A THIRTY-YEAR FERTILIZER TEST. 



131 



Plot 



? Manure 



14 N^P^K 



11 P^K 



4 K 



10 N^K 



N^P 



13 Plaster 



Thousands of Pounds 

 Period 2 4 6 



10 12 14 16 13 20 22 24 



2 P 



5 Lime 



Average Of Checks, 



Pounds Of Stov^ep 



to a Bushel of Corn- 



FiG.Jl. — South Soil Test. Total yields per acre. Ten corn crops. 



