ROTATION IN DRY AREAS 397 



follow that it leaves the soil as much lacking in moisture 

 as the wheat It draws more of the moisture used in 

 growing it from a deeper area than wheat, hence it 

 draws less heavily on moisture near the surface. Mois- 

 ture is also conserved when growing the corn, where- 

 as it is not so conserved when growing wheat. Nothing 

 can be done further to conserve it after the last harrow- 

 ing has been given to the wheat. Moreover, the broad 

 leaves of the corn furnish shade to the ground, and in 

 doing so reduce the evaporation. It follows, therefore, 

 that corn will leave much more moisture in the soil than 

 small grain, as experiment has shown, but it will be 

 less than the bare-fallow by the amount that it has 

 taken to grow it. In areas where humus is abundantly 

 present and the rainfall is fairly liberal, larger yields of 

 grain may usually be expected after grain than after 

 the bare-fallow, as an excess of straw is more liable to 

 be present after the cultivated crop. Such excess in the 

 straw, however, is less liable to occur on the soils of the 

 far west than on the prairies of the eastern portion of the 

 dry belt. But where the rainfall is not quite enough to 

 grow a crop each year as outlined, one crop only should 

 be sought in two years. 



Rotation which combines fallow and cultivated 

 crops. The discussion of this rotation will also con- 

 sider: (1) how it is conducted; (2) the benefits result- 

 ing therefrom ; (3) the area where it is to be sought, and 

 (4) the objections thereto. 



The fallow and cultivated crop in each instance is 

 followed by a crop of small grain, and these crops al- 

 ternate. The rotation, therefore, covers four years. The 

 order in 'the same is as follows : Summer-fallow, small 

 grain, cultivated 'crop and small grain. This rotation 

 grows three crops in the four years. Where it can 

 be adopted, therefore, it is more profitable than the rota- 

 tion which gives but one crop in two years. It is easily 



