Biocarbon & Climate Change
White Paper: Strategy to Remove Greenhouse Gases
A Climate Change Solution Under Our Feet
Public Policy Background Information
David Yarrow, Spring 2019
To reverse climate change, a key is to remove greenhouse gases by conversion to solid substances. Soil is one of Earth’s largest carbon sinks. Scientists calculate soil can absorb all the carbon in Earth’s air, plus the all carbon in all the green plants—and more.
Carbon Sequestration by soil regeneration is high priority to avert global thermal overload. Farms, forests, lawns, and landscapes are front lines in this urgent effort to recarbonize, remineralize and revitalize soils in this century.
Carbon-Smart is a process with net removal of carbon from atmosphere to improve soil structure, boost fertility, increase production, and optimize nutrients to assure healthy soils and profitable farms. Carbon-Smart is 180-degree reversal from 20th century farming that decarbonized & degraded soils.
Regenerative Agriculture is emerging to raise soil carbon with biocarbon, biochar, organic matter, humus, manure, cover crops, no-till, crop and livestock rotations.
Soil Food Web are communities of microbes and larger lifeforms that convert minerals into nutrients for living cells, microbes & plants.
Changing farming faces obstacles, needs a coherent plan, requires cooperative action. Growers need training & support to rapidly adopt carbon-smart methods, and markets to buy carbon-smart crops. Public opinion to endorse carbon-smart food system reforms, public policy to prioritize programs to advance carbon-smart strategy, funding for carbon-smart technology.
Soil carbon and food nutrient quality are a citizen priority. Environmental protection begun in 1970s must mature into 7th Generation Stewardship of our planet and nature. Soil Carbon Sinks are a small step in long journey to reverse global warming in a responsible relationship with the Earth.
PART ONE: Soil Carbon Geophysics
|The world’s cultivated soils
lost 50–70% of their original carbon
–much of it oxidized to CO2.
–Rattan Lal, Ohio State University
Carbon Management & Sequestration Center
Broken Carbon Cycle
In the next decade, humanity faces pivotal choices of a path to a future on this finite planet. Science warns greenhouse gases heating Earth’s air and oceans will bring catastrophic changes for climate, ecosystem stability, food supply, and human survival. Science identifies human emissions as the main source of these greenhouse gases. Changes in human behavior, energy sources and farming are required to reverse these geophysical processes and move our species—and the whole planet—out of this danger.
Effects of Eating: A third of greenhouse gas emission is directly due to food. Agriculture—farm-grown food, fiber and fuel—is a huge emitter, beginning with carbon and nitrogen from fuels, fertilizers, tillage, monoculture, and exposed, eroding soils. More emission occur to transport, process, distribute, store, cook, consume, and dispose—sewage and solid waste are mostly food. Total emission for food is greater than any other economic sector. What we eat, how it’s grown, makes a difference.
This impact of eating on global climate should startle every planetary citizen. First, to grasp the terrible total effect of a daily universal human ritual. Second, to realize we each face a choice:
— eat food that continues current excess emissions; or
— eat food grown in ways that reduce greenhouse gases.
Third, by this simple carbon-smart choice, we embrace our responsibility to affect our human and planetary future, and reverse our rush to climate calamity.
350 ppm: planetary red line
In 2008, climate scientists worldwide declared a consensus that 350 ppm is a key threshold for CO2 in Earth’s atmosphere. Beyond this, critical processes accelerate, such as melting glaciers, shrinking ice caps, intensified storms, extreme weather.
CO2 exceeded this “safe” level in 1988, is now beyond 400 ppm, and still climbing every year. And we have yet to seriously commit to curtail our emissions.
350 ppm means reducing emission isn’t enough. Even zero emission can’t move humanity out of danger. We must lower greenhouse gas levels. To have hope for a future, humans must initiate processes to remove greenhouse gases by conversion to stable substances stored in safe places.
The Soil Carbon Sink
Soil—one of Earth’s largest carbon sinks—is easy to access. All the carbon currently in Earth’s atmosphere can be stored in soil—safe, solid, stable. Any effort to confront climate change must see soil as a primary carbon asset. Putting carbon in soil is a wise investment in a sustainable future.
|The food system accounts for one third
of greenhouse gas emissions
and 70% of water use.
Advancing Regenerative Agriculture
Black is the signature of fertile soil. Carbon improves key soil properties such as tilth, structure, water holding, and aeration. Carbon also boosts nutrient cycling, ion exchange and microbe activity. Soil easily holds up to 10% carbon, with better fertility and productivity. Modern chemical-intensive agriculture has reduced carbon in soils to less than 1%.
Photosynthesis: Plants fix carbon into carbohydrate by photosynthesis. Sugar is the great gift of green growing plants to life on Earth. Most organisms depend on sweetness captured from sunshine, water and CO2. Plants use sugar as fuel for energy, and build their bodies from cellulose, Earth’s most abundant biocarbon.
Every spring, leaves emerge and photosynthesis begins. Plants remove so much CO2 from air, levels drop 5 parts per million from June 1 to July 1. Thus, plants are a principal ally in any effort to mitigate climate change. Step one to move carbon into soil is “optimize photosynthesis” by maximum green cover growing on land. Cover crops and no-till are farming methods to achieve this objective already advanced by USDA NRCS.
Soil Organic Matter: Plants die, fall to the ground, decay and dissolve into soil to become “organic matter.” This organic soil carbon is essential to support and sustain full-function fertility for health plant growth. USDA Certified Organic farms maintain a minimum 4 to 5% of soil as organic matter, but up to 10% can be biocarbon. A new regenerative agriculture is emerging to accumulate carbon in soil, reduce tillage, increase biodiversity, optimize microbes.
