226 A^^ALYSIS. 



that, so far as the processes of practical agriculture are 

 concernedj soil analysis is of but little, if any, value. 

 True, the amount of potash, for instance, which is 

 contained in the soil, may be determined with great 

 precision, and it seemed, at first, that tliis sort of 

 knowledge was enough for practical use ; but further 

 research and reasoning have shown that the question 

 of qiiantity is of no more consequence than tlie 

 question of condition. Of the potash in the soil 

 only the y^ or the -nmr P^^^ ^^ available to the 

 plants of a single year's growth ; — why the other 99, 

 or 999 parts are not available, and how they may be 

 made so, the soil analysis, from which so much was 

 hoped for, does not tell us. 



The causes of fertility and barrenness lie beyond 

 the reach of weight and measure, and it is an unfor- 

 tunate truth that, aside from a very simple indica- 

 tion of the internal character of om* soils, the science 

 of chemistry can only help us in studying their char- 

 acter when we follow it through the by-ways of its 

 more subtle reasoning. Much of what is known of 

 the manner in whicli the soil gives nutriment to the 

 plant has been learned from the bringing together of 

 the results of many experiments, — studying them by 

 the light of what chemistry has positively taught. 

 This knowledge is of great value, and is sufficient 

 to form the foundation of a really scientific agricul- 

 ture ; but there is no doubt that much more is yet to 

 be learned, and that we are still very far from know- 

 ing all that we must know of the use of manures, 

 t)\e functions of the soil, and the growth of plants. 



