Arquivo da tag: Agricultura

India’s rice revolution (The Guardian)

In a village in India’s poorest state, Bihar, farmers are growing world record amounts of rice – with no GM, and no herbicide. Is this one solution to world food shortages?

John Vidal in Bihar, India

The Observer, Saturday 16 February 2013 21.00 GMT

Sumant Kumar

Sumant Kumar photographed in Darveshpura, Bihar, India. Photograph: Chiara Goia for Observer Food Monthly

Sumant Kumar was overjoyed when he harvested his rice last year. There had been good rains in his village of Darveshpura in north-eastIndia and he knew he could improve on the four or five tonnes per hectare that he usually managed. But every stalk he cut on his paddy field near the bank of the Sakri river seemed to weigh heavier than usual, every grain of rice was bigger and when his crop was weighed on the old village scales, even Kumar was shocked.

This was not six or even 10 or 20 tonnes. Kumar, a shy young farmer in Nalanda district of India’s poorest state Bihar, had – using only farmyard manure and without any herbicides – grown an astonishing 22.4 tonnes of rice on one hectare of land. This was a world record and with rice the staple food of more than half the world’s population of seven billion, big news.

It beat not just the 19.4 tonnes achieved by the “father of rice”, the Chinese agricultural scientist Yuan Longping, but the World Bank-funded scientists at the International Rice Research Institute in the Philippines, and anything achieved by the biggest European and American seed and GM companies. And it was not just Sumant Kumar. Krishna, Nitish, Sanjay and Bijay, his friends and rivals in Darveshpura, all recorded over 17 tonnes, and many others in the villages around claimed to have more than doubled their usual yields.

The villagers, at the mercy of erratic weather and used to going without food in bad years, celebrated. But the Bihar state agricultural universities didn’t believe them at first, while India’s leading rice scientists muttered about freak results. The Nalanda farmers were accused of cheating. Only when the state’s head of agriculture, a rice farmer himself, came to the village with his own men and personally verified Sumant’s crop, was the record confirmed.

A tool used to harvest riceA tool used to harvest rice. Photograph: Chiara Goia

The rhythm of Nalanda village life was shattered. Here bullocks still pull ploughs as they have always done, their dung is still dried on the walls of houses and used to cook food. Electricity has still not reached most people. Sumant became a local hero, mentioned in the Indian parliament and asked to attend conferences. The state’s chief minister came to Darveshpura to congratulate him, and the village was rewarded with electric power, a bank and a new concrete bridge.

That might have been the end of the story had Sumant’s friend Nitish not smashed the world record for growing potatoes six months later. Shortly after Ravindra Kumar, a small farmer from a nearby Bihari village, broke the Indian record for growing wheat. Darveshpura became known as India’s “miracle village”, Nalanda became famous and teams of scientists, development groups, farmers, civil servants and politicians all descended to discover its secret.

When I meet the young farmers, all in their early 30s, they still seem slightly dazed by their fame. They’ve become unlikely heroes in a state where nearly half the families live below the Indian poverty line and 93% of the 100 million population depend on growing rice and potatoes. Nitish Kumar speaks quietly of his success and says he is determined to improve on the record. “In previous years, farming has not been very profitable,” he says. “Now I realise that it can be. My whole life has changed. I can send my children to school and spend more on health. My income has increased a lot.”

What happened in Darveshpura has divided scientists and is exciting governments and development experts. Tests on the soil show it is particularly rich in silicon but the reason for the “super yields” is entirely down to a method of growing crops called System of Rice (or root) Intensification (SRI). It has dramatically increased yields with wheat, potatoes, sugar cane, yams, tomatoes, garlic, aubergine and many other crops and is being hailed as one of the most significant developments of the past 50 years for the world’s 500 million small-scale farmers and the two billion people who depend on them.

