394 SOILS 



Root and tuber crops are more variable in their 

 demands. Potash should be the most important 

 ingredient of a fertiliser for sweet and Irish pota- 

 toes the sulphate is preferred to the muriate; 

 phosphoric acid for turnips and nitrogen for beets 

 and carrots. Root crops need quick-acting fertiliser. 



Fruits. The period of growth of tree fruits is 

 extended over a longer time than other farm crops, 

 and so slow-acting fertilisers may be used upon 

 them to advantage. The small fruits, however, 

 as strawberries and raspberries, must have quick- 

 acting fertilisers. Potash is of special importance 

 in a fruit fertiliser. 



Market-garden crops in which the chief object 

 is to secure the crispness and tenderness that comes 

 from a rapid growth, as celery, radishes, cabbage, 

 lettuce, etc., must have an abundance of quick- 

 acting fertiliser, particularly of nitrogen. 



Cotton especially enjoys an abundance of phos- 

 phoric acid. 



These general suggestions on the fertilising of 

 different crops merely indicate what many people 

 have found profitable. They are subject to many 

 exceptions, depending upon the kind of soil on 

 which the crop is grown. So it all comes back to 

 the elemental problem of questioning the soil. 

 This will ever be an experiment for each farmer; 

 no one else can perform it for him. 



THE RELATIVE IMPORTANCE OF THE 

 THREE PLANT FOODS 



Phosphoric acid is regarded by many as the 

 most important of the three plant foods; not be- 

 cause it is more essential to the profitable growth 

 of crops, but because it is more likely to be lacking 



