32 CALIFORNIA FRUITS: HOW TO GROW THEM 



as upland loams formed in place by the disintegration of local rock 

 formations. The famous fruit region extending from Oakland south- 

 ward nearly one hundred miles, including the Alameda and Santa 

 Clara Valleys, has very large areas of alluvial soil, ranging from deep, 

 rich blackish loams used for vegetables and small fruits to lighter 

 loams resulting from intermixture of sediment brought by streams 

 from adjacent hillsides with the clay -of the valley bottom. It is to 

 these deep, rich alluvial deposits that the region owes its great reputa- 

 tion in fruit lines. 



CLAY LOAMS 



Of loams containing sufficient clay to render them somewhat heavy 

 and tenacious, there is also a great variety in California. Their suit- 

 ability for different fruits depends upon selection of roots adapted to 

 their character and upon the depth and degree of retentiveness of the 

 soils themselves. They are more difficult of tillage than the free loams, 

 but offer some compensation therefor in their richness and durability. 



Clay Loams of the Foothills and Valley Border. The soils of 

 the foothills of the Sierra Nevada, throughout its courses along the 

 great valley, vary from a moderately clayey loam to a heavy, though 

 not uncommonly gravelly, often orange-red clay. This character seems 

 to be sensibly the same, whether the soil be derived from the decompo- 

 sition of the ancient slate bed-rock or directly from the dark-colored 

 granites, thus creating a presumption that the two rocks are closely 

 related. The soils are highly charged with iron to the extent of from 

 seven to over twelve per cent, which being finely divided, imparts to 

 them the intense orange-red tint. The soils of the foothills agree with 

 the soils of the valley in having a good percentage of lime, while the 

 supply of potash and phosphates, as well as of organic matter, is 

 smaller, and sometimes low, though never apparently inadequate for 

 present productiveness, in the presence of so much lime. 



Along the base of the foothills 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 condition that 

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

 citrus orchards of the Porterville and Mt. Campbell districts are chiefly 

 grown. A white, calcareous marl sometimes occurs beneath this soil 

 at varying depths, inducing chlorosis or yellowing of citrus leaves, 

 owing to its impervious nature which does not allow of good drainage 

 and therefore kills the roots through suffocation and acid production. 

 Westward of this "dry bog" land there is a belt of reddish or brown 

 loam soils, corresponding to those similarly 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 foothills, and appear to be 

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



