The prodigious methane output of cattle is bad for the environment. But grazing on grass will soak up carbon

When I grew up in the Fifties roast beef was as much a part of Sunday as the clamour of church bells and Two-Way Family Favourites on the radio.

In those austere days foods such as beef, butter and cheese were seen as the mainstay of a healthy diet. Though no one on our Reading estate had much money, the idea that you’d cut back on such essentials would have seemed tantamount to self-harming.

Today their reputation has lost its shine. For years nutritionists have warned of the dangers of saturated fats. Now environmentalists have joined the attack on livestock with dire predictions about climate change and the damaging effects of the methane emitted by cows.

But the attack has been overdone. New findings on traditionally reared beef and dairy foods could lead to their reinstatement as “protective foods”, as they were once known. Far from causing illness, they may play a key role in
defending the body against modern diseases.

Even more remarkably, their production is now being seen as part of a land management system that benefits the planet. Though methane from ruminant animals undoubtedly adds to greenhouse gases, they can play a far more important role in cutting carbon dioxide.

Britain has a long tradition of livestock farming dating from Neolithic times.
Two thirds of Britain’s farmland are occupied by grassland, much of it in the hilly West and North of the country where few other crops can be grown. The climate and soils of western Britain are well suited to grass, which is why this country has long been renowned for the quality of its beef.

Today, livestock production is moving away from grassland. Around the world, large numbers of animals are confined to sheds or yards and fed diets rich in high-energy and high-protein foods such as cereal grains, maize and soya.
These systems appeal to farmers because they reduce costs and speed up production. But because the feed crops are grown with heavy inputs of chemical fertiliser, pesticides and diesel fuel, they can hardly be considered “climate-friendly”. Even worse, large tracts of rainforest are felled to produce the grain for cattle.

Now the pendulum may be about to swing back in favour of grassland. The evidence is stacking up that meat and dairy foods from animals grazing fresh pasture are healthier than the grain-fed versions. Pasture-fed beef and lamb contain higher levels of omega-3 fatty acids and antioxidants such as vitamin E. Pasture-fed meat and milk are also rich in a remarkable compound known as CLA, which protects against many cancers and heart disease. When animals are fed large amounts of grain, the levels of these health-protecting nutrients fall rapidly in the resulting foods.

Grasslands have another gift for humanity, one only now coming to light.
Pioneering US farmers believe they could become a key weapon in the climate change battle. Scientists have long been aware of grassland’s ability to capture or “sequester” carbon. Grass leaves take in carbon dioxide from the air, converting it to sugars by photosynthesis. Some of the resulting carbon compounds are transferred to the roots and released into the soil through the normal cycles of growth and decay.

Agriculture accounts for 7 per cent of the UK’s total greenhouse gas emissions and, of this, methane from ruminant animals makes up one third. Cows on a grass diet produce more methane than those fed on cereal grains, but grasslands more than compensate in other ways. Some pasture plants, such as bird’s-foot trefoil, are known to reduce methane emissions. In any case, about 18 per cent of methane is neutralised by bacteria in the soil under grassland. Carbon capture through photosynthesis is thought by scientists to account for up to 40 per cent of the UK’s farming emissions.

But if these American farmers are right, with skilled management the grasslands can capture far more carbon. Their inspiration has been the prairie grassland that once covered vast areas west of the Mississippi. Grazed by great wandering herds of bison, these natural grasslands built up huge stores of carbon in their soils. The level of organic matter — the carbon-rich residues of decayed plants and animals — could be as high as 20 per cent. In many UK arable soils, organic matter content averages just 2 per cent. When European settlers arrived on the prairies, they ploughed the grassland, turning it over to wheat. The vast stores of soil carbon were released into the atmosphere, adding greatly to greenhouse gases. By the 1930s the prairie soils, their fertility exhausted, blew away in dustbowls, an event that inspired Steinbeck’s classic novel The Grapes of Wrath.

Today a group of US farmers are discovering that they can build up those same high levels of soil carbon under their own pastures. The key is to get their cattle to mimic the behaviour of the wild bison herds. As a defence against predators, these herds packed closely together and were constantly moving. This meant that each patch of grassland was trampled and grazed hard, then left to recover for weeks or months until the grazing herd returned.

Under this regime the soil carbon store builds rapidly, as today’s farmers are now discovering. They call it “mob grazing”. Using electric fences, farmers split their pastures into a large number of small paddocks. Putting their cattle into each paddock in turn, they graze it off quickly before moving the herd to the next. US farmers report that their animals stay very healthy on this grazing regime, putting on weight fast. At the same time the soil quickly becomes more fertile as it accumulates carbon compounds.

Joel Salatin, one of the Virginia farmers practising mob grazing, describes it as the closest thing he has found to a free lunch. “It doesn’t require combines, ploughs, tractors or buildings,” he says. “It’s the fastest way to sequester carbon, collect solar energy, and rebuild soil. Grazing is truly amazing.”

Mob grazing hasn’t yet arrived in the UK. But there is no reason why it shouldn’t be adapted in a country with such a long grazing tradition. It could give a boost to the livestock- rearing communities of the West and give hard-pressed farmers a new crop to sell — soil carbon.

Then we could tuck into a steak with a clear conscience.

Graham Harvey is a farming journalist and author of The Carbon Fields


Source: TimesOnline.co.uk, January 4, 2010
By: Graham Harvey