Want to absorb 50 POUNDS of carbon a year? Plant a tree. Want to absorb several TONS of carbon per day? Then build a single carbon sequestration plant on the edge of town.
Assuming your numbers are correct... how many is several? Let's say 50. That's a pretty generous "several." So, you're looking at 100,000 pounds of carbon a day. That's a lot! To match that with trees, it would take... 2000 trees.
I'm willing to bet that I can obtain and plant 2,000 trees cheaper than you can build a carbon sequestration plant. (I'm willing to bet this is true for 20,000 trees, too. Maybe 200,000.) Your plant is made of concrete and steel, both of which produce carbon emissions. This page suggests that I'll need somewhere in the neighborhood of 11-12 acres of land for my 2k trees (for reference, Central Park is somewhere north of 800 acres), so that's pretty manageable. In addition, I'm willing to bet I can operate my trees for less money than you can operate your sequestration plant. Then, in X years, I can if I choose harvest these trees and turn them into lumber -- this, of course, does not release (all of) their carbon into the atmosphere. And I know this is subjective, but I tend to think trees (even tree farms) are more pleasant than industrial plants.
I'm not saying carbon sequestration plants are horrible ideas, but that trees probably win economically if the numbers you cite are in the right orders of magnitude.