ig6 



SCIENCE PROGRESS. 



NITROGEN IN ROTHAMSTED BARLEY SOILS, MARCH, 1882, 



IN POUNDS PER ACRE. 



The two plots here selected as illustrations had both grown 

 barley for thirty years, and had both received every year a 

 dressing of superphosphate. The only difference between 

 them was that while plot 2 O had received no nitrogenous 

 manure, plot 2 A had received ammonium salts every year, 

 supplying forty-three lbs. of nitrogen per acre. The differ- 

 ence in fertility of the two soils is seen to be very great, the 

 soil receiving ammonia giving more than twice as large a 

 produce as the soil without nitrogenous manure. Yet the 

 soil without nitrogenous manure contained 2275 lbs. of 

 nitrogen in the first nine inches of soil, which yet could 

 only produce twenty-one and seven-eighth bushels of barley. 

 The soil with nitrogenous manure contained 2578 lbs. of 

 nitrogen in the first nine inches. Had the produce in this 

 case been in proportion to the total nitrogen in the soil and 

 manure, it should have vielded about twenty-five bushels of 

 barley. The actual produce of forty-five and a quarter 

 bushels obtained is clearly due to the much larger amount 

 of nitric nitrogen present on plot 2 A. The ratio of the 

 total nitrogen on the two plots is indeed 100: 115. The 

 ratio of the nitric nitrogen (assuming that the whole of the 

 ammonia nitrified) is 100 : 381. The ratio of the crops 

 (corn only), 100 : 207. 



Although the determination of nitric nitrogen in a soil 

 is an excellent means of ascertaining the amount of effective 

 nitrogen which it contains, the method is of little use to the 

 agricultural analyst. If the determination is to represent 

 the condition of the soil in the field, the analysis must be 