People work on a rice field in BiharPeople work on a rice field in Bihar. Photograph: Chiara Goia

Instead of planting three-week-old rice seedlings in clumps of three or four in waterlogged fields, as rice farmers around the world traditionally do, the Darveshpura farmers carefully nurture only half as many seeds, and then transplant the young plants into fields, one by one, when much younger. Additionally, they space them at 25cm intervals in a grid pattern, keep the soil much drier and carefully weed around the plants to allow air to their roots. The premise that “less is more” was taught by Rajiv Kumar, a young Bihar state government extension worker who had been trained in turn by Anil Verma of a small Indian NGO called Pran (Preservation and
Proliferation of Rural Resources and Nature), which has introduced the SRI method to hundreds of villages in the past three years.

While the “green revolution” that averted Indian famine in the 1970s relied on improved crop varieties, expensive pesticides and chemical fertilisers, SRI appears to offer a long-term, sustainable future for no extra cost. With more than one in seven of the global population going hungry and demand for rice expected to outstrip supply within 20 years, it appears to offer real hope. Even a 30% increase in the yields of the world’s small farmers would go a long way to alleviating poverty.

“Farmers use less seeds, less water and less chemicals but they get more without having to invest more. This is revolutionary,” said Dr Surendra Chaurassa from Bihar’s agriculture ministry. “I did not believe it to start with, but now I think it can potentially change the way everyone farms. I would want every state to promote it. If we get 30-40% increase in yields, that is more than enough to recommend it.”

The results in Bihar have exceeded Chaurassa’s hopes. Sudama Mahto, an agriculture officer in Nalanda, says a small investment in training a few hundred people to teach SRI methods has resulted in a 45% increase in the region’s yields. Veerapandi Arumugam, the former agriculture minister of Tamil Nadu state, hailed the system as “revolutionising” farming.

SRI’s origins go back to the 1980s in Madagascar where Henri de Laulanie, a French Jesuit priest and agronomist, observed how villagers grew rice in the uplands. He developed the method but it was an American, professor Norman Uphoff, director of the International Institute for Food, Agriculture and Development at Cornell University, who was largely responsible for spreading the word about De Laulanie’s work.

Given $15m by an anonymous billionaire to research sustainable development, Uphoff went to Madagascar in 1983 and saw the success of SRI for himself: farmers whose previous yields averaged two tonnes per hectare were harvesting eight tonnes. In 1997 he started to actively promote SRI in Asia, where more than 600 million people are malnourished.

“It is a set of ideas, the absolute opposite to the first green revolution [of the 60s] which said that you had to change the genes and the soil nutrients to improve yields. That came at a tremendous ecological cost,” says Uphoff. “Agriculture in the 21st century must be practised differently. Land and water resources are becoming scarcer, of poorer quality, or less reliable. Climatic conditions are in many places more adverse. SRI offers millions of disadvantaged households far better opportunities. Nobody is benefiting from this except the farmers; there are no patents, royalties or licensing fees.”

Rice seedsRice seeds. Photograph: Chiara Goia

For 40 years now, says Uphoff, science has been obsessed with improving seeds and using artificial fertilisers: “It’s been genes, genes, genes. There has never been talk of managing crops. Corporations say ‘we will breed you a better plant’ and breeders work hard to get 5-10% increase in yields. We have tried to make agriculture an industrial enterprise and have forgotten its biological roots.”

Not everyone agrees. Some scientists complain there is not enough peer-reviewed evidence around SRI and that it is impossible to get such returns. “SRI is a set of management practices and nothing else, many of which have been known for a long time and are best recommended practice,” says Achim Dobermann, deputy director for research at the International Rice Research Institute. “Scientifically speaking I don’t believe there is any miracle. When people independently have evaluated SRI principles then the result has usually been quite different from what has been reported on farm evaluations conducted by NGOs and others who are promoting it. Most scientists have had difficulty replicating the observations.”

Dominic Glover, a British researcher working with Wageningen University in the Netherlands, has spent years analysing the introduction of GM crops in developing countries. He is now following how SRI is being adopted in India and believes there has been a “turf war”.

