by Robert H. Faust Ph.D.
Faust Bio-Agricultural Services Inc.
There has been much interest in the subject of soil humus and humates over the years. There is basic agreement on the benefits of humus, but there is quite a controversy on the benefit of application of applied humate (the deposits containing the humic acids).
One of the most well known studies on humate was written by T. L. Senn and A. Kingman of the Horticulture Dept. of Clemson University in South Carolina (1973). Field and lab work done by the U.S. Bureau of Mines (Freeman, 1970) shows the benefit of "leonardite," a partially oxidized lignite containing 84.3% humic acids. This study showed large yield increases on potatoes, soybeans and algae cultures. The test plots were done near Grand Forks, North Dakota. Other testing done in North Dakota showed significant yield increases in barley with or without applied mineral fertilizer (Agvise Inc., 1977-1979). Other research done in Illinois (NCR-103 Committee, 1976) on corn and soybeans using leonardite show no benefit from the product.
In general there has been far more positive results on Western soils. The soil that benefits is typically high pH with low available iron and low organic matter and extractable humic acids. Like any fertilizer or soil conditioner, it only works when the conditions favor it.
There have been several reports discrediting humates due to lack of results in test plots that did not need the product. Substantial results are seen where it is needed. The North Dakota studies confirm this as do our own tests in calcarious Western soils.
There are many positive results from Russia on the benefits of humate products derived from lignite deposits. V. T. Syabryai (1965) showed 100% yield increases from fertilizers containing NPK and humic acids: "Introduction into the soil of these fertilizers increased the crop of potatoes from 6,100 to 15,000 kg/ha and that of cabbage from 5,600 to 16,500 kg/ha." Barley crops increased considerably and growth was more rapid with humic acids.
How Humates Work
There are many reasons why humates work. The work of Senn (1973) lists increased availability of phosphate and iron. The same paper mentions the presence of auxin type reactions by humic substances that result in increased growth. Humic acids are reported to increase the permeability of plant membranes, so promoting the uptake of nutrients.
Senn states, "Many investigators have observed a positive effect of humic substances on the growth of various groups of microorganisms. They attributed this effect to the presence of iron in the humic acids or to their colloidal nature or they regarded humic substances as organic catalysts." There is evidence that some of the humate materials contain large populations of Actinomycetes (microorganisms that share the properties of both fungi and bacteria). They are capable of degrading a wide range of substances including celluloses, hemicelluloses, proteins and lignin. Some members of this family, such as Streptomyces may excrete a range of vitamins, growth substances and antibiotics. The breakdown or cycling of cellulose in the soil may be the reason why organic matter readings may be increased after the application of a New Mexico humate to soils high in undecomposed organic matter.
Soviet data (Abolina 1968) states that "The coal-humic fertilizers activated the biochemical processes in plants (respiration, photosynthesis and chlorophyll content) and increased the quality and yield of potatoes." Humic substances work for many reasons, depending on soil and environmental conditions. It is clear, however, that they are a benefit to the farmer in Western soil conditions and in similar soils in the Ukraine and in China (Hsu, 1978).
The consensus is that they work well in low organic matter soils. In low amounts they do not perform in soils of high organic content, and at high rates they seem to tie-up soil nutrients.
It has been shown by Rowberry (1977) that when aluminum and iron are present they inactivate the humate. This may be the reason why humate sometimes produces no results when used on an acid soil in humid areas. Acid soils may have large amounts of soluble aluminum and iron present, therefore these soils should be limed to optimum levels to produce the best results, with or without added humates. Western soils with high free lime levels have very low iron and aluminum levels as calcium tends to precipitate soluble aluminum, iron and manganese.
It has been shown by Lee and Bartlett (1976) that corn yields were best at 5 ppm humic acid and that the addition of humates to a hydroponic solution stimulated both root and shoot development, resulting in an increase of 87%. This study also showed that as the ppm of humic acids increased so did the %P in the plant, proving that humate plays an important role in the phosphate utilization of plants. This data also seems to show that if the humate level is already high in the soil, then more may not be a benefit to the crop.
The work of K. H. Tan (Effects of Humic Acid on Aluminum Toxicity in Corn Plants, Agronomy Abstracts, 1985) shows that humic acids may protect plants against the harmful effects of aluminum. His work demonstrated the prevention of P deficiency in the presence of high aluminum and a suppression of the toxic effects of the aluminum.
Humate, like other fertilizers, is not a cure-all but is of benefit when natural levels are low. Commercial liquid and dry humates are a major benefit to high pH soils low in available iron, and acid soils low in organic matter and humus. Soils below 5 ppm humate should respond to humic products, especially liquid humate products.
The best humate in the world comes from northwest New Mexico in the United States. This is a freshwater deposit and has the highest percentage of low molecular weight humic acids, generally referred to as fulvic acids. These humates are effective at only 100 pounds per acre. The low molecular weight Humics have the cytokinnin/auxin like response and not only help in transport of trace elements, but greatly stimulate root growth.
Not all humates are created equally and hence the inconsistent results in testing.
Robert H. Faust, Ph.D.
Faust Bio-Agricultural Services Inc.
"Humates from the menefee formation of New Mexico increase tree growth, yield."
Humates have been shown by a Florida study to increase growth in new citrus of 250% with only 1/2 lb. humate per tree. In the same study humates reversed the decline symptoms in the older citrus trees measured by dramatic bark thickness increase in humate treated trees.
The best way to bring back declining trees is a combination of humates and the trace elements shown to be deficient or low by leaf analysis or soil test.
In much of the developing world trace element deficiency is a misery for plants, animals and man. Zinc, iron, boron, sulfur, manganese, copper are frequently the cause when I am questioning as to what disease this deformed leaf represents and what fungicide to use to treat it. I have seen the problem from the hills of Belize to the delta of the Nile in Egypt.
These deficiencies in fruit trees, like citrus, mango, etc., are costing millions in production yet can be remedied with a pound or two per tree of a New Mexico humate along with low cost trace elements. These major hurdles to production can be beaten. Humates provide the chelation effect and, if high in low molecular weight, humics has a high degree of auxin or cytokinnin effect to stimulate growth and production. Humates produce needed carbon, humic acids, stimulation of both tree and root system, plus microflora.
The perfect base for a tree mix would be New Mexico Humate from the U.S. It has a high rate of freshwater derived low molecular fulvic acids that are proven stimulators of plant growth at very low traces. Menefee humate is effective in increasing yield in vegetables by nearly 100% with only 100 pounds per acre. Trees respond to as little as 1/2 pound per tree.. Lignite or coal based humates have a high total humic acid but less of the vital stimulation of fulvic acids.