Unexhausted Residue of Manures. 107 



allied points. One example of the many brought under 

 notice will suffice to show the kind of information it is 

 sought to obtain under this head. Two plots, 4 A and 4 A A 

 received the same amount and description of mineral manure 

 every year from the commencement. In addition, 4 A 

 received ammonia-salts at the rate of 2001b. per acre every 

 year, but 4 A A 4001b., or double the amount the first six 

 years, and only 2001b., or the same as 4 A, the next ten years. 

 Any increase, therefore, on 4 A A over 4 A, during the ten 

 years in which they both received the same amount of 

 ammonia salts, may presumably be attributed to the extra 

 amount applied to 4 A A during the first six years. 

 Tabulated results show that, during the ten years, there was 

 an excess of produce on 4 A A compared with 4 A, due to the 

 unexhausted residue of the previous nitrogenous manuring, 

 of nearly 28 bushels of grain, and just 28cwt. of straw, or 

 an annual average of 2| bushels of grain and 2|cwt. of straw. 

 Moreover, the excess in the tenth year was almost exactly the 

 same as the average of the ten years, showing that the 

 residue was not even then exhausted. There was, then, in 

 this case, a marked effect upon the succeeding barley crops 

 from the extra ammonia-salts applied in the first six years. 

 Similar experiments, with nitrogen supplied in the form of 

 nitrate of soda, showed that, with the nitrate, as with the 

 ammonia-salts, there was a somewhat lasting effect from the 

 extra amount applied during the earlier years. 



In this section there is discussed at considerable length 

 the amount and destination of the nitrogen of the soil, and 

 Table XXIII., page 108, which explains itself, supplies for 

 comparison the results of experiments, not only on barley, 

 but on wheat and oats. 



It may be explained that the increase in the amount of 

 nitrogen in the produce by the use of it in manure is, in the 

 case of the artificial mixtures of nitrogenous and mineral 

 manure, calculated over the amount determined in the 

 produce by the corresponding mixed mineral manure without 



