Could Carbon Farming Save Our Soils?

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Declining soil health could mean problems ahead as the world's population grows. By refleXtions/Shutterstock

The world’s soils are in jeopardy. Some scientists think agricultural soils are in such serious decline that the ability of the planet’s farmers to feed future generations is seriously compromised. The United Nations is so concerned about the issue of soil health that after two years of intensive work, the General Assembly declared Dec. 5 to be World Soil Day and 2015 the International Year of Soils.

The goal of both events is to enhance awareness of the important roles soils play in human life, especially as populations increase and global demand for food, fuel and fiber rise.

Fertile soil is critical to sustaining food and nutritional security, maintaining essential ecosystem functions, mitigating the effects of climate change, reducing the occurrence of extreme weather events, eradicating hunger, reducing poverty and creating sustainable development.

By increasing global awareness that soils everywhere are in jeopardy, Year of Soils proponents hope policymakers will act to protect and manage soils in a sustainable manner for the world’s different land users and population groups.

Carbon farming as the new agriculture

This is a message that Rattan Lal, a soil science professor and founder of the Carbon Management and Sequestration Center at Ohio State University, believes leaders of governments and industry should take to heart. It’s one he’s been delivering for more than two decades and is centered on his concept of reviving soil quality through carbon farming, which he calls the new agriculture.

Lal, the incoming president of the Vienna-based International Union of Soil Sciences, describes carbon farming as a process that takes carbon dioxide out of the air though sustainable land management practices and transfers it into the soil’s organic matter pool in a form that doesn’t allow carbon to escape back into the atmosphere. If this sounds like a practice that dates to the earliest of times of human farming, in essence, it is.

Carbon is a key component of soil quality because it directly affects crop production.

“Soil organic carbon is a reservoir of essential plant nutrients such as nitrogen, phosphorous, calcium, and magnesium and micronutrients,” Lal said. “As natural ingredients in the soil break down, these nutrients are released through microbial processes associated with decomposition.

“An adequate level of soil organic carbon in the root zone is critical to several soil processes,” he continued. “These include nutrient storage, water retention, soil structure and tilth, microbial activity, soil biodiversity, including earthworms, and moderation of soil temperature. Management of soil organic carbon, such as by carbon farming techniques, is also important to improving the efficiency of fertilizers, water and energy.”

Lal said he believes the world’s soils have declined through centuries of improper land management that has removed and depleted alarming amounts of carbon from soils worldwide. He attributes the loss of soil carbon to ecosystem destruction — cutting down forested, natural ecosystems to create agricultural ecosystems, erosion and desertification — and nonsustainable farming and nutrient techniques such as plowing instead of no-till farming and using chemical fertilizers instead of spreading manure on fields. Significant areas of fertile soil also have disappeared as cities keep growing.

He compares soil carbon content to “a bank account that Mother Nature gave us. We’ve withdrawn so much carbon from that account,” he said, “that the account — the soil — has become impoverished.” The way to increase the health of the account, he said, is the same way you would improve your personal bank account, which is by putting more into it than you take out. In the case of the soil carbon “account,” though, the deposits would be in the form of carbon farmers harvest from the air and put into the soil through recycling biomass such as compost.

“Soil carbon depletion is so severe,” Lal said, “that in just 200 years of farming in the contiguous United States, the country’s agricultural soils have lost 30 to 50 percent of their carbon content. The problem is worse in the world’s poorest countries.” In Southeast Asia, India, Pakistan, Central Asia and sub-Saharan Africa, for example, Lal estimates the loss of soil carbon is as much as 70 to 80 percent.

Carbon farming 101

No-till soybeans
Soybeans grow in a no-till field in South Dakota. USDA NRCS South Dakota [CC by 2.0]/flickr

Carbon farming can be accomplished, Lal contends, though agricultural practices that add high amounts of biomass such as manure and compost to the soil, cause minimal soil disturbance, conserve soil and water, improve soil structure, and enhance soil fauna (earthworm) activity. No-till crop production is a prime example of an effective carbon farming technique, he said. Conversely, traditional plowing of fields releases carbon into the atmosphere.

In Lal’s view, once carbon is restored to the soil in sufficient quantities, it could be traded just like any other commodity is traded. In this case, though, the commodity — carbon — would not be physically transferred from one farmer or farm to another entity.

“The carbon would stay in the land to continue to improve soil quality,” he said. “It’s not like selling corn or wheat.” Lal proposes that farmers be compensated for harvesting and trading carbon credits based on cap-and-trade, maintenance fees and payments for ecosystem services.

Credits under Lal’s concept would be based on the amount of carbon farmers sequester per acre. Soil carbon can be measured, Lal said, through laboratory and field tests.

Industry also figures into Lal’s carbon farming plan. As an inducement to reducing carbon emissions from fossil fuel combustion and other carbon-emitting activities, he wants industries to be given similar credits, perhaps in the form of tax breaks.

Carbon farming, Lal emphasized, is not limited to farms or industries. It could be practiced by land managers in local, state or federal governments, or by others who oversee open spaces such as golf courses, roadsides, parks, erosion-prone areas and landscapes that have been degraded or drastically disturbed by activities such as mining, he said.

Selling the idea

Lal, as much a pragmatist as a theorist, knows his concept is not an easy sell.

Industry and modern lifestyles that burn fossil fuels are putting more carbon into the atmosphere than farmers and land managers can sequester.

“The rate at which we are burning carbon globally is 10 gigatons a year,” he said. “The rate at which the world’s farmers can absorb that carbon even though best practices is about 1 gigaton. The rate at which land managers can sequester carbon through reforestation on eroding and depleted land is only about another gigaton.”

Climate-smart farm
Bananas grow in a climate-smart farm in Kenya. CIAT [CC by 2.0]/flickr

That leaves a carbon deficit surplus of 8 gigatons a year. How does the global community remove that unwanted surplus, which many scientists believe is accelerating global warming?

“We have to eventually find noncarbon fuel sources such as wind, solar, geothermal and bio-fuels,” Lal said. “I hope in one to two centuries we are not burning fossil fuels.”

But Lal said he doesn’t think world populations have that long. He said we are just buying time as we search for alternative fuel sources and that time is running out. He puts the window of opportunity at 50 to 100 years.

If the world hasn’t embraced climate-smart agriculture by then, he fears future populations will experience what the 2015 Year of Soils is trying to head off: food insecurity, a breakdown in essential eco-system functions, more frequent extreme weather events as climate change worsens, significant increases in global hunger and poverty, and a sharp drop in sustainable development.

However, Lal said there are lots of encouraging developments: “Carbon farming is leading to increased crop yields, for example, in several countries in sub-Saharan Africa, including Ghana, Uganda, Zambia and Malawi. Agronomic production has improved in countries of Central America. In these and other countries, improved agriculture is now the engine of economic development, and there is a vast potential for further improvement.”

“Through conversion of science into action through political will power and policy interventions, sustainable intensification can be implemented based on soil-restorative options,” Lal pointed out. “With judicious management, productivity and nutritional quality can be improved to feed the current and projected population while improving the environment and restoring ecosystem functions and services.”

“Soils must never be taken for granted,” he said. “Soil resources must be used, improved and restored for generations to come.”

Inset photo (soil sample): USDA NRCS Virginia