396 SOILS 



becomes available quite slowly. The more soluble 

 a fertiliser is, the more necessary it is to apply it at 

 or about the time it will be needed most by the 

 crop. 



As a class, the nitrogen fertilisers are more 

 quickly soluble and more apt to be lost by leaching 

 than the other plant foods; they should usually 

 be applied in the spring or during the summer, as 

 needed. The potash and phosphoric acid in 

 fertilisers are not subject to serious waste; they 

 remain in the soil until taken out by plants, com- 

 bining with lime, silica and other minerals in the 

 soil. This is called the "fixing" of these plant 

 foods. It usually takes place within a week after 

 the fertiliser is applied. With the exception, in 

 some cases, of raw bone and raw mineral phos- 

 phates, it is best to apply fertilisers in the spring. 



The special needs of crops also influence the 

 time for applying fertilisers. Many crops need 

 a special stimulus at certain times and under cer- 

 tain conditions. Thus, if wheat on light land has 

 passed through a severe winter it may need an 

 application of nitrogen in the spring, in addition 

 to the regular fertiliser provided for it the fall pre- 

 vious. Or again, beets that are being forced for 

 bunching will profit by several light dressings [of 

 nitrogen at intervals of two weeks, instead of put- 

 ting all the fertiliser into the ground at planting 

 time. 



HOW TO APPLY FERTILISERS 



The method of applying fertiliser is mostly a 

 matter of expediency. In a majority of cases it is 

 best to broadcast it over the entire surface after 

 plowing and before the last harrowing. Most of 



