellular level of the soil ecosystem and the cells of the crop plants. This would only require 40-50pounds per acre of a high grade 70-80% humic acid product as opposed to the cost and expense of handling of 7-12 tons of compost. The preparation of compost is an expensive and energy intensive job and the large amount needed is expensive when compared to the approximately US$15 per acre cost of using a high grade humate. Generally we see from a 5-1 to a 8-1 return in crop value using humate at this rate and cost.
What are humates and why they are not all equal-
For the aging process and the formation of low molecular weight humic acids, a million years are needed for organic matter to break down to DNA and RNA fragments which are the main cytokinnins in humate. The low molecular weight fulvic acids have an auxin like effect on cells by increasing cell permeability due to the non-ionic and ionic in humic substance which enhance and stimulate nutrient flow to and between the cells. The cells can be plant, animal or microbial, but the effect is the same which is why humates are as useful as a livestock supplement as it is for growing the corn you feed them. - The origin of the humates used is very important and judging biological effects can not be based on content of "humic acids" alone. Biological assays are necessary to judge the effectiveness of a humate. -
Best kept secret #1 - You can reduce the amount of certain herbicides by up to 50% by using a quality humic acid in the solution. This is true for most contact-type herbicides because the humic acids can increase cell permeability and are surfactants which allow better penetration of the herbicide (or foliar fertilisers) into the leaf and then from cell to cell. One big ag-chem company is now experimenting with humic acids to put in their formula because so many farmers are doing it anyway
Best kept secret #2 - You can usually cut back on fertiliser by 25%, especially on nitrogen, and in many cases you can cut back 50% or more on phosphate. Where phosphate availability is a problem such as on western high pH and high free lime soils, humates greatly increase phosphate availability as well as iron, zinc and manganese. This is something you need to fine-tune on your own farm by doing test plots with different amounts of fertiliser and the recommended rate of the humate you are using. The reason you can cut down is because in many cases there is more and deeper root growth and increased biological activity to release nutrients.
REFERENCES Abolina, B.I. and A.T. Tashkhadzhaev. 1968. Effects of Coal-Humic fertilisers on the Activity of Physiological Processes in Plants and in the Yield of Potatoes in Uzbekistan. Guminovye Udabr. Dell'Agnola, G. and S. Nardi. News about biological effects of humic Substances. Dell'Agnola, G. and S. Nardi. Hormone-like effect and enhanced nitrate uptake induced by depolicondensed humic fraction. Biol. and Fert. of Soils.Freeman, P.S. 1970. The Use of Lignite Products as Plant Growth Stimulants. U.S. Bureau of Mines, Grand Forks, ND.Hsu, H.T. 1978. Stimulating Effects of Humic fertilisers. Hua Hsueh T'ung Pao. Peking, K'o ch'u pan she. Nov. 23, 1978.Lee and Bartlett. 1976. Soil Science Society of America Journal 40:876- 879.Rowberry and Collin. 1977. American Potato Journal 54:607-609.Russell, E.W. 1973, 10th Ed. Soil Conditions and Plant Growth. p.636-639. Longman, New York.Senn, T.L., and A.R. Kingman. 1973. A Review of Humus and Humic Acids. South Carolina Agricultural Experiment Station, Clemson, SC. Research Series Report No.145.Syabryai, V.T., V.A. Reutov and L.M. Vigdergauz. 1965. Preparation of Humic fertilisers From Brown Coal. Geol. Zh., Akad. Nauk Ukr. RSR25(6)39- 47. Jackson,W.R.1993, Organic Soil Conditioning, "Humic, Fulvic and Microbial Balance "isbn#0-9635741-0-8 .
Organic Matter, Humus, Humate, Humic Acid, Fulvic Acid And Humin:
Their Importance In Soil Fertility And Plant Health
Dr. Robert E. Pettit Emeritus
Associate Professor Texas A&M University
- Introduction -
Humic substances, such as those listed in the above title, play a vital role in soil fertility and plant nutrition. Plants grown on soils which contain adequate humin, humic adds (HAs), and fulvic adds (FAs) are less subject to stress, are healthier, produce higher yields; and the nutritional quality of harvested foods and feeds are superior. The value of humic substances in soil fertility and plant nutrition relates to the many functions these complex organic compounds perform as a part of the life cycle on earth. The life death cycle involves a recycling of the carbon containing structural components of plants and animals through the soil and air and back into the living plant.
