14 THE PRINCIPLES OF 



we want to grow a good crop of wheat we must apply nitrates, 

 not silica and not potash. Again if we want to grow a good crop 

 of turnips we must give phosphates and not potash, and not 

 even is it necessary to give nitrogen. The science of manuring, 

 or the principles which should guide us in the application of 

 fertilizers of all sorts, including farmyard manure, ought to 

 occupy the attention of all agricultural classes, and if this 

 suggestion is carried out, the result will be not only a more 

 valuable instruction, but an increase in the respect of practical 

 men for scientific knowledge. Instead of following the lines 

 which I have endeavoured to lay down, we find that agri- 

 cultural instruction is narrowed to a mere enunciation of 

 certain somewhat crude ideas conceived by theorists with 

 reference to chemical changes which are alleged to take 

 place, but which probably or possibly never take place, and 

 which, if they do take place, have little to do with the 

 practice or the control of the practice of agriculture. Among 

 such ideas I would rank the formation of double silicates in 

 the soil, which are, to say the least, doubtful compounds, 

 which possibly do not exist. Again, the struggles or conflicts 

 which appear according to some of our candidates to be 

 waged in the soil are most remarkable one constituent of 

 plant food ousting another; nitrate of soda acting as a 

 stimulant or whip; lime feeding voraciously upon organic 

 matter; alumina politely handing in recruits to the hungry 

 roots of plants, all apparently bustle and activity below 

 ground, and not entirely free from party bias, greediness, 

 voracity, friendship, and nervousness, as though the soil were 

 imbued with vitality. The passage of dormant into active 

 plant food is spoken of in language calculated to give the 

 impression of actual awakening from sleep to a sense of 

 responsibility. The manner in which the change from 

 " dormant " to " active " is worked by examinees is very trying 

 to an examiner. It appears to be the sole idea of both 



