Reducing greenhouse gases through soil stewardship BY KARIN DENEKE Carbon sequestration was not yet a part of my vocabulary when we decided to give no-till a try in 1985 on our recently purchased farm ground in southwest Ohio — ground that had been over plowed, under managed and leaking carbon. The local Soil and Water Conservation District (SWCD) had recently purchased a no-till drill, a tool available for farmers to test conservation tillage — a new alternative planting method that saved soil and reduced time in the field. It was also a push to retire the moldboard plow. Many farmers of the older generation did not readily trust this newfangled planter. For decades, moldboard plowing was part of their planting regiment. Now they cautiously observed neighbors’ fields that had been converted to conservation tillage before they finally bought in. Our farm is located in the Wisconsin Age glacial region of Ohio, where broad, gently rolling-hill plains with large areas of deep, fertile, mostly level soils are the norm. Our average annual rainfall is 36 inches — enough precipitation to support dry-land farming In May of 1985, we took advantage of the no-till drill available from the local conservation district and planted twenty acres of soybeans into previous years’ corn stubble. Harvest was a success with a slightly higher yield than that of years past. This marked the beginning of a new chapter for our farm operation. Improvements did not happen overnight — it was a steady but slow process. We observed that by not disturbing last year’s crop residue and by planting directly into it, the fields became less prone to soil erosion. The major soil types on our land were Miamian (Mhb) and Crosby (CeB) silt loams. These soils have a moderate-deep root zone over glacial till. While the Miamian soil type had good drainage, the Crosby soil pockets had moderate permeability with a seasonal, high-water table. Thus we worked with our local SWCD to install grass waterways and other erosion control practices. In later years, cover crops were introduced to protect the soil and to add nutrients as it lay fallow. As our soils improved, so did the yields. The farm produces field corn, soybeans and wheat on rotation, with some grass hay on steeper slopes. Minimum tillage helped trap or sequester carbon in the soil. By avoiding deep tillage, we gained soil organic matter, resulting in a healthier soil. What exactly is soil carbon? When you view the periodic table in your old chemistry textbook, carbon is classified as a lightweight gas with an atomic weight of 12. As plants remove carbon dioxide from the atmosphere through photosynthesis, some of this gas is stored in their foliage along with the other greenhouse gas — nitrogen. When carbon is fixed in the soil, the result is a more fertile seedbed. Moldboard plowing on the other hand rips open the soil and allows large amounts of carbon dioxide to escape into the atmosphere. In the year 1997, I had the opportunity to witness a demonstration showing how greenhouse gases are released during moldboard plowing while visiting the North Central Soil Conservation Research Lab in Morris, Minnesota, now renamed the USDA-ARS North Central Soils Lab. It is the lab where renowned soil scientist Dr. Don Reicosky researches CO2 flux from different tillage methods. At that time, I had joined the staff of the Miami SWCD — our local conservation district in Ohio — and traveled with Barb Francis, member of our board of supervisors, and her husband Bob, to Morris, Minnesota. Barb and Bob practiced no-till on their farm, and Barb was a serious advocate of soil health and carbon sequestration. Following our return from the research lab, Barb went on the speaker circuit to promote conservation tillage. As a result, in the year 2008, Barb was inducted into the Ohio Federation of Soil and Water Conservation Districts Supervisors Hall of Fame. Dr. Reicosky’s research in the field included a mobile laboratory housing gas analysis equipment, which among other things could measure and later compare the gaseous losses of various tillage methods. The machine, called MR.GEM, was equipped with a screen that graphed the escaping flux released during moldboard plowing, allowing us to watch the data while the device moved across a sod-covered field. We could not help but notice the dark, deep, rich soils of the region, an area once covered by Tall Grass Prairie. This vegetation had massive roots, roots that were three times longer than the plants above the surface — thus creating a robust network of decaying organic matter During the early 19th century, wagon trains pushed westward to start settlements, thus the prairie was attacked by the plow with a vengeance. As a result, just three percent of North America’s Tall Grass Prairie remains today. The state of Minnesota once had 18 million acres of prairie stretched across the state. Just imagine this massive carbon sink. According to Rattan Lal, director of the OSU Carbon Management and Sequestration Center, “The world’s cultivated soils have lost between 50-70 percent of their original carbon stock — much of which has oxidized upon exposure to become CO2.” Studies are underway to learn how land restoration in places like the North American Prairie, the North China Plain and the interior of Australia may help put carbon back into the soil. The USDA-NRCS Soil Survey remains an important resource for farmers, ranchers and land users. It not only lists and maps the different soils in a given area, but also addresses in detail the use and management of soils. It reviews soil properties such as shrink and swell potentials of certain clays — which is important when it comes to construction of house foundations — and describes flood plain soils and drainage potentials. The soils in every county in every state have been