The soil beneath our feet is the world’s largest terrestrial carbon store. Pioneering farmers and agronomists are working on methods to harness its potential. Their insight: Climate protection and a rewarding harvest can go hand in hand.
The soils of the world contain more carbon than its forests, woodlands and atmosphere combined,” says Professor Rattan Lal. Agriculture, by replacing forests with fields, has been depleting that vast carbon store since its birth 10,000 years ago, so “we should see recarbonization of the soil as an essential part of the solution to climate change.”
Lal, Distinguished Professor of Soil Science at Ohio State University, United States, stresses that agriculture must become nature-positive. “That means producing more from less: focusing on the efficiency of inputs, rather than the rate.” Too many agricultural systems, he explains, rely on very high volumes of fertilizers and other chemical inputs to achieve their current yields. The alternative regenerative agriculture techniques he espouses are deceptively simple: minimizing tillage, replacing flood irrigation with more water-efficient drip approaches, and using cover crops and agricultural residues to boost nutrients.
Professor Rattan Lal has spent 60 years unlocking the secrets of soils and devising farming methods that can improve them.
“And we should use less of the land itself,” he adds. Reducing demand for agricultural products through more efficient utilization and dietary changes would allow more land to be returned to nature, capturing billions of tons of carbon.
In some parts of the world, large-scale efforts to protect the soil are already under way. China’s Three-North Shelter Forest Program, known as the Great Green Wall, is the world’s largest human-made forest. Upon completion in the 2050s, it will span 4,500 kilometers, slowing the southward advance of the Gobi Desert. However, most places don’t have the political, social or economic structures that permit such sweeping changes to land use. The health of their soils depends upon the choices made by millions of individual farmers. That might just be the best place for the next green revolution to begin.
Old trees, new life
Tony Rinaudo, an Australian agronomist, has spent his career helping farmers in the Global South to adopt more sustainable practices. His work began in Niger, West Africa, in the early 1980s. “It was a landscape on the verge of ecological collapse,” he says. Deforestation had stripped protection from the soil, water shortages were rife, and the Sahara Desert was advancing from the north. Rinaudo’s tree-planting efforts were failing, however: “80 or 90 percent of the saplings we planted died or were destroyed.”
He was about to abandon the project. “Then one day I noticed one of the low bushes next to the road, and took a closer look,” he recalls. That bush, like millions of others, turned out to be a tree, regrowing from a leftover stump. “In that instant, everything changed. We didn’t need millions of dollars to make a dent in this. We didn’t need a miracle species of tree that could withstand droughts and people pulling them up. Everything you needed was literally at your feet.”
Known as “the forest maker,” Tony Rinaudo helps farmers in Africa and beyond to protect their soils by regrowing trees from left over stumps when land is cleared.
With well-established root systems to access water and nutrients from deep in the soil, trees that regrow from stumps are much more likely to survive than new seedlings. That revelation shifted Rinaudo’s approach. He started a new project, incentivizing farmers to allow a few trees – 40 per hectare – to regrow on their land. “They thought the idea was strange, but a minority could see it was doing some good,” says Rinaudo. “A little more organic matter was going into the soil, wind speeds were slower, the temperature was lower, and some of the traditional wild foods were coming back.”
In the following years, Rinaudo’s “farmer-managed natural regeneration” approach steadily took root in Niger. “After 20 years, we had 200 million trees across 5 million hectares, without planting a single one. All from an investment of about two U.S. dollars per hectare,” he says. Mature trees each absorb about 25 kilograms of carbon from the atmosphere every year, and more is captured by the improved soils on regenerated farms.
Rinaudo and his current employer, the charity World Vision, went on to launch projects in other African countries, including Ethiopia, Ghana and Senegal. Today, farmer-managed natural regeneration is used in about 25 countries. Most common in Africa, it has also been adopted in countries such as Indonesia, Myanmar and East Timor.