However, we also use broken to imply something is not in proper working order. In our case a broken heart is a spiritual necessity. I will suggest that broken hearts do not remain lacking forever they will eventually be filled.

To use Alma’s analogy a seed growing in a broken heart will begin to swell.

Your comparison to breaking ground makes sense for those of us with hard hearts that must be broken like the soil or a stubborn and undisciplined horse.

You quoted 3 Nephi 9:20.
On what altar do we offer this sacrifice and is a contrite spirit any different than a broken heart?

The use of farming analogies is good because Jesus often made such comparisons himself because they were so accessible to most people.