surveyed by soil scientists from the Natural Resources Conservation Service (NRCS), formerly called the Soil Conservation Service (SCS). It was a tremendous effort that continued for decades. My old hard copy was issued in 1978 and is no longer available. Instead, the United States Department of Agriculture Natural Resources Conservation Service upgraded to the Web Soil Survey. It provides a simple, yet comprehensive way to access soil data in three basic steps (websoilsurvey.nrcs.usda.gov). When Franklin Delano Roosevelt was sworn into office in 1933, the nation still suffered from the aftermath of the 1929 Stock Market Crash, while at the same time being threatened by a serious drought hitting the farmland of the Great Plains. FDR established the Soil Erosion Service in 1933 to address the ongoing devastating erosion issues. The agency’s mission was to introduce conservation practices to farmers and ranchers and to encourage soil stewardship. In 1935 the Soil Erosion Service was renamed the Soil Conservation Service. Almost sixty years later in 1994, the agency underwent another name change – it is now known as the Natural Resources Conservation Service (NRCS). Soil Conservation offices assisted by the NRCS are serving landowners in every county of every state.
Building Humus For All Crops This excerpt is brought to you by Book of the Week – offering you a glimpse between the pages and an exclusive discount of a new book each week. Get the Book of the Week email newsletter delivered directly to your in box! This week’s Book of the Week is Humusphere, by Herwig Pommresche. The term “soil humus content” refers to the totality of all the organic substances present in the soil. It is often expressed in terms of carbon content percentage, as carbon is the basic building block of organic material. But this definition is insufficient as it only reveals the sum of all the carbon atoms contained in the soil. How much of that is valuable compost, living soil biota, liquid manure, or other organic substances is not clarified. A relevant quote comes from M. M. Kononova’s treatise, “The Soil’s Humic Substances – Results and Problems in Humus Research” (1958): “The history of humus research is rich in incorrect approaches to clarifying important questions, which has led to contradictions and confused ideas about the nature of humic substances, their origins, and the role they play in forming the soil and determining its fertility.” But if we primarily understand “humus” as referring to the abundance of organic substances present in the soil, we overlook its mineral content. The proportion of minerals has increased in cultivated soils during our era in comparison with past eras in which consistently humid heat promoted the formation of organic soil material over huge swaths of forest for thousands of years. The ratio between the organic and mineral portions of the material has shifted, to the detriment of the soil. Incidentally, this is a particularly strong example of the importance of using the right terms with the right meanings: the word “mineral” is here used correctly to refer to everything from rocks, gravel, and sand to the very finest mechanically ground particles – it has absolutely nothing to do with NPK fertilizers or other salt ions. One small calculation is sufficient to get an idea of the significance of plant roots in the soil: “The formation of root hairs greatly increases the root’s surface area. Rye (Secale cereale) has about 13,000,000 roots with a surface area of 235 square meters, and 14,000,000,000 root hairs with a surface area of 400 square meters in 1/22 of a cubic meter of soil (…) The surface area of the underground portions is thus 130 times as large as that of the above-ground portions” (Jurzitza 1987, 28). One single rye plant has the equivalent surface area of an entire garden in direct contact with the soil in which it grows. What this soil is made up of has to be crucially important. Annie Francé-Harrar (1957) wrote the following about how healthy soil should look for plant roots to be able to optimally carry out their work: “Ideal soil should have the following composition: 65 percent organic material, 20 percent edaphic organisms, 15 percent mineral substances. (…) But this kind of abundance of organic material exists hardly anywhere on the planet any more, the highest concentrations being in untrodden corners of tropical jungles, but never in our growing soil. But it is possible to restore the organic-inorganic balance in growing soil within a practical timespan through systematically employed humus management.” These recommended ratios also provide a target to work toward in systematic humus management. But she was already well aware of how difficult it is to put this into practice: “But this (…) means a radical agricultural revolution, much larger than the one triggered by Liebig in his time” (20). How does humus form? Topsoil formation is very much a classic case study in the movement of living material from the waste material of living things into plants, of the descent of living material into Mother Earth. It’s also a study in the soil, of its many functions, of its conversions and storage until its reappearance in the world of above-ground organisms. The bulk of the soil material first becomes clearly visible as nutrient-forming chlorophyll, but that chlorophyll would never exist without the work of the countless organisms in the soil. … The same species of bacterial symbionts appear in almost all animal and plant organisms, the lactic acid bacteria. In fact, soil probes from all over the world, even if the soil in question is only slightly fertile, always contain large quantities of lactic acid bacteria. The soil contains more of them, and of better varieties, the more fertile it is. This is further evidence that the cycle of