“There are experts in their fields defending their knowledge,” he says. “But in many areas, growers have tried SRI methods and abandoned them. People are unwilling to investigate this. SRI is good for small farmers who rely on their own families for labour, but not necessarily for larger operations. Rather than any magical theory, it is good husbandry, skill and attention which results in the super yields. Clearly in certain circumstances, it is an efficient resource for farmers. But it is labour intensive and nobody has come up with the technology to transplant single seedlings yet.”

But some larger farmers in Bihar say it is not labour intensive and can actually reduce time spent in fields. “When a farmer does SRI the first time, yes it is more labour intensive,” says Santosh Kumar, who grows 15 hectares of rice and vegetables in Nalanda. “Then it gets easier and new innovations are taking place now.”

In its early days, SRI was dismissed or vilified by donors and scientists but in the past few years it has gained credibility. Uphoff estimates there are now 4-5 million farmers using SRI worldwide, with governments in China, India, Indonesia, Cambodia, Sri Lanka and Vietnam promoting it.

Sumant, Nitish and as many as 100,000 other SRI farmers in Bihar are now preparing their next rice crop. It’s back-breaking work transplanting the young rice shoots from the nursery beds to the paddy fields but buoyed by recognition and results, their confidence and optimism in the future is sky high.

Last month Nobel prize-winning economist Joseph Stiglitz visited Nalanda district and recognised the potential of this kind of organic farming, telling the villagers they were “better than scientists”. “It was amazing to see their success in organic farming,” said Stiglitz, who called for more research. “Agriculture scientists from across the world should visit and learn and be inspired by them.”

A man winnows rice in Satgharwa villageA man winnows rice in Satgharwa village. Photograph: Chiara Goia

Bihar, from being India’s poorest state, is now at the centre of what is being called a “new green grassroots revolution” with farming villages, research groups and NGOs all beginning to experiment with different crops using SRI. The state will invest $50m in SRI next year but western governments and foundations are holding back, preferring to invest in hi-tech research. The agronomist Anil Verma does not understand why: “The farmers know SRI works, but help is needed to train them. We know it works differently in different soils but the principles are solid,” he says. “The biggest problem we have is that people want to do it but we do not have enough trainers.

“If any scientist or a company came up with a technology that almost guaranteed a 50% increase in yields at no extra cost they would get a Nobel prize. But when young Biharian farmers do that they get nothing. I only want to see the poor farmers have enough to eat.”

Hardtalk: Vandana Shiva, environmentalist (BBC)

Duration: 25 minutes / First broadcast: Monday 19 November 2012

Hardtalk speaks to the original tree hugger. The phrase was coined back in the 1970s when she – along with a group of women in India – hugged trees to stop them from being chopped down. In the decades since, Vandana Shiva has become known throughout the world for her environmental campaigns. She says a billion people go hungry in the world because of the way greedy international companies go about their business. So is it a naïve world view or could we really end poverty and improve everyone’s life by returning to old fashioned ways of farming?

Embrapa envia sementes de milho e arroz para o Banco de Svalbard, na Noruega (O Globo)

JC e-mail 4577, de 05 de Setembro de 2012.

Banco nórdico é o mais seguro do mundo, construído para resistir a catástrofes climáticas e a explosão nuclear.

A Embrapa envia esta semana 264 amostras representativas de sementes de milho e 541 de arroz para o Banco Global de Sementes de Svalbard, na Noruega, como parte do acordo assinado com o Real Ministério de Agricultura e Alimentação do país em 2008. Serão enviadas ao banco genético norueguês as coleções nucleares de arroz e milho, ou seja, um grupo limitado de acessos derivados de uma coleção vegetal, escolhido para representar a variabilidade genética da coleção inteira. Tradicionalmente, as coleções nucleares são estabelecidas com tamanho em torno de 10% dos acessos de toda a coleção original e incluem aproximadamente 70% no acervo genético.

