Frequency of Irrigation 237 



every 15 to 20 days, and our experimental studies place 

 it at 15 to 27 days for yields of 100 bushels per acre. 



The intervals between the irrigations for other 

 cereals will be found to fall between those for wheat 

 and maize, oats requiring the largest amount of water 

 and barley the least, to mature a large crop. 



In the irrigation of clover and alfalfa, the usual 

 practice is to irrigate once for each crop. But there is 

 little question that larger yields for each crop may be 

 secured where the number of irrigations is doubled, 

 giving six where the number of crops is three, and ten 

 where it is five, thus making the length of the interval 

 10 or 20 days. 



With other meadows, the general custom is to give 

 these as much and as many waterings as the water 

 supply will permit. In Italy, the summer meadows are 

 watered every 14 days. In southern France they are 

 watered every 5 to 18 days, and on the average every 

 10 days. Winter water meadows, as has been stated, 

 are watered with a nearly continuous flow of water over 

 their surfaces. 



With potatoes, the custom is usually to depend upon 

 the natural rainfall to bring the crop nearly or quite 

 to blossoming, and then to irrigate twice on nearly 

 level fields, and three to four times where the slopes are 

 steep or where the soil is very porous and coarse in 

 texture, thus making an interval for this crop of 20 

 to 40 days. 



For this crop our experimental studies indicate that 

 8.24 acre-inches may produce 400 bushels per acre ; 

 hence, that two to four irrigations might be sufficient 



