402 DRY LAND FARMING 



involved the several states concerned in a loss of several 

 millions of dollars annually. 



Many farmers are apparently imbued with the idea 

 that it is impossible to secure as large profits from one 

 cereal crop grown every alternate year as from annual 

 crops of the same grown every year. Whether this can 

 or cannot be done depends entirely on the yields. Ex- 

 perience has shown that where the rainfall is not more 

 than 15 inches annually more bushels of small grain 

 will be obtained in a term of years by taking one crop 

 from the soil in two years than from cropping the land 

 every year. Though the yields should be the same the 

 profits from growing the one crop in two years will be 

 greater because of the less expense involved in grow- 

 ing it. 



Where the rainfall is more than 15 inches annually, 

 and less than 20 inches, it may be legitimate to grow 

 several grain crops in succession on land when broken 

 from the virgin prairie. But even in these areas the 

 process should not be long continued because of the 

 drain that such a system involves on the fertility and 

 also on the humus supply in the land. 



While pastures should as a rule be continued for a 

 longer period than two years, they should seldom be 

 made permanent in dry areas. The objections to such 

 permanency are: (1) the necessity that exists for renew- 

 ing the humus supply in the land ; (2) the difficulty found 

 in maintaining high relative production in such pastures, 

 and (3) the tendency in such a system to lessen the 

 store of moisture in the soil and especially in the sub- 

 soil. It is important, therefore, that such pastures will 

 not be grazed for too long a term of years. 



On arable farms the aim should be to avoid main- 

 taining alfalfa crops during a long term of years. This 

 does not follow from any real difficulty in maintaining 

 maximum production in the alfalfa crops, but rather 



