Experts look to the soil to save the climate

By Gerard Wynn Reuters
Published: March 19, 2009

BEDFORD, England: John Ibbett and pigs go back a long way. When he was still a baby, the man who took care of the pigs on the family farm ‘‘pushed me round in a pram.’’
Now he’s proud his farm can turn muck into electricity, using new technology paid for by a multimillion pound windfall from a land sale.
His Bedfordia Group is one of only a handful of companies with farm-based biogas plants in Britain. But more biogas plants are being established in Denmark, Germany and developing countries.
That momentum could be a precursor for much bigger climate benefits, from changing farming methods to using the soil’s capacity to store vast amounts of carbon. Experts say this is an area so far almost entirely ignored by policymakers.
‘‘I think we’re already beyond the safe level of greenhouse gas concentrations and the difference could be met through this terrestrial carbon approach,’’ said Thomas Lovejoy, biodiversity chair at the Heinz Center for Science, Economics and the Environment in Washington.

Crops as well as trees can suck carbon out of the air, increasing what experts call terrestrial carbon. Farmers can nurture this carbon underground as well as crops above by using longer rotations, not over-grazing pasture and plowing less.
Mr. Ibbett’s 3-year-old plant, 90 kilometers, or 56 miles, north of London, traps methane emissions from food and farm waste in giant vats and then burns the powerful greenhouse gas to produce electricity, thus preventing the gas from reaching the atmosphere.
Directly curbing greenhouse gas emissions from farming is important: Farming contributes as much to global warming as all the world’s planes, cars and trucks, and that will increase as the world tries to feed an extra three billion people by 2050.
Scientists also want more focus on agriculture, and especially on the soil, at U.N. climate talks, which resume in two weeks in Bonn, Germany. They are meant to thrash out by December a new climate treaty to replace the Kyoto Protocol.
The sticks and carrots policy makers use to drive the climate fight have so far almost exclusively focused on energy.
But soil could store as much as one-tenth of all the carbon that households and industry spew into the atmosphere, and so buy time in a gradual, global shift away from fossil fuels.
Academics have revived interest in the millennium-old technology of plowing under a carbon-rich type of charcoal called biochar, which is made from heating plant, food or animal waste.
One reason the sector has not yet captured the public imagination may be that pig manure and soil are not the stuff of public relations dreams.
‘‘Politicians can understand planting a tree and watching it grow,’’ removing carbon dioxide from the atmosphere in the process, said Pete Smith, lead author for agriculture on the U.N.’s Intergovernmental Panel on Climate Change. ‘‘In agriculture, it’s not immediately visible.’’
All plants draw carbon dioxide out of the air as they grow. But trees, rather than crops or the soil itself, have been a focus for this.
‘‘If you look across all the sectors together, farming has equivalent mitigation potential to the energy sector and to transport and industry,’’ added Mr. Smith. ‘‘We really need to get agriculture in there,’’ he added, referring to the U.N. climate talks.
Farming also accounts for half of all man-made methane emissions worldwide — from ruminant livestock like cows and sheep and from stored manures — and 60 percent of the world’s emissions of nitrous oxide, a greenhouse gas some 300 times more powerful than carbon dioxide, which is derived from using nitrogen fertilizers.
Combined, curbing these greenhouse gases and using soil sinks could remove the equivalent of up to 1 billion tons of carbon emissions annually. Storing carbon in the soil would account for about 90 percent of that.
The idea of sucking greenhouse gases from the atmosphere, rather than just curbing emissions, is gaining credibility and support as scientists say they have underestimated the urgency of fighting global warming.
Analysts estimate that the burning of forests, ploughing soils and degrading grasslands has released 200-250 billion tons of carbon in the past 300 years, about 25 times the annual carbon emissions from burning fossil fuels now.
A reward plan for systems that locking up stored carbon — like the carbon-offsetting plans that operate under the Kyoto Protocol — are being explored in the United States.
The U.S. agriculture secretary, Tom Vilsack, told farm unions last month farmers may be able to earn similar credits for locking carbon in the soil, under President Barack Obama’s planned $80 billion cap and trade scheme.
Farmers are famously not short of ideas on how to make money and the managing director of Bedfordia Group’s farming business, Ian Smith, is turning his marketing skills to a climate premium.
He estimates the Bedfordia pigs are one-third less carbon-emitting than others — and is trying to sell part of the farm’s annual production of 23,000 pigs for environmentally friendly bacon to the supermarket group J. Sainsbury.
First, he argues, the methane emissions from their manure is trapped and burned. Second, the electricity produced replaces high-carbon power. Third, the final product is a soil additive that displaces more energy-intensive nitrogen fertilizer.
‘‘They like the concept of a low-carbon pig, but even with our size of business it’s quite difficult,’’ Mr. Smith said of the supermarket’s response so far, referring to economies of scale the supermarket seeks.
‘‘I’m still talking to two supermarkets,’’ he added. ‘‘Part of the problem is people getting their head around it.’’