32 BULLETIN 211, U. S. DEPARTMENT OF AGRICULTURE. 



moisture and the soil, as well as for the maximum production of 

 forage, and it should be brought about wherever possible. 



All arroyos should be gradually filled. This can not be done 

 economically except very slowly and by letting the water do it. 

 The cutting occurs because of the velocity of the water, which de- 

 pends upon the quantity of water and the slope of the land. It is 

 necessary to begin work at the heads of such channels, deflect the 

 water from the main channels, and cause it to run over the more 

 gently sloping land as a sheet. Large obstructions across deep ditches 

 or gullies are of little value unless they are so strong as to hold all the 

 water which can collect behind them, as in a tank or lake. 



The same is, of course, true of the broader channels, where more 

 extensive dams would be necessary. If such dams were built and 

 should burst, much greater damage would be done, because of the 

 .large volume of water stored before the obstruction gave way. Small 

 obstructions which allow a small quantity of soil to collect behind 

 them upon which the grass may grow are of great advantage in chan- 

 nels, provided most of the flood waters can be kept out of the channel 

 by deflection at the head. 



All' permanent lakes or tanks become local levels below which cut- 

 ting can not occur in the drainage basin above them and are, of 

 course, desirable. 



The general principle to be kept in mind is that the transporting 

 power of water varies as the sixth power of its velocity. In other 

 words, if the velocity of a stream be doubled, the weight of the largest 

 particles it will push along is 64 times as great as that of the stream 

 at the original velocity. But the velocity increases with the depth 

 and with the gradient. The importance of inducing the water to 

 flow slowly over the surface as a thin sheet is thus apparent. And a 

 relatively small amount of work properly applied will produce im- 

 portant results in restoring to productivity land which is now only 

 used to carry away water that should go into the ground. But none 

 of this improvement work will be done until the worker knows he will 

 be allowed to reap the benefit of his labor. 



Eeseeding operations. — So far, experiments attempting to reseed 

 artificially the ranges of most of New Mexico have resulted negatively. 

 There are good reasons for this, to which we wish to call attention. 

 There are, however, large areas where artificial reseeding will prove 

 successful. Many high mountain valleys that receive considerable 

 water, but have a short, cool season, can be set in timothy or redtop. 

 Orchard grass, tall fescue, or brome-grass will grow in many localities 

 if properly treated. Oats, barley, and wheat are already grown in 

 many of the open parks of the higher mountain timbered lands, and 

 much of the plains country of the eastern side of the State will grow 

 kafir, milo, or some of the other .sorghums. Such lands are range lands 



