338 Irrigation and Drainage 



to be the rate which does not wash or erode. We 

 have seen orchards in the foothills of California irri- 

 gated by carrying the water in furrows down the hill 

 where the slopes were too great to readily plow with 

 a team and yet it was done with such skill that no 

 appreciable wash was produced, neither did any water 

 run to waste. Everything was adjusted w^ith such 

 nicety that by the time the streams had reached the 

 ends of the furrows the whole of the water had been 

 absorbed by the soil. The 30 acres referred to were 

 owned and managed by a Swede, and when he was 

 asked if he did not find it difficult to handle the water 

 so as not to wash his soil and waste the water on 

 these steep hills, with no grading or terracing, the 

 reply was : " Easy now ; but was very hard when I 

 didn't know." 



The most essential point in the distribution of 

 water is to have the furrows on a nearly uniform 

 slope, so that the velocity of flow will be closely 

 uniform through their entire length. If the same 

 grade cannot be secured throughout, it is better to 

 change from a steeper slope to one more flat than 

 the reverse, because then the reduction in velocity 

 will be partly made up by a greater depth of water 

 in the furrow on the flatter reaches. 



FIELD IRRIGATION BY FLOODING 



When large areas of land are to be irrigated in 

 single blocks, there is no method of applying water 

 which is so economical of labor and of time as the 



