There was an 'excess' of 10 bushels (over what was needed to fill the bin).
Eating anything 'in excess' [=in overly large amounts] can be bad for you.
The movie embraces all the worst 'excesses' of popular American culture.
(..) Counting on you. Whoo! So, yeah, I blew myself up. Best guess... I forgot to account for the excess oxygen... That I've been exhaling when I did my calculations. Because I'm stupid. Yeah, I'm gonna get back to work here... (..)2015 The Martian