compost as superhero

Compost is a Superhero

Sure, compost adds nutrients. But that might be this soil amendment’s least important function. 

Quite often, articles will mention compost as a replacement for some or all of the nutrients that might be provided to plants through applications of synthetic (man-made) fertilizers.   

That’s certainly true.  Compost delivers the macronutrients nitrogen, phosphorus, and potassium (NPK), plus a slew of plant-essential micronutrients that are missing from most synthesized fertilizer products.  Compost provides plants with a wholesome, well-rounded meal, not the nutritional equivalent of junk food. 

But what these fertilizer-focused articles rarely mention is the fact that the real value in compost use is not related to feeding plants, but to feeding soil … and soil does require a wholesome diet to function as a true soil and not a dead substrate. 

Compost feeds soil

Providing plant nutrients is just one of many soil functions.  Worms and other creatures that live in healthy soils help to physically break down food sources, then microbes take over to convert that food into plant-available form. 

Both physical and microbial conversion depend on a soil environment that can support those lifeforms.  If the soil is chronically too wet, too dry, too compacted  yada, yada  then it can’t support a healthy soil ecosystem.  That plot of ground may not be soil at all, but lifeless dirt. 

To countermand the impacts of human activity, disturbed soils require regular program of replenishment that includes organic matter and microbes.  Compost provides both.  Compost feeds soil.

Then, when it rains, soil retains that water, reducing runoff.  When runoff is reduced, so is erosion, sedimentation, and water pollution.  Because soil microbial activity also degrades pollutants, any stormwater that does run off is cleaner.  

That same microbial activity can help neutralize some soil-borne diseases, too. 

Improving plant nutrition, aiding in disease control, reducing water pollution, and retaining water are all important soil functions. 

But wait, there’s more. 

Compost as a carbon sink 

The build-up of greenhouse gases in the earth’s atmosphere is cause for concern.  As more greenhouse gases flood the atmosphere, temperatures increase. 

This rise in global temperatures influences many things, erratic and extreme weather being one of the most visible.  Subsequent climate shifts can impact people, crops, and livestock for hundreds of years. 

When used to amend soils, compost sequesters carbon.  This means the soil will act as a carbon “sink,” capturing and holding carbon in stasis – but only as long as the soil remains undisturbed.  When the soil is tilled, that carbon is released. 

Extensive use of compost for perennial crops and other long-term application(grasslands, tree farms, utility easements, etc.) can positively impact atmospheric conditions by reducing greenhouse gases.   

At the same time, the addition of compost rebuilds a topsoil layer that has been eroded or scraped away by farming, development, and other human activity.  Since topsoil loss has been identified as a significant threat to planetary health, second only to population growthits restoration is a global priority.   

At a time when nearly a third of the world’s arable land has become unproductive in just a few decades, compost really can be that superhero swooping in to save topsoil, save water, save the atmosphere, and save the planet. 

using compost to manage stormwater

Comparing costs per gallon retained 

Soil amendment is one of the least expensive ways to collect and manage stormwater 

Manage water where it falls.” 

This sound advice is the foundation of the Milwaukee Metropolitan Sewerage District’s Regional Green Infrastructure Plana program that identified soil amendment as one of the least expensive ways to manage stormwater.  At 28 cents per gallon, improving soil is second only to native plantings in lowest cost per gallon retained. 

Green roofs?  $4.72 per gallon.  Those fancy-schmancy deep storage tunnels?  $2.42 per gallon.  At $1.59 per gallon, even pretty little rain gardens cost more than five times that of simple soil amendment. 

Milwaukee is not alone in promoting soil amendment as a first line of defense for stormwater management  For example: 

  • Denver and GreenleyColorado, require compost use for new landscaping, as does Leander, Texas. 
  • Some state Departments of Transportation (DOTs) now routinely specify compost.  A few years ago, the Texas DOT said it was the largest single market for compost in the U.S. 

In an urban environment, opportunities for soil amendment abound.  City parks, athletic fields, planters, urban lawns, highway medians and easements, foundation backfill – anywhere there’s soil, there’s opportunity for inexpensive water retention. 

Every 1 percent increase in soil organic matter (SOM) content adds an additional 16,000 gallons of water-holding capacity per acre foot.  A site managed to maintain soil organic matter at only 2 percent can hold all the water of a typical rain event (1 inch or less), which is 27,154 gallons per acre.     

