No. 4.] KEEPING UP FERTILITY. 97 



I will call your attention to these figures tor a moment. 

 Let me say in advance they do not show the yield ; they 

 show simply the increase caused by the fertilizer used. You 

 will notice the letters, — "N.," which stands for nitrogen; 

 "P. A.," for phosphoric acid; "Pot.," for potash. In 

 supplying nitrogen' we have used nitrate of soda at the rate 

 of 1()0 pounds to the acre. In supplying phosphoric acid 

 we have used dissolved bone-black at the rate of 320 pounds 

 per acre. In supplying potash we have used muriate of 

 potash at the rate of 160 pounds per acre. There are 

 many valuable points shown by these figures. They refer 

 to an acre of land which has been for six years under the 

 same management. Upon one section of the field we have 

 been applying nitrogen, as indicated by the letter " N.," for 

 six years, beginning with 1889. The crop in that year was 

 corn ; in 1890, corn ; in 1891, oats ; in 1892 and 1893, grass 

 and clover; and in 1894, corn. 



The figures in the column headed " N." show the amount 

 of increase in the crop which resulted from applying nitrate 

 of soda alone. You will see the figures for the first two 

 years for corn are small ; in the second year there is an 

 actual decrease. That does not necessarily mean that the 

 nitrate of soda was injurious. The crop was smaller where 

 it was used; but I believe that result was due to other 

 causes. The nitrate of soda simply has no practical effect 

 in increasing the corn crop. But in the next year for oats 

 there is an increase of 15 bushels of grain and 950 pounds 

 of straw. In the next year with o-rass and clover there is 

 an increase of 640 pounds to the acre in the first crop, and 

 in 1893 an increase of 1,023 pounds. You will notice that 

 there was very little eft'ect upon the rowen crop from nitrate 

 of soda in either year. Its effect upon the first crop is great,, 

 but its virtue is soon spent. It does not benefit the rowen 

 crop. 



Phosphoric acid is at a disadvantage all the way through, 

 — a very small increase in the corn crop the first two years, 

 no efl'ect to amount to anything on the oats, and very little 

 effect on the hay, or the last year on corn. There was a large 

 increase in corn each year with potash. This last year, 

 where this laud now for six years has had yearly only 



