III. ECONOMY IN USING FERTILIZEES FOR RAISING 



POTATOES.* 



SUMMARY. 



In 1895 fertilizers were applied at the rate of 1,000 and 2,000 

 pounds an acre in raising potatoes. A second crop of potatoes 

 was raised on the same ground in 1896 without using fertilizers 

 in order to ascertain to what extent the fertilizers applied in 

 1895 would benefit the crop of 1896. 



The application of 1,000 pounds of fertilizer increased the crop 

 of marketable potatoes 48.4 bushels an acre in 1895 and 39.6 

 bushels in 1896, the total increase for the two years being 88 

 bushels. The use of 2,000 pounds of fertilizer increased the 

 yield over the foregoing to the extent of 4.4 bushels in 1895 and 

 14.1 bushels in 1896, the total increase for the two years being 

 18.5 bushels. 



The application of 1,000 pounds of fertilizer increased the pro- 

 portion of marketable potatoes 6.8 per cent in 1895 and 9 per cent 

 in 1896; while the use of an additional half ton of fertilizer in- 

 creased the percentage of marketable potatoes over the foregoing 

 to the extent of 1.3 per cent in 1895 and 2.6 per cent in 1896. 



The use of 1,000 pounds of fertilizer an acre produced an in- 

 creased yield of marketable potatoes, which, at 50 cents a bushel, 

 made a net gain of $27.58 in income during the two years. The 

 use of 2,000 pounds of fertilizer yielded in net increase of income 

 during the two years $7.12 less than did the application of 1,000 

 pounds. 



In using 1,000 pounds of fertilizer there were added to an acre 

 of soil, on an average, 36.4 pounds of nitrogen, 76.9 pounds of 

 available phosphoric acid, and 90.6 pounds of potash; and twice 

 these amounts in using 2,000 pounds of fertilizer. Adding to 

 these the amount of plant-food already known to be present in 

 the soil and then deducting the quantities removed by the two 

 crops grown, we find that excessive amounts of nitrogen, potash 



* Published also as BuUetiu No. 112. 