In fact, at 5 percent SOM, the soil can retain the water equivalent of nearly 3-inches of rainfall.  In some regions, this equal95 percent of all storm events. 

Soil amendment may not solve all rainfall issues, especially in downtown areas.  But managing water where it falls can be the most sensible, efficient, environmentally- and economically-prudent strategy for “first line of defense” stormwater management.   

organics recycling is just the halfway point

Food waste mandates are only the halfway mark 

Compost use gets organics recycling to the finish line 

Unlike a decade ago, when food waste mandates were few and far between, there is a flurry of activity these days focused on diverting food waste and other residential/commercial biodegradables from landfills and incineration. 

From the U.S. to Italy to northern India, the movement toward more sustainable management of organic waste from households and businesses is real and gaining momentum. 

But while laudable, there’s a big piece missing from some of these programs — mandated compost use.  Just making compost isn’t recycling.  The product must be used – returned to the soil – to be recycled.  That’s what makes the system “sustainable.” 

Landfilling organics isn’t sustainable because they’re buried.  Any thermal or other waste-to-energy (WTE) technology that destroys organics isn’t sustainable, either, no matter how hard technology providers try to paint them as such.  The feedstock – waste – may be considered a sustainable source, but the process is not. 

A possible exception is biochar, carbon-rich, charcoal waste material produced by pyrolysis that is sometimes used as a soil amendment.  However, not all biochar is right for this type of reuse.  It doesn’t offer as many benefits as compost, and — since the use of biochar is relatively new — there is a lack of research related to its long-term use.  While pure biochar is made from organics, of specific concern is contamination resulting from WTE biochar processes that use unsorted municipal solid waste as feedstock.  

But whether biochar or compost, the truth bears repeating — recycled organics must be used to feed the soil for a sustainable system to exist.  This is the only way to close the recycling loop for organics. 

Going the distance with food waste mandates

Football players don’t move the ball to the 50-yard line and then stand around waiting for the pigskin to get itself into the end zone. 

Establishing a curbside or drop-off program for source-separated organics is a good first step … but it’s only half the distance to the goal.   

The finish line for organics recycling is compost use.  Anything a community can do to encourage that use is important.  But sometimes, it takes more than education and outreach to get the ball rolling. 

When governmental entities write ordinances and project specifications requiring compost use, good things happen.  By creating early markets for quality compost productseveryone from green industry pros to stormwater managers to homeowners can clearly see the benefits of amending soil. 

This demonstration leads to voluntary compost use through the manufacture of quality products and product sales to high-value markets.  Product sales, not giveaway programs, is what will keep composting facilities – public or private – economically sound. 

Any community considering organics recycling needs to think about the end game.  To ignore the ultimate goal is to win the battle, but lose the war for organics recycling.  

READ:  Food waste diversion — it’s time to pursue alternatives that make environmental and economic sense

bioremediation-microbe smorgasbord

How does bioremediation work?

Organic waste offers up a smorgasbord to hungry microbes

Unseen by the human eye, microbes are the soil’s equivalent of worker bees.  They are responsible for a slew of soil functions.  Without them, soils don’t work as they should.

“Soil organisms decompose organic compounds, including manure, plant residue, and pesticides, preventing them from entering water and becoming pollutants. They sequester nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it available to plants. Many organisms enhance soil aggregation and porosity, thus increasing infiltration and reducing runoff. Soil organisms prey on crop pests and are food for above-ground animals.”   — NRCS/USDA

Algae, bacteria, fungi, nematodes, protozoa — aerobic microbes and other soil fauna need oxygen, water, and food.  Other survival influences include environmental factors like temperature and pH.

In a managed setting like composting, microbial feeding activity quickly turns organic waste — including some toxic compounds — into a safe, carbon-rich soil amendment product known as compost.

The organics can be food waste, yard debris, biosolids, petroleum derivatives, or anything else that was once alive.  As long as the waste stream is free of agents that would kill bacteria and the like, the material should compost.

Of course, the time required to break things down depends on the specific type of waste, particle size, the composting process in use, etc.  But for the most part, a few days of controlled, high-rate composting followed by a curing period of several weeks is enough to turn common organics into dark, aromatic compost.

How does bioremediation work?

All matter – including organic waste — is made up of individual atoms.  Atoms join with other atoms to become molecules.  Molecules hook up to become compounds, and they’re all held together by chemical bonds.  For organic material, that bond is commonly of the “covalent” variety.  This means the atoms share, rather than gain or lose, electrons.  This makes for a more stable molecule.