Man became distracted from the importance of organic compound cycling when it was discovered that soluble acidic based N P K "fertilisers" could stimulate plant growth. Large industrial concerns took advantage of the N P K discovery to market industrially processed "fertilisers" from mineral deposit Man needs to reconsider his approach to fertilization techniques by giving higher priority to soil humus.
The urgency to emphasize the importance of humic substances and their value as fertiliser ingredients has never been more important than it is today. All those concerned about the ability of soils to support plant growth need to assist in educating the public. Humic substances are recognized by most soil scientists and agronomists as the most important component of a healthy fertile soil. To illustrate how humic substances function, the following summary, based on published scientific data, has been prepared as a guide for an educational program. In addition, by understanding how these carbon containing substances function, professionals will have a solid foundation on which to design environmentally acceptable sustainable agriculture programs. |
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Humic substances and their influence on plant growth and development
Plant growth is influenced indirectly and directly by humic substances. Positive correlations between the humus content of the soil, plant yields and product quality have been published in many different scientific journals. Indirect effects, previously discussed, are those factors which provide energy for the beneficial organisms within the soil, influence the soil's water holding capacity, influence the soil's structure, release of plant nutrients from soft minerals, increased availability of trace minerals, and in general improved soil fertility. Direct effects include those changes in plant metabolism that occur following the uptake of organic macromolecules, such as humic acids, fulvic acids. Once these compounds enter plant cells several biochemical changes occur in membranes and various cytoplasmic components of plant cells.
Uptake of major plant nutrients is mediated by humic substances. One stimulative effect of humic substances on plant growth is enhanced uptake of major plant nutrients: nitrogen (N) phosphorus (P), and potassium (K). When adequate humic substances are present within the soil the requirement for N P K fertiliser applications is reduced. As the level of humic substances in soils become depleted the misleading demand for higher concentrations of N P K results. Many growers have over the past several years reported increasing demands for soluble acid fertilisers In order to maintain crop yields. Such observations indicate something is wrong within the soil. Increased leaching of nitrate fertiliser ingredients into the ground water is also a warning of problems to come. These trends reflect losses in soil humic substances. Growers could reduce their fertiliser requirements and retain the fertiliser ingredients within the plants rooting zone by the application of humate based fertilisers. The application of either dry or liquid humic substances to soils dramatically increases fertiliser efficiency. Other researchers have reported increased uptake of calcium (Ca), and magnesium (Mg) when plants are irrigated with liquid suspensions of humic acids (HAs) or fulvic acids (FAs). Another key mechanism, which maximizes fertiliser efficiency and relates to a function of humic substances. These binding processes reduce leaching nitrogen into the subsoil and help prevent volatilization into the atmosphere.
The absorption of humic substances into seeds has a positive influence on seed germination and seedling development. The application of humic (HA) or fulvic acids (FA) to seeds will increase the seed germination; resulting in higher seed germination rates. Application rates of humic acids (HAs) or fulvic acids (FAs), required for improved seed germination, range from 20 to 100 mg/liter of seed. In order for improved germination to occur the humic substances must be present within the cells of seeds. As the humic substance enter the seed cells, respiration rate increases, and cell division processes are accelerated. These same respiratory processes enhance root meristem development and activate other growing points within the seedlings. Humic substances have been demonstrated to enhance mitotic activity during cell division under carefully controlled experiments. Placement of these humic substances on seeds (seed treatment) or within the seed furrow will significantly improve seed germination and seedling development. Excessive concentrations of humic acids (HAs) and/or fulvic acids (FAs) can inhibit seed germination and at high concentrations can kill young seedlings. Therefore follow recommended rates when applying humic substances.
