I have a plastic composting bin courtesy of Milton Keynes council ( dont ask!!) with a lid and unless I put about 20 litres of water into it every week it just dries out.
I assume it has an open bottom (if I can put it that way) ::) in which case I guess the water would just run througjh the compost and leach away into the ground ?
Perfect snake breeding ground 
As for weeds the chickens and turkeys eat all of them, so the only stuff I have left to compost is tea bags, about 200 a day
Do you think your chickens and turkeys could manage 4 hectares ? :-/
I might end up just growing potatoes in it.
The donkeys eat all the olive prunings.
I do use the donkey manure as a mulch, even the fresh stuff, as its not acidic like horse manure. It helps keep the soil moist so less watering.
I put my brash through a shredder and use that for mulch.