306 



THE IK RIG ATI ON AGE. 



soils generally, and it is of especial importance in rela- 

 tion to the position of the water table in the soil when 

 considered as a source of water supply or shallow root- 

 ing plants. Gravity draws the water downward toward 

 a water table, and in a dry subsoil it is capillary attrac- 

 tion that impels it down. But when the water in the 

 surface soil is less than that below an upward movement 

 begins as though nature were desirous of maintaining 

 an equilibrium which, scientifically speaking, it always 

 does, or attempts to do. However, there is a zone of 

 capillary action, a 

 space between the 

 water table and the ' 

 surface, in which 

 moisture rises and 

 with it carries food 

 substances to the 

 roots of plants. 

 Where the water 

 itself rises it means 

 more than capil- 

 lary attraction, . it 

 means a rise of the 

 water table through 

 addi tionsfrom 

 some new water 

 supply or satura- 

 tion of the soil, in 

 which case plants 

 are injured vitally 

 and drainage must 

 come to the rescue. 

 It is the rise of the 

 water table that i? 

 to be feared in irri- 

 gation. The rea- 

 son is because 1he 

 rise of alkaline so- 

 lutions is greater 

 than in the case of 

 pure water. Thus, 

 a fifty per cent so- 

 lution of sodium 

 chloride (common 

 salt) and sodium 

 sulphate will rise 

 faster than pure 

 water, and a much 

 stronger concentra- 

 tion of soda car- 

 bonate will rise still 

 faster. Hence the 

 necessity of pre- 

 venting soil satura- 

 tion and the main- 

 taining of a zone of 

 capillary action, in 

 which the roots of 

 plants may be fed 

 by material furnished through that action when they 

 would be killed if saturation were permitted to over- 

 come it. 



A few practical ideas may be gathered from the 

 foregoing which are worth considering: 



First It is evident that deep plowing will enable 

 the rainfall or the irrigation water to penetrate deeper 

 into the soil, in which case it will remain longer and the 

 effects of a small quantity of rain may extend over a 



SOME PUBLIC SCHOOLS, OGDEN, UTAH. 



40. Five Points. 



41. Grant. 



period long enough to mature a crop where half as 

 much iigain would show nothing. 



Second To be effective and beneficial to vegeta- 

 tion the water in the subsoil must be in constant motion. 

 When water ceases to flow in the subsoil streams, or 

 when capillary action is entirely suspended, the water 

 becomes stagnant, ceases to imbibe oxygen, nitrogen and 

 carbonic acid, and practically rots, causing vegetation 

 within its influence also to decay. .Running water com- 

 ing from the clouds or irrigating ditch enters the soil 



charged with gase- 

 ous matters above 

 specified, mixed in 

 their proper propor- 

 tions, and carries 

 along with it various 

 dissolved inorganic 

 .^ubstunces which 

 are not permitted 

 to be deposited out 

 of it while it is in 

 motion Hence, to 

 derive tire 1'nll bene- 

 fit of the water, the 

 land must bd 

 drained py^n where 

 irrigation is prac- 

 ticed so that the 

 surplus water, after 

 irrigation is stop- 

 ped, may find a 

 ready outlet. If 

 there should be no 

 t-urphi-s no harm is 

 dore by drainage 

 faclities; on the 

 contrary, the ten- 

 dency of all drain- 

 age is to <''pen the 

 soil below and 

 "draw" the mois- 

 ture, from above as 

 well ac to carry oil 

 the surplus water 

 in n soaked subsoil 

 if there be one. 

 Drainage does not 

 carry off moisture, 

 but unly the sur- 

 plus water; capil- 

 lary- attraction will 

 always hold the 

 moisture. 



Third When- 

 ever sufficient water 

 is added to the soil 

 to compensate for 

 loss by evaporation 

 from soil and plant 

 the business of the irrigator is accomplished. To 

 keep on adding, to soak the soil continually, would be to 

 injure vegetation as much as by furnishing too little 

 water, as it is only by keeping the surface soil loose and 

 finely pulverized the deeper the better that evapora- 

 tion from the soil may be retarded. 



As to the quality of the water the more impure it 

 is, particularly in organic matter, the better it is for 

 vegetation. There is no more impure water in the world 



42. Central. 



43. Madison. 