During composting, hungry microbes dine on the waste stream’s inherent sugars and proteins, releasing enzymes as they digest their food.

These critters are mostly after the carbon, but their feeding also releases the nitrogen, potassium and phosphorus that plants use as food.  (There are also some microbes that can pull nitrogen from the air and convert it to plant-available form.)

Their enzymes break chemical bonds, eventually reducing compounds to molecules and molecules to atoms.  Toxic compounds disintegrate.  Along the way, elements and simple compounds realign, creating more benign substances like carbon dioxide and water.

Controlling the composting environment ensures ideal conditions for these microbes, setting the stage for rapid biodegradation.  Where decomposition and stabilization could take months (or years) in a natural setting, composting achieves the same outcome in a matter of weeks.

The tighter the control, the faster the bioremediation process.

How does bioremediation work?  Very well.


perennial food crops and carbon storage

Can compost and perennial food crops save the planet?

A match made in food science heaven has the potential to forever change agriculture’s environmental impact.

Long ago, humans abandoned the hunter-gatherer lifestyle in favor of agriculture. They tweaked deep-rooted perennial grasses, turning them into shallow-rooted annual grain crops with higher yields.

But farming came at a price.  Domestication of wild edibles set off a destructive cycle of soil depletion.

Seasonal tilling loosened soil particles. Wind and rain carried topsoil away. With it went the earth’s ability to store water and sequester carbon.

In the last 200 years alone, the top 2 meters of the earth’s soil have lost 133 billion tons of carbon.

Soil loss has turned into a big problem for today’s humanoids. Topsoil is at a fraction of historic levels.  Storage capacity is dwindling.  Greenhouse gases are building, and global temperatures are rising.

No-till agriculture was once thought a solution to soil loss. By planting in the rubble of the previous crop, farmers didn’t need to plow the soil.  But many no-till farmers rely on heavy doses of chemicals to control weeds. This, we now know, generated its own set of problems.

But no-till put agriculture on the right track.

Perennial crops like orchard fruit, tree nuts, berries, and asparagus produce food.  Because the soil remains undisturbed season to season, these crops are also no-till.

Through photosynthesis, they sequester carbon in the soil for many years.  By adding carbon-rich compost before planting and throughout the crop’s lifecycle, carbon storage becomes even more significant.

But from maize to melons, most of today’s plant-based foods are annuals. These dead-within-a-year plants constitute 85 percent of human calorie intake.  Yet they offer no long-term carbon sequestration and require tillage year after year.

Compost application may boost soil productivity on annual cropland. But much of its carbon is released with the next tilling, too.

So scientists began to ask:

Is it possible to revert more crops, especially grains, to perennial form? Could agriculture meet this goal without sacrificing yields?

Back to the future with Kernza®

The answer appears to be a resounding … could be. Probably … yes. A cautious … quite likely.

Researchers have gone back through time to marry the characteristics of two crops. One is an ancient perennial wheat-like grass. The other is a modern, annual wheat.

Together, they have produced a perennial wheat with the trademarked name, Kernza. This year, General Mills’ Cascadian Farms plans to produce 6,000 boxes of a breakfast cereal featuring the grain as a research fund-raiser. Though total acreage is still small, other commercial applications for Kernza include bread and beer.

In photographs, Kernza kernels look more like a wild rice (a grass) than a wheat berry. But it is considered flavorful and can be harvested using conventional farming equipment.

Deep-rooted (10-20 ft.), this intermediate wheatgrass grows from a rhizome.  It is planted in the fall (in Minnesota).  Most growers plant in rows, but solid seeding is also used.  Weeds are not a big issue, because as the rhizomes spread, they choke out weeds.

The problem is that the kernel is small, like the yield per acre.  Conventional milling equipment doesn’t work.  And, currently, Kernza growers reap a meager 500 pounds per acre. Their conventional wheat-growing counterparts get an average of 2,856 pounds in the U.S.

After a few years, those thick, horizontal stems can run out of expansion space, too. Yields decrease.  As a result, some growers replant every 3-5 years. At least one farmer is experimenting with chisel plow strips to extend productivity to lengthen the time between replanting.  (More cultivation information:  Farmers voice their experience growing intermediate wheatgrass for grain)

The importance of deep root systems and perennial food crops

Worldwide, several annual food crops, including rice, have become the focus of similar research.  Perennials for biofuel production are being studied, too.

