Value of Turbid Water 259 



THE VALUE OP TURBID WATER IN IRRIGATION 



Next in value to warm sewage water for irrigation 

 must be placed that of streams carrying considerable 

 quantities of suspended solids. It is generally recog- 

 nized that the richest and most enduring soils of the 

 world are those formed from the alluvium of streams 

 laid down by the water on its flood plains, and 

 reworked many times over as the stream shifts its 

 course from side to side in the valley; and when this 

 is true, it will not be strange that the water of turbid 

 streams has generally been held in great esteem for 

 irrigation, on account of its high fertilizing value. 



In the case of the Rio Grande river, Goss has 

 shown that the application of 24 inches of this water 

 would add nearly one -quarter of an inch of soil to 

 the field in the form of river sediment, and that this 

 sediment would contain per acre 1,821 pounds of 

 potassium sulphate, 116 pounds of phosphoric acid 

 (P2Os), and 107 pounds of nitrogen. Four years of 

 irrigation at this rate would add an inch of soil to 

 the field, and 24 years would cover it 6 inches deep 

 with a sediment containing three times the amount 

 of potash found in the average clay soil, and the same 

 percentage of phosphoric acid and a high percentage 

 of nitrogen. 



When such sediments are laid down upon coarse, 

 sandy soils, it will be readily appreciated that the 

 gain to the field is far greater than that due to the 

 mere plant -food which the sediments contain; for such 

 sediments, being composed of very fine grains, their 



