ARID AGEICULTDEE. 75 



of the bacteria on their roots, gather nitrogen 

 from, the air. Grain, peas or potatoes may be 

 grown as the first crop after breaking the sod. 

 If grain is the principal crop produced, the soil 

 should be improved by raising a crop of peas, 

 beans, vetches or alfalfa. Peas may be grown 

 and plowed under to add vegetable matter. Al- 

 falfa continually enriches the soil in nitrogen 

 and at the same time produces profitable crops 

 where ever the conditions are favorable. Where 

 alfalfa is easily grown it may be plowed up at 

 the end of three, four or five years, but if diffi- 

 cult to get a stand and a good field is secured, the 

 farmer would be reluctant to plow his alfalfa so 

 long as it is giving him good results. It usually 

 begins to deteriorate after seven or eight years. 

 This is due to wrong management. Alfalfa 

 rightly managed, in some parts of the world has 

 stood the test of time not 8 years but 180 years 

 or more. Each farmer must work out his own 

 system of rotation which is applicable to his con- 

 ditions, but these suggestions will be valuable to 

 him. 



PEBTixiziNO Arid soils are so rich in mineral elements of 



fertility which are made available by thoroijgli 

 systems of tillage, that the use of complete fer- 

 tilizers has not become a question of importance. 

 These soils are generally poor in nitrogen and 

 decaying vegetable matter, and adding these 

 tfiings always brings important increase in yield. 



THE SOIXi 



