24 SURFACE- AND SUB-IRRIGATION 



water to be carried in it. Where pipes are used the cost will 

 vary according to their diameter and kind of material used. 



The cost of the tiles and the expense of laving them for dis- 

 tribution in sub-irrigation is said to vary from twenty-five to 

 forty dollars per acre. Where they are laid near or on the sur- 

 face as described under head of " New System," the only ex- 

 pense practically is that of the tiles, as the laying of them is a 

 very simple matter. The tiles, size two inches, cost about 

 fifteen dollars per thousand, and the three-inch about twenty 

 dollars. The expense of course is in proportion to the number 

 of tiles used. Test them on a small scale at first and find out 

 whether you would be benefited by the extra expense. Should 

 they prove a success more can be used ; if a failure the tiles are 

 always a good investment for drainage. 



Cut 4 shows the method of surface irrigation. A slope of six 

 inches in every one hundred feet is considered a good flow for 

 furrow irrigation, while one foot to the hundred is about as 

 much as one can handle. 



CULTIVATION 



To get the best results cultivation goes hand in hand with 

 irrigation. It is a necessity for plant growth ; it not only keeps 

 the weeds down but gives better ventilation, more sunlight, and 

 reduces the amount of evaporation from the soil. Frequent 

 shallow cultivation, say once a week or thereabouts, retains 

 the moisture in the soil sufficiently many times to bridge over 

 short drouths. It should be begun as soon after a rain as the 

 land can be worked. By deep plowing, which may mean sub- 

 plowing in some cases, together with the cultivation already 

 mentioned for cultivated crops, and proper cultivation before 

 planting with other field crops, the plants will withstand a 

 comparatively severe drouth before demanding irrigation. 

 The more one can counteract drouth by proper cultivation, 

 therefore, the less the number of applications of artificial water- 

 ing. The only thing to be understood is that when artificial 

 watering is necessary to secure desired results, the supply 

 should be adequate, which means, as already stated, one barrel 

 (thirty-two gallons) per tree, or five hundred to eight hundred 



