Replenish the soil (& feed everyone!)

On this page..

  1. Soil: an incredible new science, but we are learning how to feed the world
  2. Water solutions
  3. Peak phosphorus
  4. Local city inputs
    1. Biochar — the ultimate soil repair kit
    2. Biochar — sucks CO2 out of the air and locks it in the soil
    3. Biochar — both centralised and mobile systems
    4. Biochar — George Monbiot’s unreasonable attack
    1. Polyface farms: feed cows grass, not industrially grown corn
    2. Polyface farms: objection: Polyface chickens and pigs eat industrially grown feed!
  5. Rotate cows and crops!


1. Soil: an incredible new science, but we are learning how to feed the world

Soil is an exciting new science where astonishing breakthroughs are just beginning to occur. I am likely to tinker with this page some more over the coming years simply because of the startling new developments in our understanding of soil.

“We know more about the movement of celestial bodies than about the soil underfoot.” – Leonardo da Vinci, circa 1500s”In many ways the ground beneath our feet is as alien as a distant planet. The processes occurring in the top few centimenters of Earth’s surface are the basis of all life on dry land but the opacity of soil has severely limited our understanding of how it functions…. However, perspectives are beginning to change… Interest in soil is booming, spurred in part by technical advances of the past decade.”
Science, June 2004.
For more see Energy Bulletin

The agricultural solutions I am most interested in have permaculture systems thinking that bring the soil back to life and put food on the table permanently, but do it on an industrial scale!

2. Water solutions

As I highlighted on my soil crisis page, the world is facing increasing water stress and shortages that threaten to become droughts of biblical proportions. Fortunately there are a variety of new water efficiency, recycling and desalination technologies that may even begin to supply water at an agricultural scale. (Which is an impressive statement, as agriculture demands roughly 5 to 10 times as much water than our cities, and cities are supplied by desalination). My Regreen the deserts page covers technologies for farming in the desert. My focus for agriculture on this page will assume normal rainfall and best water efficiency practices for existing farmlands.

3. Peak phosphorus

Unlike nitrogen that we chemically extract from the air (or which nitrogen fixing plants can put in our soils), phosphorus is a rare mineral currently on a one-way trip down our toilets to the bottom of the ocean. We need phosphorus. It is one of the most critical fertilisers. We must create closed nutrient cycles, and stop flushing this irreplaceable resource out to sea. As the wiki says:-

According to some researchers, Earth’s phosphorus reserves are expected to be completely depleted in 50–100 years and peak phosphorus to be reached in approximately 2030.[2][3]

Later, it explains how phosphorus is transported in food and huge quantities move huge distances in food. EG: Soy from South America dumps phosphorus (via sewage) in American lakes and rivers. The Rock and a Hard Place 2010 report by the UK’s Soil Association (23 page PDF) makes some interesting points.

  • Concern about heavy metals is reducing as new industrial waste processes remove it from our sewage.
  • Agricultural wastes should be used including lifestock manure and composting of plant wastes. Page 13 says about half the world’s lifestock manure ends up in landfill or washing away in rivers!
  • Micro-organisms and micro-fungi increase phosphorus uptake in plantsn (which I note is another useful effect of biochar — see below).
  • Urine (when separated from the waste stream) could provide about half the phosphorus necessary for cereal crops.
  • Urine can be stored in local tanks and collected once a year, while other collection methods are proposed for pooh.

Existing sewerage systems can implement Enhanced Biological Phosphorus removal while all new homes and streets should be connected to the local collection tanks mentioned above.