living material takes place in the topsoil through the mediation of bacteria. The remnants of biological processes on the surface, processed by countless species of small creatures, are first processes into precursors by budding fungi species, predominantly yeasts and molds, and then passed along to the bacterial symbionts in the soil. According to the most recent research, these symbionts—lactic acid bacteria in this case—can be directly consumed and digested as food via endocytosis by plant root hairs (Rateaver and Rateaver 1993), and they leave all kinds of organic material behind after they die, especially in the fall. These particles, as well as the bacteria themselves (i.e., the living material in the soil bacteria), are a prerequisite for the formation of high-quality soil: topsoil that is aerated, loose, water-retaining, capable of biological tillage (Sekera 2012), safe from erosion, and fertile, the result of the functions of the edaphon, as outlined by Henning (2011). The adhesiveness of the microorganism residues cements the inorganic mineral substances of rock erosion into soil crumbs. In contrast to the views of agrochemists, it is this alone that deserves the name “humus” in the biological sense: a conglomeration of organic and inorganic material. And this means that it is completely impossible to describe humus as a dead, chemical substance! Humus formation is a sort of “organic predigestion” for plants; and at the same time, humic soil serves as a pantry of living nutrients during the growing season, when plants can grow only if supplied with sufficient warmth, water, and sunlight. Otherwise, however, the parallels between animal and plant digestion are unmistakable. In both cases, microorganisms serve as an intermediate station, as “nutrient facilitators,” and in both cases organic or inorganic material can be extracted as needed from the nutrient substrate and used to build cells and tissues. … Edaphon: The “Residents” of the Humusphere Just as the water has plankton, there is also “the plankton of the soil,” as Raoul H. Francé so singularly described and illustrated the term “edaphon” for us in 1911. The whole fertility of the humusphere depends on this edaphon, and it contains the entire existential basis of our life on this planet. The biosphere carries out its own cycle via its own living beings. Euglena spec. is a single-celled organism containing chlorophyll and a member of the “plankton of the soil.” Under the heading “Ein Buch mit vielen Siegeln” (“A Book with Many Seals”) in “Mensch und Umwelt,” J. Filser (1997) writes: “Microorganisms in the soil can contribute to the nutrition of a plant or strengthen its resistance to pathogenic organisms or the effects of environmental damage. [. . .] They represent a biological potential that promises a wide variety of useful applications in protecting our resources in agriculture and forestry. [. . .] Thus far, only a limited portion of the soil microflora has been cultivated and examined in more detail. We are not even aware of an estimated 90 to 99 percent of soil organisms.” … Edaphon: Plankton of the soil Just as plankton provides the basic conditions for all further life in the hydrosphere (i.e., in the water) the edaphon provides the basic conditions for all further life in and on the soil. … But it’s possible that even larger quantities of proteins are hidden within it than in plankton! A comparison accentuates this point: the average human biomass in the United States is 18 kilograms per hectare. On the other hand, the average biomass over the same area of insects, earthworms, single-celled organisms, algae, bacteria, and fungi is about 6,500 kilograms. That’s more than 350 times as much! To break it down more specifically, that’s 150 kilograms of single-celled organisms, 1,000 kilograms of earthworms, 1,000 kilograms of insects, 1,700 kilograms of bacteria, and 2,500 kilograms of fungi (Gaia 1985, 150). And what’s the breakdown in our gardens? In a 1,000-square-meter garden, 1,000 kilograms of edaphon lives and works in complete silence, without disturbing the neighbors, all year long. The biomass of the earthworms alone—who represent a part of the edaphon—can be determined by any interested layman by collecting and weighing them. In sandy soil beneath conventional barley, I’ve found 9 grams per square meter of surface area (to the depth of a spade), 49 grams beneath conventional pasture, and 840 grams in my own biologically cultivated garden soil. Per hectare, or 10,000 square meters, that comes out to 90, 490, and up to 8,400 kilograms of living biomass respectively. And that’s just the earthworms? The ideal for fertile growing soil is (Francé 1911, 1995): 1 kilogram of living biomass or edaphon per square meter of garden or field soil. One kilogram of living cytoplasm per square meter corresponds to 1 metric ton of biomass per 1,000 square meters, or 10 metric tons per hectare. Ten hectares of cultivated field soil thus come with 100 metric tons of living biomass in the form of the edaphon beneath the ground—and that’s without even considering what can be achieved above the ground. That comes out to the weight of one thousand hogs or two hundred cows! For readers who are farmers: these numbers reveal how much “livestock” you have hidden on your farm, without ever seeing or noticing it. If you converted this quantity into actual livestock, how much would you have to supply them with on your farm in terms of feed, stalling, ventilation, weather protection, and eventual excrement disposal? How about veterinary costs, consultation, and researching? This is only hard for us to conceptualize because we have neglected it in the models we use to teach and think about agriculture. If you think about these numbers in the context of the new, still unfamiliar “plants can digest protein” model, you