20 
Phosphoric Acid, Potash and Nitrogen, N P K (Plats 10 2 , 5 
and 6). When all three of the fertilizer materials were used together 
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 
largest average increased yields over unfertilized plats (18.8 bushels 
per acre), than phosphoric acid and potash (16.5 bushels per acre), 
and nitrogen, phosphoric acid and potash were larger than either of 
the other two (19.1 bushels per acre). This indicates that nitrogen 
is more important on this soil than potash for corn production. 
Lime, L (Plats 4 4 , 14 2 , and 7 2 ). Lime was applied at the rate 
of 500 pounds rock or 1,000 pounds slaked lime per acre every 
fourth year. On the plats in Field B during four years there was 
a profit of 14 cents per acre from the use of lime On the plats in 
Field A there was a loss of $9.10 annually per acre, and on the plat 
in Field O in one year’s test a profit of $6.23, the average for the 
seven years being a loss of $1.66 per acre. The plat in Field C, 
where there was a profit from the use of lime, had been in peas after 
grain during four previous years. 
Lime with Complete Fertilizer N P K L (Plats 6 4 , 15 2 and 9 2 ). 
When lime was used in combination with the three fertilizer con¬ 
stituents there was less corn produced on all the plats in Fields B 
and A than where the three fertilizer constituents were used with¬ 
out lime, but on the plat in Field C, which had previously been in 
peas and grain for four years, there was a decided gain from the 
use of lime. As an average of all the tests there was smaller increased 
yield of corn and profit where lime was used than where it was not. 
As an average of all the results, the experiments show— 
(1) That nitrogen alone on this soil for the production of eorn 
was used at a loss; 
(2) That potash alone had practically no effect on the yield and 
was used at a loss; 
(3) That nitrogen and potash combined increased the yield very 
slightly but at a loss; 
(4) That lime alone, except where peas had been previously grown, 
was used at a loss; 
(5) That phosphoric acid alone gave increased yields and profits 
in all cases, showing that it is the most important constituent for 
corn production on this soil; 
(6) That nitrogen combined with phosphoric acid added decidedly 
to the increased yields and profits, the average annual increase for 
phosphoric acid alone being 6.2 bushels and for nitrogen and phos¬ 
phoric acid 18.8 bushels per acre; 
