49 



TONS PER ACRE 



2 - 



80 160 240 



LB. OF AVAILABLE NITROGEN APPLIED 



320 



U, S. DEPARTMENT OF AGRICULTURE 



NEC. 59(3)-2654 AGRICULTURAL RESEARCH SERVICE 



Figure 6. Estimated nitrogen response curves showing relationship between 

 rate of application of nitrogen fertilizer and yield of hay under selected 

 conditions. 



(fig. 6) shows that after the first 38 pounds of nitrogen have been applied, 

 an additional application of 32 pounds increases the yield by 0. 25 tons. In 

 this instance, the theoretical most profitable rate is halfway between 38 and 

 70 pounds of nitrogen, or 54 pounds, 15/ and the theoretical production per 

 acre is 1.21 tons. 



This method is used also in determining the most profitable rate of nitrogen 

 application based on curve "B", but a different answer is obtained because of 

 the difference in the nature of the meadow's response to nitrogen. In this 

 instance, increasing the application of fertilizer from 60 to 92 pounds (32 

 pounds) increased production per acre from 2. 30 to 2. 55 tons per acre, or 

 0. 25 ton. Therefore, the most profitable rate is 76 pounds per acre (halfway 

 between 60 and 92 pounds). 



15/ See pages 50 and 51 for explanation. 