quickly recognize the new possibilities that they reveal for our agricultural practices. Source: Humusphere About the Author Herwig Pommeresche was born in Hamburg in 1938 and has lived in Norway since 1974. He received a degree in architecture from the University of Hanover. He has spent many years active as an architect and urban planner in Norway. After finishing his studies in architecture, he became a trained permaculture designer and teacher under the instruction of Professor Declan Kennedy. Alongside other permaculture experts, he served as an organizer of the third International Permaculture Convergence in Scandinavia in 1993. He later served as a visiting lecturer at the University of Oslo. Today, Herwig Pommeresche is seen as a pillar of the Norwegian permaculture movement. He also serves as an author and a speaker. Herwig Pommeresche is a holder of the prestigious Francé Medal, awarded in 2010 by the Gesellschaft für Boden, Technik, Qualität (BTQ) e.V. (founded in 1993) in recognition of his contributions to organic methods and ways of thinking and to the preservation and improvement of the humusphere.
What, Exactly, Is Humus Made Of? By Herwig Pommeresche The term “soil humus content” refers to the totality of all the organic substances present in the soil. It is often expressed in terms of carbon content percentage, as carbon is the basic building block of organic material. But this definition is insufficient as it only reveals the sum of all the carbon atoms contained in the soil. How much of that is valuable compost, living soil biota, liquid manure, or other organic substances is not clarified. A relevant quote comes from M. M. Kononova’s treatise, “The Soil’s Humic Substances — Results and Problems in Humus Research” (1958): “The history of humus research is rich in incorrect approaches to clarifying important questions, which has led to contradictions and confused ideas about the nature of humic substances, their origins, and the role they play in forming the soil and determining its fertility.” But if we primarily understand “humus” as referring to the abundance of organic substances present in the soil, we overlook its mineral content. The proportion of minerals has increased in cultivated soils during our era in comparison with past eras in which consistently humid heat promoted the formation of organic soil material over huge swaths of forest for thousands of years. The ratio between the organic and mineral portions of the material has shifted, to the detriment of the soil. Incidentally, this is a particularly strong example of the importance of using the right terms with the right meanings: the word “mineral” is here used correctly to refer to everything from rocks, gravel, and sand to the very finest mechanically ground particles — it has absolutely nothing to do with NPK fertilizers or other salt ions. One small calculation is sufficient to get an idea of the significance of plant roots in the soil: “The formation of root hairs greatly increases the root’s surface area. Rye (Secale cereale) has about 13,000,000 roots with a surface area of 235 square meters, and 14,000,000,000 root hairs with a surface area of 400 square meters in 1/22 of a cubic meter of soil. [. . .] The surface area of the underground portions is thus 130 times as large as that of the above-ground portions” (Jurzitza 1987, 28). One single rye plant has the equivalent surface area of an entire garden in direct contact with the soil in which it grows. What this soil is made up of has to be crucially important. Annie Francé-Harrar (1957) wrote the following about how healthy soil should look for plant roots to be able to optimally carry out their work: “Ideal soil should have the following composition: 65 percent organic material, 20 percent edaphic organisms, 15 percent mineral substances. [. . .] But this kind of abundance of organic material exists hardly anywhere on the planet any more, the highest concentrations being in untrodden corners of tropical jungles, but never in our growing soil. But it is possible to restore the organic-inorganic balance in growing soil within a practical timespan through systematically employed humus management.” These recommended ratios also provide a target to work toward in systematic humus management. But she was already well aware of how difficult it is to put this into practice: “But this [. . .] means a radical agricultural revolution, much larger than the one triggered by Liebig in his time” (20). How does the humusphere form? Topsoil formation is very much a classic case study in the movement of living material from the waste material of living things into plants, of the descent of living material into Mother Earth. It’s also a study in the soil, of its many functions, of its conversions and storage until its reappearance in the world of above-ground organisms. The bulk of the soil material first becomes clearly visible as nutrient-forming chlorophyll, but that chlorophyll would never exist without the work of the countless organisms in the soil. The conceptual model of mineralization — the complete breakdown of all organic material into inorganic base materials — is first of all (and I cannot emphasize this enough) a technically incorrect use of the terminology. Second, it is logically improbable that it takes place, because that would leave only one possible explanation for the new life that forms, that being the concept of spontaneous generation, which has been rejected by the same scientific establishment. The same species of bacterial symbionts appear in almost all animal and plant organisms, the lactic acid bacteria. In fact, soil probes from all over the world, even if the soil in question is only slightly fertile, always contain large quantities of lactic acid bacteria. The soil contains more of them, and of better