USES OF HEAVY LOAMS 



35 



though never apparently inadequate for present productiveness, in 

 the presence of so much lime. 



Along the base of the foot-hills of the Sierra there is in Fresno, 

 Tulare, and part of Kern county, a narrow belt, irregular in width, 

 of partly red and partly black clay or adobe, so highly calcareous 

 as to break up, when dry, into small fragments, producing a con- 

 dition that has received the name "dry bog." It is upon this that 

 the citrus orchards of the Porterville district are chiefly grown. A 

 white, calcareous marl sometimes occurs beneath this soil at vary- 

 ing depths, producing chlorosis or yellowing of citrus leaves when 

 reached by the roots. Westward of this "dry bog" land there is a 

 belt of reddish or brown loam soils, corresponding to those simi- 

 larly located in the Sacramento Valley, but generally more clayey, 

 and hence frequently designated as adobe by contrast with the 

 very sandy soils of the valley at large, although properly they 

 should be classed simply as clayey loams. This belt is eight to ten 

 miles wide in middle Tulare county and narrows to the north and 

 south. Here these lands have a gentle slope of ten to twenty feet 

 per mile from the base of the foot-hills, and appear to be underlaid 

 at a depth of twelve to fifteen feet by water-bearing gravel. The 

 soil is a reddish, more or less sandy, loam, changing little in its 

 aspect for several feet. Its adaptation to fruit is shown by the 

 products of the Lindsay region. 



CLAY SOILS 







Thus far a very small area of true adobe* soil has been employed 

 in horticulture. There is a great difference in the character of 

 what is known as adobe in different localities. Its color varies, as 

 the popular terms "black waxy," "black," "brown," and "gray" 

 adobe indicate. Its physical condition and chemical composition 

 also vary greatly. The black adobe of the east side of the Sacra- 

 mento Valley is easily tilled as compared with the gray adobe 

 on the west side, which is very refractory and often largely impreg- 

 nated with alkali. To render soil of adobe character useful for 

 fruit growing, this tendency to dry out and crack, thus allowing 

 evaporation from below as well as from the surface, must be over- 

 come. The discussion of this point belongs to the chapter on 

 cultivation. Adobe soils are, as a rule, rich and durable and there- 

 fore promise long fruitfulness to trees and vines with roots adapted 

 to heavy soils, but difficulty of cultivation, excessive retention of 

 water, and other evils are always present. Some suggestions on 

 the treatment of such soils will be given in the chapter on 

 fertilization. 



* This name has been erroneously applied to the loam commonly used in the 

 construction of adobe houses. Agriculturally, it means "a heavy clay soil," such as 

 could not be used in building. 