Humic substances have a very pronounced influence on the growth of plant roots. When humic acids (HAs) and/or fulvic acids (FAs) are applied to soil enhancement of root initiation and increased root growth are observed. Thus the common observation that humic acids (HAs) and fulvic adds (FAs) are root simulators. In most experimental studies plant root growth is stimulated to a greater extent compared to stimulation of above ground plant parts. Carefully designed experiments have been conducted under controlled conditions to measure plant response. For example, replicated treatments of plants grown within the greenhouse, with and without humic acid and fulvic acids has illustrated how humic substances influence root growth. In repeated experiments the treated root weights averaged from 20 to 50% heavier compared to the weights of non treated roots. The type of humic substance applied had a significant influence on the percent of increase. Not all humic substances contain a desirable molecular mixture of humins, humic acids (HAs) and fulvic acids (FAs) capable of rapid stimulation of root growth. Some humic substances, because of their large molecular sizes, failed to stimulate plant root development. Root stimulation occurs when the smaller molecular components within fulvic acid (FA) occur at a concentration which ranges from 10 to 100 mg/liter of solution. Growth is further stimulated when fulvic acids (FAs) are used in combination with humic acids (HAs) and other required plant nutrients. Humic substances improve plant nutrition, however they are not complete nutrients by themselves. Excessively high concentrations of humic substances can result in a reduction in root weight. For optimum plant growth humic acids (HAs) and fulvic acids (FAs) should be applied at relatively low concentrations. Humic acids (HAs) and fulvic acids (FAs) are excellent foliar fertiliser carriers and activators. Application of humic acids (HAs) or fulvic acids (FAs) in combination with trace elements and other plant nutrients, as foliar sprays, can improve the growth of plant foliage, roots, and fruits. By increasing plant growth processes within the leaves an increase in carbohydrates content of the leaves and stems occurs. These carbohydrates are then transported down the stems into the roots where they are in part released from the root to provide nutrients for various soil microorganisms on the rhizoplane and in the rhizosphere. The microorganisms then release acids and other organic compounds which increase the availability of plant nutrients. Other microorganisms release "hormone like" compounds which are taken up by plant roots. The required concentration of humic acids (HAs) and/or fulvic acids (FAs) within the foliar spray should be relatively low, generally less than 50 mg of concentrated dry humic substance per liter of water. Foliar fertilisers containing humic acids (HAs) and fulvic acids (FAs) in combination with nitrogen, potassium, phosphorus and various trace minerals have been demonstrated to be from 100 to 500 % more efficient compared to applications of similar fertilisers to the soil. Foliar fertilisers are also more economical because smaller quantities of fertiliser are required to obtain significant plant response. Plant nutrients within foliar fertilisers are rapidly absorbed by the plant leaves. Enhanced carbohydrate production can either result in improved product quality or increased yields. Foliar applications of relatively small molecular units of humic substances containing trace minerals (to actively growing plants) can be timed to meet the needs of specific plant growth requirements. Applications can be timed to activate vegetative growth, flowering, fruit set, or filling and ripening of fruits.
Sources of humic substance and their value as fertiliser ingredients
Humic substances commonly occur within soils waters, compost, peat, and in carbon containing minerals such as brown coals, low grade lignites, and leonardites. Most soils and waters on the earth surface contain some humic substances in the form of humin, humic acids (HAs), or fulvic acids (FAs). However the concentration of humic substances in agricultural soils has reached seriously low levels. In general, soils contain a higher concentrations of humin and humic acids (HAs). In contrast, since fulvic acid (FA) is water soluble it occurs at relatively high concentrations in both soils and water. Soil humic substances consist of a higher percentage of ring compounds (aromatic) compared to humic substances from water. Fertiliser grade humic substances can be obtained from carbon containing mineral deposits throughout many parts of the world. Within the United States there are several mines and seams of carbon containing mineral deposits suitable for obtaining good agricultural grade humic substances.
