A farming method that doesn’t require fertilizer, uses a fraction of water and increases yields two to six times has lifted over 6500 farmers from subsistence to money oriented agriculture.

Waithera Kimotho beams as she shows off her farm, irrigated with her family’s new water pump. The mother of seven kids no longer has to lug water uphill from a nearby river. Around her, long narrow beds of corn, beans, kale and pumpkins are flourishing. Some are ready for harvest. Others are in various stages of growth, assuring the family will have a continuous food supply. The African air is clean and crisp as the sun beats down, nourishing the plants.

The farm is tiny. It takes up perhaps a quarter of an acre in Thika. It’s astonishing to think Kimotho and her husband, Francis, grow enough food to feed themselves and still have some left over to sell. Yet after changing to a new method of farming about a year ago, they do — that’s how she bought the water pump.

And for that wonderfully productive quarter acre, she can thank an American. John Jeavons teamed up with Alan Chadwick in California in the 1970s to work on developing high-yield farming methods that didn’t need fertilizer, which is made from fossil fuels, a non-renewable resource that was growing increasingly expensive as the OPEC oil crisis mounted.

They came up with something they named Grow Biointensive, a combination of two farming methods they drew from, Biodynamic and French intensive. Grow Biointensive increased crop yields by two to six times and used a fraction of the energy and water required for conventional agriculture. Jeavons thought it would mean better lives for subsistence farmers.

It took a long time to popularize Grow Biointensive. But the method is now spreading in Kenya and elsewhere through organizations like GBIACK, which won NGO of the Year in 2010 from the United Nations Food and Agriculture Organization and the Kenyan government.  Started in 2008, GBIACK has trained over 6,500 farmers. “Here, in Kenya, if you plant anything without chemical fertilizer, if you don’t know anything about organic farming, it can’t grow,” says GBIACK co-founder Samuel Nderitu, who became interested in Grow Biointensive because fertilizer was a huge expense for his own farm.

At first, Kimotho’s farm would look familiar to anyone who knows organic farming. She rotates crops from place to place in her tiny lot. She uses cover crops that are planted solely to improve soil that won’t be cultivated. She applies mulches and composts and manure to fertilize.

But visitors would note she uses three-foot wide beds. Most farms plant in rows, but Jeavons found that a long three-foot wide bed allowed for more planted space while still allowing the farmer to reach into the center of the bed to seed, weed, or harvest without trampling the plants. They would also see that crops are planted in a triangular pattern, ensuring maximum use of space.

Before planting for the first time, Kimotho loosened the top two feet of soil throughout each bed and mixed in large amounts of compost and manure. Called a “double dig,” this labor-intensive effort is done only once in Grow Biointensive farming; after that, the farmers do not walk on the beds, ensuring that the loosened, aerated soil is not compacted under their feet.

Each season thereafter, Kimotho works compost and manure into the top few inches of soil, but she does not till or plow like most organic farmers would. Plowing aerates soil, but also kills beneficial fungi that help preserve precious topsoil. Adding compost and manure to the topsoil mimics what happens in nature.

Such methods matter in the country, where enormous population growth has eaten up farmlands. Kenyan farmers no longer can allow land to lie fallow to regenerate soil fertility. And fertilizer costs have skyrocketed to Sh2900 a bag. Even on her tiny farm, Kimotho needed two bags of fertilizer.

As he walks around Robert Mwangi’s farm, Nderitu shows Mwangi how to recognize plant diseases. They discuss how to save and replant seeds so Mwangi will not need to buy seeds from the store. Robert shows Nderitu his fish ponds and asks how to produce tilapia feed with waste products from the farm in order to avoid buying it. Mwangi also conducts experiments of his own and shares what he learns with Nderitu. Right now he is trying to grow strawberries for the first time to see if they might work out as a cash crop. Mwangi was an early adopter of Grow Biointensive . Since he started three and a half years ago, his farm has grown so profitable, his neighbors have asked for training to emulate him.

The system has been effective because it’s easy to learn, says Heather Day,  director of the Community Alliance for Global Justice, who visited Thika in 2010. It also helps deal with the side effects of fertilizer, which can damage soils over the long term. “It helps them replenish often very depleted soils,” Day said.

With the additional income generated by switching to Grow Biointensive, farmers reap very real improvements in living standards, proponents said. Evidence in Kenya is anecdotal, but some people have drilled wells or paid school fees for their children. For the most vulnerable, the biggest benefit is producing enough food to eat.

Jeavons feels gratified. He’d always wanted his work to matter globally, but for many years the methods seemed to appeal only to gardeners. Now, he says, “It is widespread throughout Latin America, and we have Grow Biointensive farmers in Africa, Russia, the Czech Republic, and even Afghanistan.”