A escolha dessas culturas atende a uma das recomendações do Banco de Svalbard quanto à relevância para a segurança alimentar e agricultura sustentável. Embora não sejam culturas originárias do Brasil, são cultivadas no país há séculos e têm características de rusticidade e adaptabilidade às condições nacionais. A próxima cultura agrícola a ser encaminhada para o banco norueguês será o feijão, o que deve acontecer até o fim de 2012.

O envio de amostras para Svalbard é mais uma garantia de segurança, já que o banco nórdico é o mais seguro do mundo, construído com total segurança para resistir a catástrofes climáticas e até a uma explosão nuclear. O banco tem capacidade para quatro milhões e quinhentas mil amostras de sementes. O conjunto arquitetônico conta com três câmaras de segurança máxima situadas ao final de um túnel de 125 metros dentro de uma montanha em uma pequena ilha do arquipélago de Svalbard situado no paralelo 780 N, próximo do Pólo Norte.

As sementes são armazenadas a 20ºC abaixo de zero em embalagens hermeticamente fechadas, guardadas em caixas armazenadas em prateleiras. O depósito está rodeado pelo clima glacial do Ártico, o que assegura as baixas temperaturas, mesmo se houver falha no suprimento de energia elétrica. As baixas temperatura e umidade garantem a baixa atividade metabólica, mantendo a viabilidade das sementes por um milênio ou mais.

Farmers in Mozambique trying to adapt farming to climate change (

Published 29 January, 2012 11:15:00 Living on Earth

Rui Alberto Campira hoes the soil. He’s part of a group of farmers who received a grant from Save the Children to grow cash crops. (Photo by Rowan Moore Gerety.)

As the rain and water in Mozambique becomes less predictable and less suited to subsistence farming, aid groups and the local government are trying to help some change the way they farm so they’re not so paralyzed by a flood or a drought. But there’s a lot of work to do.

Over the past two decades, Mozambique has suffered more than its fair share of weather disasters.

The east African nation has seen more devastating cyclones, droughts and floods than any country on the continent. Farmers in Mozambique have been particularly hard hit. This year alone, torrential rains in the mountains sent flood waters onto fields below, submerging tens of thousands of acres of crops.

And now, farmers are in the midst of another rainy season, which started in December.

Officials at Mozambique’s National Institute for Disaster Management have to prepare for rescue operations this time of year. Figueredo de Araujo, the institute’s information manager, said the emergency operations center is equipped with rescue boats as well as warehouses with various goods for humanitarian assistance: maize flour, tents, tarps, boots and rain coats among them.

Caia, where Mozambique’s main highway crosses the Zambezi river, sits in the middle of a vast, flat, floodplain that is home to nearly a million people. In 2000, the area was hit by the worst flooding in memory. The floods killed 700 people, displaced 100,000, and cost Mozambique a 1.5 percent loss in GDP through destruction of crops.

To Belem Monteiro, the emergency center’s director, much of Mozambique’s misfortune is a matter of geography.

“The fact that we have a problem is not news to us: given its location, Mozambique could only be vulnerable to these changes in climate,” Monteiro said.

Nearly 80 percent of Mozambican families are subsistence farmers, relying on rain-fed agriculture to produce their food. After the 2000 floods, farmers near the Zambezi River repeatedly lost their homes and crops.

“In the past, it happened every five years, now we have annual emergencies, which shows that the situation has changed,” Monteiro said.

But that’s presented a major challenge for the disaster management institute, which was conceived to intervene during freak emergencies, but has been forced to evolve to a permanent mission.

Some 30 miles from Caia, a resettlement zone called Tchetcha Um is home to some 5,000 families who were moved to higher ground. The organization Save the Children has partnered with the government in a program promoting livelihood resilience, diversifying their income sources, said Clemente Lourenço, a project officer for the group.

