This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The grower who wishes to save money by purchasing only the manures he requires should also make himself acquainted with the different chemical effects of one manure upon another; otherwise it may happen that what is saved in one direction may be lost in another. If certain manures are mixed with others, the fertilizing value may be either neutralized or lost altogether, owing to chemical changes taking place. The following hints as to the manures that may or may not be mixed with each other may be useful: -
Farmyard or stable manure should not be mixed with lime, because the lime drives off the ammonia gas into the air and thus causes it to be lost.
Nitrate of soda should not be mixed (except in small quantities) with superphosphate, as the sulphuric acid in the latter sets free nitric acid in the form of poisonous fumes, and the nitrogen is lost.
Sulphate of ammonia should not be mixed with basic slag or nitrolim, because the free lime in these manures would drive off the ammonia gas, and, if in an enclosed place, is so overpowering as to be dangerous.
The following mixtures may be made with safety: -
Nitrate of soda with basic slag, nitrolim, meat meal, kainit.
Kainit or muriate of potash may be mixed with superphosphate, although a little hydrochloric acid may be given off in fumes. [J. w.]