IRRIGATION OF CEREALS 



251 



decrease in the total yield. Further, an excess of water 

 delays ripening, and thus subjects the grain to the dangers 

 of late growth when the fall frosts are at hand. When too 

 much water is used, the plant becomes converted into a 

 pumping system, having for its purpose the ridding of the 

 soil of the injurious excess of moisture. Such over-irriga- 

 tion is, naturally, less likely to occur on porous than on 

 compact soils; but, on the other hand, the excess of water 



FIG. 61. Irrigated oats in Montana. 



applied to porous soils moves downward more easily tot\ 

 raise the standing water table. Fortunately for the 

 pioneers who laid the foundations of irrigation, and who 

 were not well acquainted with the dangers of over-irriga- 

 tion, the small grains endure fairly well an excess of 

 water. Wheat can probably endure over-irrigation better 

 than either oats or barley. However, the practice is un- 

 wise; and the ridiculously large quantities of water often 

 applied in the hope of large yields are a serious menace 

 to the permanence of irrigation agriculture. 



