The Bulletin. 25 



Nitrogen and Phosplioric Acid N P (Plats 7", 5 and 4). From 

 iiitro{:;en aiul jiliosjjlioric acid increased yields over the unfertilized 

 ])lats were obtained in all seven years in the three fields, the aver- 

 age annual increase for the four years in Field B being 17.5 bushels 

 of corn i)er acre; for two years in Field A 22.4 bushels of corn per 

 acre, and for one year in Field C 10.3 bushels, or an average annual 

 increase for seven years in the three fields of 18.8 bushels of corn, 

 worth 10.03 over cost of fertilizer for corn alone, or $13.76 for the 

 increased yield of corn and stover. This was 12.02 bushels more 

 corn, wtu'th $0.74, than phosphoric acid alone produced, showing 

 that nitrogen has added decidedly to the yield and profit when com- 

 bined with phos])horic acid, though alone it was used at a loss. 



JS'ilrocjeii and Potash, N K (Plats S'^, G and 5). There were 

 small average increased yields of corn in the three fields from ap- 

 plications of nitrogen and potash combined, the average for the 

 seven years in the three fields being 1.5 bushels per acre, which 

 was not sufficient to pay for the fertilizer. This fertilization was 

 therefore at a loss, having cost $1.20 per acre more annually than 

 the value of the increased yield of corn. 



Pliosphoric Acid and Potash, P K (Plats 9", 7 and 12"). 

 Phosphoric acid and potash combined gave increased yields on all the 

 plats in the three fields, the average annual increase for four years 

 in Field B being 15.2 bushels of corn per acre, for two years in 

 Field A 21 bushels, and for one year in Field C 12.5 bushels, or an 

 average for the seven years in the two fields of 10.5 bushels, worth 

 $10.27 over cost of fertilizer on basis of corn alone, or $14.25 on 

 basis of corn and stover. From this it is seen that potash added to 

 ])hosphoi-ic acid has increased the yield of corn 10.3 bushels more 

 than phosphoric acid alone, at a ])rofit of $0.98 over cost of fer- 

 tilizer, showing that potash was effective in corn production on this 

 soil when used in connection with phosphoric acid, but valueless 

 when used alone. ^ 



Phosphoric Acid, Potash and Nitrogen, N P K (Plats 10", 8 

 and 0.) When all three of the fertilizer materials were used to- 

 gether to make a complete fertilizer, increased yields were obtained 

 on all three plats in the three fields, the average annual increase for 

 four years in Field B being 17.8 bushels of corn per acre, for two 

 years in Field A 21.9 bushels and for one year in Field C 18.7 

 bushels, or an annual average increase for the seven years in the 

 three fields of 19.1 bushels, worth $10.01 over cost of fertilizer on 

 basis of corn alone, or $14.29 on basis of corn and stover. 



When compared with each other these results show that nitrogen 

 added to phosphoric acid, potash added to phosphoric acid, and nitro- 

 gen and potash added to phosphoric acid have yielded practically 

 the same profits, though nitrogen and phosphoric acid have produced 



