|Professor Gilles Lemieux, the father of pedogenesis applied to agriculture.|
By Céline Caron
Soil is much more than “dirt.” Why is such a disrespectful word still used for one of the major components of life on Earth?
Humanity could not be sustained without the living soils and the living oceans. Let’s banish the word “dirt” from our vocabulary when we talk about soil.
Good, living soil has evolved over millennia in only a few privileged areas of the world where deciduous forest soils evolved from rock to mull, a porous mix of humus and mineral soil, to support stable, long-lived humus. The processes involved in forming these soils have been at the heart of work done by Professor Gilles Lemieux and his colleagues at Laval University in Quebec since the 1970s.
The steppe ecosystems (the Asian steppe, the South American pampas and the central prairies of North America) are primarily grass, growing where precipitation is low. We must distinguish between prairie and forest soils. Prairie grasses have a different type of lignin than woody plants of climacic forests. Because the lignin of prairie plants does not lead to production of highly stable, long-lived humus, natural prairie soils will always remain fragile and unable to support dense human populations.
If biodynamic agriculture integrated agricultural pedogenesis (soil formation) into its technical methods, we would have the best way to produce food worldwide while preserving soil fertility and ecosystem diversity. Biodynamic systems integrate microorganisms and short-lived humus, while sylvagriculture is sustained by fungi and stable humus. So why not develop sylvagrarian biodynamic farming, which would have a good mix of fungal and microbial life and a good mix of short-lived humus and stable humus?
As forests disappear under cities, highways, concrete and asphalt, good, living agricultural soils are vanishing at an alarming rate. Added to the declining health of oceans, famine is lurking for humanity – unless we save living agricultural soils.
But our supermarkets are full of food, you may say. This is an illusion of abundance; most of this so-called food is artificial.
Modeling the Climacic Deciduous Forest
The soil has four solid components: mineral, of geologic origin; chemical, which is labile (easily altered), perishable and unstable, especially to heat; biochemical, with its enzymes, molecules and aggregates; and biological – trophic chains involving bacteria, protozoans, algae, fungi and animals in a matrix of polyphenolic compounds.
Humus began to form on Earth when deciduous trees appeared 60 million years ago. It has progressed at a rate of a few inches per thousand years since.
Early peasant agriculture used slash and burn techniques to farm these deciduous forests, and later applied animal manures and rotated crops. Then chemical agriculture appeared, ignoring time, contours and biodiversity, and destroying hedges. At the same time, forestry focused on growing conifers to feed paper mills. Humus production has declined since, and the precious mull has washed into waterways or gone with the wind.
The lack of understanding of natural forest ecosystems, the soil in particular, is so deep that almost all sylvicultural practices use agriculture as a model, and forestry research has been directed toward managing an agricultural system in the forest (Lemieux). In agriculture as well as in forestry, the focus has been on mineralization (releasing inorganic nutrients from organic matter) with very little research or interest in humification (forming humus), which regulates mineralization and fertility (Lemieux).
Three types of humus – more appropriately called “the humic bowl” – exist: mull, long-lived humus that is scarcely visible, is totally integrated with the mineral substances and transfers nutrients to plants; moder, in brunisols (immature forest soils), where the humic bowl is poorly incorporated with the soil fauna and is much less efficient for pedogenesis; and mor, characteristic of coniferous or leafy transitory forests. The latter supports pedogenesis poorly and must be avoided in sylvagriculture.
Only climacic deciduous forests make mull or long-lived humus. Animal manures, green manures and composts supply primarily short-lived humus and support primarily bacteria, which encyst and go dormant in winter; but fungi – characteristic of mull soils – survive and continue to work in winter. Fungi are undervalued because so little is known about them, yet fungi and lignin from climacic deciduous trees are at the root of soil fertility and long-lived humus.
We must find a way to cultivate grains and produce our food by imitating processes of the climacic deciduous forest or by practicing sylvagriculture. One way to do this is to use ramial chipped wood (RCW), procured from these trees (see bibliography), and green manures, and not till the soil. Ramial chipped wood contains lignin and polyphenols, so is unsurpassed for making mull. It also controls water movement and limits weed proliferation.
Green manures, on the other hand, if incorporated into the soil before they go to seed, add fresh organic matter that is rapidly mineralized (broken down, becoming available to plants). They do not allow a rapid increase in humus content (0.1 percent per year, according to Steve Groff) but do what RCW cannot: their roots aerate and break up the soil while nourishing different fauna and flora from those that feed on RCW. Creating fertile soil is complex and takes a long time.
Sylvagriculture applies the ecosystem processes of the deciduous forest to farming and is characterized by soil aggradation instead of degradation; sweet rather than sour smelling soils; humification associated with mineralization; and biodiversity and complementarity, because live organisms work the soil in lieu of the farmer.
In contrast, agroforestry applies agricultural techniques in the forest.
We are beginning to observe agricultural fields where green manures and legumes are sown, and soy is rotated with corn (often grown for fuel), but this is not sylvagriculture. Too much liquid manure is still spread, delaying humification in the soil.
Maintaining biological activity in soils is essential for long-term fertility. Using living soil organisms – fungi; mesofauna such as acarians (mites and relatives), collembola, enchytreides (pot worms) and isoptera (termites); algae, bacteria, mycorrhizae, wild plants, legumes and others – implies caring for each of them and thinking globally.