Farmer Rui Alberto Campira received a grant from Save the Children in 2009, which enabled he and 11 other farmers to built a 5-acre farm where they can grow crops for both consumption at home and sale at the local market. Campira says the soil is great for cash crops.

“It’s good. Especially for tomatoes. Tomatoes, onions, cabbage, collard greens. That’s what we usually plant here. There we only plant maize. Maize and sweet potatoes,” Campira said of his former home.

The land he’s farming now will also flood during the rainy season, but the irrigation system the grant enabled him to install allows him to farm during the dry season, when cash crops would typically die.

About 55 associations like Campira’s have formed in Caia district, not just growing cash crops, but trading in fish, beans, and clothing, and using animal traction to plow fields. Save the Children funds about 4500 farmers across three provinces.

Joao Novage is raising seven goats, as part of another association. The grant originally bought 40 goats that have in turn born another 20.

“When I see that I have 12 or 13 goats, I’ll take four and sell them to buy school supplies and clothes for my children. Children are our wealth. They’ll bring a better future for us,” Novage said.

Though the projects have been wildly successful, everyone admits they serve an insignificant portion of the population at this point. It remains to be seen if they can be expanded to make a measurable difference in the unger and poverty around this portion of east Africa.

Profits Before Environment (N.Y. Times)

August 30, 2011, 10:27 PM

I wasn’t surprised when the administration of George W. Bush sacrificed the environment for corporate profits. But when the same thing happens under a Democratic administration, it’s depressing. With little or no public input, policies that benefit corporations regardless of the consequences continue to be enacted.

No wonder an April 2010 poll from the Pew Research Center found that about only 20 percent of Americans have faith in the government (it’s one thing upon which the left and right and maybe even the center agree). But maybe this is nothing new: as Glenda Farrell, as Genevieve “Gen” Larkin, put it in “Gold Diggers of 1937,” “It’s so hard to be good under the capitalistic system.”

But is anyone in power even trying? Last winter, the Department of Agriculture deregulated Monsanto’s genetically modified alfalfa, despite concerns about cross-pollination of non-genetically modified crops. It then defied a court order banning the planting of genetically modified sugar beets pending completion of an environmental impact study.

Monsanto engineers these plants and makes Roundup, the herbicide they resist. But Roundup-ready crops don’t increase long-term yields, a host of farmers are now dealing with “superweeds” and there is worry about superbugs, nearly all courtesy of Monsanto. In fact, this system doesn’t contribute to much of anything except Monsanto’s bottom line. Yet Agriculture Secretary Tom Vilsack gave Monsanto the nod, perhaps yielding to pressure from the White House.

The United States exerts that same kind of pressure abroad. WikiLeaks cables show that U.S. “biotechnology outreach programs” have promoted genetically modified crops in Africa, Asia and South America; they’ve also revealed that diplomats schemed to retaliate against any European Union countries that oppose those crops.

Sacrificing the environment for profits didn’t stop with Bush, and it doesn’t stop with genetically modified organisms. Take, for example, the Keystone XL pipeline extension. XL is right: the 36-inch-wide pipeline, which will stretch from the Alberta tar sands across the Great Plains to the Gulf Coast, will cost $7 billion and run for 1,711 miles — more than twice as long as the Alaska pipeline. It will cross nearly 2,000 rivers, the huge wetlands ecosystem called the Nebraska Sandhills and the Ogallala aquifer, the country’s biggest underground freshwater supply.

If Keystone is built, we’ll see rising greenhouse gas emissions right away (tar sands production creates three times as many greenhouse gases as does conventional oil), and our increased dependence on fossil fuels will further the likelihood of climate-change disaster. Then there is the disastrous potential of leaks of the non-Wiki-variety. (It’s happened before.)

Proponents say the pipeline will ease gas prices and oil “insecurity.” But domestic drilling has raised, not lowered, oil prices, and as for the insecurity — what we need is to develop wiser ways to use the oil we have.

