FARM IRRIGATION 257 



flow into the depressions, from which it is directed 

 into the other furrows. The furrows are not 

 necessarily parallel; they follow the contour, 

 making really a series of checks not bounded by 

 levees. The canvas dam is often dispensed with. 



In all systems of irrigating by flooding it is often 

 necessary and practicable to level off small in- 

 equalities before applying the water. There are 

 many styles of levels and scrapers, both home-made 

 and patented, which answer the purpose. One 

 built of two braced 2-inch planks, forming the 

 letter A, does very well if weighted and shod with 

 steel strips. 



FURROW IRRIGATION 



When the land has too steep a slope to be flooded 

 advantageously, and when crops are grown that 

 do not cover the ground and must be tilled, it is 

 usually best to irrigate by furrows. The furrow 

 System is also used very commonly on land that 

 could be flooded, and for sown crops as well as for 

 hoed crops. On steep land the furrows may be 

 permanent, either for a number of years or for one 

 season, but they hinder cultivation. Temporary 

 furrows are best in most cases. If the soil needs 

 watering before planting, however, it is customary 

 to irrigate by flooding until the soil is wet at least 

 four feet deep. The crop is then grown as long as 

 possible without irrigation by giving it thorough 

 tillage, for four feet of wet soil should contain six 

 to eight inches of water. 



When irrigation becomes necessary take water 

 from the supply, which runs along the highest 

 point of the fiela. This may be a head ditch, or a 

 wooden or cement flume, with holes an inch or 



