308 LUTHER BURBANK 



better for early crops. A slope toward the sun 

 even of only one or two inches to the rod makes 

 a difference in earliness of a week or more. This 

 has been proven by many experiments. 



The northern and eastern slopes hold the 

 moisture longer, but do not warm up so quickly. 

 For this reason they are able to withstand 

 drought better, but never yield as early crops as 

 the southern or western slopes. 



A clay subsoil a foot or more below the surface 

 with a sandy surface layer is the ideal soil for 

 fruit trees. In fact, such a soil is good for most 

 any crop. If the subsoil slopes sufficiently to 

 drain off surplus water, such a soil will always 

 produce good crops. 



Chemistry and Physics of the Soil 



Plants secure their food from the soil through 

 minute hairline appendages on the roots, known 

 as root hairs. The roots thus serve only as 

 canals. The root hairs collect the food. 



Because of the extremely small size of these 

 root hairs it is plainly seen that any food used by 

 the plant must be thoroughly dissolved before 

 being taken up. These root hairs are deciduous 

 like the leaves, and are only active to any extent 

 where the leaves are in existence and active. All 

 food taken up by the roots is secured in solution 



