If the moisture content of the compost is constant, but the compost itself varies in structure and extent of colonization, the first time water is given has an immense influence on production. Too much water immediately after or during filling with badly incubated compost will cause damage.
Good assessment of the compost using colour smell and structure as indicators is essential. A reliable and good indicator of the extent of colonization by mycelium in compost is the pH value. For each day of incubation the PH value should decrease by 01. With an incubation period of 15 days (minus day 1 and day 15) the pH at the end should be 13 points lower than at inoculation.
If in any doubt, don't spray. Water is absorbed quicker if the compost structure is shorter than usual. Finally if the upper layer is compacted too much during filling a compost layer that is too wet and with too little activity will occur a few days after spraying. Keep your wits about you with water!
Jeroen van Lier, C point