PLANT NUTRITION. 31 



ON PLANT NUTRITION. 



By Prof. Levi Stockbridge, of the Mass. Agricultural College. 



As has been announced in your programme, I am to speak to 

 you this evening upon the subject of plant nutrition or the feeding 

 of plants, a subject which has attracted the attention of the 

 scientific men of both Europe and America, and which as matter 

 of pure scientific inquiry and investigation, is one of utmost im- 

 portance. But to the farmer, to the practical man, to him whose 

 business it is to make plants as crops, it is a great deal more than 

 this. For as he is enabled to apply the principles of plant 

 nutrition right or wrong, whether he knows those principles or 

 not, depends the result in his life work which may be success or 

 failure. 



We agree that the investigation of the principles of plant 

 nutrition is a subject altogether of modern inquiry, and the 

 opinions of scientific men for forty years have been in a sort of 

 transition state in regard to it. 



The time was when it was believed that to afford food for plants 

 there should be a large percentage of organic matter in the soil, 

 and that the value of all land depended on its quantity of organic 

 matter. But when the chemist got at his work and showed that 

 some soils were wonderfully fertile with but two or three per 

 cent, of organic matter, and others very infertile with from ten to 

 fifty per cent., the old organic theory was driven to the wall never 

 to be revived. 



Again the theory was advanced, and supported too by the 

 highest scientific authority, that for the development of plants the 

 mineral elements were required, that the ash constituents of the 

 soil were first exhausted, and that to maintain it in perennial 

 fertility it was only necessary that these should be returned. 

 This theory, however, was met by the counter one that nitrogen 

 was the essential element, and between the advocates of these 

 two theories the contest went on year after year, and I am sorry 

 to say it was sometimes an acrimonious one. On the one side 



