You're equating the 2 wrong things. You need to compare emissions with the sequestration of CO2 from the atmosphere by the plants involved in the whole biogenic cycle. Soil carbon arising from root exudation by those plants is a very small fraction of that. Of course it doesn't 'add up'.

Not sure what you're trying to say but there's more sequestration from plants when they are not constantly (over)grazed, and the grazing animals constantly extracted from ecosystems.