CITRUS FRUITS 



493 



length of the furrows or of the "run" ordinarily ranges from 400 to 700 

 feet. While 600 and 700-foot runs are common, this is too long to give the 

 best results. 



In the basin system of irrigation, square or round basins, about eight 

 to twelve inches deep, are formed around the trees, into which the water is 

 run either by means of a single central furrow, from which it is turned into 

 each basin successively, or by means of steel irrigation pipes fitted together 

 like joints of a stove-pipe. In making the basins the soil should be left for 

 a radius of about two or three feet around the base of the tree, so that the 

 water will not come in contact with the trunk. 



The water is brought into the grove usually either by open cement 

 flumes or by buried cement pipes. These are run across the rows along the 

 upper edge of the grove to be irrigated. With the open flume, gates are put 

 in at intervals to discharge the water wherever a stream is desired. With 

 the covered cement pipe flumes, a standpipe is placed at the end of each row 

 of trees in which several gates are inserted according to the number of 

 furrows or streams desired to be taken from it. 



The length of time necessary to run the water is determined by the 

 rapidity of penetration. The application should be continued until the 

 water has penetrated to a depth of three or four feet. 



Fertilization. — The great majority of soils on which citrus trees are 

 grown require manuring to maintain the fertility, and yet no subject is so 

 little understood as the fertilizer requirements. If the soil fertility is 

 sufficient to provide for good growth in the beginning, then the addition 

 of the materials removed by the crop, it would seem, should be sufficient 

 to maintain the fertility. The following table shows the average percentage 

 of nitrogen, phosphoric acid and potash in orange and lemon fruits and the 

 pounds of these materials removed by a ton of fruit. 



Fertilizer Analysis of the Fruit of Oranges and Lemons. 



(Computed from Bulletin No. 93, University of California 



Agricultural Experiment Station.) 



Such a table as the above is suggestive only as a guide to fertilization, 

 and the same may be said regarding soil analyses. The test of a fertilizer 

 on the soil and the crop is the only safe guide. 



In Florida a fertilizer containing about 3 to 4 per cent of nitrogen, 6 to 

 8 per cent of phosphoric acid and 8 to 12 per cent of potash is commonly 

 used. In California the proportions commonly recommended are 4 per 



