Then they started to bundle them together in a form that we would recognise as plants
These strands of cyanobacteria became the earliest plants, such as horsetail
Plants were an efficient way to comb CO2 out of the air. The original plants didn't even have roots, the fungi had their own root system inside the plant to extract the sugar as soon as it was made. The plants were the root extensions of the fungi, not the other way round, which is how it appears today. Plants evolved with root systems and the fungi continued to keep their root network in the plant's root system. These fungi are called 'vesicular arbuscular mycorrhizal fungi' ‘Arbuscular’ means 'tree-shaped' and reflects the form they take when the occupy the root system of a plant. 'Myco' means 'mushroom' and 'rhizzal' comes from rhizome and means 'root' - so they are ‘tree-shaped root mushrooms’. ‘Vesicular’ refers to the vesicles that are the storage areas where the mycorrhizae hold a stock of nutrients and sugar.
A plant will deliver in its sap from 10-20% of the sugar it makes in its leaves to the mycorrhizae, retaining the rest for its own growth. The mycorrhizae increase the reach of the plant’s roots by up to 10 times, penetrating soil that plant roots can’t access.
The ‘arbuscular’ shape of the fungus is shown in a root cell – this tree-like shape is a mirror of a root system – the fungus has its roots in the plant, the plant has its roots in the soil.
There are other organisms in the soil that live symbiotically with the mycorrizae. Most notable are the actinomycetes bacteria – originally they were thought to be fungi because they copied the form of fungal hyphae, with filamentous threads. With the advent of electron microscopes they turned out to be bacteria that had strung themselves together in chains in order to efficiently ferry nutrients to the mycorrhizae in exchange for sugar. Most of our antibiotics come from soil bacteria. Streptomycin When a plant needs medicine, the mycorrhizae can farm it by feeding sugar to the bacteria that can produce that particular antidote – most commonly jasmonic acid, salicylic acid (aspirin) or ethylene. These medicines are sent up with the sap of the plant to provide it with immunity to fungal and insect attack.
One example of how mycorrhizae are used in farming is the French practice of ‘alley cropping’ where rows of fruit trees keep the fungal network going and enable crops planted in between to flourish rapidly thanks to the existing network of mycorrhizae supported by the trees. In Windsor Great Park an oak nursery accelerates the growth of oak saplings by raising them in ground surrounded by mature oaks – the big oaks provide the sugar to support a large mycorrhizal population. The baby oaks get sugar and nutrients from the mycorrhizae and grow away rapidly and healthily.
Soil is fascinating. It’s wonderful stuff. So what do humans do with it? Since the dawn of agriculture we mostly just kill it. Ploughing breaks up the neural network within the soil, though it reconnects fairly quickly but with a lot of casualties. Adding chemical fertilisers breaks up the symbiosis – the mycorrhizae no longer can exchange mineral nutrients for sugars because the farmers is providing them for free. The plant cuts off the sugar supply to the mycrorrhizae clustered around its roots and the mycorrhizae die off. Their 10,000 or so co-dependent microbial species also die off. The plant is then exposed to the challenge of fungi and other pests that give it nothing and just want to consume it. This creates the need for pesticides including fungicides, which further deplete the microbial population of the soil.
I have several generations of form in the area. My great great grandfather farmed virgin soil on the Koshkonong Prairie in 1842, cutting down trees and raising crops of grain and grazing cattle. My great grandfather farmed virgin prairie in Nebraska. These Norwegian farmers were notoriously stingy. They were frugal people in everything they did, they wasted nothing and recycled everything. Here’s an example:
My grandfather would deliver eggs from his chicken houses to the Safeway supermarket and other stores in Sioux City. He would then purchase tools, sugar, flour, salt, paper and other essentials that could not be produced on the farm. The flour sacks were made of calico, so the farmer’s wives would recycle the bags to make overalls for their boys and dresses for the girls.
Flour is a commodity – one bag of white dusty flour is just like the next. So the Nell Rose flour company marketing people got clever and printed nice floral patterns on their flour bags.
This appealed to people like my grandmother and she used Nell Rose flour to make the dresses for my mother (on the right) with her sister Thelma and their cousins.
This remarkable frugalism and avoidance of waste stands in stark contrast to the way that the soils of the Midwest were relentlessly wasted, often beyond recovery. Here there was no recycling, just relentless ploughing and harvesting, breaking down the soil. The farmer’s wives wasted nothing, their husbands wasted the fertile heritage of millennia. When land was ‘farmed out’ people would just move further west.
