Extension Work in Horticdlture. 185 



3. What stock, and how many, can the fruit-grower with 80 acres 

 of land keep witli profit ? How to procure good stock. 



Chemistry of the Soil and of the Grape. 



(Given at first Fredonia School.) 



(By Professor Caldwell.) 

 I. The Chemistry of the Soil. 



(a) An arable soil in its best condition for producing crops contains 



seven essential parts : 

 (1) Clay ; (2) sand; (3) assimilable plant food; (4) moisture; 

 (5) humus; (6) air; (7) micro-organisms. 



(b) Clay furnishes the substantial medium required by the plant 



as a root-hold, and is also a storehouse for preserving some of 

 its food from waste. 



(c) Sand is required to inake more friable and porous the too stiff 



and compact soil that clay alone would yield. 



(d) The most important part of the food of the plant that is in the 



soil consists of nitrogen, lime, potash and phosphoric acid 

 forming a very small part of the soil, and mostly insoluble, 

 or unassimilable. 



(e) Plant growth involves unceasing chemical change in the soil as 



well as in the plant itself, and this cannot go on without 

 water, nor can plant food be taken up without it. 



(f) Humus or decaying vegetable and animal matter is, as it 



decays, a source of carbonic acid, which is an important sol- 

 vent of plant food ; humus also itself contains plant food, 

 and it is a loosener of the soil. 



(g) Air is necessary in the soil for its oxygen, without which the 



humus is not formed, and cannot decay, 

 (h) An important feature of this decay is the progress of nitrifica- 

 tion ; this does not go on without the assistance of micro- 

 organisms. 

 II. The Chemistry of the grape. 



(a) The vine as a whole is composed of three parts : Water, com- 



bustible matter, and incombustible matter. 



(b) The largest part of the dry plant is combustible, consists of 



what is called carbonaceous matter, and is derived from the 

 air. 



