SEASONAL EFFECTS 



129 



Sept. Oct. Nov. Dec. Jan. Feb. Man Apn May June July Aug. Sept. 



\ 



50 



00 



Q. 

 O 



30 



10 



Oct. Nov. Dec. Jan. Feb. Ma?? Apr May June July Aug. Sept. 



191 1 1912 W5 



FIG. 8 Amounts of carbon dioxide in soil air, and of nitrate in soil, at different seasons of the year. 



