630 



THE IRRIGATION AGE. 



(Continued from page 608.) 



The cotton planting season in the valley begins about 

 the middle of February. It has been found that the best 

 results are accomplished by thoroughly irrigating the soil 

 before planting. The irrigation is done slowly so that the 

 water will reach down to the subsoil. Before this first irri- 

 gation the land is plowed deep and thrown into furrows. 

 After the irrigation is finished the ridges are leveled and the 

 planting done where they were formerly located. Constant 

 and frequent cultivation is given the growing plants. It is 

 claimed that it is not necessary to give the growing crop more 

 than two irrigations. An average yield of one bale per acre 

 has been obtained where only one irrigation was given after 

 the cotton was up. Picking begins about June 10 to 15. and 

 by the middle of September most of the picking is done. 

 Much of the cotton land is plowed up by September 1, the 

 fields having been cleared of the staple by that time. Even 

 when no effort is made to increase the yield by a late top 

 crop, the average yield runs from three-fourths to one bale 

 per acre, it is stated. 



The early cleaning up of the crop and the burning of the 

 stalks and plowing of the fields in the fall prevent the breed- 

 ing of the last two generations of the weevil, which takes place 

 in the fall. A new generation of weevil is produced every 

 thirty days, from the middle of May until the time comes for 

 the insects to go into their annual period of hibernation, un- 

 less they are destroyed by cultural methods. It is claimed by 

 entomologists that it is the last two broods of the boll wee- 

 vils in the fall that hibernate and go through the winter. 

 They are more hardy than the generations which precede them 

 each season, and, as they are to a large degree destroyed* by 

 the methods which the cotton irrigationists are practicing in 

 this region, the complete eradication of the pest is in a fair 

 way to be finally accomplished in the region where it made 

 its first appearance in the South. 



(Continued from page 601.) 



Nitric Acid. 



This acid consists of nitrogen combined with oxygen, 

 and never occurs in nature in a free state, but is found in 

 many semi-tropical regions in combination with potash, 

 soda and lime, in what are known as "nitrates." They 

 are all, like the salts of ammonia, very soluble in water, 

 those of soda, lime and magnesia attracting moisture from 

 the air, and in a damp atmosphere gradually assume a 

 liquid form. Saltpeter is a compound of nitric acid with 



Elk Mountain, near Saratoga, Wyo. 



potash (nitrate of potash), and it may sometimes be used 

 as an influential agent in promoting vegetation. Like the 

 acid itself, these nitrates, when present in large quantities, 

 are destructive of vegetation, and are frequently the cause, 

 in arid and semi-arid regions, of utter barrenness, the 

 nitrous incrustations accumulating upon the surface of the 

 soil. In small quantities, however, they exercise an im- 

 portant and salutary influence on the rapidity of growth. 



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