Any production practice which damages
the activities of living components of the sod should be avoided. Protect the beneficial organisms responsible for forming humus, and they will perform their jobs. Humus building practices are slow, time consuming, and may be costly, however they pay large dividends over time. In order to rapidly return many damaged soils to their former productive capacity growers should consider additional alternatives. An analysis of this situation indicates that the most rapid and practical solution to improving soil fertility is the addition of humates; (mined humic substances) directly to the soil or as foliar fertilisers. In most soils the applications of humate based fertilisers is more important than applying traditional N P K fertilisers. For many years growers have been applying excess N P K fertilisers. Humic substances will maximize the efficient use of residual plant nutrients, reduce fertiliser costs, and help release those plant nutrients presently bound is minerals and salts.
Naturally occurring humic substances from low grade lignites and leonardites (natures soil conditioners), are superior fertiliser ingredients. The best source of humic substances for fertiliser use is from leonardites. The quality and value of any one mined humate or humic add product depends on many different factors. A good humic material can be destroyed by improper mining or processing. Thus not all commercially marketed humic substances are equal in quality. It is very difficult for individuals purchasing a humate based fertiliser to tell the difference between a high quality humic substance and a low quality humic material, without laboratory tests. The real test of any humic product is in the field. Growers interested in improving soil fertility and plant health need to set up field tests, with an open mind. Many growers have tried several different commercial humic substances before discovering one that improves crop yields and product quality on their soils. In setting up test plots it is best to establish side by side comparisons in a field with a uniform soil type. In selecting a specific commercial humate product the major concern relates to product quality. Determine if the humate is a blend of humic acids (HAs) and fulvic acids (FAs) or is primarily humic acids (HAs). Avoid purchasing pure humic acids (HAs). Secondly does the marketed product have consistency between different batches. An erratically performing product is of minimal value. Another important question is, how rapidly does the product perform in term of its ability to improve plant growth? One of the best approaches is to ask around and find out which company has quality control procedures in their mining and industrial processing operations. Established companies with experience of working with humates and have a good track record generally market superior humate based fertilisers.
New standards are needed to monitor the quality of humate based fertilisers currently marketed. The consumer needs protection from inferior products. There are many "humic acid type" products currently marketed in the United States. Some of these "humic" products have been developed by industrial chemists. Industrial concerns have made many attempts to manufacture humic acids using different industrial processes. As a result several "synthetics" have been produced, marketed, purchased, and used. Most of these synthetics have been polymers of vinyl acetate, maleic acid, polyvinyl alcohol, hydrolyzed polyacrylonitrile, carboxymethlcellulose, polyacrylates, isporpyl acrylamide and poly quaternary ammonium compounds. Generally these synthetic humic molecules have performed poorly in terms of their ability to improve. soil fertility or plant growth. These products should not be defined as humate based fertiliser ingredients since their performance under field conditions are very erratic. A chemical analysis of their molecular features reveals that these "synthetics" lack many of the properties of naturally occurring humic substances. They lack the molecular features which improve soil fertility and are frequently incompatible with plant metabolic processes.
Application of humate based dry or liquid fertilisers can improve product quality and increase production. As outlined above humic substances are the building blocks of fertile soils and healthy plants. One important reason for adding humate based fertilisers to the soil is that the producer can again become a steward of the soil. By developing a more ecologically sound agricultural productions system it is possible to reduce soil, water, and air pollution. In addition crop yields will improve and the nutritional value of the harvested products will significantly improve in quality. The extent to which humate based fertilisers improve crop yields depends on the history of cropping practices used on each field. Soils severely damaged by excessive use of acidic fertilisers or pesticides generally respond slowly the first year. Generally the first improvements observed are in product quality. As toxic soil conditions are remediated (corrected) and additional humate based fertilisers are applied, crop yields and product quality continue to improve
A word of caution
Avoid applying excess fertilisers (of any type) to soils or plant surfaces. Individuals who apply fertilisers to soils (eg. producers, farmers, and gardeners) should keep in mind that excessive applications of any fertiliser can create imbalances and even reduce soil fertility. The positive impact of humic substances on plant growth can be reversed by applying excessively high concentrations of these fertilisers. |
