4 



when it should have its most liberal irrigation, After this it should 

 be allowed to become dry during fruiting and maturity. Of course this 

 represents ideal conditions which can not be completely secured in 

 practice, but it suggests how irrigation water may be greetly econo- 

 mized at the same time that the most favourable conditions of growth 

 are secured for the crop. 



This alternation of dry and wet periods has another important point 

 in its favour on ordinary soils. Hilgard has shown that it furnishes the 

 ideal conditions under which the soluble constituents of the soil rise to 

 the surface. The evaporating water leaves the matter which it holds 

 in solution at the place where it evaporates, i.e., at the surface of the 

 soil. It thus keeps the valuable fertilizing constituents of the soil 

 within easy reach of the crop. On "alkali" soils, however, under the 

 above conditions the corrosive poisonous alkaline salts would accum- 

 late at the surface to the destiuctlon or great injury of the crop. 



Methods of applying irrigation water, especially surface irrigation 

 and subirrigation, have been tested by a number of the experiment 

 stations in both arid and humid regions. The results have generally 

 been unfavourable to subirrigation. The laying of the underground 

 pipes necessary in this system is of course expensive, and, moreover, it 

 is difficult, if not impossible, in subirrigation to obtain a uniform dis- 

 tribution of the water throughout the soil on account of the fact that 

 while water moves up and down in the soil with comparative rap ; dity 

 it moves from side to side very slowly. The irrigation pipes being out 

 of sight it is impossible to note the movement of the water with accu- 

 racy. The soil immediately surrounding the pipes may become exces- 

 sively wet, while a large proportion of the soil between the pipes is 

 insufficiently irrigated. Moreover a considerable amount of the water 

 may pass down into the lower layers of the soil without being of the 

 slightest benefit to the crop. King found that a given amount of water 

 was much more effective in increasing the yield of corn when applied 

 by surface irrigation than when applied by subirrigation. 



Eane, of the New Hampshire Experiment Station, in experiments 

 with celery on clay loam soil " with water applied both through ditches 

 for surface irrigation &nd through tiles below the reach of the plough 

 for subirrigation" found that " the latter system required much more 

 water than the former for the same results." 



[A method of tile irrigation which he has found to possess decided advantage 8 

 over ordinary subirrigation] was to place common porous 2£ inch drain tiles in 

 a continuous row, end to end, on the surface of the soil, vegetables being planted 

 on eithtr or both sides of the line. The tiles were 1 foot long, and by pouring in 

 the water at one end of the line it was distributed at the joints throughout the 

 length desired when the opposite end was stopped up. Take celery as an example 

 crop for irrigation on uplands. We plant the celery as above stated, and while it is 

 young we have simple surface irrigation ; but as the crop grows we bank it up, 

 and finally have the tiles covered, and thus have subirrigation. The tiles are 

 cheap and last indefinitely. When the celery is harvested, the tiles are dug out 

 also and piled up or used for subirrigation in the greenhouse beds. Potatoes and 

 various other crops can be grown in the same way. The celery watered this year 

 grew well and did not rust. Besides this, we were able to water twenty times as 

 much space in the same time as in the ordinary way with ditches. Besides sav- 

 ing time, this plan delivers water where it is most needed, and we have reason to 

 believe is fully as economical with water as with time. 



Experiments during two seasons have shown that with this method 