As the Oxford Journal BioScience says:

The Green Revolution has led to a threefold growth in food production in the last 50 to 75 years, but increases in crop production have required a concurrent increase in the use of inorganic phosphorus as fertilizer. A sustainable phosphorus supply is not assured, though, and food production depends on mineral phosphorus supplies that are nonrenewable and are being depleted. Phosphorus is effectively a nonsubstitutable necessity for all life. Because mineral phosphorus deposits are not distributed evenly, future phosphorus scarcity may have national security implications. Some projections show economically viable mineral reserves becoming depleted within a few decades. Phosphorus-induced food shortages are therefore a possibility, particularly in developing countries where farmers are more vulnerable to volatile fertilizer prices. Sustainable solutions to such future challenges exist, and involve closing the loop on the human phosphorus cycle. We review the current state of knowledge about human phosphorus use and dependence and present examples of these sustainable solutions.
BioScience (2011) 61(2): 117-124.doi:10.1525/bio.2011.61.2.6

I uploaded the ABC’s Catalyst to youtube, but unfortunately it is very low resolution. Just watch it in a small window. ;-)

4. Local city inputs

Local green bins

Local council green bins should collect garden waste and kitchen food scraps. Many city people are not that interested in gardening or running their own composts. So the answer could be placing kitchen scraps in biodegradable plastic bags and throwing them in the green bins, which the councils then collect and process in a local centre. As the ABC environment podcast says:

A lot of kitchen waste is dumped into landfill. At the same time, farmers are crying out for nutrients to add to their soils. The solution is obvious. Someone should collect all those scraps and turn them into compost. Kim Russell has taken on the challenge.
He’s executive director of Zero Waste Australia and he wants to get organic waste out of landfill and onto farms.

Local rubbish

See my Recycle page for a garbage sorting company that collects organics out of household waste and composts them into a farming loam 3 times richer than backyard composting! This could be scaled up to process all of Sydney’s waste, separating out the batteries and plastics and glass and paper, and then composting all the organics that are left over. I don’t wish to repeat everything on my rubbish recycling page here, except merely to point out that some spoiled food wastes can either be composted in these recycling centres, or added to sewage waste centres to run through a digester there. As Yale Environment reports:

Waste Management collects food scraps from restaurants, grocery stores, hotels, and food processing plants, takes them to a company facility in Carson City, and grinds them into a slurry. That liquid is taken to a Los Angeles County wastewater treatment plant, where it is mixed in with sewage — one part food waste to nine parts human waste — and processed in an anaerobic digester.  The end result? Biogas that can be burned as fuel — a benefit that may encourage the Los Angeles County Sanitation District to expand the initiative into a full-scale program after two years.

Local sewage

Some sustainable agriculture planners are so concerned about peak phosphorus (and other fertiliser problems and soil inefficiencies) that they are even designing town plans around the quickest way to get nutrients back to the soil! But given that local urine collection tanks only require emptying once a year (see above under peak phosphorus) I’m not sure we have to design our entire town plan around phosphorus cycles!


5. A. Biochar — the ultimate soil repair kit

The now famous system called biochar cooks up agricultural waste like corn stalks, wheat stems or rice husks and cooks it in a low oxygen process called Pyrolysis. This produces syngas and charcoal. The charcoal is returned to the soil where it becomes a habitat for all sorts of micro-organisms and fungi. The fungi grows in all the nooks and crannies of the charcoal, sucking Nitrogen and more CO2 out of the air as it grows through the soil, adding organic mass. This partially fertilises the soil, reducing the fertiliser requirements of agriculture.

At BestEnergies half of the syngas is then used to cook the next load of Biomass into Biochar, and the other half can be used as gas on the farm. Rob from Transition Culture attended a lecture with the following summary ratio of Biochar products.

“…The machine they have developed for doing the charcoal burning basically takes 10 tons of any woody or plant biomass and turns it into 1 ton of charcoal and 3.2 tons of diesel.”

Check out this must read article by Big Gav at Terra Preta: Biochar and the MEGO effect | Energy Bulletin. Note that I do not regard biochar as solving our liquid fuel energy needs, but it might just provide some niche fuels for the farming sector.

Why does biochar have such a powerful effect?

