How can moist grit be a danger to the birds? Pigeons who take in moist grit day in and day out, have a tendency to drink too much, and run the risk of getting sick. The best way to give grit is after every meal; give only a handful in a trough. You may be sure that in a short time, all the grit will be gone. In this way, the birds will have no chance to dirty the grit; at the same time, the grit will not have the opportunity to absorb moisture. If you have more than one loft at your disposal, try an experiment, and compare the condition of the birds after one week. According to Leopold Bostyn, there will be a remarkable difference.
Taken from 101 methods - Part 1 - third print
by Jules Gallez