To maintain soil biological activity, we must aim for aggradation of live organic matter, that is, soil that contains fungi and smells good. Degradation occurs with manures and unfinished composts, attracts flies and smells bad.
More research should document pedogenesis, starting with a more detailed definition of organic matter. All organic matter is not equal in nutritional or structural content and value.
Aggradation – a dynamic upgrading process; the opposite of degradation.
Aggregates – groups of particles held together by a “cement” or “glue” of biological origin and acting as structural elements for the soil. Soil aggregates provide refuge and food for microfauna and microflora.
Biotransformation – the transformation of twigs, roots and leaves into humus by fungi and microorganisms.
Climacic – relating to all phenomena deriving from the climax (such as a climax forest), which is the most stable ecological structure that can renew itself under local constraints of climate and geomorphology.
Deciduous – trees that drop all their leaves every fall.
Ecosystem – a biological system allowing beings of different levels to live in harmony in more or less closed cycles.
Epigeous – above; applies to autotrophic plant ecosystems such as the forest.
Humic bowl – encompasses digestive and fecal systems of mesofauna.
Hypogeous – under; particularly ecosystems inside the soil.
Lignin – a macromolecule that makes up about one-quarter to one-third of the dry mass of wood.
Mesofauna – intermediate-sized animals in soils, including acarians, collembola, enchytreides and isoptera
Moder – a type of humus characteristic of brunisols (immature forest soils), where the humic bowl is poorly incorporated with the soil fauna and is much less efficient for pedogenesis.
Mor – the humus layer in coniferous or leafy transitory forests.
Mull – a humus-rich soil layer in deciduous forests; the best type of humic bowl, with integrated organic and mineral substances.
Pedogenesis – the whole, natural process (including effects of organisms) of creating and maintaining soils within a dynamic that includes rodents, fungi, lignin, polyphenols, sugars, etc. Pedogenesis creates soils that can supply the nutrients necessary for plant growth and can maintain hypogeous and epigeous biological balances.
Polyphenols – compounds derived from phenol and formed of benzene rings and hydroxyl groups.
Ramial wood – twigs less than 3 inches in diameter and coming from deciduous trees.
Stable or long-lived humus; humus formed from the lignin of deciduous trees, as opposed to short-term humus derived from animal and green manures and compost.
Short-term humus – humus derived from compost, animal and green manure.
Trophic chains – communities of plants and animals that transform plant tissues and transfer the nutrients and energy of the soil toward plants.
Caron, Céline, G. Lemieux, Lionel Lachance, “Building Soils with Ramial Chipped Wood,” The Maine Organic Farmer & Gardener, Dec. 1998/Feb. 1999.
Caron, Céline, G. Lemieux, Lionel Lachance, “Regenerating Soils with Ramial Chipped Wood,” Eco-Farm & Garden, Summer 1999.
Caron, Céline, “Pedogenesis: The Importance of Deciduous Trees in Forest Ecosystems,” The Maine Organic Farmer & Gardener, Dec. 1999/Feb. 2000.
Caron, Céline, “Oak Trees from Seed to Seed,” The Maine Organic Farmer & Gardener, March/May 2000.
Caron, Céline, “What is a Forest,” The Maine Organic Farmer & Gardener, Sept./Nov. 2000.
Caron, Céline, “Connecting with the Terrestrial Ecosphere,” The Maine Organic Farmer & Gardener, March/May 2006; www.mofga.org/Publications/MaineOrganicFarmerGardener/Spring2006/Ecoshpere/tabid/206/Default.aspx
Caron, Céline, “There is no soil fertility without a healthy forest,” The Maine Organic Farmer & Gardener, March/May 2007; www.mofga.org/Default.aspx?tabid=700
Professor Gilles Lemieux Leaves, Almost Unnoticed
Galileo and Darwin were not the only great contributors to science who died before being widely recognized. As the German philosopher Arthur Schopenhauer (1788-1860) said: “All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.” Professor Gilles Lemieux, the father of pedogenesis applied to agriculture, was also relatively unknown during his lifetime. His passing on April 29, 2009, has not garnered much attention in the agricultural or forestry world, even in Quebec, where RCW research originated.
Humanity owes a lot to Professor Lemieux. He defined and explained the evolution of fertile soil, one of the major elements on this planet – but also the least understood and least respected. He opened a new field of exploration of our soils: that of pedogenesis applied to agriculture.
He created new words, such as “ramial wood” for the small tree branches at the root of soil fertility. These branches were previously seen as trash and were burned or buried all around the world. Prof. Lemieux’s rigor, tenacity and perseverance established the basis for this new science. He deserved a Nobel Prize for his work. For Canadians, his contribution compares with that of geographer Louis-Edmond Hamelin for his work on the northern hemisphere.
Small biological processes, whether fungal, vegetal, mineral or animal, are the essence of balanced terrestrial ecosystems. All the veins where precious water percolates enable life on this planet. Agricultural soil is the energy of the sun and water stored in the deciduous forests over millennia. The soil has a vital heritage and is fragile and alive where the leafy forest is essential to its fertility and to the welfare of all living beings.
Thank you, Professor Lemieux, for enlarging our awareness of the value of fertile soil.
Céline Caron is an ecologist and Earth doctor. She is a long-time practitioner of organic agriculture in Quebec, a friend of rivers, wetlands, forest, soil, biodiversity and simple living. She writes in both French and English.