16 LANDSCAPE GAEDENING 



the soil^ He considers carefully such questions as 

 soil drainage and soil composition, from the 

 physical and chemical point of view, to determine 

 what plants are best adapted to each particular 

 locality. This consideration is most essential in 

 the planting of such species as the rhododendrons, 

 which require that the soil contains no lime, but 

 must possess the presence of humus. In soil 

 drainage the landscape-architect is concerned 

 chiefly with the draining of large areas for open 

 lawns, leaving undrained spaces to be used for 

 bogs and rock-gardens. 



Agriculture is also concerned with soil cultiva- 

 tion, or the methods of caring for the planted 

 areas in such a manner as to secure the best 

 growth of plant materials. Another important 

 interest included under the head of agriculture is 

 plant pathology, under which come spraying and 

 the control of insect pests. 



HORTICULTURE 



(In horticulture the landscape-architect is con- 

 cerned with a study of the plant as an individual, 

 its growth, propagation, the formation of new va- 

 rieties, pruning, spraying, and the best methods of 

 planting and handling.^ 