The original Louisiana Territory and adjacent territories embraced the great river network of the Mississippi, Ohio and Missouri Rivers, a 2000 mile wide water system draining into the Gulf of Mexico.
By 1925 more than 80% of the trees in this great river network had been cut down in order to create productive farmland.
The result was inevitable – the Mississippi Floods of 1927 were devastating – 27,000 square miles were inundated, up to depths of 30 feet. It triggered huge migrations of Afro-American farmers to Northern cities. Below Memphis Tennessee the Mississippi was 60 miles wide, 3 times the width of the Straits of Dover. The land was flooded from April to June.
This great flood was followed by further devastation. The weakened fractured soils of the prairie began to turn to dust and the winds blew up vast clouds of dust that reached as far as Washington DC, prompting Congressional action. President Roosevelt created the Civil Conservation Corps and 3 million recruits planted 10 billion trees from Mexico to Canada to try to hold down the soil.
This destruction of soil happened also in Argentina, Manchuria, Ukraine, and other fertile breadbaskets around the world as tractors and chemical fertilizer accelerated the rate of soil destruction.
The greenhouse gases carbon dioxide, nitrous oxide and methane that were emitted accounted for half of all the increase in greenhouse gas levels between 1850 and 1980. Since then agriculture’s annual rate of emissions has continued to grow, but has fallen behind the astronomic rate of emissions growth from manufacturing, energy and transport. But it is still responsible for at least one third of our excess emissions.
Total CO2 from Farming: 160 Billion Tonnes
Total CO2 from Fossil Fuels: 165 Billion Tonnes
How can we stop this wasteful and environmentally damaging activity?
Part of the answer lies in a discover that was made nearly 500 years ago. When the Spanish conquistador Francisco Pizzarro was buy looting the silver and gold of the Incas he heard about cities of gold with even greater wealth. He deputed his brother and Francisco de Orellana to find these cities and to bring back their gold.
The parties were separated and Orellana could not return up river. The chaplain on his boat kept records of their travels. They encountered wealthy populations but were repelled by armed natives, led by fierce women warriors. These natives knew already that if you came close to a white man you would break out in red spots of measles or smallpox and then, because they had no immunity, die. They attacked and drove them away – Orellana described his boat as looking like a porcupine after one such attack. They called this region the Land of the Amazons and this is how the river got its name. When explorers sailed up the Amazon about 30 years later the wealthy civilisations Orellana had described were gone – wiped out by disease. People questioned whether the ‘El Dorado’ he had described ever really existed.
Within the past 50 years archaeologists have found that the areas he described as populated coincide with areas where the soil is black to a depth of several metres - the ‘Terra Preta’ of the Amazon river settlements. Farmers who have Terra Preta have little need for fertilizer and even sell their soil to less fortunate farmers who are on the typical infertile jungle soils. The Terra Preta was made by the Amazons by taking all their waste, including animal bones and forest waste and domestic waste, piling it into pits, covering it with clay and setting fire to it. Once it was burning hot they’d cut off the supply of air and the material became charcoal and provided the growing medium for the next season’s crop. The contrast between Terra Preta and soils of the forest is apparent when the land is cut away.
Brazilian farmers who farm on Terra Preta benefit from its fertility and crops like corn grow vigorously when planted in black earth. They sell it to other farmers and bag it up for sale in garden centres. It is what we now call ‘Biochar’ – charcoal for use in the soil rather than charcoal for use for barbecuing sausages.
So what is Biochar? What does it do?
Biochar provides a supportive environment for mycorrhizae and their associated microorganisms. This leads to a doubling or more of the microbial population that is the living essence of soil.
Biochar had a high surface area – a single gram of biochar can have twice the surface area of 2 tennis courts – this means there are lots of points where minerals can stick, each point has a negative charge, so it sticks to minerals with a positive charge – this stops the leaching of nutrients from soil, keeping it in the zone where it can reach the plant.
Biochar also helps retain moisture. The result is healthier plants, more nutrient availability, more water availability and better soil structure.
Biochar also reduces soil emissions of nitrous oxide, a greenhouse gas 300 times more harmful than carbon dioxide.
