Grassland does not tend to develop soil, so if employed in feeding cattle, the cattle is where the carbon is "sequestered" to - into and through them, out the rear end. If the grass is cut and harvested (at some expense) instead of fed to cattle, then we get a lot of carbon negative hay to do something with. Bury it maybe (to sequester) or biofuels (to release again).

With traditional timber plantations we get the carbon in a load of timber mostly. Build with some of it, pulp and burn the rest. Timber plantations tend not to build soil either.

With relatively unheard of silviculture - the detailed management of mixed forest, the optimum efficiency of carbon absorption can be arranged with select and native symbiotic species, while producing wood and foods and building soil mass. In addition to economic (and atmospheric) services advanced management of mixed forestry and groves can tolerate and support ancient plant and animal species - for future generations - which have been critically devastated by the persistent strategy of individuating production goals.

We don't need to get any smarter at all, we need to get wiser. There is plenty enough grassland now, its time to grow trees.