[alisonwo]

I have read that dolomite lime is the only substance that can be put onto the hens soil in the outside run to neutralise the hens poo and sweeten the soil without it burning them.  Does anyone know where I can buy some? thanks

[Lindeggs]

Garden centres often sell dolomite as it is used to sweeten garden soil (especially for plants that don't like acid soils). 

I use it for lots of purposes around the garden, including in my worm bin and to sweeten the compost if I'm putting a lot of citrus in there.  I can verify that it is harmless to sprinkle in your chicken run and won't hurt the chickens.