Biochar stays in the soil, too, for anything from 10 years to 4000 years, depending on the type of biochar, the soil type and the farming system. The scientific consensus settles around 1000 years. This represents carbon dioxide that is kept out of the atmosphere – most woody biomass ends up returning to the atmosphere by rotting or being burned. Thus biochar can be an important tool for reducing atmospheric greenhouse gas levels. It is estimated that recycling woody waste as biochar could remove 1 billion tonnes of CO2 annually from the atmosphere. Instead we burn it.
Biochar retains the cell structure of the original feedstock. So biochar from bamboo has larger pores, biochar from chestnut has small pores. But all those pores provide a refuge for mycorrhizae and a base from which they can expand even if they are disturbed by ploughing or by predators such as mites, protozoa or nematodes that feed on them.
Imagine the pieces of biochar as a ‘five star hotel’ for mycorrhizae or, even as Norman castles in the English countryside. Each biochar particle is a base for a contingent of mycorrhizae, helping them to weather the stresses and pressures of life in the soil.
We have an image of mushrooms as passive softies but they are much more than that. When nematodes that threaten a plant enter mycorrhizal territory they get more than they bargained for. The mycorrhizae attach to them with sticky substances that hold them fast, then insert their filamentous hyphae into the tiny worm and suck out its amino acids, providing protein for more mycorrhizal growth and nitrogen for ‘their’ plants. Some mycorrhizae form lassoes that are scented with fragrances that attract nematodes – the nematode pokes through the lasso that then snaps tight, holding the nematode while it is digested.
Mycorrhizae also oversee the production of insecticides and fungicides. When there is a threatening insect or fungal pest the news travels fast through the underground internet – the mycelial network. The appropriate preventive medicine such as jasmonic acid, salicylic acid or ethylene is produced and delivered via the plant’s sap to the threatened area. How is this done? We don’t really know but it is likely that the mycorrhizae simply feed more sugar to the bacteria that produce these defensive chemicals and then pass them over to the plant.
It may be that the plant produces the defensive chemical itself or that it produces it in conjunction with the soil microbes. Both the plant and its supportive microbial community have a shared interest in defeating any disease threats quickly, before they have time to weaken the plant.
Biochar, by providing a resilient and abundant network of soil fungi and bacteria, is the framework of the plant’s immune system and helps it with nourishment and water.
So what have we done at Carbon Gold to turn this theoretical ideal situation into a reality?
The first thing we discovered was that the production method for charcoal was expensive, slow and inefficient – we wanted to reduce our carbon footprint in biochar production as much as possible and make it available cheaply to small farmers. We developed the Superchar 100 kiln.
It makes a 100 Kg batch of biochar in 8 hours instead of the usual 3 days. It delivers double the yield of traditional ring kilns. It has greatly reduced emissions – we recycle the gases emitted by the wood and burn them to heat the kiln contents instead of letting them escape into the atmosphere. They’re now hard at work in Belize, Botswana, Turkmenistan, Fiji, Brazil and the UK, with orders for more in the pipeline.
We also make a double-barrelled kiln that will produce 2 x 400 kg batches of biochar in a 12 hour day.
This one is part of a marshland regeneration project north of Perth, in Scotland
Whitmuir Organics, just south of Edinburgh, are making biochar for their horticultural operation and are experimenting with it in pig feed, where a small amount makes a big difference to pig health and feed conversion.
The first UK field trials of biochar were on my smallholding near Hastings in September 2010. We planted cabbages and winter lettuce in late September, some with biochar and some without. In November we had heavy snows and the lettuces were covered in snow for 3 days. When the snow melted the winter lettuces without biochar had died. Those with biochar were intact. I think this could be that a high microbiological population in the soil acts as underfloor central heating, biological activity generates heat and this is probably what saved the plants. We also discovered that biochar has no repellent effect on hungry pigeons, which destroyed the cabbage crop completely.
We work closely with Rijk Zwaan, the world’s 5th largest seed company and one that regards GMOs as an obsolete technology – they are world leaders at using natural breeding methods harnessed to genomic data. Their Field Trials Manager, Martin Kyte, stopped a comparative trial of Carbon Gold seed compost and peat compost after a few months because the results were so obviously in favour of our seed compost.
And Fergus Garrett, head gardener at the marvelous Great Dixter gardens in Sussex, has switched to biochar.
Stephanie Donaldson, Gardening Editor of Country Living magazine, trialled Carbon Gold with lettuces. After one month the difference was significant: