ARID AGRICULTURE. 135 



after each cutting, providing there is time after 

 irrigation and before the plants get too high. 

 Such cultivation lets air into the soil, saves 

 moisture, kills weeds, destroys insects, makes 

 plant food available, increases the crop. 



INOCULA- In most of our western soils alfalfa will not 



need artificial inoculation. By inoculation we 

 mean supplying the bacteria which live on al 

 falfa roots and gather nitrogen from the air. 

 Alfalfa will live without the presence of these 

 bacteria, but it does not do well. These bacteria 

 produce little nodules or tubercles on the roots, 

 take the nitrogen gas of the air and change it 

 into nitric acid, which in turn becomes valuable 

 plant food, and the kind most needed in the 

 West Where alfalfa plants do not thrive, look 

 yellow or appear to be in a dying condition, it is 

 usually due to the absence of nitrogen bacteria. 

 Artificial inoculation material has been on the 

 market, but it has so generally failed that farm- 

 ers should not spend good money for such cul- 

 tures. A practical method of inoculation is to 

 take soil from an old alfalfa field or from a place 

 where sweet clover is growing and sow it over the 

 field to be inoculated. A thin sowing of a few 

 pounds per acre will get the bacteria started 

 after which it will increase and spread. We 

 have sent such alfalfa soil in four-pound pack- 

 ages by mail to farmers who have changed their 

 success with alfalfa by sowing upon and harrow- 

 ing it into their fields. 



