SOIL SURVEY OF THE EEDDING AEEA, CALIFORNIA. 17 



pact roots do not penetrate deeply, rendering the trees and plants 

 particularly sensitive to drought if not irrigated. 



The agricultural value of this soil type and its adaptation to crops 

 is thus in a great tlegree dependent upon the occurrence and position 

 of the hardpan. The soil is not adapted to the culture of prunes or 

 other deep-rooted trees. If the hardpan is nearer the surface than 

 4 or 5 feet the planting of peaches or vines is attended with consider- 

 able risk, unless the layer is soft enough to permit the roots to pene- 

 trate it or unless irrigation is practiced. With adequate facilities 

 for irrigation the deeper phases of the soil type are among the most 

 valuable soils for peach culture in the Redding area. Grapes could 

 undoubtedly be produced profitably in such areas in commercial 

 quantities without irrigation by proper care and frequent cultiva- 

 tion during the dry season. Strawberries and bramble fruits yield 

 abundantly, and if irrigated the shallower phases of this soil not 

 adapted to tree fruits could be utilized for these small fruits. 



Where orchards are to be set out the shattering of the underlying 

 impenetrable hardpan by the use of moderate charges of explosives 

 is sometimes resorted to in other districts with beneficial results. 

 For this purpose Hilgard" recommends the use of from one-half to 

 three-fourths pound of No. 2 dynamite placed from 3 to 5 feet below 

 the surface. Enough should be used thoroughly to break up the 

 formation, otherwise in particularly dense strata of considerable 

 thickness the explosion may merely form potholes in which perco- 

 lating soil waters may collect, and give rise to water-logging and 

 unsanitary conditions about the roots. 



The careful examination of the soil with reference to hardpan and 

 adaptability for irrigation is obviously of great importance for fruit 

 growing in the uplands. It may be said, however, that with proper 

 irrigation and cultural methods the fruit industry in the Happy 

 Valley section and in other upland districts where the deeper soils 

 are found is a reasonably safe and profitable investment. 



A fine silty phase of this soil type occurs in which surface gravel 

 is absent, the color of the soil ranging from a light yellowish gray to 

 dark brown. This material is shallow and underlain by the typical 

 soil or by hardpan. The surface is frequently puddled and in the 

 dry season baked and checked. Such soil bodies occur upon the ele- 

 vated upland plains in small potholes or local drainage depressions, 

 usually a few rods in diameter and rarely covering an acre in extent. 

 In such local depressions percolation of rain or drainage waters is 

 usually arrested by the underlying hardpan, leading to the forma- 

 tion of pools during the rainy season followed by a baking of the soil 

 when dry. 



aSee "Soils" by E. W. Hilgard, p. 181. 



