Mrs. Loudon,
The Lady's Country Companion; Or…
“ No kind of animal manure should be used in a garden (except for making hotbeds) till it is thoroughly decayed and all fermentation is gone off; as while it is in process of decay the gases it evolves are decidedly hurtful to plants. Those manures which abound in nitrogen, such as stable manure and the dung of birds, are the strongest and most dangerous; as if used incautiously they will blacken and shrivel up the leaves of the plants to which they are applied. Guano and pigeon's dung are very much alike in their properties, and both are of an extremely caustic nature ”
