COMMERCIAL FERTILIZERS AND THEIR USE 



249 



Should good results be obtained on plot No. 3, the 

 indications are that there is a deficiency of the two 

 elements, nitrogen and phosphoric acid. An increased 

 yield from No. 4 indicates deficiency of nitrogen and 

 potash. Under such conditions the use of a complete 

 fertilizer would be unnecessary. If No. 5 gives an ad- 

 ditional yield, the soil is in want of nitrogen. From 

 the eight plots it will be seen which of the various ele- 

 ments it is advisable to use. The fertilizers should be 

 applied after the land has been thoroughly prepared and 

 before seeding. Corn is a good crop for the first trial. 

 The number of plots may be increased by using well- 

 prepared stable manure and gypsum on plots 9 and 10, 

 respectively. The second year the results should be 

 verified. 



297. Deficiency of Nitrogen. If the results indicate 

 a deficiency of nitrogen, select two crops, one as wheat, 

 which is particularly benefited by dressings of nitrogen, 

 and another as corn which has less difficulty in obtain- 

 ing this element. The cultivation of each crop should 

 be that which experience has shown to be the best. On 

 one wheat and one corn plot 8 pounds of nitrate of 

 soda should be used, a plot each of wheat and corn being 



