76 CALIFORNIA VEGETABLES 



tables, therefore underdrainage of the orchard is a different propo- 

 sition from that of the garden. It should be stated for the distant 

 reader that the term garden in California is not understood to in- 

 clude fruit trees, except in villages or suburban places. 



The growing season of the vegetable crop is also related to 

 the matter of underdrainage. While the winter garden on a re- 

 tentive soil in a region of quite large rainfall, may be greatly im- 

 proved by underdrainage, the summer growth of the same plants 

 perhaps, and of field crops of shallow rooting vegetables, may be 

 benefited by such surface treatment during the winter as shall pro- 

 mote the absorption and retention of the whole rainfall in the soil 

 and subsoil. This practice may insure the perfection of a crop 

 without irrigation which could not be -grown on a less retentive soil 

 nor on one currently drained of its surplus water. 



The practice of irrigation may create a need for underdrain- 

 age which may not exist on land used for rainfall-gardening. If 

 the soil is naturally well drained this need will not however occur 

 unless the natural escape of surplus water has been destroyed by 

 rise of the bottom water which has, in some large districts in Cali- 

 fornia, followed excessive irrigation, and the seepage of water from 

 leaky ditches. Especially unfortunate too has it been that this rise 

 of the ground water has brought within reach of capillary action 

 and surface evaporation, alkaline salts which are destructive to vege- 

 tation. 2 But here again the growth of vegetables can be success- 

 fully pursued on lands with water too near the surface to favor fruit 

 trees, providing the rise of alkali does not occur. For the growth of 

 vegetables then, it is not generally imperative that the land be under- 

 drained even if irrigation is practiced though there are cases of 

 retentive soils in which this is desirable. In irrigation in a humid 

 climate where a heavy downfall of rain may immediately follow a 

 saturation by irrigation, underdrainage is a safeguard. California 

 with a rainless summer, is freed from this danger. 



Too great emphasis, even to indulgence in repetition, can 

 hardly be placed upon the point of view held in this work. We 

 are dealing for the most part with plants which are used before 

 maturity and in which large free growth of foliage, stem and seed 

 vessel are the points desired and not mature seed. Most of these 

 plants are also shallow-rooted and are concerned in the lower layers 



2 A full exposition of this matter may be found in the publications of 

 the University of California, Berkeley, on "alkali soils." 



