Depending on how the compost is used, sure, but you have to do a lifecycle analysis to determine whether this ultimately results in more carbon fixed than carbon (or carbon-equivalent greenhouse gases) released.

https://pubs.acs.org/doi/suppl/10.1021/acs.est.2c05846/suppl...

> Offsetting nitrogen fertilizer use is particularly important with respect to net GHG emissions because fertilizer production (e.g., urea) is energy- and emissions-intensive to produce.