7^ THE CEREALS IN AMERICA 



in a five year rotation of maize, oats, wheat, each one year, and 

 clover and timothy two years, fertihzer being applied to each 

 of the grain crops : 



"WTien phosphoric acid has been applied alone in superphosphate, 20 per 

 cent of the quantity applied in the fertilizer has been recovered in the crop. When 

 phosphoric acid has been reinforced with potash, there has been a recoveiy of 27 

 per cent of the former. When phosphoric acid has been reinforced with nitrogen 

 instead of potash the recovery has reached 38 per cent of the phosphoric acid 

 applied, and when both potash and nitrogen have been added, the recovery of the 

 phosphoric acid has amounted to 46 to 50 per cent." 1 



Wheat does not appear to be benefited directly by the appli- 

 cation of lime. If the soil needs liming, it is best applied to 

 the land prior to planting it to maize. 



122. Amount of Fertilizers. — A standard application of fer- 

 tilizer may be said to be one that furnishes from ten to twenty 

 pounds each of ammonia and potash and from thirty to sixty 

 pounds of phosphoric acid. This can be obtained by apply- 

 ing from 250 to 500 pounds of a commercial fertilizer con- 

 taining four per cent of ammonia, twelve per cent of available 

 phosphoric acid, and four per cent of potash. This is often 

 referred to as a 4-12-4 fertilizer and is a grade that usually 

 can be found on the market. 



The ratio of phosphoric acid to nitrogen and potash should 

 be varied somewhat with state of fertility. With soil quite ex- 

 hausted through continuous culture the proportion of nitrogen 

 and potash to phosphoric acid should be increased, while with 

 land of higher fertility and with favorable rotation, nitrogen and 

 potash may be reduced. The above figures are at best only 

 general averages. 



When it is necessary to apply lime to wheat land, an amount 

 equal to 1,000 to 1,500 pounds of quick or freshly burned lime 

 (CaO) may be applied. When it is water-slaked it will have in- ' 

 creased in weight thirty-two per cent (CaO : Ca(H0)3 : : 100 : 132). 



I Ohio Bui. no (1899), p. 57. 



