PULSE OF THE IRRIGATION INDUSTRY. 



CULTIVATION AFTER 

 CATION. 



1RRI- 



AS generally applied irrigation leaves 

 the soil compact and in condition to 

 become very hard as it dries says the Field 

 and Farm. The compacting of soil after 

 irrigation is remedied by cultivation of the 

 surface as aoon as the soil reaches a condi- 

 tion to be worked, as explained in an irri- 

 gation paper of the United States geologi- 

 cal survey. This cultivation after irriga- 

 tion serves the double purpose of checking 

 the growth of weeds, which is sure to be 

 copious, and of leaving a soil mulch of 

 loose earth over the surface, which pre- 

 vents the rapid evaporation of the moisture 

 stored in the siibsoil. The importance of 

 cultivation after each irrigation cannot be 

 overestimated. 



In general the application of water with- 

 out the subsequent cultivation is of little 

 value, and, indeed, in many cases it is ab- 

 solutely detrimental. The general experi- 

 ence is that, with the average soil, after 

 the application of water the ground soon 

 becomes very dry and very hard and evap- 

 oration proceeds to rob both the soil and 

 the subsoil of moisture with surprising 

 rapidity. If the irrigator thinks to rem- 

 edy the case by another irrigation, he usu- 

 ally only makes the matter worse, for the 

 soil by this time, especially that along the 

 borders of the furrows, has become quite 

 thoroughly puddled, so that the second ap- 

 plication of water with no intervening cul- 

 tivation amounts to little more than flood- 

 ing over the surface, with but slight mois- 

 tening of the under soil. 



It may be stated in general that the ir- 

 rigator who fails to cultivate soon after- 

 each irrigation will make a failure of ir- 

 rigation. Indeed, in almost any part of 

 the great plains, if either irrigation or cul- 



tivation must be omitted, it will be better 

 to omit the irrigation than the cultivation 

 for all such crops as admit of cultivation. 

 The case with meadows and with sowed 

 crops in general is somewhat different, the 

 soil being to some extent protected and 

 supported against excesssive settling by 

 the general distribution of the plants and 

 roots. 



It is not improbable, however, that in 

 the case of annuals, as wheat, rye, barley 

 and oats, it will be found profitable to 

 make the drill rows far enough apart to 

 admit of cultivation while the plants are 

 small. In she case of meadows, especially 

 with alfalfa, the influence of the extensive 

 root growth is such as to keep the soil in 

 condition favorable to rapid growth with- 

 out cultivation. It is noticeable, however, 

 that even alfalfa shows the marked influ- 

 ence of cultivation where a meadow of this 

 legume joins a cultivated field. 



GREAT DAMS IN SPAIN. 

 With the possible exception of the 

 ancient dam in Ceylon, the oldest masonry 

 dams in existence are in Spain, where 

 irrigation is as necessary to successful ag- 

 riculture as in India. The oldest of the 

 Spanish dams is that of Almanza, 68 feet 

 high. The date of its erection is uncer- 

 tain, but it is known to have been in use 

 in 1586. The great dam at Alicante was 

 finished in 1594. The name of its builder 

 is not known with certainty, but it has 

 been attributed to Herreras, the famous 

 architect of the Escurial palace. It is the 

 largest of the ancient dams, being no less 

 than 134.5 feet in height. Other Spanish 

 dams which are large enough to deserve 

 special mention are, with their heights, as 

 follows: Elche, 76 feet; Nijar, 101.5; 

 Lozoya, 105; Val de Infierno, 116.5; the 

 two dams at Hijar, each 141, and the great 



