Communications. 305 



to limited information or almost entire ignorance concerning the 

 following points : 



1. What are the mutual, physical and chemical reactions of the 

 various kinds of soil on the different materials we apply for fertiliz- 

 ing purposes? In other w^ords, what becomes of the fertilizer in 

 the soil ? 



2. In what jiaiiicular form do the different plants absorb the 

 various kinds of mineral plant food ? 



3. What are the specific functions of the different mineral sub- 

 stances of the plant food in the life of plants? What effect do 

 tbey produce when applied in different combination ? 



The history of all well conducted field experiments points upon 

 every page to the necessity of a closer study of every one of the 

 above specified points, before any material improvement in our 

 present mode of fertilizing our lands can be expected. The re- 

 cently introduced practice of supplying our markets with special 

 fertilizers for particular crops, if carried on beyond a limited gen- 

 eralization, deserves attention on account of the purpose of deal- 

 ers to meet the desire of the farmers, rather than on account of 

 either good economy or of a superior information in regard to the 

 special wants of the particular kind of crop raised under all condi' 

 tions. This remark applies with particular force to their use in 

 horticulture and fruit culture ; for the composition of most garden 

 crops, as well as of fruits, is far less known than that of the major- 

 ity of our farm crops. 



A few ash analyses of plants do not suffice to decide what kind 

 and what amount of mineral plant food a crop needs^ and still less 

 in what combination they produce the best effect. They simply 

 tell what kinds and amount the plants under examination contain. 

 It is a well established fact that the same variety of plants, when 

 raised upon different kinds of soil, or upon the same soil of a 

 varying degree of richness, may contain a widely differing absolute 

 amount of the same mineral constituents. There is, apparently, 

 in plant life, a possibility of an excessive consumption of food, as 

 we know there is in the case of animal life. Science has not been 

 able, thus far, to ascertain the existence of »any definite numerical 

 relation hetween the exact amount of essential mineral elements of 



20 — HORT. 