Biochar locks away carbon and rejuvenate the soil, becoming a ‘coral reef’ of the soil that micro-organisms can flourish in.

Biochar reduces fertiliser inputs, it does not eliminate them. However by making fertliser and water uptake so much more efficient, it increases crop yeilds and on-site economics for the farmer.

As Keplie Wilson of puts it…

“Field trials and experiments in pots show impressive yield gains in charcoal-amended soils, but so far researchers don’t completely understand why. One question is whether the effect is primarily chemical and physical or primarily biological. Charcoal is a highly porous material that is very good at holding nutrients like nitrogen and phosphorus and making them available to plant roots. It also aerates soil and helps it retain water. Charcoal’s pores also make excellent habitat for a variety of soil microorganisms and fungi. Think of a coral reef that provides structure and habitat for a bewildering variety of marine species. Charcoal is like a reef on a micro-scale.

One of the research papers presented at the conference documented an increased diversity of beneficial microbes in terra preta soils as compared with unamended soils, but there are still no answers about whether the fertility increase is due to physical or biological factors. The best answer may be that it is both.”

Not only that, but it retains other NPK nutrients as well.

“Lehmann explains that nutrients from plant and animal remains—like nitrogen, phosphate, and potassium—bind to charcoal or biochar, drastically reducing how much is washed away by the constant rains. It is a gradual process that begins with the charcoal breaking down in the soil over time. Tiny pores in the charcoal, along with changes in its chemistry, provide more surfaces for nutrients to adhere to, which in turn encourages microorganisms to colonize the soil. “With a handful of biochar you can keep many more nutrients in the soil than with a handful of mulch or compost. It is like mopping up nutrients with a magnet that looks like a sponge—that is, it has high surface area like a sponge but can attract a thin layer of material like a magnet,” Lehmann says.”
Discover Magazine

5. B. Biochar — sucks CO2 out of the air and locks it in the soil

An International Biochar Initiative PDF states:

“2. What is IBI’s goal for carbon removal from the atmosphere?
IBI is focusing presently on the feasibility of one “wedge,” which equals one gigaton of carbon per year. The term “wedge” comes from an often-quoted analysis (Pacala and Socolow, 2004) showing a need to have seven gigatons of carbon per year (seven wedges) of reduced carbon emissions by 2054 to keep emissions at the 2004 level.
3. Is a one gigaton per year biochar wedge achievable by 2054?
Yes. In the four basic scenarios we have examined, we found several ways to create at least one wedge by 2054.”

Worldchanging continues the discussion about ultimate potential in Black is the new green.

“The difference between terra preta and ordinary soils is immense. A hectare of meter-deep terra preta can contain 250 tonnes of carbon, as opposed to 100 tonnes in unimproved soils from similar parent material, according to Bruno Glaser, of the University of Bayreuth, Germany. To understand what this means, the difference in the carbon between these soils matches all of the vegetation on top of them. Furthermore, there is no clear limit to just how much biochar can be added to the soil.

Claims for biochar’s capacity to capture carbon sound almost audacious. Johannes Lehmann, soil scientist and author of Amazonian Dark Earths: Origin, Properties, Management, believes that a strategy combining biochar with biofuels could ultimately offset 9.5 billion tons of carbon per year-an amount equal to the total current fossil fuel emissions!”
Black is the new green

Even Tim Flannery, author of “The Weather Makers” and 2007 Australian of the Year, has stated to Podcast “Beyond Zero Emissions” that permanently sequestering “6 gigaton per annum … is eminently feasible”.
(About 9 minutes into 24 minute podcast).

5. C. Biochar — both centralised and mobile systems


Given that we can produce all the high ERoEI cheap electricity we need to cook up a variety of alternative fuels, I’m not some doomer peak oiler wondering how we’re going to generate enough energy to move the biomass to the biochar plant. Doomers worry that there simply will not be enough energy to do all this, let alone economic concerns. (I have clearly stated my reasons to dismiss this fatalistic worldview in the links above). But let us recap that:

“…The machine they have developed for doing the charcoal burning basically takes 10 tons of any woody or plant biomass and turns it into 1 ton of charcoal and 3.2 tons of diesel.”