varieties, the more fertile it is. This is further evidence that the cycle of living material takes place in the topsoil through the mediation of bacteria. The remnants of biological processes on the surface, processed by countless species of small creatures, are first processed into precursors by budding fungi species, predominantly yeasts and molds, and then passed along to the bacterial symbionts in the soil. According to the most recent research, these symbionts — lactic acid bacteria in this case — can be directly consumed and digested as food via endocytosis by plant root hairs (Rateaver and Rateaver 1993), and they leave all kinds of organic material behind after they die, especially in the fall. These particles, as well as the bacteria themselves (i.e., the living material in the soil bacteria), are a prerequisite for the formation of high-quality soil: topsoil that is aerated, loose, water-retaining, capable of biological tillage (Sekera 2012), safe from erosion, and fertile, the result of the functions of the edaphon, as outlined by Henning (2011). The adhesiveness of the microorganism residues cements the inorganic mineral substances of rock erosion into soil crumbs. In contrast to the views of agrochemists, it is this alone that deserves the name “humus” in the biological sense: a conglomeration of organic and inorganic material. And this means that it is completely impossible to describe humus as a dead, chemical substance! Humus formation is a sort of “organic predigestion” for plants; and at the same time, humic soil serves as a pantry of living nutrients during the growing season, when plants can grow only if supplied with sufficient warmth, water, and sunlight. Otherwise, however, the parallels between animal and plant digestion are unmistakable. In both cases, microorganisms serve as an intermediate station, as “nutrient facilitators,” and in both cases organic or inorganic material can be extracted as needed from the nutrient substrate and used to build cells and tissues. In purely spatial terms, the humusphere is the sphere between the atmosphere (the gas sphere) and the lithosphere (the rock sphere) and constitutes the biosphere together with the hydrosphere (the water sphere). In the humusphere, the entire metabolism of all dead and living material is carried out in a continuous cycle. It is driven by the oldest life-forms that we know of: microorganisms. According to the cycle of living material model, we can attest that humus is created by life, out of life, for life. Source: Humusphere: Humus, a Substance or a Living System? LEARN ABOUT HEALTHY SOIL WITH ACRES U.S.A. The second annual Healthy Soil Summit took place on August 25-26, 2020. It featured 2 days of high quality soil education and interaction with experts, with Klaas Martens as the keynote speaker. And the best part is – you can still purchase the replay! Learn more here.
Humic Acid: The Science of Humus and How it Benefits Soil By Michael Martin Meléndrez Humic acid is a group of molecules that bind to, and help plant roots receive, water and nutrients. High humic acid levels can dramatically increase yields. Humic acid deficiency can prevent farmers and gardeners from growing crops with optimum nutrition. Conventional wisdom today ignores humic acids, though, holding that it is impossible to grow and maintain an urban landscape such as a park, golf course, or lawn without high-analysis NPK fertilizers. This article will drill down into the details on humus. We can adjust our soil biology and chemistry and achieve better yields if we understand its characteristics. Humus vs. Organic Matter We must begin by understanding that there is a difference between soil organic matter and humus. “Humus” is a general term that describes a group of separate but distinct humic substances. “Soil organic matter” is material that is decomposing at various rates in the ground. Some of the most common substances we collectively refer to as “humus” include: Fulvic acid: a yellow to yellow-brown humic substance that is soluble in water under all pH conditions and is of low molecular weight.Humic acid: a dark-brown humic substance that is soluble in water only at higher soil pH values and is of greater molecular weight than fulvic acid. Humic acid may remain for centuries in undisturbed soil.Humin: a black humic substance that is not soluble in water at any pH, has a high molecular weight, and is never found in base-extracted liquid humic acid products. Adding a small amount of humus to an acre of soil can achieve positive results. Applying organic matter is certainly an excellent way to remineralize a soil that has been leached or has no chemical reactions, such as with some sands. Sand with a low cation exchange capacity (CEC) has difficulty holding onto the cations of nutrients, and these cations can easily leach deep into the soil and become unavailable for plant uptake. Sandy soils are also unable to hold onto water when arid conditions prevail and humus is lacking. Sands reside in a condition of “feast or famine,” since water and nutrients are only available for a short time after they are applied. Biomolecules of humus can help retain water and the ionized nutrients that are produced by the natural cycling of organic biomass, compost, or other sources of fertilizer. The electronegativity factor of humic acids is key in developing and maintaining a healthy and sustainable soil. The source of these humic acids in a sustainable agricultural program, organic certified farm, or urban landscape can be decaying organic matter such as compost. In essence, this is fertilizer in an organic form. It is therefore important to know the ingredient source and the nutrient analysis of your compost. Humus is powerful stuff, and a tiny amount can produce a huge measurable result. We have seen as little