202 FERTILIZERS 



lizers and do his own mixing before application, or he may 

 apply them singly to the soil. Each purchaser should decide 

 for himself which way is the best for him. There are 

 advantages and disadvantages in the use of either form. 

 Ready mixed, complete fertilizers are easily purchased in 

 any quantity, with a wide variety of combinations in nitrogen, 

 phosphoric acid, and potash, and in a fine, dry condition 

 which will run readily through a fertilizer drill. The mixture 

 is uniform throughout. On the other hand, they are expensive 

 and the farmer does not know what the various ingredients 

 are. Particularly in the case of nitrogen, the farmer does 

 not know the source. It may be readily available and it 

 may not, although in a majority of cases it is in a reasonably 

 soluble form. 



Home mixed goods are cheaper, the farmer knows the 

 source of his materials, and he can apply one element at a 

 time or only those which are necessary, without adding plant 

 food which is not needed in order to get that which is re- 

 quired. On the other hand, it is not always easy to get small 

 amounts of the separate ingredients — and this is because 

 the manufacturer prefers to sell the single ingredients in 

 mixed form if possible. Again, it is not always easy to get a 

 uniform mixture and this may result in uneven yields. And 

 finally the mechanical condition may be such that the 

 material can not be drilled, and even otherwise must be 

 broken up before use. This is due to absorption of moisture 

 as above indicated. 



154. Mixtures to be Avoided. — In mixing fertilizers care 

 must be taken not to put together two or more substances 

 which will cause loss of plant food or conversion to an 

 insoluble form. Lime in any form, or basic slag and basic 

 calcium nitrate, both of which contain an excess of lime, or 

 wood ashes, should not be mixed with ammonium sulphate, 

 or with organic nitrogenous materials, for loss of ammonia 

 would occur. The same compounds should not be mixed 

 with acid phosphate because reversion to the insoluble 

 form takes place and the fertilizer loses its immediate 

 value. 



Unless a mixture is to be used at once it is better not to 