In other words, an enormous road train — lets say this one carries 100 tons — goes collecting agriwaste from a variety of farms. Maybe it weighs each pickup and offers the farmer a price, or even a future discount on the biochar and diesel? It depends on the local economy and setup. Anyway, our 100 ton truck dumps it all a central biochar plant, refuels on diesel the plant itself is refining, and drives off to collect more. Meanwhile the power plant cooks up that 100 tons of agriwaste and makes 32 tons of diesel! That’s a great win to the rural economy. A smaller truck can then deliver the highly concentrated 10 tons of biochar back to the farm/s.

Second, given my views on alternative fuels this is not about energy but money: its about the cheapest way to lock up greenhouse gases, fertilise our soils, and help reduce fertiliser requirements on our farms. It’s about replenishing our soils and rural communities. These road trains could go from infamously carrying fossil fuelled diesel to agriwaste and biochar diesel.
Road trains

Decentralised and mobile:
As the wiki says:

“In a centralized system, all biomass in a region is brought to a central plant for processing. Alternatively, each farmer or group of farmers can operate a lower-tech kiln. Finally, a truck equipped with a pyrolyzer can move from place to place to pyrolyze biomass. Vehicle power comes from the syngas stream, while the biochar remains on the farm. The biofuel is sent to a refinery or storage site. Factors that influence the choice of system type include the cost of transportation of the liquid and solid byproducts, the amount of material to be processed, and the ability to feed directly into the power grid.

For crops that are not exclusively for biochar production, the residue-to-product ratio (RPR) and the collection factor (CF) the percent of the residue not used for other things, measure the approximate amount of feedstock that can be obtained for pyrolysis after harvesting the primary product. For instance, Brazil harvests approximately 460 million tons (MT) ofsugarcane annually,[12] with an RPR of 0.30, and a CF of 0.70 for the sugarcane tops, which normally are burned in the field.[13] This translates into approximately 100 MT of residue annually which could be pyrolyzed to create energy and soil additives. Adding in the bagasse (sugarcane waste) (RPR=0.29 CF=1.0) which is otherwise burned (inefficiently) in boilers, raises the total to 230 MT of pyrolysis feedstock. Some plant residue, however, must remain on the soil to avoid increased costs and emissions from nitrogen fertilizers.[14] Pyrolysis technologies for processing loose and leafy biomass produce both biochar and syngas.[15]

5. D. Biochar — George Monbiot’s unreasonable attack

In March 2009, George Monbiot famously attacked biochar in his article Woodchips with that? He attacked a straw-man, a biochar enthusiast raving that biochar could save the world and provide all the food and energy we need! I have never claimed that, and a week later George apologised for some of his attack. I don’t think he has really analysed the technology properly, or given it a fair treatment as the important tool it is in our kit against climate change and farmland erosion.

Other references for biochar

ABC’s Catalyst 2007: Reduces nitrous oxide emissions from farming! (Thankfully these emissions are relatively smaller than Co2 because they are hundreds of times more powerful than Co2, and eliminating them is very important. They are caused by over-use of Nitrogen fertilizer, which Biochar helps reduce the use of anyway.)
The Case for burying Charcoal at Technology Review shows that it is cheaper and safer than carbon geo-sequestration or so called “clean coal”.
University of Georgia — Can work with wood chips!
The International Biochar Initiative (IBI)
Eprida — It builds soil organic content with Mychoryzal Fungi as described above
The Biochar wiki is now gaining momentum and scope.
Beyond Zero Emissions — an Australian global warming activist group — have many podcasts on Biochar.
Best Energies
Advanced Biorefinery — Green chemicals
Technology review — Turning Slash into cash

