A few links for anyone interested in how farmers can sequester carbon in their soil.
NZ research that found that stocks of carbon and nitrogen in the soil vary with land use. In their paired samples, dairy farming was found to deplete these resources while other pastoral grazing had no significant effect over time. This is the kind of work that I reckon should be used to compare "normal" dairying with the biological farming that is being steadfastly ignored by DairyNZ and by those receiving large research grants from the public purse.
A well-documented investigation by the UK Soil Association in 2009 supports the view that farming practices can sequester large amounts of carbon dioxide. Their meta analysis of matched comparison studies across many countries suggests carbon stocks are around 20 - 25% higher in biologically farmed soils.
Finally, Soil Carbon Cowboys is a short (12min) video outlining the practices of three USA farmers. Kiwis might smirk at the radical concept of "paddocks" but these guys are building soil rapidly (h/t John King).