Minimizing soil disturbance is one reason. The benefits that come with deep-rooted crops is another.

Living plants remove carbon dioxide (CO2) from the air. They keep some of the carbon (C) and release the rest, along with the oxygen (O2), back to the atmosphere. The retained carbon resides in stems, leaves, and roots. Plants use water and light to turn that carbon into sugars to fuel growth. When plants die and decompose, the carbon becomes a constituent of soil organic matter (SOM).

Deep roots extend the rhizosphere, the zone where roots, soil, and microbes interact. Microbes aid in the transfer of carbon from plants to soil.  Researchers say increasing this area could raise soil carbon storage.

Deep-rooted crops are a tool of what has become known as “carbon farming.”  The goal is carbon sequestration — removing excess from the atmosphere and storing it in the soil, instead.

Moisture and temperature increases could speed up carbon release at lesser depths.   But research suggests deeper soils buffer that carbon from climatic change.

If true, consider the carbon impact of a 20-ft. Kernza root compared to the typical agricultural plant (~3 ft. root depth).  To better understand the potential, this article includes an image comparing perennial Kernza and annual wheat root systems.

Assessing carbon storage potential of perennial food crops

Estimates of the carbon storage potential of “perennialized” annuals are sketchy, at best. None of the new grains have yet to hit their commercial stride.

Research on deep-soil carbon storage is a bit thin, too. It’s difficult to find sequestration estimates that consider all possible impacts like:

  • Reductions in fossil fuel extraction and use
  • Conversion of annuals to perennial crops+
  • Capture of all organics for composting and reuse

But as food for thought, here are some numbers from recent articles and research papers:

  • The soil carbon storage from improved root growth in agricultural crops could offset human-caused environmental emissions for the next 40 years.
  • Reuters: The U.S. emits around 5 billion tonnes of carbon dioxide per year. Better soil management could boost carbon stored in the top layer of the soil by up to 1.85 gigatonnes each year. This is about the same as the carbon emissions of transport globally.
  • Peak Prosperity: A 1 percent increase in SOM stores approximately 10 tons of carbon per acre. Doing the math: There are about 130 million U.S. acres in major annual grain crops. If converted to perennial varieties, carbon storage potential equals 1.3 billion tons.  That’s roughly 1/5 of the U.S. carbon pollution.
  • Bulletin of Atomic Scientists: Devote 5 percent of the world’s cropland to plants bred for carbon storage. Capture ~50 percent of current global CO2 emissions.  (That’s an area about the size of Egypt.)
  • USEPA: In 2015, about 38 million tons of food waste were burned or buried. Only 2 million tons went to composting. Doing the math: Composting all 40 million tons would produce ~20 million tons of soil amendment. This would cover roughly 600,000 acres in 1/2 inch of compost. Its ~11 million tons of carbon (20 million tons of compost @ 54 percent carbon) could go to deep-soil storage under perennials.
  • Life Cycle Assessment (LCA) of landfilling organic waste vs. composting and recycling estimated a net greenhouse gas mitigation benefit of 23tCO2eq/ha over a 3-year period when organics were composted. That’s 23 tonnes (1 tonne = 1,000 kilograms) of carbon dioxide equivalent per hectare — about 25 tons spread over 57 acres.  As little as a 1.3 cm (about a half inch) topdressing of compost resulted in “substantial” increases in carbon storage on rangeland, too, attributed to better water retention and improved grass productivity.

 Economic benefits add up, too

Looks like there’s yet one more reason to bank on perennials — economics.

Agricultural investors say annualized income for perennials rose ~13 percent over 10 years. Income from annual cropland stagnated at about 4 percent during the same period.

And in a few spots, Kernza is generating more profit than the more traditional corn and soybeans. In addition, Kernza leaves and stems remain green at ripening, making its hay more valuable than wheat straw.

Commercialization of annual-to-perennial food crops is a tantalizing possibility.  The day may come when “perennial food” labels sway consumer purchases, just like organic, gluten-free, and other profitable food-niche certifications.

But most enticing is this factoid — at $0-$100 per ton, soil carbon sequestration is the cheapest carbon mitigation tool currently available.

It should be noted that soils can eventually reach a point where no additional C can be absorbed.  Sequestration is not a miracle cure.  People still need to work on reducing CO2 generation.

