Rotating cows

At a climate-change conference, Mark Stevenson heard Australian accountant Tony Lovell talk about a new method of farming that enriches the land and saves it from eroding while the crop draws CO₂ from the atmosphere.

Lovell explained the natural relationship between grasses and grazing animals:

The growing buds are at the base of the plant and they need sunlight. If the plant gets too tall it starts to kill itself by hiding those buds in its own shade. It can’t photosynthesise. … In nature, the herd would have come along, eaten the tops off the plants, exposing the growth buds, and moved on. By the time they came back, the grass would have regrown.

Bison herd grazing at the National Bison Range

“The problem with the way we farm livestock is we don’t let them roam,” said Lovell’s partner, Bruce Ward.

We split up big herds between separate paddocks and keep them there for way too long. With no predators, they can wander where they like in that space. The grass never gets a chance to grow back. An animal will have a go at it as soon as it starts sprouting.

 

Photograph taken from Coleshill Hall Bridge on Birmingham Road

English cows grazing. Carl Baker for geograph.org.uk

Stevenson continues in the New Statesman:

The effect of such poor land management is a sharp decline in soil carbon levels across grasslands over the past 150 years, directly related to the loss of vegetation. Ward tells me that grass plants grow roughly the same amount of root matter as leaf matter. If the plant gets nibbled by a cow or sheep, it’ll slough off a corresponding amount of root matter into the soil in minutes, enriching it with carbon.

“A plant is roughly 58 per cent carbon – from CO2 in the air,” says Ward, “and while nearly all of the lost root matter will rot, returning that carbon to the atmosphere, it leaves behind a small amount of residue.”

“It’s only a small amount of the carbon that makes up the plant,” says Lovell, “but a little bit of a bloody big amount soon adds up.” He’s not wrong. The UN estimates there are 3.5 billion hectares of agricultural grasslands on our planet. Increase the organic carbon content of their soils by just 1 per cent, and this would offset nearly 12 years of global CO2 emissions.

I’m reminded of a similar, sustainable farming method in which the grazing animals keep moving to new pastures as described by Michael Pollan in “The Omnivore’s Dilemma.”

Hat tip: 3 Quarks Daily

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