21 



LATE PROGRESS IN THE APPLICATION OF 

 SCIENCE TO PLANT CULTURE. 



Extract from a Lecture delivered before the Massachu- 

 setts Horticultural Society, February 11, 1888, by 

 Prof. W. O. Atwater of Middletown, Conn. 



Permit me to recapitulate at the outset some of the funda- 

 mental principles of plant nutrition as applied to the ingredi- 

 ents of the food of plants, their sources, and their artificial 

 supply. 



1. Plants, like animals, require food for life and growth. A 

 part of the food of plants comes from the atmosphere ; the 

 rest is furnished by the soil. No ordinary cultivated plant can 

 thrive without a sufficient supply of each of a number of sub- 

 stances needed for its food. With an abundance of all these, in 

 forms in which the plant can use them, and with other circum- 

 stances favorable, the crop will flourish and the yield be large. 

 But if the available supply of any one of them be too small, a 

 light yield is inevitable. If all the other conditions for a profit- 

 able crop of corn, potatoes or other plants are fulfilled in the 

 soil, except that potash is deficient, the crop will surely fail ; 

 but if the potash be supplied, the yield will be abundant. 



2. The most important soil ingredients of plant food — the 

 ones that the atmosphere cannot supply at all, or not in sufficient 

 quantity, and which the soil or fertilizers must supply, so that the 

 plant can absorb them through its roots — are potash, lime, mag- 

 nesia, iron, phosphoric acid, sulphuric acid, chlorine, and some 

 compound of nitrogen. Plants also take silica, soda, and some 

 other materials from the soil, but these are needed only in minute 

 quantities, or not at all. 



3. In removing crops from the soil ; we take away plant food. 

 This is the chief cause of soil exhaustion. Lack of fertility is 

 commonly due, in large part or entirely, to lack of plant food. 



4. Soils vary greatly in their capabilities of supplying food to 

 crops. Different ingredients are deficient in different soils. The 

 chief lack of one may be potash, of another phosphoric acid, of 

 another several ingredients, and so on. 