December 1, 2015, at COP21 Paris Climate Summit, France proposed a goal to raise soil carbon in farmland by .4% per year. The French calculate this annual soil increase sequesters six gigatons of CO2 to offset the 4.3 gigatons humans emit yearly.
Stable Humic Carbon: Microbes have enzymes to disassemble complex biocarbons such as cellulose. Some biomass molecules resist this digestion, especially carbon-carbon bonds in rings. Microbe breakdown results in residues of 10%, even 15%, of original biomass. The black matter that remains after microbe digestion is “humus.” This stable carbon can stay in soil for decades, even centuries.
pulls carbon from the air
to store in soil to help land
be more resilient to climate change.
Carbonates: Carbon-Fixing Bedrock
Exposed to air, certain rocks react with CO2 to form solid chemicals. Geology’s main way to fix carbon is carbonates (CO3) by volcanic rocks, such as basalt. Carbonates benefit life and soil as pH buffers for stable electrolytes, since cells thrive in steady, constant pH. Calcium is the most important carbonate rock: “limestone.”
Research reveals carbon-fixing rock reactions with CO2 to create CO3 depend on:
1) fresh-fractured rock from deep sources;
2) small size to optimize surface area;
3) accelerated digestion by catalytic enzymes of bacteria and a diversity of larger organisms.
Thousands of tons of igneous rockdust are piled in aggregate and stone quarries, with ongoing production. These residual fresh fines can undergo “accelerated weathering” in composts and soils. This synergy of rockdust, biochar and microbes in soil can unleash a cascade of further carbon-fixing sequestration.
Carbon/Nitrogen Ratio: These primary elements build living cells in an ancient ratio and relationship. Nitrogen is the #1 fertilizer and #2 greenhouse gas. Nitrogen/Carbon balance is a ratio fundamental to healthy soil, thriving biology and stable ecology. Holistic fertilizer strategy adds Nitrogen with Carbon in proper ratio, and other nutrients, in a complete, balanced package that offers more efficient delivery, better response, less fertilizer use, less stress for soil and microbes, less leaching and loss, and, yes, less emissions.
Biochar: super-stable carbon
Biochar is a special, super-stable charcoal made by baking plant biomass at 700–1000 degrees C. In soil, this black residue resists decay and weathering to persist centuries, even thousands of years. Charcoal use in soil began 6000 years ago by tribes in Amazon rainforest, and was discovered by scientists in the 1960s.
Biochar is our best strategy to sequester carbon. Soil can easily absorb 5% biochar, and easily contain 10%.
Biochar benefits to soil begin with improved structure, softer tilth, lighter texture. Biochar’s micropore sponge allows each grain to hold water inside and keep soil wetter for longer. This baked biocarbon is hungry to adsorb ions and store nutrients to enhance fertility, improve fertilizer delivery, increase fertilizer efficiency, decrease fertilizer use, reduce leaching. Biochar’s empty micropore architecture is shelter and habitat for microbes to form stable communities that boost plant growth and health.
Renewable Bioenergy from Biomass: Making biochar releases energy to harness. Research on biomass-to-energy technology includes “micro-gasification.” Pyrolysis cooks volatile chemicals from biomass to refine by fractional distillation into liquid and gas biofuels. Renewable energy from biomass can replace fossil fuels to cut emissions and fossil fuel dependence.
Soil Carbon Cascades
Carbon added to soil—in particular, biocarbon, especially biochar—can initiate cascades of effects that store several times more carbon in soil and biomass. Carbon we put in soil can initiate biological processes that capture ever more carbon as biomass. Soil’s capacity to capture, store and sequester carbon expands in a positive feedback cycle each growing season.
Plant Growth Cascade is first. Biocarbon-rich, mineral-charged, nutrient-balanced soil grows more biomass, to capture more carbon each growing season. As soil regenerates, plants grow larger, thicker, and photosynthesis kicks into higher gear. This mostly affects roots—unseen life underground—not visible, measurable, above-ground top growth. This growth boost increases each year in positive feedbacks to increase soil capacity to capture carbon held as new green growth.
Green Carbon Cascade is second. Plants make sugar in green leaves, then send sweetness down to roots to secrete into soil. Plants create a “sweet spot” of these root exudates. Symbiotic microbes thrive in this enriched zone, sharing nutrients with each other and plants. Half or more of sugars plants make in green leaves is secreted into this Underground Carbon Economy.
White Carbon Cascade: Soil isn’t mere inert mineral dirt. Soil is complex structures and infrastructures made by microbe digestion and breakdown. “White carbon”—the living, dead, decaying bodies of microbes—is a significant carbon reservoir.
In 1996, USDA scientist Sara Wright detected a new biocarbon, named “Glomalin,” after Glomales fungi that use it to grow their whisker-thin threads of hyphae to search through soil for water, minerals and nutrients. One third of soil carbon disappears into this previously undetected fungal form.
When fungi die, this glyco-protein residue is sticky with electric charges. This thin biofilm glues soil particles into larger “aggregates.” Even sand coated by this fungal film clumps, and attracts water and nutrient ions. Ultimately, this biological infrastructure is what identifies productive soils. Soil isn’t inert mineral dirt, but a living matrix made by, for and of microbes.
Again, effects are underground, unseen, unmeasured. Too tiny to see without magnifier, microbes are mostly water, thus transparent and invisible. To detect and understand living soil carbon is a science frontier and pivot point for climate action.