Feeding our livestock grass, not grain, will slow climate change ?

Further to my recent posting on meat and climate, this article makes interesting reading. The comments are worth checking out too. Here's an interesting point.Graham Harvey: Feeding our livestock grass, not grain, will slow climate change guardian.co.uk: "And even as Britain's pastures supplied us with healthy foods, they were taking carbon from the atmosphere and storing it away safely in organic material in the soil. Far from damaging the world's climate, grasslands help to stabilise it. There are even plants in traditional grasslands – the yellow-flowering bird's-foot trefoil is one – which reduce the methane emissions of ruminant animals."
Of course, it doesn't address the issue of land use and protein production per hectare under pasturage or arable usage, the only mitigant in that for meat production being raising livestock on land which is too marginal for grain or similar. But it is true that 'proper' field rearing is better and there are advantages to good soil-care in locking up CO2.