Definitely not carbon neutral:
https://www.forbes.com/sites/jeffmcmahon/2019/12/02/5-reason...
https://www.forbes.com/sites/jeffmcmahon/2019/12/02/5-reason...
For starters, as far as lost sequestration goes, even with the grain removed from the equation, a dense field of corn produces a similar amount or more biomass than the same field would laying fallow.
Another point that is constantly brought up is the methane emissions of cows. Cows do not produce methane in a vacuum, they produce it by digesting grain, so the comparison must be made relative to that same amount of grain being digested elsewhere or decomposing on its own.
Their point about the need to adopt things like silvopasture, no-till, or crop rotation sound great, they but fail to acknowledge that in vast portions of the US they are already the norm, not the exception.