as 40 total pounds on an acre of farmland increase the yield of a crop dramatically. The Physics of Humic Acid Humic acids are extremely important as a medium for transporting nutrients from the soil to the plant because they can hold onto ionized nutrients, preventing them from leaching away. Humic acids are also attracted to the depletion zone of the plant root. When they arrive at the roots, they bring along water and nutrients the plant needs. long grass and soil The depletion zone is the area close to the root of a plant from which the root draws (depletes) nutrients. This zone can become particularly depleted if there is a lack of either humic acid or mycorrhizal fungus. When plants are mycorrhizal, the depletion zone is of less importance. Mycorrhizae have hyphae micro-tubes that can extend much further into the soil than the host plant can reach. They can gather mineral nutrition for the benefit of the host plant from outside the depletion zone. Humus is even more critical for plant nutrient availability and uptake if there aren’t healthy mycorrhizal relationships in the soil. Positive ions are more easily absorbed by a plant’s root because the root has a negative charge. In other words, the positive (cation) is attracted to negative (the living root). Humic acids hold cations (positive ions) in a way they can be more easily absorbed by a plant’s root, improving micronutrient transfer to the plant’s circulation system. This works because humic acids (ulmic, humic, and fulvic) pick up positive ions and are then attracted to the root depletion zone and to the hyphae micro-tubes of mycorrhizae. Since the root’s negative charge is greater than humic acid biomolecules’ negative charge, scientists theorize that the micronutrients are taken up by the plant’s root and are absorbed by the plant’s circulation system. Some of the micronutrients are released from the humic acid molecule as they enter the root membrane, but we are now realizing that the plant will also uptake some of the lighter molecular-weight humic acids as well. In essence, the humic substances are chelating such cations as magnesium (Mg2+), calcium (Ca2+), and iron (Fe2+). Through chelation, humic substances increase the availability of these cations to plants. How to Build Humic Acid Levels Compost and other sources of decomposing organic matter are not an efficient way to build soil humus levels. Compost rapidly decomposes and leaves its minerals behind, releasing carbon into the atmosphere as CO2. Humic substances, on the other hand, are stable, long-lasting biomolecules. Components of humus have a mean residence time (based on radiocarbon dating, using extracts from non-disturbed soils) of 1,140 to 1,235 years, depending on the molecular weight of the humic acid. If you really want to fix or rehabilitate a soil, increase its CEC, improve its tilth and porosity, improve water availability for conservation, and therefore make a soil a healthier terrestrial biosphere for all plants, roots, microorganisms, you must depend on humus. Humus is a product of soil chemistry, and is dependent upon a source of its precursor chemicals: amino acids. Amino acids are the building blocks of protein. The best source of the amino acids in a natural ecotone are produced by the Glomus species of mycorrhizae. These are associated with any grass in a natural, undisturbed site. The tallgrass prairies of the Midwest exemplify this soil-building process better than any ecotone on earth, because grasses utilize a Glomus-mycorrhizal relationship. This is why there is was so much humus-rich topsoil in the Tall Grass Prairies. Glomus makes a soil protein called glomalin, a substance that is rich in amino acids. Combined with humus, they create a huge carbon sequestering and banking factor. Scientists can measure the percentage of calories in compost that come from proteins (the amino acids), carbohydrates, and fats. This enables them to measure the lack of humus-making potential of compost. Even in supreme-quality compost, the percentage of calories coming from amino acids (protein) is less than 5 percent. Since it is difficult to rely on the perfect amino acid ratio in compost because of differing manufacturing quality controls and ingredient consistency, we cannot predict a 100 percent efficient conversion of all these amino acids into humic substances. Compost or other soil amendments of organic matter are therefore not a reliable way of increasing soil humic substances. Attempting to add adequate amounts of humic acid through application of compost would require such a huge amount that it could lead to overdosing the site with nutrients. In fact, the better the quality of the compost, the more concentrated the nutrients will be, and the less you should use. In the case of our TTP Supreme Compost, for example, we recommend using it sparingly – never more than 60 pounds per 1,000 square feet or 2,600 pounds per acre. And this is assuming no other fertilizer is being used at the same time. Humus supplementation is necessary if you want humus. You can measure the quantity of humic acid in a compost product at a qualified lab. A good quality compost will measure around 5 to 8 percent humic acids. Benefits of High Humic Acid Levels One obvious benefit of humus we have seen at our Arboretum in Los Lunas, New Mexico, has been the aggregation of clay. This aggregation has made the clay more porous, soft, and aerobic, with better drainage, resulting in deeper root growth of all plants. The site was purchased in 1986 with clay soil 12 feet deep and a pH ranging from 8.3 to 9.2 – so alkaline that in the winter the site would turn white. Today we have one of the largest oak species collections of the Quercus genus in the United States, and the largest collection of native oaks of the Chihuahuan Desert Region in North America. Also