But in the interim, agriculture offers one opportunity to reduce the human carbon footprint.  And compost under foot makes this challenge easier.

deep-soil carbon storage

Can compost use impact deep-soil carbon storage?

Atmospheric carbon dioxide (CO2) levels have reached a 3-million-year high.  The overload has been building up since the Industrial Revolution hit its stride about 200 years ago.  One culprit is conventional farming, which releases stored soil carbon, (C) relies on synthetic input, and degrades soils.  The use of fossil fuels — which adds even more carbon to the air — is another major contributor to the increase. 

Impacts include reduction in carbon storage capacity due to topsoil loss, pollution, and climactic changes linked to global warming.

While some say CO2 levels are a non-issue, others believe the opposite and are working to reduce atmospheric carbon by cutting greenhouse gas emissions and sequestering more carbon.

Proposed solutions include ideas like basalt rock injection and ocean storage.   But one of the simplest and most cost-effective options already in play is to simply return carbon to soils.

But there is a catch.  Since soil disturbance releases carbon, farmland dedicated to annual crops offers little to no upper layer storage potential.  Unless the farm — organic or conventional — has adopted no-till practices, the soil is disrupted every year during planting.  Therefore, acres that will remain undisturbed for long periods of time are the best candidates for long-term carbon storage, a.k.a. carbon farming.

This translates into a need for conversion of annual grains and other crops to perennials to maximize soil carbon storage potential.  But developing high-yielding perennial grains is a process that will take time.

Applying compost to both annual and perennial acres is something that can be done now.

Long-term soil carbon storage has two primary pathways — plant-based via deep-rooted perennials (like some trees and grasses) and soil amendment.  Compost leads the pack as the amendment of choice, offering a plethora of soil- and crop-enhancing benefits in addition to carbon storage.

The carbon sequestration benefit of compost use is two-fold.  It adds compost’s inherent carbon content to the soil.  But it also improves soil productivity, increasing above- and below-ground biomass, which stores more carbon.  This positive impact can persist for many years from just one compost application.

Microorganisms and insects like earthworms and ants also influence carbon storage.

Current research emphasis seems to focus on C storage potential in agriculture.  That’s because worldwide, farmers crop 4.62 billion acres — a treasure-trove of carbon storage potential.

But it should be noted there are many more non-ag acres that can offer long-term, deep-soil carbon storage, too.  No need to wait for researchers to develop new perennial grains or convince farmers to make the switch from annuals to perennials.

In the U.S. alone, millions of acres could take and store compost-applied carbon today:

  • 40 million acres of lawns
  • 50 million acres of managed turf including 700,000 athletic fields and 17,000 golf courses
  • 7 million acres of public lands under the jurisdiction of the Bureau of Land Management (FY 2017)
  • Umpteen million acres in government-controlled roadside easements, utility rights-of-way, local and state parklands, and other managed greenspace, both public and private.

Just a 1% increase in soil organic matter (about 20 tons of compost per acre or a 1/4-inch application depth) can store 10 tons of carbon per acre

While it may not be practical or possible to add compost to all those acres, the potential for long-term, compost-based carbon storage in the U.S. alone is … well … pretty big.  And the deeper the storage, the longer the retention time.  Even annually tilled acres can offer C sequestration if that carbon can find a pathway to deeper soils below the plow layer.

But how does compost-applied carbon migrate from upper soil levels to deep-soil storage?

Below the plow layer — deep-soil carbon storage

A “plow layer” is the layer of soil disturbed when a plow (plough) is dragged through a field.  Depending on the type of plow used and its settings, the layer depth can range from a typical 8 inches to 20 inches or more.

The trick is to facilitate the movement of carbon from the plow layer to deeper soils where it can lie locked up and undisturbed for centuries.

Typically, the root systems of trees and perennial grasses grow deeper than annuals.  As the root systems of plants bury themselves in soil, they do more than just carry carbon in their tissues.

Downward growth also creates passageways for water and a transportation route for microbes.

Critter burrows create pathways for water and microbes, too.  Well below the plow line, termite colonies can be found as deep as 6 meters.  Some types of ants live at depths of 3-4 meters.  (1 yard = .91 meters)

Nightcrawlers will work their way down several meters into the soil, bringing organic matter with them.  Their castings (excreta) have a carbon-to-nitrogen ratio of 12-15:1 and include beneficial microbes.  A healthy soil layer above ensures plenty of available carbon for below-the-plow-layer earthworm storage.

