THE FLOWER GARDEN 319 



roots can develop much more quickly and with 

 less effort than if the deep-rooting crop had not 

 been grown on the soil before it. 



It is quite evident that the addition of barn- 

 yard manure has almost as much beneficial effect 

 upon the phj^sical and bacterial condition of the 

 soil as upon its chemical condition. 



The effects of rotation are most astonishing as 

 shown by the results attained especially in Cali- 

 fornia when grain follows a corn crop. There is 

 usually fully twice the yield secured from the 

 small grain crop following a crop of corn than 

 when small grain follows a crop of small grain. 



No doubt, the cultivation given the corn dur- 

 ing the summer has much to do with putting the 

 soil in the proper physical condition for plant 

 growth. This cultivation destroys more of the 

 microscopic organisms which are injurious to 

 plant life, and releases elements which otherwise 

 would be unavailable. 



With the present varieties of plants, it will 

 probably always be necessary to practice rotation 

 of crops. But when plants are developed whicK 

 are resistant to the various conditions which have 

 been mentioned, rotation will perhaps not be so 

 necessary. 



Already certain plants have been developed 

 which are resistant to numerous diseases and 



