COMPOUND AND MISCELLANEOUS MANUEES 289 



crops alike. Even in the case of those intended for par- 

 ticular crops, it is evident that the nature and require- 

 ments of the soil cannot be taken into account in pre- 

 paring the mixture. Compound manures are, however, 

 very convenient for those who, like .gardeners, use only, 

 small quantities, and for any who do not understand the 

 nature of the different kinds of artificial manures. If 

 they are to be employed it will generally be found cheaper 

 to buy them from a manufacturer than to attempt to 

 prepare them at home. 



MISCELLANEOUS MANURES. 



Common salt, gypsum, copperas and some other sub- 

 stances of minor importance which are occasionally 

 applied to the soil are commonly classed together as 

 miscellaneous manures. They contain no nitrogen, phos- 

 phates or potash ; some of them are destitute of any 

 essential element of plant food and their action, if any, 

 must be attributed to other causes. 



Common Salt. The presence of common salt in kainite 

 is considered objectionable because its effects on most 

 plants are deleterious rather than beneficial. Some 

 crops, it is true, can withstand the application of con- 

 siderable quantities, and others, e.g., mangolds, aspara- 

 gus, etc., actually appear to thrive on it. Common salt 

 consists of sodium chloride, and the deleterious effects 

 appear to be due to the chlorine. Other chlorides have 

 an equally bad effect ; that of calcium chloride is worse, 

 probably because that compound is more soluble. Other 

 sodium compounds, e.g., sodium sulphate, seem to 

 be harmless. It does not appear that their presence 

 in the soil is of any advantage to the majority of crops, 

 but it is possible that the beneficial effects of common 

 salt on mangolds may be due to the sodium. On the 



S.M. U 