They say, too, that the pipeline could create 100,000 new jobs. But even the Amalgamated Transit Union and the Transport Workers Union oppose the pipeline, saying, “We need jobs, but not ones based on increasing our reliance on Tar Sands oil.”

Sounds as if union officials have been reading the writer and activist Bill McKibben, who calls the pipeline “a fuse to the biggest carbon bomb on the continent,” and NASA scientist Jim Hansen, who says the oil Keystone will deliver “is essentially game over” for the planet.

Game over? No problem, says the State Department, which concluded that the project will have no significant impact on “most resources along the proposed pipeline corridor.” The Sierra Club quickly responded by calling the report “an insult to anyone who expects government to work for the interests of the American people.”

I do expect that, and I am insulted. President Obama can deny Keystone the permit. A truly environmentally friendly president (like the one candidate Obama appeared to be) would be looking for creative ways to leave fossil fuels underground, not extract them. Perhaps he doesn’t “believe in” global warming at this point, like many Republicans?

When government defends corporate interests, citizens must fight. McKibben has helped organize protests at the White House against Keystone, and he’s one of hundreds who’ve been arrested in the last couple of weeks. These people are showing that the role of government as corporate ally must be challenged.

As it will be in the fight against carte blanche for genetically modified organisms: From Oct. 1 to Oct. 16, there will be a march from New York City to Washington to demand that genetically modified foods be labeled, something a majority of Americans want. This small, perfectly reasonable request has run into joint opposition from the biotech industry and (here we go again) the Food and Drug Administration.

Why are most of us are filled with mistrust of the government? Maybe because we, like Gen Larkin, know it’s so hard to be good under the capitalistic system.

Antigos índios da Amazônia contribuíram para a fertilidade da terra preta (FAPESP)

Adubo pré-colombiano
Marcos Pivetta
Edição Impressa 183 – Maio de 2011

Perfil mostra a diferença entre a fértil terra preta (alto) e o latossolo típico e pobre da Amazônia. À direita, imagem de microscopia por fluorescência da superfície de carbono pirogênico. © EDUARDO GÓES NEVES (ESQUERDA) / CENA/USP (DIREITA)

Os arqueólogos costumam debater qual o real significado das manchas de terra preta encontradas em sítios pré-históricos da Amazônia Central, um tipo de solo escuro que se destaca visualmente da monotonia marrom-amarelada característica das áreas de terra firme da região. Para alguns, elas são um indicativo de que grupos indígenas pré-colombianos viveram por centenas ou até uns poucos milhares de anos em sociedades complexas e estruturadas, baseadas na agricultura sedentária e no manejo do ambiente, em meio à floresta. Para outros, a existência desse tipo de terreno mais escuro, frequentemente recheado de fragmentos de peças de cerâmica, não é uma prova cabal de que houve ali um processo de ocupação humana antiga e prolongada antes do desembarque do conquistador europeu. Mas sobre uma questão, mais relacionada às ciências agrárias do que às humanidades, há consenso generalizado: a terra preta é um oásis quase permanente de fertilidade numa zona recheada de solos pobres e incapazes de reter nutrientes por muito tempo. Estudo recente confirma que um componente importante dessa variante de solo é um vestígio inequívoco do estabelecimento de assentamentos humanos: as fezes dos índios.

Concentrações de um biomarcador associado à deposição de excrementos humanos no ambiente, o coprostranol (5ß-stanol), foram encontradas em amostras de terra preta oriundas de cinco sítios pré-históricos da Amazônia, de acordo com um artigo científico a ser publicado por uma equipe de pesquisadores do Brasil e da Alemanha na edição de junho da revista Journal of Archaeological Science. Quatro sítios estão localizados no Amazonas, a sudoeste de Manaus, numa faixa de terra firme na confluência entre os rios Negro e Solimões, e um se situa no Pará, a sudoeste de Santarém, no baixo Tapajós. “A rigor, o biomarcador também poderia indicar a presença de fezes de porcos domesticados”, afirma o engenheiro agrônomo Wenceslau Geraldes Teixeira, da Embrapa Solos, do Rio de Janeiro, um dos autores do trabalho. “Mas, como esse animal só foi introduzido na América do Sul depois da chegada dos europeus, descartamos essa possibilidade.” Todos os exemplares de terra preta analisados se formaram entre 500 e 2.500 anos atrás, antes da descoberta oficial do continente por Cristóvão Colombo.

