142 THE MONTHLY BULLETIN. 



in proper moisture content for root feeding. The check system by 

 which the furrow next the tree is cut into the space between the trees 

 in the row is just another way of keeping- all the soil moist. The 

 question as to which of these methods is the better is solely one of local 

 conditions, such as grade of furrows and size of trees. In some cases 

 one metliod will be less costly in labor than the other, depending as 

 before on local conditions. 



When the distance between the furrows on the two sides of the 

 tree is so great that the soil in the tree row is dry and hard all sum- 

 mer, some scheme whereby this area is kept irrigated with the rest of 

 the soil becomes an absolute necessity. Only that portion of the soil 

 which is permanently moist is of any value to the tree, so far as the 

 plant food contained therein is concerned. Some orchards which I 

 have examined immediately after an irrigation show that fully one 

 third of the soil had not been moistened in the least by the irrigation. 

 The fertilizer had been applied to all of the soil, l)ut the trees were only 

 able to get in contact with one third of the fertility, whether native 

 or artificially applied. Thus as the trees grow older and parallel fur- 

 rows do not moisten all of the soil some checking or zigzag method must 

 be inaugurated, if best results are to be obtained. 



The proper length of the furrow is another important item. In my 

 opinion more water is lost in citrus irrigation through too long fur- 

 rows than from any other one cause. 



I have examined soils which showed irrigation water down to a depth 

 of 22 feet near the upper end of the furrow, while at the lower end 

 only the upper two or three feet of soil had been moistened. In this 

 orchard the roots rarely penetrated below the six foot level. Thus 

 practically all water below this point was lost. This loss was largely 

 caused by having furrows too long in a sandy soil with a gravel subsoil. 



As a general rule furrows should not be more than 300 feet^ in 

 length in sandy soils, while on heavy soils a length of even 500 feet 

 is frequently satisfactory. 



The grade at which the furrows should be run is an item of par- 

 ticular importance to the man preparing to plant ovit an orchard. 

 AVhere land is uniformly level a grade of one inch to a hundred feet 

 will suffice, but irrigation will be much less difficult if a grade of 

 three or four inches to the hundred feet can be given. When it is 

 impossible to irrigate in straight furrows without a very uneven grade 

 or "a grade of six inches to the hundred feet or over, the trees should 

 be planted after the contour system to suit the irrigations to follow; 

 that is, lav off lines for the tree rows having a grade of three to six 

 inches per" one hundred feet. The irrigations then will be accomplished 

 without severe washing of the soil and a nuich nuich uniform distribu- 

 tion of the water will result. 



In starting the water in the furrows few irrigators agree in then- 

 methods. Some start a large head of water down the furrow, cutting 

 the head down as the water reaches the lower end. Others turn in a 

 small head and let it take its time to reach the lower end, feeling that 

 shortly after the water has reached the bottom they have a good soak- 

 ing all the way along. The turning in of as large a head as can run in 

 the furrow without serious washing is in my estimation the better 

 scheme, for the sooner the lower end of the furrow is wet the more 



