posted 8 years ago
Disturbance is a factor of time and intensity, but is also influenced by what specifically you're intending to have disturbed. In general, though, more birds and/or more time will result in more disturbance.
I agree with the above--spread whole grains to encourage the birds to scratch (they call them "scratch grains" for a reason).
Ducks don't scratch, but they grow quickly, tramp down vegetation, and deposit prodigious amounts of manure, the latter two of which ought to help with improving ground.