6. A. Feed cows grass, not industrially grown corn

Polyface Farm (wiki) mimics the way cattle ‘mob, move, and mow’ in the wild to maximise grass health for maximum cattle health. Regular farms get about 80 cow-days per acre (which could feed 1 cow for 80 days, 2 cows for 40 days, or 80 cows for 1 day: you get the picture), but Joel gets 400 cow-days per acre using this method. In other words, he can grow about 4 times as many cattle on healthier land. And this without industrial fertiliser to force the grass to grow, or worse, grow industrial corn to shove into cattle that don’t really like eating corn in the first place! (That we then inject antibiotics into because we packed the cattle too close together ankle-deep in manure in gigantic, disease breeding cattle yards!)

Straight from the wiki:

“Salatin bases his farm’s ecosystem on the principle of watching animals’ activities in nature and emulating those conditions as closely as possible. Salatin grazes his cattle outdoors within small pastures enclosed by high-tech, electrified fencing that is easily and daily moved at 4pm to ensure that the animals always have fresh grass; grass has had time, about 100 days, to mature and grow tall, which increases levels of starch. Animal manure fertilizes the pastures and enables Polyface Farm to graze about four times as many cattle as on a conventional farm, thus also saving feed costs. The small size of the pastures forces the cattle to ‘mob stock’-to eat all the grass.

In addition his chickens are housed in portable coops that follow 4 days after the cattle, when flies in the manure are pupating; the chickens get 15% of their feed from this. The chickens while finding the pupae distribute the manure across the field.[3] Salatin’s pastures, barn, and farmhouse are located on land below a nearby pond that “feeds the farm” by using 15 miles of piping. Salatin also harvests 450 acres of woodlands and uses the lumber to construct farm buildings.[4] One of Salatin’s principles is that “plants and animals should be provided a habitat that allows them to express their physiological distinctiveness. Respecting and honoring the pigness of the pig is a foundation for societal health.”[5]

Portable coopMedia Attention

Polyface Farm was featured in the book The Omnivore’s Dilemma by Michael Pollan as exemplary sustainable agriculture, contrasting Polyface Farm favorably to factory farming. An excerpt of the book was published in the May/June 2006 of Mother Jones magazine. The farm is covered in the August/September 2008 issue of Mother Earth News. [6] Pollan’s book describes Polyface Farm’s method of exemplary sustainable agriculture as being built on the efficiencies that come from mimicking relationships found in nature and layering one farm enterprise over another on the same base of land. In effect, Joel is farming in time as well as in space—in four dimensions rather than three. He calls this intricate layering “stacking” and points out that “it is exactly the model God used in building nature.” The idea is not to slavishly imitate nature, but to model a natural ecosystem in all its diversity and interdependence, one where all the species “fully express their physiological distinctiveness.” [7]

The farm is also featured in the documentary film Food, Inc.[8]. Polyface Farm is a participant in Humane Farm Animal Care‘s Certified Humane Raised and Handled program.”

I like the thinking behind this Joel’s work! It seems a little bit more expensive than regular meet, but at this stage I side with Joel’s response to this question. Mother Jones asks the hip-pocket question:

I asked Joel how he answers the charge that because food like his is more expensive, it is inherently elitist. “I don’t accept the premise,” he replied. “First off, those weren’t any ‘elitists’ you met on the farm this morning. We sell to all kinds of people. Second, whenever I hear people say clean food is expensive, I tell them it’s actually the cheapest food you can buy. That always gets their attention. Then I explain that, with our food, all of the costs are figured into the price. Society is not bearing the cost of water pollution, of antibiotic resistance, of food-borne illnesses, of crop subsidies, of subsidized oil and water—of all the hidden costs to the environment and the taxpayer that make cheap food seem cheap. No thinking person will tell you they don’t care about all that. I tell them the choice is simple: You can buy honestly priced food or you can buy irresponsibly priced food.”
via No Bar Code | Mother Jones.