C storage depends on many factors

It is important to remember neither the C cycle nor microbial metabolic processes operate in isolation. These functions are influenced by many factors like:

  • Nutrients
  • Temperature
  • Moisture
  • pH

Climate plays a role, too.  Globally, cool-wet regions tend to have the highest concentrations of soil carbon and deserts the lowest.  One of the more disturbing aspects of a warming planet is that more soil-bound carbon may be released to atmosphere as temperatures rise.

Effective solutions will require wholistic approaches, but compost use continues to rank among the top options due to its affordability, universal applicability, ease of use, and immediate availability.

Bottom line:  The potential for deep-soil carbon storage exists, even on annually tilled cropland, through management programs designed to improve soil health and encourage symbiotic facilitators like nightcrawlers.

 

reclaiming the desert

Can organic waste help green the Sahara for carbon storage?

It has been suggested devoting 5 percent of the earth’s land mass to plants bred for carbon storage could capture about half of global CO2 emissions.

That’s an area about the size of Egypt, a country that has already embarked on a program to reclaim some of the Sahara.  Project drivers are linked to food production, not climate change.  But the Land of the Pharaohs has not had an easy time of it, and some question the plan’s chances for long-term success.

Yet, as agricultural acreage declines worldwide and so many global minds focus on ways to feed a growing earth population, the Egyptian effort does beg the question:

Can reclaimed deserts store carbon and grow food?  More to the point, could composted organic waste help green up deserts like the Sahara or the Kalahari or the Sonoran?

Search the web for successful desert reclamation projects.  The use of compost is integral to all and has been referred to as “fertility priming.”

Capturing and composting organics would be the easy part. Unfortunately, there are major hurdles between barren sand and arable acres:

  • Tilling releases carbon. Unless the crops planted are perennial, some of that applied carbon will be lost.  In Egypt’s case, the goal is more annual grains like wheat and corn, perennials.  However, it should be noted, soil sampling at two of Egypt’s desert farms suggest carbon supplied from organic soil amendments will accumulate, even in oft-tilled fields.
  • While compost holds water, that water has to come from somewhere — if not rain, then rivers and aquifers or, as a last resort, desalination. But river water can be diverted by projects upstream.  Fossil aquifers, like those under northern Africa, are not replenished and will, eventually, dry up.  Desalination is still considered an expensive solution.  This means water availability will continue as the most critical factor to project success.
  • Desert soils tend to be salty, too, which creates unfavorable growing conditions. Fortunately, one permaculture specialist has reported a de-salting effect from building a living soil in the desert.

There seems to be a wealth of anecdotal material out there on desert reclamation, but not much peer-reviewed, scientific research.  Some “research” is based on calculations, not long-term field testing/studies.

In addition, the reclamation farms tend to be smaller “niche” operations — organic, biodynamic, permaculture, etc. — and not large, conventionally managed acreage.

That said, by simply looking at photos and videos, it’s obvious that desert reclamation is possible.  Whether or not it can also be profitable on a large scale remains to be seen.

But if these issues could be resolved, resulting in a clear path for resurrecting vast expanses of sandy soil, how much compost would it take to green a desert?

Most desert soils contain less than 1 percent organic matter.  To make the calculation easy, assume that number to be zero and add enough compost to boost organic matter content (OM) to the recommended 5 percent.

Based on this example,  a 1 inch application requires 135 cubic yards or 54 tons of compost per acre.  This assumes a 60 percent organic matter content, a bulk density of 800 lbs./cubic yard, and 30 percent moisture.

The author of this article about raising soil organic matter (SOM) levels says bumping SOM 1 percent “requires an additional 20,000 lbs. (10 tons) of soil organic matter or 11,600 lbs. (5.8 tons) of carbon, as soil organic matter is roughly 58 percent of carbon.”

The article further calculates stover and root mass from a no-till wheat cover crop system can only be expected to add about 0.1 percent of organic matter to soil.  Obviously, though that percentage might fluctuate a bit depending on the crop and cropping system, one of the fastest ways to build soil organic matter content is not through plants, but through compost use.

At 3.6 million square miles or about 2.3 billion acres, the Sahara is roughly the size of the United States.  It would take billions of tons to make those acres productive.

But balancing out CO2 emissions only requires a couple of plots the size of Egypt.  That’s about 500 million acres.  It sounds like a daunting task until considering there are nearly twice that many farm acres — more than 900 million as of the 2017 agricultural census — in the U.S. alone.

