78 CALIFORNIA VEGETABLES. 



is an exaggeration anywhere in the world probably, be- 

 cause there are areas of naturally well-drained soil every- 

 where. Enough has been said of California garden soils 

 to show that the most of them are of this character and 

 that no probable amount of rainfall would injure them. 

 The exception has also been sufficiently characterized in 

 the chapter on soils. 



To reach assurance for or against underdrainage in par- 

 ticular cases one has to consider the soil, the rainfall, 

 the character of the root growth to be ministered to, the 

 growing season of the crop, and the practice of irrigation. 



The mere amount of rainfall is so intimately related 

 to soil texture, depth, subsoil, slope, and exposure that, 

 considered alone, it affords no guide whatever to the 

 need of artificial drainage. There are many situations re- 

 ceiving an annual rainfall of forty to sixty inches which 

 not only do not need underdrainage but, on the other 

 hand, irrigation must be employed as early as May to 

 supply the requirements of shallow-rooting plants. There 

 are either coarse, leachy soils or else shallow loams lying 

 upon sloping and porous bedrock. Leaving these out of 

 consideration, it is doubtful whether any land, even of 

 quite retentive character, receiving a rainfall of not more 

 than twenty-five inches, distributed as California rainfall 

 usually is, needs underdrainage for garden purposes. Of 

 course, this claim clearly presupposes that the land in 

 question does not receive any considerable amount of 

 water by overflow or underflow by seepage from higher 

 land. Any such rainfall as noted can probably be con- 

 trolled by such surface use or surface release as have 

 already been described, or by such early and deep culti- 

 vation as the garden should receive, there can be stored 

 in the soil the moderate residuum remaining from the 

 amount of rainfall indicated, and under favorable circum- 

 stances a greater rainfall can be thus disposed of. 



Deep-rooting plants like fruit trees will of course be 

 injured by saturation of the subsoil which would not in- 



