52 



the fruit. This, of course, is a very serious objection, to obviate" 

 which it might be necessary to reservoir the water so as to allow it to 

 warm before being applied to the trees. In furrow irrigation the 

 amount of soil soaked with the water is so great that the latter is soon 

 effectually warmed up, besides not coming in contact too intimately 

 with the main roots of the tree ; along which the water soaks very 

 readily when applied to the trunk, thus affecting their temperature much 

 more directly. It is for the fruit-grower to determine which considera- 

 tion should prevail in a given case. If the water-supply be scant and 

 warm, the most effectual use that can be made of it is to apply it im- 

 mediately around the trunk of the tree, in a circular trench dug for the 

 purpose. When, on the contrary, irrigation water is abundant and 

 its temperature low, it will be preferable to practice furrow irrigation, 

 or possibly even flooding. As to the more complete use of the soil 

 under the latter two methods, it must be remembered that while this 

 is the case in a horizontal direction, yet unless irrigation is practiced 

 rather sparingly under the furrow system, it may easily happen that 

 the gain made horizontally is more than off-set by a corresponding 

 loss in the vertical penetration of the root- system. This is amply 

 apparent in some of the irrigated orange groves of Southern California, 

 where the fine roots of the trees fill the surface soil as do the roots of 

 maize in a com field of the Mississippi States ; so that the plough can 

 hardly be run without turning them up and under. In these same 

 orchards it will be observed, in digging down, that at a depth of a few 

 feet the soil is too water-soaked to permit of the proper exercise of the 

 root functions, and that the roots existing there are either inactive or 

 diseased. That in such cases abundant irrigation and abundant fertili- 

 zation alone can maintain an orchard in bearing condition, is a matter 

 of course ; and there can be no question that a great deal of the con- 

 stant cry for the fertilization ot orchards in the irrigated sections is 

 due quite as much to the shallowness of rooting induced by over-irriga- 

 tion, as to any really necessary exhaustion of the land. When the 

 roots are induced to come to and remain at the surface, within a sur- 

 face layer of eighteen to twenty inches, it naturally becomes neces- 

 sary to feed these roots abundantly, both with moisture and with plant 

 food. This has as naturally led to an over-estimate of the require- 

 ments of the trees in both respects. Had deep rooting been encouraged 

 at first, instead of over- stimulating the growth by surface fertiliza- 

 tion and frequent irrigation, some delay in bearing would have been 

 amply compensated for by less of current outlay for fertilizers, and 

 less liability to injury from frequently unavoidable delay, or from 

 inadequacy, of irrigation. 



Conservation or Soil Moisture, — Alongside of economy in the 

 use of irrigation water, the conservation of the moisture imparted to 

 the soil either by rains or irrigation is most important ; critically so 

 where irrigation is unavailable. 



Utilization of winter rains and winter irrigation. — However strong 

 is the popular demand for storage of the winter rainfall and flood 

 waters, too many do not appreciate the importance of the storage they 

 can command without the use of reservoirs, within their own soil 

 mass. While there is a well-grounded objection to subjecting plough 

 land to the leaching action of the abundant rains in the humid region. 