6. B. Polyface farms: objection: Polyface chickens and pigs eat industrially grown feed!

  • A concerned peakoiler might point out that Joel’s pigs and chickens eat industrially grown feed. The chicken and pig manure fertilises his fields. No wonder he grows such amazing grass for his cattle! It has industrial inputs, disguised as his chickens and pigs.
  • This used to concern me until I started researching how we were going to recycle phosphorus (above).
  • How are we going to grow our crops again? Nitrogen is not a problem when abundant nuclear energy can just suck it out of the air. Phosphorus and potassium will be recycled out of our sewage.
  • The sewage itself might even have NPK topped up from the oceans: we’ll still be fishing (sustainably).
  • So the NPK from sewage and local council rubbish compost goes to biochar reinforced fields, grows the crops which feed the chicken and pigs which both feed us and provide manure for Joel’s fields.
  • And the grass? It feeds the beef, whose cow-pats then give the chickens 15% of their protein through natural maggots (and avoids 15% of that industrial chicken feed we are worried about).
  • And then the pork and chicken and beef all feeds us: which we flush down the toilet, which feeds the crops which feeds the chickens and pigs and cows and feeds us again.
  • The efficiency of this system is staggering. It is estimated that about 80% of the phosphorus we put on our fields is never really utilised by the crops we grow. It seems to me that biofarming increases soil utilisation of NPK to account for all that extra biomass in these fast growing soils.


7. Rotate cows and crops!

Do you remember from history how in the later middle ages we used to let fields lie fallow to build up nitrogen in the soil? Then we learned to plant nitrogen-fixing crops in between growing our desired crops, and this is crop rotation. But what about rotating cows and crops? What about sending cows through after harvest to munch on the stubble? Cam McKellar explained to Landine (October 2004) that he:-

  • Used electric fencing to gradually move cattle through sorghum and corn stubble after harvesting
  • “We’ve flown barley over the corn and sorghum before and that keeps something growing in the soil to keep a house going for the microbiology, the cattle go through they eat that out,” he said.  “They then with the hoof action are breaking up that stubble which is very hard to do so otherwise and then as quickly as possible we’re getting another crop in it.”
  • 300 cattle add 4 tonnes of wet manure a day
  • Makes the soil softer, eliminates deep soil tilling which is a “brushfire for the soil” and kills microbiology
  • Worms grow
  • After just a few years it has reduced his chemical inputs by 1/3rd
  • Aiming for higher: “”If I can cut my fertiliser and chemical man by 90% that’ll be a push in the right direction which hopefully will cut my fuel, which hopefully will cut my seed, which hopefully will give the bank man a bit of a shock too,” Mr McKellar said.”
  • Regarding crown rot disease: “”We believe part of the story involved fungus, soil beneficial fungi that live in the soil,” farmer John Kirkegaard said. “These fungi can help to compete and reduce the level of crown rot in the soil,” he said. “We’ve found these beneficial fungi trichoderma they’re called, we found higher levels of trichoderma in soils following break crops of canola compared to other break crops like chick pea and this was associated with lower levels of crown rot and higher yields in wheat following canola. “We believe that maybe part of the reason the disease levels were lower and we’re now really trying to see if there’s any opportunities to increase the level of trichoderma in the system.”  (Eclipse note: biochar produces extra fungi and so could help in the war against crown rot disease).


Radio National also investigated an Australian ‘green cow’ movement where cows were allowed to intensively graze certain patches of field, fertilise it, and then move on to graze the next patch of field: while increasing soil biodiversity and health and this having spin-off effects through the local kangaroo and bird populations.

Other References

Wiki on Soil conservation
Wiki on Soil erosion
Australian Academy of Science — Feeding the future – sustainable agriculture
News: Positive agriculture news at Worldchanging and enter “agriculture” in the search field

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