

CULTIVATION. S3 



not be manured with too soluble plant food. Soluble 

 manures must be applied to crops with a short period of 

 growth or to crops which receive very little water. Crops 

 should generally be manured when they are growing, but 

 in the following cases the manure may be applied before 

 sowing. ( 1 ) When insoluble manures or only very slightly 

 soluble manures are applied, (2) when the manure is very 

 bulky as farmyard manure, (3) when the crop wih 1 receive 

 only very little water, e.g. wheat. The manures must be 

 applied to growing crops when the plants are free from 

 dew, and lumpy rich manures must be powdered before 

 application. Manures are mixed to obtain (1) a cheap 

 general manure, (2) a manure containing particular plant 

 foods (3) a manure containing the plant foods of different 

 degrees of solubility. After mixing the manures they should 

 be applied immediately to the soil, otherwise the constitu- 

 ents of the mixed manure may react on one another. Thus 

 when nitrate of soda is left mixed with superphosphate 

 there may be a loss of nitrogen. When sulphate of am- 

 monia is mixed with slag there may be a ]oss of ammonia. 

 When superphosphate is mixed for some time with slag 

 there is a loss of solubility. And generally when artificial 

 manures are left mixed they form hard lumps. Theoreti- 

 cally, the crops which require manure are (1) those which 

 produce valuable out-turns, (2) those which take much 

 plant food and have a long period of growth, like cotton 

 and sugar-cane, (3) those which take little or much plant 

 food but remain on the land only a short time, like maize, 

 sesame, and most vegetables, (4) those which have a weakly 

 developed root system, like flax. In every rotation a part 