on the site are several types of redwoods, maples, dogwoods and giant timber bamboo. None of these plants should be able to grow on soils with the conditions we started with, but with the power (or magic) of humic acids we have rehabilitated the soils to a productive and healthy level. Finally, “Humic Acids: Marvelous Products of Soil Chemistry” (The Journal of Chemical Education, December 2001) states, “Humic acids are remarkable brown to black products of soil chemistry that are essential for healthy and productive soils. They are functionalized molecules that can act as photosensitizers, retain water, bind to clays, act as plant growth stimulants, and scavenge toxic pollutants. No synthetic material can match humic acid’s physical and chemical versatility.” Editor’s Note: This story was first published in the August 2009 issue of Acres U.S.A. magazine. LEARN ABOUT HEALTHY SOIL The virtual Healthy Soil Summit event August 25-26, 2021, featured speakers like Rick Clark, Dennis Warnecke, Dan Kittredge, Kelse Ducheneaux, Mimi Casteel, Meagan Perry, Steve Becker, Ryan Fillmore and more! Head over to Eco-Ag U Online for the replay, which includes all educational presentations and Q&A sessions from the event.
Humus: What is it and How is it Formed? By Erhard Hennig Humus forms as a result of the complicated interplay between inorganic conversions and organic creatures such as microbes, nematodes, and earthworms. Humus formation is carried out in two steps. First, the organic substances and minerals in the soil disintegrate. Next, totally new combinations of these broken-down products develop. This leads to the initial stages of humus. Humus formation is a biological process. Only 4-12 inches (10-30 centimeters) of humus-containing soil are available in the Earth’s upper crust. This thin layer of earth is all that exists to provide nutrition to all human life. The destiny of mankind depends on these 12 inches! Humus Formation Cultivated soils with 2 percent humus content are today considered high-quality farmland. What makes up the remaining 98 percent? Depending on the soil type, organisms contribute about 8 percent, the remains of plants and animals about 5 percent, and air and water around 15 percent. The other 70 percent of soil mass is thus of purely mineral origin. The mineral part of the soil results from the decomposition and erosion of rock. The dissolution of these components is carried out by organisms called lithobionts, which are the mediators between stone and life. Raoul H. Francé coined the term “lithobiont,” which means “those who live on stone.” Lithobionts are the group of microbes that begin the formation of humus. They produce a life-giving substance from the nonliving mineral. On the basis of this process, living matter, earth, plants, animals, and human beings can begin, step by step, to build. Humus formation is a biological process. Only soils with optimal structural tilth have a humus content of 8-10 percent. Untouched soils in primeval forests can at best reach 20 percent. A tropical jungle can’t use up all its organic waste, so it can store humus. All forests accumulate humus, but real humus stores only emerge over the course of millennia. Once upon a time, accumulations of humus known as chernozem (Russian for black earth) could be found in the Ukraine. Almost all plant communities (except for leguminous plants and untouched forests) use up more humus than they can produce. Strictly speaking, each harvest and each growth of cultivated plants is accompanied by a loss of humus. The lost humus cannot be replaced by any kind of mineral fertilizer. Both deciduous woods and mixed forests can provide their own humus because they are able to make use of their own discarded leaves. Even in nature, without human influence, humus is only produced in deciduous forests and on undisturbed land. Humus and Manure Humus is favorably disposed toward the vegetable rather than the animal metabolism. This is why manure, with its high proportion of animal excrement, cannot support natural humus formation. Manure has to be turned into humus before it can be used for fertilization. Manure has to be turned into humus before it can be used for fertilization. Why is this? The microbes living in the soil are more favorably disposed toward the decomposition of pure cellulose than the disintegration of animal excrement, which leaves the intestines in an anaerobic state. This fact was unfortunately not recognized by earlier generations. Rather than being subjected to aerobic decomposition, manure was simply buried in the field. When introduced to the soil in this way, rotting anaerobic matter remains as an alien element for quite a long time. The manure is disintegrated by specific rot microbes, whereas the microbes inherent to the soil — living under aerobic conditions — are driven out. The question of whether anaerobic or aerobic microbes predominate, and therefore whether rot or decomposition occurs, is crucial for the health of the plants. The following example reveals how little humus is produced when manure is used: if a dose of 400 quintals (roughly 88,000 pounds) of stable manure is applied to each hectare of soil (on light soils), after half a year, half of the amount of the manure can be found; after one year, only a fifth; and after two years, practically nothing of the manure is left. The organic matter in the soil is quickly consumed and assimilated; it is then mineralized without the production of humus. Typical manure cultivation has been practiced in Germany for the last 200 years. If manure cultivation were effective, German soils would be very rich in humus. But this isn’t the case. Manure is only the remains of the substances that served the animal as nutrition. All the highly nutritive proteins, carbohydrates, fats, and so on that were produced