This is doable.  And the best news?  Nary an ounce of waste or compost needs to be hauled to Egypt.  Those 500 million acres can be divvied up and spread across the globe.  From tenders of 10,000-acre ranches to diggers of 100 sq. ft. gardens, anyone can contribute to carbon sequestration.

Of course, playing with numbers is just that — play.   A tremendous amount of effort, plus a megadose of dollars, would be required to convert all world organics to compost.  But rough numbers and real-world economics suggest sequestering carbon through compost use is possible.  (View the SlideShare title: Compost to the Rescue)

And as the World Bank expects the global waste stream to grow by 70 percent by 2050, it sounds like there will be plenty of organics available to get the job done.

Bottom line:  We have the know-how.  We have the technology.  We have the organics.  Costs to produce compost are competitive with landfilling and WTE/incineration.  And whether existing farmland, greenspace, or desert, whether Africa, Asia, or the Americas, we have the acreage needed to clear the air.  The only thing missing? The will to do so.

Organic waste - french fries container

What is organic waste?

When talking waste management, organic is a broad, generic term describing waste derived from any type of living matter.

A mighty oak, the family dog, and icky germs are all examples of living things. As they feed, grow, and die, living things create organic waste.

Organic waste is decomposed by other living organisms. These degradation catalysts can rely on physical decomposition (like earthworms and dung beetles) or chemical (like bacteria and fungi). Their preferred environment can be aerobic (with air) or anaerobic (without air).

Paper, cardboard, and pallets are all organic wastes because they’re manufactured from trees, cotton, kenaf or other fibrous plants. Egg shells, fish bones, and moldy cheese are organic waste because they came from animals. A discarded biodegradable bag is considered organic waste because it was made from a plant-based polymer that can be decomposed by bacteria. Potatoes and wheat are examples of plants that can be used to make these types of plastics.

“Biodegradable” is not necessarily compostable at all types of composting facilities. Some biodegradable materials don’t breakdown fast enough using slower composting processes and, like conventional plastics, can be considered contaminants. On the other hand, many high-rate processes will be able to handle both biodegradable and compostable plastics. Waste that has been certified “compostable” by the BPI or other certification agency can usually be accepted and managed by the widest range of composting facilities.

Given enough time, all organic matter will biodegrade. However, some ingredients or finishes can be toxic to feeding microbes. Therefore, most composting facilities, including high-rate operations, do not accept things like treated lumber, even though they may be derived from organic materials. Exceptions might be made for paints and treatments that have been tested to prove they will biodegrade within an acceptable timeframe.

Organic is not the same as “certified organic”

Within the organic waste management arena, the word organic is not to be confused with the commercial “certified organic” marketing label used by growers and manufacturers.

The 1990 congressional decision  resulting in the designation of “organic” as restricted marketing lingo was probably not representative of that august body’s finest hour. The conscription of a term that had been used generally in chemistry and other common vocabulary for hundreds of years – and then attempting to give it a very narrow definition — has created quite a bit of consumer confusion in the ensuing decades.

But organic waste is not always as nature made it, either. Food and other biodegradable wastes can contain man-made additives. Fortunately, a modern, high-rate composting system is capable of degrading many synthesized chemical compounds as it breaks down organic material. Therefore, when the urban area is served by one of these advanced systems, the organic fraction of the municipal solid waste stream is, most likely, both biodegradable and compostable. Even some non-organic wastes, like (untreated) gypsum board, can be added to the compost blend to improve its market value.

Composted organic waste as a soil amendment

As a soil amendment, compost is always organic, but may not be “certified organic” – unless it has met certain criteria for certification. Most of the time, the word organic on a compost label simply means the soil amendment was made from organic (the generic use) material and is not a synthetic fertilizer/amendment product.

If “certified organic” compost is preferred, then the consumer needs to look for a product sporting a certification symbol from a legitimate, USDA-accredited certifier.  But know that organic certification addresses ingredients and processing methods only, not product quality. 

Quality standards for compost products are established under the U.S. Composting Council’s (USCC)  Seal of Testing Assurance (STA) program. Compost manufacturers certifying products under the STA label focus on meeting requirements related to maturity, pH, salts and other quality indicators, all verified by regular product testing by USCC-approved laboratories.

Approved labs are required to use equipment and testing methods specific to compost products, which differ from the more commonly-used soil testing criteria.