188 CALIFORNIA FRUITS! HOW TO GROW THEM 



SUB-IRRIGATION IN CALIFORNIA 



The word "sub-irrigated" is freely used in California to describe 

 land which is moistened below by underflow or seepage from streams 

 or springs, or from open irrigation ditches, traversing higher levels. 

 This land is sub-irrigated, it is true, but there is no system about it, 

 except the natural distribution of water, which is to seek its level. 

 Some of our most productive lands are of this character, and where 

 the soil and subsoil are fitted to the movement of this living water, 

 and not apt to retain it up to the point of saturation, most satisfactory 

 growth of deep-rooting field crops and of trees and vines are secured. 

 But this is not sub-irrigation in the ordinary signification of the term. 



Several systems of sub-irrigation by subterranean pipes have been 

 devised by California inventors, but none have passed beyond the 

 experimental stage, and no acreage has been continually operated. 



DRAINAGE IN CALIFORNIA 



There was for a long time a very erroneous popular generalization 

 that California soils do not need drainage ; that in a dry state the aim 

 should be to retain the moisture, not to part with it. It is, of course, 

 true that we have vast areas of naturally well-drained soil, upon which 

 any money spent for drainage would be in a great part thrown away, 

 but we have, also, both in the valley and on the hillsides, localities 

 where, by peculiar character and conformation of the subsoil, water is 

 held in the soil until evaporated from the surface, and the result is a 

 boggy, miry condition, which prevents proper winter cultivation, and 

 at the same time injures the roots of the trees or vines. This defective 

 cultivation, added to the puddling effect of standing water, makes the 

 soil dry out completely under the fervid sun of summer, and the result 

 is that the wettest soil of the winter is the driest in the summer, and 

 plants which are injured by soaking in winter suffer again from lack 

 of moisture and sustenance in summer. Thus it is a fact, clearly 

 proven by observation and experience, that thorough under-drainage 

 removes surplus water in winter, and ministers to the retention of 

 moisture in summer. More than this, a soil puddled by standing water 

 can not present its contents in available form for plant nutrition, and 

 besides, it loses the fertilizing effects of atmospheric currents, which 

 pass through an open, well-dried soil. Wet land is cold and late in 

 spring, and hot as a baked brick under the summer sun ; it is no fiction 

 of the imagination to say that well drained land is warm in winter 

 and cool in summer that is, cool to a degree which favors quick and 

 free root growth, and cool enough to escape the parching effect of 

 deeply baked soil. 



These, and a host of similar considerations, which have made 

 under-drainage popular in older countries, are of weight in California. 

 Possibly, as a rule, because of our vast area of deep, kind loams, the 

 proportion of land needing drainage in this State is less than else- 

 where, and yet there is a vast extent of country to be improved by 

 tilling. There have been large losses of trees from planting upon soils 



