COMMERCIAL FERTILIZERS 



209 



The sixth plot receives phosphoric acid and potash. 



The seventh plot receives potash. 



The eighth plot receives phosphoric acid. 



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 

 additional yield the soil is in want of nitrogen. From 

 the eight plots it will be possible to tell which of the 

 various elements 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 trials. 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. 



283. Deficiency of Nitrogen. If the results indi- 

 cate 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 obtaining this element. The cultivation of each 



(14) 



