140 



IRRIGATION. 



ByF.H. Newell* 



While methods of conserving and conducting water have been im- 

 proved under the stimulus of modern invention, the application of 

 water to the soil has been left to experience gained largely by accident 

 and through failure. There is great need of long-continued systematic 

 study and acquisition of knowledge concerning the actual effect which 

 the water has upon the soil and upon the plants. We can see the ulti- 

 mate result, but have only a vague conception of the steps by which 

 this result is produced. 



Most of the farmers practising irrigation in the United States use 

 quantities of water far in excess of those theoretically demanded or 

 actually beneficial to the crops. This is in line with the general prodi- 

 gality of pioneer life, and with the habits of shiftlessness so easily ac- 

 quired where an abundant supply of water can be had. It is so much 

 easier to open the ditches and let the water flow freely than it is to 

 guard and guide each tiny rill, that for economy of time and labour, 

 if not from actual indolence, the irrigator is apt to let the water go its 

 own way. 



It is sometimes stated that irrigation is a lazy man's way of culti- 

 vation. The reverse is the case wherever the best results are obtained. 

 Irrigation, properly conducted, means intensive farming and applica- 

 tion of water with great care, followed by thorough cultivation of the 

 moistened soil. 



Different plants require different amounts of water. Some are 

 satisfied with a very little. Others require a great deal, and cannot 

 do without it. Still others are relatively indifferent as to whether 

 much or little water is applied; they have the habit of adjusting 

 themselves to circumstances. Each crop therefore has different needs, 

 and the practice of irrigation must vary accordingly. 



It is not merely the character of the plant which has to be consi- 

 dered, but also the quality of the soil. Certain soils receive and trans- 

 mit water with great rapidity, — such, for example, as sand and gravel. 

 Others, like clay, take water slowly and hold it with great tenacity. 

 Thus the manner and time of irrigating certain plants will vary accord- 

 ing to the ability of the soil to hold and supply water as needed. If 

 the moisture escapes rapidly, as from sand, the plant after a few days 

 is not able to receive enough and begins to droop. On the other hand 

 if the soil is very compact and the water is held from escaping, the soil 

 may become water-logged, air cannot penetrate the interstices, and the 

 plant suffers from drowning. 



There is still another factor in the production of crops which must 



be considered besides sunshine, soil, and water. This is the low order 



of vegetable Kfe known as nitrifying organisms. These, in the presence 



of air and moisture, manufacture food for the plant and are its servants 



£n preparing material upon which it*'thrives. A certain amount of 



*JFrom " Irrigation in Unitei States", by F. H. N"ewell, Hydraulic Engiaear and 

 Chief of the . .ision of Hydrography of the U. S. Geological Survey Depirtiueat. 



