234 THE 1RRIGA Tl ON A GE. 



ly cultivated. The soil underlaid with hard-pan more easily parts with its moisture 

 than that which has no under crust. 



The three factors in evaporation are temperature, humidity and wind, and these 

 three can be determined with a fair degree of accuracy, and a knowledge of them is 

 most necessary in determining the fitness of a location for the growing of any crop* 

 That some crops require vastly more water than others is well, known to all of us, 

 and after noting the local conditions of soil and climate and deciding the kind of 

 crops to be grown, we could tell about how much water would be needed. 



It was interesting to note at the San Francisco convention the different results 

 recorded from a similar treatment of soils to conserve moisture. One man thought 

 it possible to so saturate the soil in winter and cultivate it in the warm months as to- 

 require little or no summer irrigation. The theory of thorough winter wetting, deep 

 spring plowing and perfect summer cultivatioo is right and should always be adopt- 

 ed where there is drainage, but while some lands will retain and furnish sufficient 

 moisture to fully mature deciduous crops, other soils, such as the foothill adobe, dry 

 out very quickly, though at the same time if saturated with water in the winter and 

 kept thoroughly cultivated in summer; they require comparatively little subsequent 

 additions of water to perfectly mature the crop. It should be noted in this connec- 

 tion, that whereas crops have been raised in Southern California on one-half an acre 

 foot of water and even less that is about one inch to ten acres yet the experience 

 of intelligent men is a safer guide than the theory of the scientist, and though in- 

 theory an inch may do service on twenty acres of land, yet no careful orchardist 

 would run this risk of raising a citrus crop on a less amount of water than one inch 

 to eight acres, and it is generally conceded, that for citrus fruits and alfalfa one inch 

 to six acres is the minimum and for deciduous one inch to ten acres. 



5. What water tax can the increased productiveness of the soil easily afford to 

 pay? and notice, please the emphasis upon the word '"easily." 



This problem can be readily solved when the preceding questions have been an- 

 swered, but, in addition, the personnel of the prospective settlers should always be 

 taken into account. Given every physical advantage, some men will make aflat fail- 

 ure of farming, while others will make a fair success under adverse conditions, as 

 another writer has said: 



"Farming under favorable conditions is a reasonably safe business, but it must 

 be conducted with intelligence and economy to ensure that its results will be satis- 

 factory and certain. The margin of profits is not generally sufficient to overcome the 

 effects of numerous blunders following each other in rapid succession. Therefore 

 any investment, which depends for its revenue upon the results of farming, to be 

 successful, must be conceived and conducted upon the lines of economy, which are 

 necessary to the success of the latter." 



The margin of profit, therefore, being as a rule moderate, the water tax must be 

 also moderate. A wide margin should always be reserved for land under the system 

 remaining unproductive. It requires a long time to fully develop an irrigation sys- 

 tem, many authorities saying from fifteen to twenty years is the shortest time a com- 

 plete development can be expected. The tax for water, therefore, must not only be 

 moderate, but the revenue must be expected to be furnished by not over two-thirds 

 or three-fourths of the total area of the system. Promoters of irrigation enterprises 

 in the past have usually deluded themselves by computing a speedy revenue from all 

 the system and many failures have resulted from this cause. 



In genei'al it might be a conservative estimate to say that the land can stand a 