Rica em minerais associados à fertilidade dos solos, a terra preta deve sua cor enegrecida à elevada presença em sua composição do chamado carbono pirogênico, uma forma estável de carvão aromático produzida pela combustão incompleta de biomassa. O modo de vida dos antigos índios da Amazônia – que queimavam os restos de animais consumidos, enterravam os mortos  e depositavam lixo e excrementos nos arredores de suas comunidades – deve ter sido o responsável pela formação desse tipo de solo. “Estamos tentando entender a composição química da terra preta e descobrir qual aporte de material orgânico a mantém fértil até hoje”, afirma o arqueólogo Eduardo Góes Neves, da Universidade de São Paulo (USP), outro autor do estudo e coordenador de um projeto temático da FAPESP sobre a história pré-colonial da Amazônia. “Se tivermos sucesso nesse objetivo, talvez possamos aprender a melhorar a fertilidade em solos pobres e dar uma contribuição para uma agricultura tropical mais sustentável.” Existem tentativas de reproduzir artificialmente as propriedades da terra preta, mas os esforços ainda estão nos trabalhos iniciais.

Alguns especialistas acreditam que compostos presentes nas fezes humanas desempenham um papel importante na manutenção a longo prazo da fecundidade dessa variante do chão amazônico.  Ao contrário dos empobrecidos latossolos típicos da Amazônia, a terra preta sofre pouca lixiviação, processo caracterizado pela perda de nutrientes devido à infiltração da água da chuva que “lava” o solo e lhe rouba os componentes químicos.  “Os excrementos dão uma contribuição significativa para o conteúdo de nutrientes encontrados na terra preta, como nitrogênio e fósforo, e a ajudam a reciclar seus nutrientes”, afirma Bruno Glaser, da Universidade Martinho Lutero de Halle-Wittenberg, Alemanha, estudioso da biogeoquímica de solos e também coautor do artigo. “Nas sociedades modernas isso não ocorre mais, pois esses nutrientes são perdidos com a deposição do lodo de esgoto em reservatórios.” Na terra preta as fezes provavelmente se misturam ao solo devido à ação de minhocas, cupins, formigas e outros organismos.

Embora não costume ser diretamente apontado como um elemento capaz de conferir fertilidade ao solo, o carbono pirogênico parece conter uma conjunto único de fungos e bactérias, cuja sinergia pode estar relacionada à fertilidade da terra preta. Trabalhos feitos pela equipe da engenheira agrônoma Siu Mui Tsai, do Centro de Energia Nuclear na Agricultura, da USP, em Piracicaba, mostram que a forma de carvão presente nesse tipo de solo abriga o DNA de até 3 mil espécies de microrganismos. “Essa biodiversidade  é bem maior do que a encontrada em solos amazônicos vizinhos à terra preta”, afirma Siu. “Os índios não usavam produtos tóxicos e seu sistema estava em equilíbrio.” Ninguém sabe, no entanto, se os povos pré-colombianos criaram intencionalmente a terra preta, como  forma de enriquecer o solo destinado à agricultura,  ou se ela é uma mera decorrência acidental dos dejetos e do lixo produzidos por seu modo de vida.

Artigo científico: BIRK, J.J. et alFaeces deposition on Amazonian Anthrosols as assessed from 5ß -stanolsJournal of Archaeological Science. v. 38 (6). p-1209-20, jun. 2011.