A THIRTY-YEAR FERTILIZER TEST. 



131 



Plot 



7 Manure 



14 N^P^K 



U P^K 



4 K 

 10 N^K 



8 N^P 



13 Plaster 



.1 N 



2 P 



5 Lime 



Thousands of Pounds 

 Period 2 4 6 8 10 12 14 16 IS 20 22 24 



24 



is-t 



2n_d 

 lit 



2"i 



ls_t 



2"i 



ls_t 



2"i 



2n_d 

 ]st 



2nd 



lit 

 2nd 



lit 

 2nd 



1st 



2"i 



Average Of Checks, 



1st 



Pounds Of StoVep 



to a Bushel of Corn- 



Fia.;i. —South Soil Test. Total yields per acre. Ten corn crops. 