by the plant have been taken away from the soil, and what remains is poor in nutrients. In spite of these shortcomings, the custom of manure spreading is still widely practiced. Here is an example: several years ago a renowned child specialist wanted to find out whether the quality of vegetables grown for babies and young children was influenced by fertilization. How did he go about it? He tested the influence of: a) only manure; and b) manure plus mineral fertilizer. The result: the vegetables fertilized exclusively with manure proved not only inferior, but actually dangerous for human health — many of the children in this group were diagnosed with hypochromic anemia. The report about the influence of stable manure on the quality of vegetables even referred to humus-fertilized soils. Such misinformed ideas about humus are still common. Researchers apparently failed to notice that manure is a rot product that contains poisonous substances like indole, skatole, putrescine, and toxic phenols, and that the quality of manured soil is bound to be toxic. What is Humus? The question, “What is humus?” is not easy to answer. A German layman, if asked, would probably check the Brockhaus Encyclopedia for an answer. There he would find the following definition: “Humus, black-brown matter in the topsoil, is produced by the putrefaction of vegetable and animal matter. Humus is rich in carbon and is generally acidic as a result of its humic acid content. It increases the water storage potential of the soil and produces carbonic acid, which disintegrates minerals.” “Humus, black-brown matter in the topsoil, is produced by the putrefaction of vegetable and animal matter.” Even though this statement is quite basic, one can glean from it some important functions of humus. We know today that plant remains decompose down to their most basic components and plasma residues. Only after the total disintegration of all substances into the elements carbon, nitrogen, potassium, phosphorus, and magnesium can construction begin on what today is generally called humus. Researchers have proven that plants can receive the final forms of plasma (matter that is not decomposed to the state of mineralization) up to a certain molecular weight. This plasma is then included in their systems. This brings us back to the cycle of living substances, which we have already mentioned above. Humus cannot be regarded as a real substance but rather as a process — a formation — built from a multitude of constantly changing factors. In order to define humus, the living substance factor has to be taken into consideration. The law of harmony — that is, the law of balance — reigns over all living things. We know all too well the consequences of a disturbed harmony in the soil, this harmony being the precondition for a normal soil life. One could also say, “Harmony equals balance through well-functioning regulative systems in the soil.” Humus and soil are subject to the same laws as all other living things. But modern agriculture refuses to work in the same way, and the results of ignoring these laws can be seen in our ailing fields with their depleted soils and damaged structures, and in our disease-prone cultivated plants. Dead soils eventually become barren desert land. Until recently, humus could not be analyzed using the usual chemical methods. Acids, bases, and salts had to be used for chemical investigations, but those substances destroy life and its functions. Incineration did not reveal anything about the structure or the capillary system of the former humus. Without knowledge of this capillary system, nothing would have been discovered about the organisms, how they related to each other, and the harmony in which they worked. We can discern one key to determining the value of humus from the relationship between carbon and nitrogen. Highly fertile soils should show a carbon/nitrogen relationship of 10:1. Biological investigations, however, are far more interesting because they refer to the living milieu, and in order to form an idea of the world of little creatures one has to study the symbiosis of the living communities. The Clay-Humus Complex Even with the above factors, the definition of humus has not yet been exhausted. In this “primitive tissue,” colloids — the very finest soil particles — play a particularly important role. In humus, different nutrients are bound together with clay minerals through adsorption processes. This association of organic fragments such as humic substances with inorganic particles such as clay minerals is usually called the “clay-humus complex.” Without minerals, a true humus formation would not be possible. Clay and humus colloids are able, mainly due to their electronegative properties, to take up the bases present in the soil, hold them tight, and absorb them. Clay and humus are thus generally referred to as an adsorption complex. Humus as the clay-humus complex — in other words, as the living organic matter in the soil — also has a buffering effect. Nutrients are only given to the plant if they are required, so an overdose is impossible. However, plants growing on soils lacking in humus take in more nutrients than are needed for the accumulation of plant matter when mineral fertilization occurs. Because organic fertilization prevents superfluous consumption, it can be seen as an energy-saving measure. We should bear in mind that humus (which our ancestors referred to as the “Primeval Force” of soil) is not matter according to most recent knowledge, but a biological performance. This performance is typical of Mother Earth, and such performances cannot be found anywhere else. Editor’s Note: This is an excerpt from Secrets of Fertile Soils: Humus as the Guardian of the Fundamentals of Natural Life, published by Acres U.S.A. For more information, visit www.acresusa.com.