70 THE RAISIN INDUSTRY. 



Muscat grape has proved a failure. The best Riverside soil is red or 

 chocolate-colored sandy loam, so often spoken of. Towards Rincon 

 we find alluvial bottom soils producing grapes of superb quality and 

 size. The soil of the San Bernardino district resemble the red Fresno 

 soils, while the white ashy soil is not found there. 



El Cajon. The El Cajon valley soils are of three or more kinds: 

 Rich red clay mixed with gravel, with the color changing from lighter 

 chocolate to deeper reddish. This is a very desirable soil, a steel gray 

 or slate gray adobe with much gravel of a coarse nature; a black adobe 

 with some gravel; an alluvial sandy loam consisting of decomposed 

 granite mixed with much vegetable matter and humus. The El Cajon 

 soils, while sandy and gravelly, produce exceedingly sweet and highly 

 flavored grapes but comparatively small crops. 



Subsoils. The subsoil in a raisin vineyard is of great importance. 

 Properly irrigated soils, if they are sufficiently rich, need not neces- 

 sarily be very deep, as the raisin grapes, especially the Muscat, seldom 

 extend deeper than eight feet below the surface. Even from four to 

 five feet of rich soil may be considered as enough in irrigated vine- 

 yards, where the water is abundant. In poorer soils, or in districts 

 with less irrigation, the roots of the vines penetrate much deeper, and 

 the importance of the subsoil in such cases is apparent. Any rich 

 subsoil will serve our purpose. It is always best to thoroughly inves- 

 tigate the subsoil before the vineyard is planted, and in doing this the 

 following points must be considered: The subsoil should be as rich as 

 possible, and there should, in no instance, be less than four feet of rich 

 top soil. Very sandy soil or pure sand is not a proper subsoil for raisin 

 grapes. Such soil will cause the top soil to dry too quickly after 

 each irrigation, and will cause the top soil to leach out, while it besides 

 gives no nourishment to the vines. Hardpan is not desirable, not even 

 admissible, except in places * that are or will become subirrigated. 

 Alkali or salty subsoils will soon spoil the quality of even the best top 

 soil. This especially is the case in irrigated districts, where the salts 

 of the subsoil are carried to the top by the rising waters or by the 

 continued irrigation. Hardpan which readily dissolves when wet is 

 not injurious. 



Hardpan Soils. While I have alluded to them already, a few more 

 remarks on these soils are here in place. The hardpan consists of a 

 stratum of hard soil or hard rocky substance below the top soil. The 

 depth at which the hardpan is found varies. In places where it is 

 situated eight or ten feet below the top surface it does but very little 

 harm, and may even prove beneficial in localities where water for irriga- 

 tion is scarce, as it checks too rapid drainage. If the hardpan is 

 situated closer to the top soil, it may seriously interfere with the 

 vines, and if too close, or say within two or three feet from the top, 

 it makes such soils entirely unfit for raisin grapes. If situated 

 somewhat lower down, say from four to six feet, the hardpan does no 

 great harm in subirrigated districts, while, in places where irriga- 

 tion is not used, it leaves the top soil too shallow and too dry. But 

 allowance must always be made as to the nature of the hardpan. Some 

 varieties of hardpan are so hard that they can best be compared to 



